1. Review: Phospholipids and Phospholipid Bilayers

In Topic 1.4, Part 2, we talked about phospholipids, the molecule that creates the framework of cell membranes in Eukaryotes and Bacteria. If you want to review the material in that tutorial, you can use the preceding link or watch the video below. The material about phospholipids runs from 02:13 through 04:19.

Here are the key points.

Phospholipid diagram. 1 is the phosphate-bearing head. 2 is the glycerol. 3 is the two fatty acids.

The key molecule in the membrane is a phospholipid.
Phospholipids consist of a nonpolar, hydrophobic tail region consisting of two fatty acids; and a polar, hydrophilic tail region that contains a phosphate group. The head and tail are both attached to a 3-carbon glycerol.
Because the tails are hydrophobic and the heads are hydrophilic, phospholipids, when mixed with water, spontaneously form a bilayer.
The phospholipid bilayer creates the framework of cell membranes.

The fatty acid tails are two lines extending from the circular phosphate-bearing head. — A phospholipid. The fatty acid tails are on the right, in orange. The phosphate-bearing head is on the left, in red.

Phospholipid bilayer in water. — Orientation of phospholipids in a bilayer. The heads seek out water above and below the bilayer. The tails cluster together in a water-free zone.

One of the key ideas of the cell theory is that all cells come from other cells. Today, new cells are formed as a parent cell divides into two smaller daughter cells. But for understanding the origin of life, it’s important to understand that if some non-living process can create phospholipids, then these phospholipids can spontaneously organize themselves into cell-like structures. Add some genetic material, and a system for taking in energy and for cell replication (the origin of both of which requires a lot of explanation), then you have a plausible scenario for the emergence of the first cells.

We’ll learn more about the origin of life later in Unit 7 of this course but, for now, consolidate your understanding by taking the quiz below.

2. Phospholipids and the Phospholipid Bilayer: Checking Understanding

[qwiz style=”width: 528px; border: 2px solid black; ” qrecord_id=”sciencemusicvideosMeister1961-Phospholipid Bilayer FIB (2.0)”]

[h]The phospholipid bilayer: Fill-in-the-Blanks

[i]

[q]The molecules that make up that basic structure of the membrane are called [hangman].

[c]IA==cGhvc3Bob2xpcGlkcw==[Qq]

[q]The two fatty acid chains make up the phospholipid’s “[hangman]”. In terms of polarity, the tail region is [hangman]. In terms of interaction with water, the tail region is [hangman].

[c]dGFpbA==[Qq]

[c]bm9ucG9sYXI=[Qq]

[c]aHlkcm9waG9iaWM=[Qq]

[q]The phosphate-containing part makes up the phospholipid’s “[hangman]”. In terms of polarity, this region is [hangman]. In terms of interaction with water, it’s [hangman].

[c]aGVhZA==[Qq]

[c]cG9sYXI=[Qq]

[c]aHlkcm9waGlsaWM=[Qq]

[q]The arrangement of phospholipids shown below is called a phospholipid [hangman].

[c]YmlsYXllcg==[Qq]

[q]In the diagram of a phospholipid shown below, which shaded area is covering the fatty acids?

[c]MQ==[Qq]

[c]Mg==[Qq]

[c]Mw ==[Qq]

[f]Tm8uIE51bWJlciAxIGlzIGNvdmVyaW5nIHRoZSBpb25pY2FsbHkgY2hhcmdlZMKgJiM4MjIwO2hlYWQmIzgyMjE7IG9mIHRoZSBwaG9zcGhvbGlwaWQgbW9sZWN1bGUuIFRoZSBmYXR0eSBhY2lkcyBhcmUgdGhlIGxvbmcgaHlkcm9jYXJib24gY2hhaW5zLg==[Qq]

[f]Tm8uIE51bWJlciAyIGlzIGNvdmVyaW5nIHRoZSBnbHljZXJvbC7CoFRoZSBmYXR0eSBhY2lkcyBhcmUgdGhlIGxvbmcgaHlkcm9jYXJib24gY2hhaW5zLg==[Qq]

[f]WWVzLiBOdW1iZXIgMyBpcyBjb3ZlcmluZyB0aGUgZmF0dHkgYWNpZHMsIGlkZW50aWZpZWQgYnkgdGhlaXIgbG9uZyBoeWRyb2NhcmJvbiBjaGFpbnMu

Cg==

[Qq]

[q]In the diagram of a phospholipid shown below, which shaded area is covering the molecule’s polar “head.”

[c]MQ ==[Qq]

[c]Mg==[Qq]

[c]Mw==[Qq]

[f]WWVzLiBOdW1iZXIgMSBpcyBjb3ZlcmluZyB0aGUgaW9uaWNhbGx5IGNoYXJnZWTCoCYjODIyMDtoZWFkJiM4MjIxOyBvZiB0aGUgcGhvc3Bob2xpcGlkIG1vbGVjdWxlLsKgVGhlIGNoYXJnZWQgbW9sZWN1bGFyIHBpZWNlcyBpbsKgdGhpcyByZWdpb27CoG1ha2UgaXQgcG9sYXIgKGFzIG9wcG9zZWQgdG8gdGhlIHJlc3Qgb2YgdGhlIG1vbGVjdWxlKS4=[Qq]

[f]Tm8uIE51bWJlciAyIGlzIGNvdmVyaW5nIHRoZSBnbHljZXJvbC7CoFRoZSBwb2xhciBoZWFkIGNhbiBiZSBpZGVudGlmaWVkIGJ5IHRoZSBpb25pYyBjaGFyZ2VzwqBmb3VuZCBpbiB0aGlzIHJlZ2lvbi4=[Qq]

[f]Tm8uIE51bWJlciAzIGlzIGNvdmVyaW5nIHRoZSBmYXR0eSBhY2lkcy7CoFRoZSBwb2xhciBoZWFkIGNhbiBiZSBpZGVudGlmaWVkIGJ5IHRoZSBpb25pYyBjaGFyZ2VzwqBmb3VuZCBpbiB0aGlzIHJlZ2lvbi4=

Cg==

[Qq]

[q]In the diagram of a phospholipid shown below, which shaded area is covering the glycerol?

[c]MQ==[Qq]

[c]Mg ==[Qq]

[c]Mw==[Qq]

[f]Tm8uIE51bWJlciAxIGlzIGNvdmVyaW5nIHRoZSBpb25pY2FsbHkgY2hhcmdlZCAmIzgyMjA7aGVhZCYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZCBtb2xlY3VsZS4gR2x5Y2Vyb2wgaXMgYSAzLWNhcmJvbiBhbGNvaG9sLiBXaGVyZSBkbyB5b3Ugc2VlIGEgMyBjYXJib24gdW5pdD8=[Qq]

[f]WWVzLiBOdW1iZXIgMiBpcyBjb3ZlcmluZyB0aGUgZ2x5Y2Vyb2wu[Qq]

[f]Tm8uIE51bWJlciAzIGlzIGNvdmVyaW5nIHRoZSBmYXR0eSBhY2lkcy4gR2x5Y2Vyb2wgaXMgYSAzLWNhcmJvbiBhbGNvaG9sLiBXaGVyZSBkbyB5b3Ugc2VlIGEgMyBjYXJib24gdW5pdD8=

Cg==

[Qq]

[q labels = “top”]Drag the terms below onto the appropriate places on the phospholipid molecule below.

[l]hydrophobic

[fx] No. Please try again.

[f*] Great!

[l]hydrophilic

[fx] No. Please try again.

[f*] Correct!

[q labels = “top”]Drag the terms below onto the appropriate places on the phospholipid molecule below.

[l]non-polar

[fx] No. Please try again.

[f*] Great!

[l]polar

[fx] No. Please try again.

[f*] Correct!

[q labels = “top”]Drag the terms below onto the appropriate places on the phospholipid molecule.

[l]hydrophobic

[fx] No, that’s not correct. Please try again.

[f*] Great!

[l]hydrophilic

[fx] No, that’s not correct. Please try again.

[f*] Correct!

[q] Which of the following best describes how phospholipids arrange themselves in the cell membrane?

[c]IFRoZSBwaG9zcGhvbGlwaWRzIGZvcm0gYSBiaWxheWVyIHdoZXJlIHRoZSBoeWRyb3BoaWxpYyBoZWFkcyBmYWNlIG91dHdhcmQgdG93YXJkIHRoZSB3YXRlcnkgZXh0 ZXJpb3Igb3IgdGhlIHdhdGVyeSBjeXRvcGxhc20sIGFuZCB0aGUgaHlkcm9waG9iaWMgdGFpbHMgY2x1c3RlciB0b2dldGhlciBpbiBhIHdhdGVyLWZyZWUgem9uZS4=[Qq]

[c]IFRoZSBwaG9zcGhvbGlwaWRzIGZvcm0gYSBiaWxheWVyIHdoZXJlIHRoZSBoeWRyb3Bob2JpYyBoZWFkcyBmb3JtIGh5ZHJvZ2VuIGJvbmRzIHdpdGggb25lIGFub3RoZXIgb24gYW4gaW5uZXIgbGF5ZXIsIHdpdGggdGhlIGh5ZHJvcGhvYmljIHRhaWxzIGZhY2luZyBvdXR3YXJkIHRvd2FyZCB0aGUgY2VsbOKAmXMgd2F0ZXJ5IGV4dGVyaW9yLCBvciB0aGUgd2F0ZXJ5IGN5dG9wbGFzbWljIGludGVyaW9yLg==[Qq]

[c]IEludGVybG9ja2luZyBib25kcyBmb3JtIGJldHdlZW4gdGhlIGh5ZHJvcGhvYmljIGhlYWRzIGFuZCB0aGUgaHlkcm9waGlsaWMgdGFpbHMuIFRoaXMgaXMgcmVwZWF0ZWQgb24gdGhlIGluc2lkZSBhbmQgb3V0c2lkZSBvZiB0aGUgbWVtYnJhbmUsIGVuYWJsaW5nIGl0IHRvIGZvcm0gYSBkb3VibGUgbGF5ZXIu[Qq]

[c]IFRoZSBwaG9zcGhvbGlwaWRzIGZvcm0gYSBiaWxheWVyIHdpdGggdGhlIGh5ZHJvcGhvYmljIGhlYWRzIGZhY2luZyBvdXQgYW5kIGludGVyYWN0aW5nIHdpdGggdGhlIHdhdGVyeSBjZWxsIGV4dGVyaW9yIG9yIHRoZSB3YXRlcnkgY3l0b3BsYXNtLCB3aGlsZSB0aGUgaHlkcm9waGlsaWMgdGFpbHMgZm9ybSBhbiBpbm5lciBsYXllci4=[Qq]

[f]IFRoYXTigJlzIGV4YWN0bHkgcmlnaHQuIEp1c3QgcmVtZW1iZXIg4oCYaGVhZHMgb3V0LOKAmSDigJh0YWlscyBpbizigJkgYW5kIHlvdeKAmWxsIHVuZGVyc3RhbmQgdGhlIHN0cnVjdHVyZSBvZiB0aGUgbWVtYnJhbmXigJlzIHBob3NwaG9saXBpZCBiaWxheWVyLg==

Cg==

[Qq]

[f]IFRoYXTigJlzIG5vdCByaWdodC4gVGhlIGtleSB0aGluZyB0byByZW1lbWJlciBhYm91dCB0aGUgbWVtYnJhbmXigJlzIHN0cnVjdHVyZSBpcyB0aGF0IGl04oCZcyBidWlsdCBhcm91bmQgYSBwaG9zcGhvbGlwaWQgYmlsYXllci4gUGhvc3Bob2xpcGlkIG1vbGVjdWxlcyBhcnJhbmdlIHRoZW1zZWx2ZXMgaW50byBhIGJpbGF5ZXIgaW4gd2hpY2ggdGhlIHBob3NwaG9saXBpZHPigJkgaHlkcm9waG9iaWMgdGFpbHMgYXJlIGZhY2luZyBpbndhcmQsIGNyZWF0aW5nIGEgd2F0ZXItZnJlZSB6b25lLCBhbmQgdGhlIGh5ZHJvcGhpbGljIGhlYWRzIGFyZSBmYWNpbmcgb3V0d2FyZHMu[Qq]

[f]IE5vLCBidXQgeW914oCZcmUgY2xvc2UuIEFzIHlvdSBzZWVtIHRvIHVuZGVyc3RhbmQsIHRoZSBwaG9zcGhvbGlwaWRzIGRvIGZvcm0gYSBiaWxheWVyLiBCdXQgdGhlaXIgYXJyYW5nZW1lbnQgaXMgZGlmZmVyZW50IGZyb20gd2hhdCB5b3UgY2hvc2UuIEluIHRoZSBiaWxheWVyLCB0aGUgcGhvc3Bob2xpcGlkc+KAmSBoeWRyb3Bob2JpYyB0YWlscyBhcmUgZmFjaW5nIGlud2FyZCwgY3JlYXRpbmcgYSB3YXRlci1mcmVlIHpvbmUsIGFuZCB0aGUgaHlkcm9waGlsaWMgaGVhZHMgYXJlIGZhY2luZyBvdXR3YXJkcy4=[Qq]

[q]A more scientific way to say “water-fearing” is [hangman].

[c]aHlkcm9waG9iaWM=[Qq]

[x]

[restart]

[/qwiz]

3. The fluid mosaic model accounts for the structure and function of the membrane

As we saw above, phospholipids make up the basic structure of the membrane. But additional membrane functions come from proteins, cholesterol, and carbohydrates that are embedded within the phospholipid bilayer, as shown below. Cell membrane diagram labeling the phospholipid bilayer, membrane proteins, carbohydrates, and cholesterol.

3a. Membrane Proteins

Proteins are classified by their position in the membrane.

Any protein embedded in the phospholipid bilayer is called an integral protein. In the diagram on the right, proteins 1, 5, and 6 are integral proteins.
If the protein passes all the way through the membrane, like 1 and 6 above, it’s a transmembrane protein.
If the protein hangs on to the membrane, attached to the phospholipid heads (but not extending into the hydrophobic tails), then it’s a peripheral protein. Number 3 above is peripheral.

Note that there’s some overlap in these designations. All transmembrane proteins are also integral proteins (though the reverse is not true).

How do these proteins fit into the membrane? Think of a transmembrane protein as a cylinder. The top and the bottom of the cylinder would be composed of hydrophilic amino acids that interact with the watery cell exterior or the cytoplasm. The region in between would be composed of hydrophobic amino acids which can integrate into the hydrophobic core of the phospholipid bilayer. An alpha helix with hydrophobic amino acid residues is often used to span the membrane. An integral protein that juts out into the cytoplasm (such as the one at 5) might have a nonpolar region that embeds into the hydrophobic membrane middle, with a single hydrophilic region that juts into the cytoplasm. Peripheral proteins (3) attach to phospholipid heads that are either on the cytoplasmic side of the membrane or the cell exterior.

Here are some membrane-protein functions.

Some transmembrane proteins act as channels or ports (6), allowing the cell to take in and let out molecules that can’t diffuse through the phospholipid bilayer portion of the membrane. That includes large molecules, charged particles (ions), and polar substances.
Other transmembrane proteins (not explicitly shown) are pumps or carriers, allowing the cell to perform active transport, moving molecules from low concentration to high concentration.
Peripheral proteins (3) or integral proteins that jut out into the cytoplasm (5) can act as attachment points for the fibers of the cytoskeleton, allowing the cell to change its shape and move (3).
Proteins can act as membrane-embedded enzymes. We’ll see these at work in essential cell processes like photosynthesis and cellular respiration.
Some transmembrane proteins (like the one with the alpha-helix on the right side of the diagram) can act as receptors, receiving chemical messages (including hormones) and relaying these messages into the cytoplasm.

3b. Cholesterol

Cholesterol (7) is a lipid that plays a key role in maintaining membrane integrity and fluidity. When cell membranes become too warm, cholesterol keeps the phospholipid bilayer intact. When cell membranes become too cold, cholesterol acts as an anti-freeze, keeping the membrane fluid.

3c. Membrane Carbohydrates

Membrane carbohydrates (8) play a key role in allowing the immune system to recognize a cell as belonging to the multicellular organism that it’s a part of (as opposed to some invading bacterium). You can think of these carbohydrates as little flags. They’re the key markers, for example, in the A, AB, B, and O blood type system.

Membrane carbohydrates are referred to in a variety of ways. Because they’re usually short-chain carbohydrates, they’re sometimes referred to as membrane oligosaccharides. When these carbohydrates are attached to phospholipids, they’re referred to as glycolipids. When they’re attached to integral or peripheral proteins, they’re referred to as glycoproteins.

Described under the heading 3c. Membrane Carbohydrates. — The spike protein is at “A.” The ACE2 protein is at “B.” Created with Biorender.

If this sounds abstract, consider this. When SARS-CoV-2 (the virus that causes COVID-19) infects a cell, it does so by using its spike glycoprotein (at ”A” on left). The spike protein’s shape has evolved to be complementary to a membrane protein on the surface of our epithelial cells (the cells that cover tissues and organs). That protein is called ACE2. It’s a membrane-embedded enzyme. When the SARS’ spike protein binds with ACE2, it tricks the cell into inviting the virus into the cytoplasm, leading to infection.

3d. The membrane is a fluid mosaic

Diagrams like these can leave you with the misunderstanding that membranes are fixed: kind of like a chocolate bar with almonds, with the almonds locked into place. In fact, the membrane is a dynamic fluid, with all of its parts in constant motion. This model of membrane structure is called the fluid mosaic model.

A tile mosaic.

It’s fluid because all of the parts are moving around.
It’s a mosaic because it’s made of small pieces that are assembled to create a picture or pattern, like this mosaic portrait composed of small pieces of ceramic tiles.

Use the flashcards below to master these membrane components.

4. Cell Membrane Structure Flashcards

[qdeck random = “true” style=”width: 528px; border: 2px solid black; ” qrecord_id=”sciencemusicvideosMeister1961-Cell Membrane Structure FC (2.0)”]

[h] Flashcards: Cell Membrane Structure

[i] If you haven’t used a set of flashcards on Learn-Biology.com before, here’s what you need to know.

Click ‘Check Answer’ to see the answer to each card.
If you know it, click ‘Got it.”
If you don’t know it as well as you’d like, click ‘Need more practice,’ and that card will go to the bottom of the deck so you can practice it again.
‘Shuffle’ lets you shuffle the deck.

[q]In relationship to membranes, define the term selectively permeable.

[a] Membranes allow certain molecules to pass through but not others. In other words, membranes are selectively permeable. (Note that the term semi-permeable means just about the same as selectively permeable, and the two are used interchangeably).

[q]Review: How does the phospholipid bilayer arise?

[a]Phospholipids have a polar, hydrophilic head and a nonpolar, hydrophobic tail. Consequently, when mixed with water they’ll spontaneously organize themselves into a bilayer. In the bilayer, the heads face out as they form hydrogen bonds with the water that’s in the cell exterior and in the cytoplasm. By contrast, tails cluster together, avoiding water, and forming weak, intermolecular bonds with one another.

[q]Describe the fluid-mosaic model of the cell membrane.

[a]The fluid mosaic model of the membrane involves two key features. 1) The membrane is made of a variety of small components (phospholipids, proteins, cholesterol, and carbohydrates). That’s the mosaic part. 2) These components are in constant motion. That’s the fluid part.

[q]Define integral proteins, and identify the integral proteins in the diagram below.

[a]Membrane proteins which are embedded in the phospholipid bilayer are known at are known as integral proteins. In the diagram below, integral proteins are at 1, 5, and 6.

[!] Card 15+++++++++++++++++++++++++++++++++++[/!]

[q]Define transmembrane proteins, and identify the transmembrane proteins in the diagram below.

[a]Transmembrane proteins span the width of the phospholipid bilayer. In the diagram below, transmembrane proteins are at 1 and 6.

[q]Name the molecule at “7,” and describe its structure and function.

[a]In the diagram below, the molecule shown at 7 is cholesterol. It’s a type of lipid called a steroid, composed of fused carbon rings with various functional groups attached. Cholesterol’s function is to stabilize the membrane at high temperatures and to keep it fluid at low temperatures.

[q]Define “peripheral protein,” and identify the peripheral proteins in the diagram below.

[a]Peripheral proteins are attached to the polar heads of the phospholipid bilayer but don’t extend into the hydrophobic portion. The protein at “3” is a peripheral protein.

[q]What are some of the functions of membrane carbohydrates? Identify the membrane carbohydrates in the diagram below.

[a]Membrane carbohydrates play a key role in cell recognition, allowing our immune systems to recognize our cells as belonging to our bodies, as opposed to being some foreign invader. In the diagram below, membrane carbohydrates are shown at 8.

[q]How do membrane proteins fit into the phospholipid bilayer?

[a]Transmembrane proteins (1) have a central region with hydrophobic amino acid residues that integrate into the nonpolar inner portion of the bilayer, with hydrophilic regions extending into the watery cytoplasm and the cell exterior. Other proteins (5) might have a nonpolar region that embeds into the hydrophobic portion of the bilayer, with a hydrophilic region that juts into the cytoplasm or cell exterior. Peripheral proteins (3) attach to phospholipid heads that are either on the cytoplasm side of the membrane or the cell exterior.

[x]

If you want more practice, please press the restart button below. Otherwise, follow the links below.
[restart]
[/qdeck]

5. Quiz: Cell Membrane Structure

This quiz tests you on the diagram you just worked with above, plus this one:

A – phospholipid molecule;
A1 – hydrophilic phosphate head group of phospholipid;
A2 – Fatty acid tail (x 2) of phospholipid;
B – a phospholipid with a carbohydrate chain attached to it)
C– a protein with a carbohydrate chain attached to it);
D – carbohydrate chain of glycoprotein;
E – cholesterol;
F – protein;
G – a protein channel (pore)
H-I: Phospholipid bilayer

[qwiz random = “true;” style = ” border: 3px solid black; ” qrecord_id=”sciencemusicvideosMeister1961-Cell Membrane Structure”]

[h]Cell Membrane Structure Quiz

[i]

[q labels = “top”]

[l]phospholipid bilayer

[fx] No. Please try again.

[f*] Correct!

[l]phospholipid
head

[fx] No. Please try again.

[f*] Excellent!

[l]phospholipid
tail

[fx] No, that’s not correct. Please try again.

[f*] Good!

[l]protein channel

[fx] No, that’s not correct. Please try again.

[f*] Good!

[q labels = “top”]

[l]cholesterol

[fx] No. Please try again.

[f*] Good!

[l]integral protein

[fx] No. Please try again.

[f*] Excellent!

[l]membrane carbohydrate

[fx] No, that’s not correct. Please try again.

[f*] Good!

[l]peripheral protein

[fx] No, that’s not correct. Please try again.

[f*] Excellent!

[l]phospholipid bilayer

[fx] No, that’s not correct. Please try again.

[f*] Great!

[l]phospholipid head

[fx] No, that’s not correct. Please try again.

[f*] Great!

[l]phospholipid tail

[fx] No, that’s not correct. Please try again.

[f*] Good!

[l]protein channel

[fx] No, that’s not correct. Please try again.

[f*] Great!

[l]trans-membrane protein

[fx] No. Please try again.

[f*] Correct!

[q] In the diagram below, which number is pointing to the phospholipid bilayer?

[c]IDEgwqDCoA==[Qq][c]IDIgwqDCoA==[Qq][c]IDMgwqDCoA==[Qq][c]ID Q=

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgMSBpcyBwb2ludGluZyB0byB0aGUgdGFpbCBvZiBhIHBob3NwaG9saXBpZC4gSGVyZSYjODIxNztzIGEgaGludDogdGhlIHRlcm0gJiM4MjIwO2JpbGF5ZXImIzgyMjE7IG1lYW5zICYjODIyMDt0d28gbGF5ZXJzLiYjODIyMTsgV2hhdCBsb29rcyBsaWtlIGl0JiM4MjE3O3MgbWFkZSBvZiB0d28gbGF5ZXJzPw==[Qq]

[f]IE5vLiBOdW1iZXIgMiBpcyBwb2ludGluZyB0byBhIHBob3NwaG9saXBpZCBoZWFkLiBIZXJlJiM4MjE3O3MgYSBoaW50OiB0aGUgdGVybSAmIzgyMjA7YmlsYXllciYjODIyMTsgbWVhbnMgJiM4MjIwO3R3byBsYXllcnMuJiM4MjIxOyBXaGF0IGxvb2tzIGxpa2UgaXQmIzgyMTc7cyBtYWRlIG9mIHR3byBsYXllcnM/[Qq]

[f]IE5vLiBOdW1iZXIgMyBpcyBwb2ludGluZyB0byBhIHByb3RlaW4gY2hhbm5lbC7CoEhlcmUmIzgyMTc7cyBhIGhpbnQ6IHRoZSB0ZXJtICYjODIyMDtiaWxheWVyJiM4MjIxOyBtZWFucyAmIzgyMjA7dHdvIGxheWVycy4mIzgyMjE7IFdoYXQgbG9va3MgbGlrZSBpdCYjODIxNztzIG1hZGUgb2YgdHdvIGxheWVycz8=[Qq]

[f]IEV4Y2VsbGVudC4gTnVtYmVyIDQgaXMgcG9pbnRpbmcgdG8gdGhlIHBob3NwaG9saXBpZCBiaWxheWVyLg==

Cg==

[Qq]

[q] In the diagram below, which number is pointing to the hydrophobic tail of a phospholipid?

[c]IDEgwq AgwqA=[Qq][c]IDIgwqAgwqA=[Qq][c]IDMgwqAgwqA=[Qq][c]IDQ=

Cg==[Qq]

[f]IFllcy4gTnVtYmVyIDEgaXMgcG9pbnRpbmcgdG8gdGhlIHRhaWwgb2YgYSBwaG9zcGhvbGlwaWQu[Qq]

[f]IE5vLsKgTnVtYmVyIDIgaXMgcG9pbnRpbmcgdG8gYSBwaG9zcGhvbGlwaWQgaGVhZC4gV2hhdCBsb29rcyBsaWtlIGEgdGFpbD8=[Qq]

[f]IE5vLsKgTnVtYmVyIDMgaXMgcG9pbnRpbmcgdG8gYSBwcm90ZWluIGNoYW5uZWwuwqBXaGF0IGxvb2tzIGxpa2UgYSB0YWlsPw==[Qq]

[f]IE5vLiBOdW1iZXIgNCBpcyBwb2ludGluZyB0byB0aGUgcGhvc3Bob2xpcGlkIGJpbGF5ZXIuIFdoYXQgbG9va3MgbGlrZSBhIHRhaWw/

Cg==

[Qq]

[q] In the diagram below, which number is pointing to a protein channel?

[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDMgwqAg wqDCoA==[Qq][c]IDQ=

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgMSBpcyBwb2ludGluZyB0byB0aGUgdGFpbCBvZiBhIHBob3NwaG9saXBpZC4gSW4gdGhlIGNvbnRleHQgb2YgbWVtYnJhbmVzLCBhwqBjaGFubmVsIGlzIGEgc3RydWN0dXJlIHRoYXQgbGV0cyBtb2xlY3VsZXMgcGFzcyB0aHJvdWdowqAobGlrZSBhIGJyaWRnZSBvciBhIHR1bm5lbCkuIFdoYXQgbG9va3MgbGlrZSBhIGNoYW5uZWw/[Qq]

[f]IE5vLiBOdW1iZXIgMiBpcyBwb2ludGluZyB0byBhIHBob3NwaG9saXBpZCBoZWFkLsKgSW4gdGhlIGNvbnRleHQgb2YgbWVtYnJhbmVzLCBhwqBjaGFubmVsIGlzIGEgc3RydWN0dXJlIHRoYXQgbGV0cyBtb2xlY3VsZXMgcGFzcyB0aHJvdWdowqAobGlrZSBhIGJyaWRnZSBvciBhIHR1bm5lbCkuIFdoYXQgbG9va3MgbGlrZSBhIGNoYW5uZWw/[Qq]

[f]IFllcy4gTnVtYmVyIDMgaXMgcG9pbnRpbmcgdG8gYSBwcm90ZWluIGNoYW5uZWwu[Qq]

[f]IE5vLiBOdW1iZXIgNCBpcyBwb2ludGluZyB0byB0aGUgcGhvc3Bob2xpcGlkIGJpbGF5ZXIuwqBJbiB0aGUgY29udGV4dCBvZiBtZW1icmFuZXMsIGHCoGNoYW5uZWwgaXMgYSBzdHJ1Y3R1cmUgdGhhdCBsZXRzIG1vbGVjdWxlcyBwYXNzIHRocm91Z2jCoChsaWtlIGEgYnJpZGdlIG9yIGEgdHVubmVsKS4gV2hhdCBsb29rcyBsaWtlIGEgY2hhbm5lbD8=

Cg==

[Qq]

[q] In the diagram below, which number is pointing to the phospholipid bilayer?[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAg wqDCoA==[Qq][c]IDMgwqAgwqDCoA==[Qq][c]IDQgwqAgwqDCoA==[Qq][c]NcKgIMKgIA==[Qq][c]NsKgIMKgIMKg[Qq][c]N8KgIMKgIMKg[Qq][c]OCDCoCDCoA==[Qq][c]OQ==

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgMSBpcyBwb2ludGluZyB0byB0d28gdHJhbnNtZW1icmFuZSBwcm90ZWlucy4gVGhlIHBob3NwaG9saXBpZCBiaWxheWVyIGlzIHRoZSBtYWluIHN0cnVjdHVyZSBvZiB0aGUgbWVtYnJhbmUsIGFuZCBpdCYjODIxNztzIG1hZGUgb2YgdHdvIGxheWVycyBvZiBwaG9zcGhvbGlwaWRzLCB0aGUgbG93ZXIgb25lIHdpdGggaXRzIGhlYWRzIGRvd24sIGFuZCB0aGUgdG9wIG9uZSB3aXRoIGl0cyBoZWFkcyB1cC4gV2hhdCBudW1iZXIgcG9pbnRzIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=[Qq]

[f]IFllcy4gTnVtYmVyIDIgaXMgcG9pbnRpbmcgdG8gdGhlIHBob3NwaG9saXBpZCBiaWxheWVyLg==[Qq]

[f]IE5vLiBOdW1iZXIgMyBpcyBwb2ludGluZyB0byBhIHBlcmlwaGVyYWwgcHJvdGVpbi4gVGhlIHBob3NwaG9saXBpZCBiaWxheWVyIGlzIHRoZSBtYWluIHN0cnVjdHVyZSBvZiB0aGUgbWVtYnJhbmUsIGFuZCBpdCYjODIxNztzIG1hZGUgb2YgdHdvIGxheWVycyBvZiBwaG9zcGhvbGlwaWRzLCB0aGUgbG93ZXIgb25lIHdpdGggaXRzIGhlYWRzIGRvd24sIGFuZCB0aGUgdG9wIG9uZSB3aXRoIGl0cyBoZWFkcyB1cC4gV2hhdCBudW1iZXIgcG9pbnRzIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=[Qq]

[f]IE5vLCBidXQgeW91JiM4MjE3O3JlIGNsb3NlLiBOdW1iZXIgNCBpcyBwb2ludGluZyB0byB0aGUgdGFpbCBvZiBhIHNpbmdsZSBwaG9zcGhvbGlwaWQuwqBUaGUgcGhvc3Bob2xpcGlkIA==YmlsYXllcg==IGlzIHRoZSBtYWluIHN0cnVjdHVyZSBvZiB0aGUgbWVtYnJhbmUsIGFuZCBpdCYjODIxNztzIG1hZGUgb2YgdHdvIGxheWVycyBvZiBwaG9zcGhvbGlwaWRzLCB0aGUgbG93ZXIgb25lIHdpdGggaXRzIGhlYWRzIGRvd24sIGFuZCB0aGUgdG9wIG9uZSB3aXRoIGl0cyBoZWFkcyB1cC4gV2hhdCBudW1iZXIgcG9pbnRzIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=[Qq]

[f]IE5vLiBOdW1iZXIgNSBpcyBwb2ludGluZyB0byBhbiBpbnRlZ3JhbCBwcm90ZWluLiBUaGUgcGhvc3Bob2xpcGlkIGJpbGF5ZXIgaXMgdGhlIG1haW4gc3RydWN0dXJlIG9mIHRoZSBtZW1icmFuZSwgYW5kIGl0JiM4MjE3O3MgbWFkZSBvZiB0d28gbGF5ZXJzIG9mIHBob3NwaG9saXBpZHMsIHRoZSBsb3dlciBvbmUgd2l0aCBpdHMgaGVhZHMgZG93biwgYW5kIHRoZSB0b3Agb25lIHdpdGggaXRzIGhlYWRzIHVwLiBXaGF0IG51bWJlciBwb2ludHMgdG8gc29tZXRoaW5nIHRoYXQgZml0cyB0aGF0IGRlc2NyaXB0aW9uPw==[Qq]

[f]IE5vISBOdW1iZXIgNiBpcyBwb2ludGluZyB0byBhIHByb3RlaW4gY2hhbm5lbC4gVGhlIHBob3NwaG9saXBpZCBiaWxheWVyIGlzIHRoZSBtYWluIHN0cnVjdHVyZSBvZiB0aGUgbWVtYnJhbmUsIGFuZCBpdCYjODIxNztzIG1hZGUgb2YgdHdvIGxheWVycyBvZiBwaG9zcGhvbGlwaWRzLCB0aGUgbG93ZXIgb25lIHdpdGggaXRzIGhlYWRzIGRvd24sIGFuZCB0aGUgdG9wIG9uZSB3aXRoIGl0cyBoZWFkcyB1cC4gV2hhdCBudW1iZXIgcG9pbnRzIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=[Qq]

[f]IE5vLiBOdW1iZXIgNyBpcyBwb2ludGluZyB0byBjaG9sZXN0ZXJvbC4gVGhlIHBob3NwaG9saXBpZCBiaWxheWVyIGlzIHRoZSBtYWluIHN0cnVjdHVyZSBvZiB0aGUgbWVtYnJhbmUsIGFuZCBpdCYjODIxNztzIG1hZGUgb2YgdHdvIGxheWVycyBvZiBwaG9zcGhvbGlwaWRzLCB0aGUgbG93ZXIgb25lIHdpdGggaXRzIGhlYWRzIGRvd24sIGFuZCB0aGUgdG9wIG9uZSB3aXRoIGl0cyBoZWFkcyB1cC4gV2hhdCBudW1iZXIgcG9pbnRzIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=[Qq]

[f]IE5vLiBOdW1iZXIgOCBpcyBwb2ludGluZyB0byBhIG1lbWJyYW5lIGNhcmJvaHlkcmF0ZS4gVGhlIHBob3NwaG9saXBpZCBiaWxheWVyIGlzIHRoZSBtYWluIHN0cnVjdHVyZSBvZiB0aGUgbWVtYnJhbmUsIGFuZCBpdCYjODIxNztzIG1hZGUgb2YgdHdvIGxheWVycyBvZiBwaG9zcGhvbGlwaWRzLCB0aGUgbG93ZXIgb25lIHdpdGggaXRzIGhlYWRzIGRvd24sIGFuZCB0aGUgdG9wIG9uZSB3aXRoIGl0cyBoZWFkcyB1cC4gV2hhdCBudW1iZXIgcG9pbnRzIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=[Qq]

[f]IE5vLCBidXQgeW91JiM4MjE3O3JlIGNsb3NlLiBOdW1iZXIgOcKgaXMgcG9pbnRpbmcgdG8gdGhlIGhlYWQgb2YgYSBwaG9zcGhvbGlwaWQuwqBUaGUgcGhvc3Bob2xpcGlkIA==YmlsYXllcg==IGlzIHRoZSBtYWluIHN0cnVjdHVyZSBvZiB0aGUgbWVtYnJhbmUsIGFuZCBpdCYjODIxNztzIG1hZGUgb2YgdHdvIGxheWVycyBvZiBwaG9zcGhvbGlwaWRzLCB0aGUgbG93ZXIgb25lIHdpdGggaXRzIGhlYWRzIGRvd24sIGFuZCB0aGUgdG9wIG9uZSB3aXRoIGl0cyBoZWFkcyB1cC4gV2hhdCBudW1iZXIgcG9pbnRzIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=

Cg==

[Qq]

[q] In the diagram below, which number is pointing to a molecule of cholesterol?
[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDMgwqAgwqDCoA==[Qq][c]IDQgwqAgwqDCoA==[Qq][c]NcKgIMKgIA==[Qq][c]NsKgIMKgIMKg[Qq][c]N8KgIM KgIMKg[Qq][c]OCDCoCDCoA==[Qq][c]OQ==

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgMSBpcyBwb2ludGluZyB0byB0d28gdHJhbnNtZW1icmFuZSBwcm90ZWlucy4gQ2hvbGVzdGVyb2wgaXMgYSBsaXBpZCB0aGF0JiM4MjE3O3MgZW1iZWRkZWQgaW4gdGhlIG1lbWJyYW5lLCBidXQgaXQmIzgyMTc7cyBub3QgYSBwaG9zcGhvbGlwaWQuIEVsaW1pbmF0ZSB0aGUgcHJvdGVpbnMgKGFsbCBzaGFkZWQgaW4gYmx1ZSksIGFuZCBzZWUgaWYgeW91IGNhbiBmaWd1cmUgb3V0IHRoZSBhbnN3ZXIu[Qq]

[f]IE5vLiBOdW1iZXIgMiBpcyBwb2ludGluZyB0byB0aGUgcGhvc3Bob2xpcGlkIGJpbGF5ZXIuwqBDaG9sZXN0ZXJvbCBpcyBhIGxpcGlkIHRoYXQmIzgyMTc7cyBlbWJlZGRlZCBpbiB0aGUgbWVtYnJhbmUsIGJ1dCBpdCYjODIxNztzIG5vdCBhIHBob3NwaG9saXBpZC4gRWxpbWluYXRlIHRoZSBwcm90ZWlucyAoYWxsIHNoYWRlZCBpbiBibHVlKSwgYW5kIHNlZSBpZiB5b3UgY2FuIGZpZ3VyZSBvdXQgdGhlIGFuc3dlci4=[Qq]

[f]IE5vLiBOdW1iZXIgMyBpcyBwb2ludGluZyB0byBhIHBlcmlwaGVyYWwgcHJvdGVpbi4gQ2hvbGVzdGVyb2wgaXMgYSBsaXBpZCB0aGF0JiM4MjE3O3MgZW1iZWRkZWQgaW4gdGhlIG1lbWJyYW5lLCBidXQgaXQmIzgyMTc7cyBub3QgYSBwaG9zcGhvbGlwaWQuIEVsaW1pbmF0ZSB0aGUgcHJvdGVpbnMgKGFsbCBzaGFkZWQgaW4gYmx1ZSksIGFuZCBzZWUgaWYgeW91IGNhbiBmaWd1cmUgb3V0IHRoZSBhbnN3ZXIu[Qq]

[f]IE5vLiBOdW1iZXIgNCBpcyBwb2ludGluZyB0byB0aGUgdGFpbCBvZiBhIHBob3NwaG9saXBpZC7CoENob2xlc3Rlcm9sIGlzIGEgbGlwaWQgdGhhdCYjODIxNztzIGVtYmVkZGVkIGluIHRoZSBtZW1icmFuZSwgYnV0IGl0JiM4MjE3O3Mgbm90IGEgcGhvc3Bob2xpcGlkLiBFbGltaW5hdGUgdGhlIHByb3RlaW5zIChhbGwgc2hhZGVkIGluIGJsdWUpLCBhbmQgc2VlIGlmIHlvdSBjYW4gZmlndXJlIG91dCB0aGUgYW5zd2VyLg==[Qq]

[f]IE5vLiBOdW1iZXIgNcKgaXMgcG9pbnRpbmcgdG/CoGFuIGludGVncmFsIHByb3RlaW4uwqBDaG9sZXN0ZXJvbCBpcyBhIGxpcGlkIHRoYXQmIzgyMTc7cyBlbWJlZGRlZCBpbiB0aGUgbWVtYnJhbmUsIGJ1dCBpdCYjODIxNztzIG5vdCBhIHBob3NwaG9saXBpZC4gRWxpbWluYXRlIHRoZSBwcm90ZWlucyAoYWxsIHNoYWRlZCBpbiBibHVlKSwgYW5kIHNlZSBpZiB5b3UgY2FuIGZpZ3VyZSBvdXQgdGhlIGFuc3dlci4=[Qq]

[f]IE5vLiBOdW1iZXIgNiBpcyBwb2ludGluZyB0byBhIHByb3RlaW4gY2hhbm5lbC4gQ2hvbGVzdGVyb2wgaXMgYSBsaXBpZCB0aGF0JiM4MjE3O3MgZW1iZWRkZWQgaW4gdGhlIG1lbWJyYW5lLCBidXQgaXQmIzgyMTc7cyBub3QgYSBwaG9zcGhvbGlwaWQuIEVsaW1pbmF0ZSB0aGUgcHJvdGVpbnMgKGFsbCBzaGFkZWQgaW4gYmx1ZSksIGFuZCBzZWUgaWYgeW91IGNhbiBmaWd1cmUgb3V0IHRoZSBhbnN3ZXIu[Qq]

[f]IFllcy4gTnVtYmVyIDfCoGlzIHBvaW50aW5nIHRvIGNob2xlc3Rlcm9sLg==[Qq]

[f]IE5vLiBOdW1iZXIgOMKgaXMgcG9pbnRpbmcgdG8gYSBtZW1icmFuZSBjYXJib2h5ZHJhdGUuwqBDaG9sZXN0ZXJvbCBpcyBhIGxpcGlkIHRoYXQmIzgyMTc7cyBlbWJlZGRlZCBpbiB0aGUgbWVtYnJhbmUsIGJ1dCBpdCYjODIxNztzIG5vdCBhIHBob3NwaG9saXBpZC4gRWxpbWluYXRlIHRoZSBwcm90ZWlucyAoYWxsIHNoYWRlZCBpbiBibHVlKSwgYW5kIHNlZSBpZiB5b3UgY2FuIGZpZ3VyZSBvdXQgdGhlIGFuc3dlci4=[Qq]

[f]IE5vLiBOdW1iZXIgOcKgaXMgcG9pbnRpbmcgdG8gdGhlIGhlYWQgb2YgYSBwaG9zcGhvbGlwaWQuwqBDaG9sZXN0ZXJvbCBpcyBhIGxpcGlkIHRoYXQmIzgyMTc7cyBlbWJlZGRlZCBpbiB0aGUgbWVtYnJhbmUsIGJ1dCBpdCYjODIxNztzIG5vdCBhIHBob3NwaG9saXBpZC4gRWxpbWluYXRlIHRoZSBwcm90ZWlucyAoYWxsIHNoYWRlZCBpbiBibHVlKSwgYW5kIHNlZSBpZiB5b3UgY2FuIGZpZ3VyZSBvdXQgdGhlIGFuc3dlci4=

Cg==

[Qq]

[q] In the diagram below, which number is pointing to a phospholipid head?
[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDMgwqAgwqDCoA==[Qq][c]IDQgwqAgwqDCoA==[Qq][c]NcKgIMKgIA==[Qq][c]NsKgIMKgIMKg[Qq][c]N8KgIMKgIMKg[Qq][c]OCDCoCDCoA==[Qq][c]OQ ==

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgMSBpcyBwb2ludGluZyB0byB0d28gdHJhbnNtZW1icmFuZSBwcm90ZWlucy4gVGhlIHBob3NwaG9saXBpZHMgYXJlIHRoZSBtYWluIHN0cnVjdHVyYWwgbW9sZWN1bGVzIG1ha2luZyB1cCB0aGUgbWVtYnJhbmUuIFRoZSBwb2xhciAmIzgyMjA7aGVhZHMmIzgyMjE7IG9mIHRoZSBwaG9zcGhvbGlwaWRzIGZhY2UgdG93YXJkcyB0aGUgb3V0c2lkZSBvZiB0aGUgbWVtYnJhbmUgKHdoaWNoIG1lYW5zIHVwLCB0b3dhcmQgdGhlIGV4dHJhY2VsbHVsYXIgZmx1aWQsIGFuZCBkb3duLCB0b3dhcmRzIHRoZSBjeXRvcGxhc20pLiBXaXRoIHRoYXQgaW4gbWluZCwgc2VlIGlmIHlvdSBjYW4gZmluZCBhIHBob3NwaG9saXBpZCBoZWFkLg==[Qq]

[f]IE5vLCBidXQgeW91JiM4MjE3O3JlIGNsb3NlLiBOdW1iZXIgMiBpcyBwb2ludGluZyB0byB0aGUgZW50aXJlIHBob3NwaG9saXBpZCBiaWxheWVyLiBUaGUgcG9sYXIgJiM4MjIwO2hlYWRzJiM4MjIxOyBvZiB0aGUgcGhvc3Bob2xpcGlkcyBmYWNlIHRvd2FyZHMgdGhlIG91dHNpZGUgb2YgdGhlIG1lbWJyYW5lICh3aGljaCBtZWFucyB1cCwgdG93YXJkIHRoZSBleHRyYWNlbGx1bGFyIGZsdWlkLCBhbmQgZG93biwgdG93YXJkcyB0aGUgY3l0b3BsYXNtKS4gV2l0aCB0aGF0IGluIG1pbmQsIHNlZSBpZiB5b3UgY2FuIGZpbmQgYSBwaG9zcGhvbGlwaWQgaGVhZC4=[Qq]

[f]IE5vLiBOdW1iZXIgMyBpcyBwb2ludGluZyB0byBhwqBwZXJpcGhlcmFsIHByb3RlaW4uwqBUaGUgcGhvc3Bob2xpcGlkcyBhcmUgdGhlIG1haW4gc3RydWN0dXJhbCBtb2xlY3VsZXMgbWFraW5nIHVwIHRoZSBtZW1icmFuZS4gVGhlIHBvbGFyICYjODIyMDtoZWFkcyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBvdXRzaWRlIG9mIHRoZSBtZW1icmFuZSAod2hpY2ggbWVhbnMgdXAsIHRvd2FyZCB0aGUgZXh0cmFjZWxsdWxhciBmbHVpZCwgYW5kIGRvd24sIHRvd2FyZHMgdGhlIGN5dG9wbGFzbSkuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]

[f]IE5vLCBidXQgeW91JiM4MjE3O3JlIGNsb3NlLiBOdW1iZXIgNCBpcyBwb2ludGluZyB0byB0aGUgdGFpbCBvZiBhIHBob3NwaG9saXBpZC4gVGhlIHBvbGFyICYjODIyMDtoZWFkcyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBvdXRzaWRlIG9mIHRoZSBtZW1icmFuZSAod2hpY2ggbWVhbnMgdXAsIHRvd2FyZCB0aGUgZXh0cmFjZWxsdWxhciBmbHVpZCwgYW5kIGRvd24sIHRvd2FyZHMgdGhlIGN5dG9wbGFzbSkuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]
[f]IE5vLiBOdW1iZXIgNcKgaXMgcG9pbnRpbmcgdG/CoGFuIGludGVncmFsIHByb3RlaW4uwqBUaGUgcGhvc3Bob2xpcGlkcyBhcmUgdGhlIG1haW4gc3RydWN0dXJhbCBtb2xlY3VsZXMgbWFraW5nIHVwIHRoZSBtZW1icmFuZS4gVGhlIHBvbGFyICYjODIyMDtoZWFkcyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBvdXRzaWRlIG9mIHRoZSBtZW1icmFuZSAod2hpY2ggbWVhbnMgdXAsIHRvd2FyZCB0aGUgZXh0cmFjZWxsdWxhciBmbHVpZCwgYW5kIGRvd24sIHRvd2FyZHMgdGhlIGN5dG9wbGFzbSkuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]
[f]IE5vLiBOdW1iZXIgNiBpcyBwb2ludGluZyB0byBhIHByb3RlaW4gY2hhbm5lbC4gVGhlIHBob3NwaG9saXBpZHMgYXJlIHRoZSBtYWluIHN0cnVjdHVyYWwgbW9sZWN1bGVzIG1ha2luZyB1cCB0aGUgbWVtYnJhbmUuIFRoZSBwb2xhciAmIzgyMjA7aGVhZHMmIzgyMjE7IG9mIHRoZSBwaG9zcGhvbGlwaWRzIGZhY2UgdG93YXJkcyB0aGUgb3V0c2lkZSBvZiB0aGUgbWVtYnJhbmUgKHdoaWNoIG1lYW5zIHVwLCB0b3dhcmQgdGhlIGV4dHJhY2VsbHVsYXIgZmx1aWQsIGFuZCBkb3duLCB0b3dhcmRzIHRoZSBjeXRvcGxhc20pLiBXaXRoIHRoYXQgaW4gbWluZCwgc2VlIGlmIHlvdSBjYW4gZmluZCBhIHBob3NwaG9saXBpZCBoZWFkLg==

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgN8KgaXMgcG9pbnRpbmcgdG8gY2hvbGVzdGVyb2wuwqBUaGUgcGhvc3Bob2xpcGlkcyBhcmUgdGhlIG1haW4gc3RydWN0dXJhbCBtb2xlY3VsZXMgbWFraW5nIHVwIHRoZSBtZW1icmFuZS4gVGhlIHBvbGFyICYjODIyMDtoZWFkcyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBvdXRzaWRlIG9mIHRoZSBtZW1icmFuZSAod2hpY2ggbWVhbnMgdXAsIHRvd2FyZCB0aGUgZXh0cmFjZWxsdWxhciBmbHVpZCwgYW5kIGRvd24sIHRvd2FyZHMgdGhlIGN5dG9wbGFzbSkuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]

[f]IE5vLiBOdW1iZXIgOMKgaXMgcG9pbnRpbmcgdG8gYSBtZW1icmFuZSBjYXJib2h5ZHJhdGUuwqBUaGUgcGhvc3Bob2xpcGlkcyBhcmUgdGhlIG1haW4gc3RydWN0dXJhbCBtb2xlY3VsZXMgbWFraW5nIHVwIHRoZSBtZW1icmFuZS4gVGhlIHBvbGFyICYjODIyMDtoZWFkcyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBvdXRzaWRlIG9mIHRoZSBtZW1icmFuZSAod2hpY2ggbWVhbnMgdXAsIHRvd2FyZCB0aGUgZXh0cmFjZWxsdWxhciBmbHVpZCwgYW5kIGRvd24sIHRvd2FyZHMgdGhlIGN5dG9wbGFzbSkuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]

[f]IFllcy4gTnVtYmVyIDnCoGlzIHBvaW50aW5nIHRvIHRoZSBoZWFkIG9mIGEgcGhvc3Bob2xpcGlkLg==

Cg==

[Qq]

[q] In the diagram below, which number is pointing to a peripheral protein?
[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDMgwqAg wqDCoA==[Qq][c]IDQgwqAgwqDCoA==[Qq][c]NcKgIMKgIA==[Qq][c]NsKgIMKgIMKg[Qq][c]N8KgIMKgIMKg[Qq][c]OCDCoCDCoA==[Qq][c]OQ==

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgMSBwb2ludHMgdG8gdHdvIHRyYW5zbWVtYnJhbmUgcHJvdGVpbnMuIFBlcmlwaGVyYWwgcHJvdGVpbnMgaGFuZyBvbnRvIHRoZSBwaG9zcGhvbGlwaWQgaGVhZHMgb2YgdGhlIGJpbGF5ZXIsIHdpdGhvdXQgcGVuZXRyYXRpbmcgaW50byB0aGUgbWlkZGxlLCBoeWRyb3Bob2JpYyBwb3J0aW9uLiBHaXZlbiB0aGF0IGluIHRoaXMgZGlhZ3JhbSB0aGUgcHJvdGVpbnMgYXJlIHNoYWRlZCBibHVlLCB3aGljaCBudW1iZXIgaXMgcG9pbnRpbmcgdG8gc29tZXRoaW5nIHRoYXQgZml0cyB0aGF0IGRlc2NyaXB0aW9uPw==[Qq]

[f]IE5vLiBOdW1iZXIgMiBpcyBwb2ludGluZyB0byB0aGUgZW50aXJlIHBob3NwaG9saXBpZCBiaWxheWVyLsKgUGVyaXBoZXJhbCBwcm90ZWlucyBoYW5nIG9udG8gdGhlIHBob3NwaG9saXBpZCBoZWFkcyBvZiB0aGUgYmlsYXllciwgd2l0aG91dCBwZW5ldHJhdGluZyBpbnRvIHRoZSBtaWRkbGUsIGh5ZHJvcGhvYmljIHBvcnRpb24uIEdpdmVuIHRoYXQgaW4gdGhpcyBkaWFncmFtIHRoZSBwcm90ZWlucyBhcmUgc2hhZGVkIGJsdWUsIHdoaWNoIG51bWJlciBpcyBwb2ludGluZyB0byBzb21ldGhpbmcgdGhhdCBmaXRzIHRoYXQgZGVzY3JpcHRpb24/[Qq]

[f]IFllcy4gTnVtYmVyIDMgaXMgcG9pbnRpbmcgdG8gYcKgcGVyaXBoZXJhbCBwcm90ZWluLg==[Qq]

[f]IE5vLiBOdW1iZXIgNCBpcyBwb2ludGluZyB0byB0aGUgdGFpbCBvZiBhIHBob3NwaG9saXBpZC7CoFBlcmlwaGVyYWwgcHJvdGVpbnMgaGFuZyBvbnRvIHRoZSBwaG9zcGhvbGlwaWQgaGVhZHMgb2YgdGhlIGJpbGF5ZXIsIHdpdGhvdXQgcGVuZXRyYXRpbmcgaW50byB0aGUgbWlkZGxlLCBoeWRyb3Bob2JpYyBwb3J0aW9uLiBHaXZlbiB0aGF0IGluIHRoaXMgZGlhZ3JhbSB0aGUgcHJvdGVpbnMgYXJlIHNoYWRlZCBibHVlLCB3aGljaCBudW1iZXIgaXMgcG9pbnRpbmcgdG8gc29tZXRoaW5nIHRoYXQgZml0cyB0aGXCoGRlc2NyaXB0aW9uIG9mIGEgcGVyaXBoZXJhbCBwcm90ZWluPw==[Qq]

[f]IE5vLiBOdW1iZXIgNcKgaXMgcG9pbnRpbmcgdG/CoGFuIGludGVncmFsIHByb3RlaW4uwqBQZXJpcGhlcmFsIHByb3RlaW5zIGhhbmcgb250byB0aGUgcGhvc3Bob2xpcGlkIGhlYWRzIG9mIHRoZSBiaWxheWVyLCB3aXRob3V0IHBlbmV0cmF0aW5nIGludG8gdGhlIG1pZGRsZSwgaHlkcm9waG9iaWMgcG9ydGlvbi4gR2l2ZW4gdGhhdCBpbiB0aGlzIGRpYWdyYW0gdGhlIHByb3RlaW5zIGFyZSBzaGFkZWQgYmx1ZSwgd2hpY2ggbnVtYmVyIGlzIHBvaW50aW5nIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhlwqBkZXNjcmlwdGlvbiBvZiBhIHBlcmlwaGVyYWwgcHJvdGVpbj8=[Qq]

[f]IE5vLiBOdW1iZXIgNiBpcyBwb2ludGluZyB0byBhIHByb3RlaW4gY2hhbm5lbC4gUGVyaXBoZXJhbCBwcm90ZWlucyBoYW5nIG9udG8gdGhlIHBob3NwaG9saXBpZCBoZWFkcyBvZiB0aGUgYmlsYXllciwgd2l0aG91dCBwZW5ldHJhdGluZyBpbnRvIHRoZSBtaWRkbGUsIGh5ZHJvcGhvYmljIHBvcnRpb24uIEdpdmVuIHRoYXQgaW4gdGhpcyBkaWFncmFtIHRoZSBwcm90ZWlucyBhcmUgc2hhZGVkIGJsdWUsIHdoaWNoIG51bWJlciBpcyBwb2ludGluZyB0byBzb21ldGhpbmcgdGhhdCBmaXRzIHRoZSBkZXNjcmlwdGlvbiBvZiBhIHBlcmlwaGVyYWwgcHJvdGVpbj8=[Qq]

[f]IE5vLiBOdW1iZXIgN8KgaXMgcG9pbnRpbmcgdG8gY2hvbGVzdGVyb2wuwqBQZXJpcGhlcmFsIHByb3RlaW5zIGhhbmcgb250byB0aGUgcGhvc3Bob2xpcGlkIGhlYWRzIG9mIHRoZSBiaWxheWVyLCB3aXRob3V0IHBlbmV0cmF0aW5nIGludG8gdGhlIG1pZGRsZSwgaHlkcm9waG9iaWMgcG9ydGlvbi4gR2l2ZW4gdGhhdCBpbiB0aGlzIGRpYWdyYW0gdGhlIHByb3RlaW5zIGFyZSBzaGFkZWQgYmx1ZSwgd2hpY2ggbnVtYmVyIGlzIHBvaW50aW5nIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhlwqBkZXNjcmlwdGlvbiBvZiBhIHBlcmlwaGVyYWwgcHJvdGVpbj8=[Qq]

[f]IE5vLiBOdW1iZXIgOMKgaXMgcG9pbnRpbmcgdG8gYSBtZW1icmFuZSBjYXJib2h5ZHJhdGUuwqBQZXJpcGhlcmFsIHByb3RlaW5zIGhhbmcgb250byB0aGUgcGhvc3Bob2xpcGlkIGhlYWRzIG9mIHRoZSBiaWxheWVyLCB3aXRob3V0IHBlbmV0cmF0aW5nIGludG8gdGhlIG1pZGRsZSwgaHlkcm9waG9iaWMgcG9ydGlvbi4gR2l2ZW4gdGhhdCBpbiB0aGlzIGRpYWdyYW0gdGhlIHByb3RlaW5zIGFyZSBzaGFkZWQgYmx1ZSwgd2hpY2ggbnVtYmVyIGlzIHBvaW50aW5nIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhlwqBkZXNjcmlwdGlvbiBvZiBhIHBlcmlwaGVyYWwgcHJvdGVpbj8=[Qq]

[f]IE5vLiBOdW1iZXIgOcKgaXMgcG9pbnRpbmcgdG8gdGhlIGhlYWQgb2YgYSBwaG9zcGhvbGlwaWQuwqBQZXJpcGhlcmFsIHByb3RlaW5zIGhhbmcgb250byB0aGUgcGhvc3Bob2xpcGlkIGhlYWRzIG9mIHRoZSBiaWxheWVyLCB3aXRob3V0IHBlbmV0cmF0aW5nIGludG8gdGhlIG1pZGRsZSwgaHlkcm9waG9iaWMgcG9ydGlvbi4gR2l2ZW4gdGhhdCBpbiB0aGlzIGRpYWdyYW0gdGhlIHByb3RlaW5zIGFyZSBzaGFkZWQgYmx1ZSwgd2hpY2ggbnVtYmVyIGlzIHBvaW50aW5nIHRvIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhlwqBkZXNjcmlwdGlvbiBvZiBhIHBlcmlwaGVyYWwgcHJvdGVpbj8=

Cg==

[Qq]

[q] In the diagram below, which number is pointing to a protein channel?
[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDMgwqAgwqDCoA==[Qq][c]IDQgwqAgwqDCoA==[Qq][c]NcKgIMKgIA==[Qq][c]NsKgIM KgIMKg[Qq][c]N8KgIMKgIMKg[Qq][c]OCDCoCDCoA==[Qq][c]OQ==

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgMSBpcyBwb2ludGluZyB0byB0d28gdHJhbnNtZW1icmFuZSBwcm90ZWlucy4gQSBjaGFubmVsIGlzIGEgc3RydWN0dXJlIHRoYXQgbGV0cyBtb2xlY3VsZXMgcGFzcyB0aHJvdWdoIChsaWtlIGEgYnJpZGdlIG9yIGEgdHVubmVsKS4gV2hhdCBsb29rcyBsaWtlIGEgY2hhbm5lbD8=[Qq]

[f]IE5vLiBOdW1iZXIgMiBpcyBwb2ludGluZyB0byB0aGUgcGhvc3Bob2xpcGlkIGJpbGF5ZXIuwqBJbiB0aGUgY29udGV4dCBvZiBtZW1icmFuZXMsIGHCoGNoYW5uZWwgaXMgYSBzdHJ1Y3R1cmUgdGhhdCBsZXRzIG1vbGVjdWxlcyBwYXNzIHRocm91Z2jCoChsaWtlIGEgYnJpZGdlIG9yIGEgdHVubmVsKS4gV2hhdCBsb29rcyBsaWtlIGEgY2hhbm5lbD8=[Qq]

[f]IE5vLiBOdW1iZXIgMyBpcyBwb2ludGluZyB0byBhIHBlcmlwaGVyYWwgcHJvdGVpbi4gSW4gdGhlIGNvbnRleHQgb2YgbWVtYnJhbmVzLCBhIGNoYW5uZWwgaXMgYSBzdHJ1Y3R1cmUgdGhhdCBsZXRzIG1vbGVjdWxlcyBwYXNzIHRocm91Z2ggKGxpa2UgYSBicmlkZ2Ugb3IgYSB0dW5uZWwpLiBXaGF0IGxvb2tzIGxpa2UgYSBjaGFubmVsPw==[Qq]

[f]IE5vLiBOdW1iZXIgNCBpcyBwb2ludGluZyB0byB0aGUgdGFpbCBvZiBhIHBob3NwaG9saXBpZC7CoEluIHRoZSBjb250ZXh0IG9mIG1lbWJyYW5lcywgYcKgY2hhbm5lbCBpcyBhIHN0cnVjdHVyZSB0aGF0IGxldHMgbW9sZWN1bGVzIHBhc3MgdGhyb3VnaMKgKGxpa2UgYSBicmlkZ2Ugb3IgYSB0dW5uZWwpLiBXaGF0IGxvb2tzIGxpa2UgYSBjaGFubmVsPw==[Qq]

[f]IE5vLiBOdW1iZXIgNSBpcyBwb2ludGluZyB0byBhbiBpbnRlZ3JhbCBwcm90ZWluIChidXQgb25lIHRoYXQmIzgyMTc7cyBub3QgYSB0cmFuc21lbWJyYW5lIHByb3RlaW4pLiBJbiB0aGUgY29udGV4dCBvZiBtZW1icmFuZXMsIGEgY2hhbm5lbCBpcyBhIHN0cnVjdHVyZSB0aGF0IGxldHMgbW9sZWN1bGVzIHBhc3MgdGhyb3VnaCAobGlrZSBhIGJyaWRnZSBvciBhIHR1bm5lbCkuIFdoYXQgbG9va3MgbGlrZSBhIGNoYW5uZWw/[Qq]

[f]IEV4Y2VsbGVudCEgTnVtYmVyIDYgaXMgcG9pbnRpbmcgdG8gYSBwcm90ZWluIGNoYW5uZWwu[Qq]

[f]IE5vLiBOdW1iZXIgN8KgaXMgcG9pbnRpbmcgdG8gY2hvbGVzdGVyb2wuwqBJbiB0aGUgY29udGV4dCBvZiBtZW1icmFuZXMsIGHCoGNoYW5uZWwgaXMgYSBzdHJ1Y3R1cmUgdGhhdCBsZXRzIG1vbGVjdWxlcyBwYXNzIHRocm91Z2jCoChsaWtlIGEgYnJpZGdlIG9yIGEgdHVubmVsKS4gV2hhdCBsb29rcyBsaWtlIGEgY2hhbm5lbD8=[Qq]

[f]IE5vLiBOdW1iZXIgOMKgaXMgcG9pbnRpbmcgdG8gYSBtZW1icmFuZSBjYXJib2h5ZHJhdGUuwqBJbiB0aGUgY29udGV4dCBvZiBtZW1icmFuZXMsIGHCoGNoYW5uZWwgaXMgYSBzdHJ1Y3R1cmUgdGhhdCBsZXRzIG1vbGVjdWxlcyBwYXNzIHRocm91Z2jCoChsaWtlIGEgYnJpZGdlIG9yIGEgdHVubmVsKS4gV2hhdCBsb29rcyBsaWtlIGEgY2hhbm5lbD8=[Qq]

[f]IE5vLiBOdW1iZXIgOcKgaXMgcG9pbnRpbmcgdG8gdGhlIGhlYWQgb2YgYSBwaG9zcGhvbGlwaWQuwqBJbiB0aGUgY29udGV4dCBvZiBtZW1icmFuZXMsIGHCoGNoYW5uZWwgaXMgYSBzdHJ1Y3R1cmUgdGhhdCBsZXRzIG1vbGVjdWxlcyBwYXNzIHRocm91Z2jCoChsaWtlIGEgYnJpZGdlIG9yIGEgdHVubmVsKS4gV2hhdCBsb29rcyBsaWtlIGEgY2hhbm5lbD8=

Cg==

[Qq]

[q] In the diagram below, which number is pointing to a phospholipid tail?
[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDMgwqAgwqDCoA==[Qq][c]IDQgwqAg wqDCoA==[Qq][c]NcKgIMKgIA==[Qq][c]NsKgIMKgIMKg[Qq][c]N8KgIMKgIMKg[Qq][c]OCDCoCDCoA==[Qq][c]OQ==

Cg==[Qq]

[f]IE5vLiBOdW1iZXIgMSBpcyBwb2ludGluZyB0byB0d28gdHJhbnNtZW1icmFuZSBwcm90ZWlucy4gVGhlIHBob3NwaG9saXBpZHMgYXJlIHRoZSBtYWluIHN0cnVjdHVyYWwgbW9sZWN1bGVzIG1ha2luZyB1cCB0aGUgbWVtYnJhbmUuIFRoZSBub24tcG9sYXIgJiM4MjIwO3RhaWxzJiM4MjIxOyBvZiB0aGUgcGhvc3Bob2xpcGlkcyBmYWNlIHRvd2FyZHMgdGhlIGluc2lkZSBvZiB0aGUgbWVtYnJhbmUsIGF3YXkgZnJvbSB0aGUgY3l0b3BsYXNtIG9yIHRoZSBleHRyYWNlbGx1bGFyIGZsdWlkLiBXaXRoIHRoYXQgaW4gbWluZCwgc2VlIGlmIHlvdSBjYW4gZmluZCBhIHBob3NwaG9saXBpZCBoZWFkLg==[Qq]

[f]IE5vLCBidXQgeW91JiM4MjE3O3JlIGNsb3NlLiBOdW1iZXIgMiBpcyBwb2ludGluZyB0byB0aGUgZW50aXJlIHBob3NwaG9saXBpZCBiaWxheWVyLiBUaGUgbm9uLXBvbGFyICYjODIyMDt0YWlscyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBpbnNpZGXCoG9mIHRoZSBtZW1icmFuZSwgYXdheSBmcm9tIHRoZSBjeXRvcGxhc20gb3IgdGhlIGV4dHJhY2VsbHVsYXIgZmx1aWQuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]

[f]IE5vLiBOdW1iZXIgMyBpcyBwb2ludGluZyB0byBhwqBwZXJpcGhlcmFsIHByb3RlaW4uIFRoZSBwaG9zcGhvbGlwaWRzIGFyZSB0aGUgbWFpbiBzdHJ1Y3R1cmFsIG1vbGVjdWxlcyBtYWtpbmcgdXAgdGhlIG1lbWJyYW5lLiBUaGUgbm9uLXBvbGFyICYjODIyMDt0YWlscyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBpbnNpZGXCoG9mIHRoZSBtZW1icmFuZSwgYXdheSBmcm9tIHRoZSBjeXRvcGxhc20gb3IgdGhlIGV4dHJhY2VsbHVsYXIgZmx1aWQuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]

[f]IFllcy4gTnVtYmVyIDQgaXMgcG9pbnRpbmcgdG8gdGhlIHRhaWwgb2YgYSBwaG9zcGhvbGlwaWQu[Qq]

[f]IE5vLiBOdW1iZXIgNcKgaXMgcG9pbnRpbmcgdG/CoGFuIGludGVncmFsIHByb3RlaW4uIFRoZSBwaG9zcGhvbGlwaWRzIGFyZSB0aGUgbWFpbiBzdHJ1Y3R1cmFsIG1vbGVjdWxlcyBtYWtpbmcgdXAgdGhlIG1lbWJyYW5lLiBUaGUgbm9uLXBvbGFyICYjODIyMDt0YWlscyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBpbnNpZGXCoG9mIHRoZSBtZW1icmFuZSwgYXdheSBmcm9tIHRoZSBjeXRvcGxhc20gb3IgdGhlIGV4dHJhY2VsbHVsYXIgZmx1aWQuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]

[f]IE5vISBOdW1iZXIgNiBpcyBwb2ludGluZyB0byBhIHByb3RlaW4gY2hhbm5lbC4gVGhlIHBob3NwaG9saXBpZHMgYXJlIHRoZSBtYWluIHN0cnVjdHVyYWwgbW9sZWN1bGVzIG1ha2luZyB1cCB0aGUgbWVtYnJhbmUuIFRoZSBub24tcG9sYXIgJiM4MjIwO3RhaWxzJiM4MjIxOyBvZiB0aGUgcGhvc3Bob2xpcGlkcyBmYWNlIHRvd2FyZHMgdGhlIGluc2lkZSBvZiB0aGUgbWVtYnJhbmUsIGF3YXkgZnJvbSB0aGUgY3l0b3BsYXNtIG9yIHRoZSBleHRyYWNlbGx1bGFyIGZsdWlkLiBXaXRoIHRoYXQgaW4gbWluZCwgc2VlIGlmIHlvdSBjYW4gZmluZCBhIHBob3NwaG9saXBpZCBoZWFkLg==[Qq]

[f]IE5vLiBOdW1iZXIgN8KgaXMgcG9pbnRpbmcgdG8gY2hvbGVzdGVyb2wuIFRoZSBwaG9zcGhvbGlwaWRzIGFyZSB0aGUgbWFpbiBzdHJ1Y3R1cmFsIG1vbGVjdWxlcyBtYWtpbmcgdXAgdGhlIG1lbWJyYW5lLiBUaGUgbm9uLXBvbGFyICYjODIyMDt0YWlscyYjODIyMTsgb2YgdGhlIHBob3NwaG9saXBpZHMgZmFjZSB0b3dhcmRzIHRoZSBpbnNpZGXCoG9mIHRoZSBtZW1icmFuZSwgYXdheSBmcm9tIHRoZSBjeXRvcGxhc20gb3IgdGhlIGV4dHJhY2VsbHVsYXIgZmx1aWQuIFdpdGggdGhhdCBpbiBtaW5kLCBzZWUgaWYgeW91IGNhbiBmaW5kIGEgcGhvc3Bob2xpcGlkIGhlYWQu[Qq]

[f]IE5vLiBOdW1iZXIgOMKgaXMgcG9pbnRpbmcgdG8gYSBtZW1icmFuZSBjYXJib2h5ZHJhdGUuwqBUaGUgcGhvc3Bob2xpcGlkcyBhcmUgdGhlIG1haW4gc3RydWN0dXJhbCBtb2xlY3VsZXMgbWFraW5nIHVwIHRoZSBtZW1icmFuZS4gVGhlIG5vbi1wb2xhciAmIzgyMjA7dGFpbHMmIzgyMjE7IG9mIHRoZSBwaG9zcGhvbGlwaWRzIGZhY2UgdG93YXJkcyB0aGUgaW5zaWRlwqBvZiB0aGUgbWVtYnJhbmUsIGF3YXkgZnJvbSB0aGUgY3l0b3BsYXNtIG9yIHRoZSBleHRyYWNlbGx1bGFyIGZsdWlkLiBXaXRoIHRoYXQgaW4gbWluZCwgc2VlIGlmIHlvdSBjYW4gZmluZCBhIHBob3NwaG9saXBpZCBoZWFkLg==[Qq]

[f]IE5vLiBOdW1iZXIgOcKgaXMgcG9pbnRpbmcgdG8gdGhlIGhlYWQgb2YgYSBwaG9zcGhvbGlwaWQuwqBUaGUgcGhvc3Bob2xpcGlkcyBhcmUgdGhlIG1haW4gc3RydWN0dXJhbCBtb2xlY3VsZXMgbWFraW5nIHVwIHRoZSBtZW1icmFuZS4gVGhlIG5vbi1wb2xhciAmIzgyMjA7dGFpbHMmIzgyMjE7IG9mIHRoZSBwaG9zcGhvbGlwaWRzIGZhY2UgdG93YXJkcyB0aGUgaW5zaWRlwqBvZiB0aGUgbWVtYnJhbmUsIGF3YXkgZnJvbSB0aGUgY3l0b3BsYXNtIG9yIHRoZSBleHRyYWNlbGx1bGFyIGZsdWlkLiBXaXRoIHRoYXQgaW4gbWluZCwgc2VlIGlmIHlvdSBjYW4gZmluZCBhIHBob3NwaG9saXBpZCBoZWFkLg==

Cg==

[Qq]

[q]In the diagram below, which letter represents a membrane carbohydrate?

[c]IEHCoCDCoCDCoA==[Qq][c]IETCoC DCoA==[Qq][c]RSDCoCDCoCDCoCA=[Qq][c]SC1JIMKgIMKgIA==[Qq][c]Rw==

Cg==[Qq]

[f]Tm8uIEEgaXMgcG9pbnRpbmcgdG8gYSBwaG9zcGhvbGlwaWQuIE1lbWJyYW5lIGNhcmJvaHlkcmF0ZXMgYXJlIHVzdWFsbHkgc2hvcnQsIGJyYW5jaGVkIHBvbHlzYWNjaGFyaWRlcy4gTG9vayBjbG9zZWx5IGFuZCBzZWUgaWYgeW91IGNhbiBmaW5kIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbi4=[Qq]

[f]WWVzLiBEIGlzIHBvaW50aW5nIHRvIGEgbWVtYnJhbmUgY2FyYm9oeWRyYXRlLg==[Qq]

[f]Tm8uIEUgaXMgcG9pbnRpbmcgdG8gYSBtb2xlY3VsZSBvZiBjaG9sZXN0ZXJvbC4gTWVtYnJhbmUgY2FyYm9oeWRyYXRlcyBhcmUgdXN1YWxseSBzaG9ydCwgYnJhbmNoZWQgcG9seXNhY2NoYXJpZGVzLiBMb29rIGNsb3NlbHkgYW5kIHNlZSBpZiB5b3UgY2FuIGZpbmQgc29tZXRoaW5nIHRoYXQgZml0cyB0aGF0IGRlc2NyaXB0aW9uLg==[Qq]

[f]Tm8uIEgtSSBpcyBwb2ludGluZyB0byB0aGUgcGhvc3Bob2xpcGlkIGJpbGF5ZXIuIE1lbWJyYW5lIGNhcmJvaHlkcmF0ZXMgYXJlIHVzdWFsbHkgc2hvcnQsIGJyYW5jaGVkIHBvbHlzYWNjaGFyaWRlcy4gTG9vayBjbG9zZWx5IGFuZCBzZWUgaWYgeW91IGNhbiBmaW5kIHNvbWV0aGluZyB0aGF0IGZpdHMgdGhhdCBkZXNjcmlwdGlvbi4=[Qq]

[f]Tm8uIEfCoGlzIHBvaW50aW5nIHRvIGEgcHJvdGVpbiBjaGFubmVsLiBNZW1icmFuZSBjYXJib2h5ZHJhdGVzIGFyZSB1c3VhbGx5IHNob3J0LCBicmFuY2hlZCBwb2x5c2FjY2hhcmlkZXMuIExvb2sgY2xvc2VseSBhbmQgc2VlIGlmIHlvdSBjYW4gZmluZCBzb21ldGhpbmcgdGhhdCBmaXRzIHRoYXQgZGVzY3JpcHRpb24u

Cg==

[Qq]

[q]In the diagram below, which letter represents a protein channel?

[c]IEHCoCDCoCDCoA==[Qq][c]IETCoCDCoA==[Qq][c]RSDCoCDCoCDCoCA=[Qq][c]SC1JIMKgIMKgIA==[Qq][c]Rw ==

Cg==[Qq]

[f]Tm8uIEEgaXMgcG9pbnRpbmcgdG8gYSBwaG9zcGhvbGlwaWQuIEEgcHJvdGVpbiBjaGFubmVsIGlzIGxpa2UgYSBwb3JlIG9yIGEgdHVubmVsLiBJdCBhbGxvd3MgbW9sZWN1bGVzIHRvIHBhc3MgdGhyb3VnaC4gV2hhdCwgaW4gdGhpcyBkaWFncmFtLCBsb29rcyBsaWtlIGEgdHVubmVsPw==[Qq]

[f]Tm8uIEQgaXMgcG9pbnRpbmcgdG8gYSBtZW1icmFuZSBjYXJib2h5ZHJhdGUuwqDCoEEgcHJvdGVpbiBjaGFubmVsIGlzIGxpa2UgYSBwb3JlIG9yIGEgdHVubmVsLiBJdCBhbGxvd3MgbW9sZWN1bGVzIHRvIHBhc3MgdGhyb3VnaC4gV2hhdCwgaW4gdGhpcyBkaWFncmFtLCBsb29rcyBsaWtlIGEgdHVubmVsPw==[Qq]

[f]Tm8uIEUgaXMgcG9pbnRpbmcgdG8gYSBtb2xlY3VsZSBvZiBjaG9sZXN0ZXJvbC4gQSBwcm90ZWluIGNoYW5uZWwgaXMgbGlrZSBhIHBvcmUgb3IgYSB0dW5uZWwuIEl0IGFsbG93cyBtb2xlY3VsZXMgdG8gcGFzcyB0aHJvdWdoLiBXaGF0LCBpbiB0aGlzIGRpYWdyYW0sIGxvb2tzIGxpa2UgYSB0dW5uZWw/[Qq]

[f]Tm8uIEgtSSBpcyBwb2ludGluZyB0byB0aGUgcGhvc3Bob2xpcGlkIGJpbGF5ZXIuwqDCoEEgcHJvdGVpbiBjaGFubmVsIGlzIGxpa2UgYSBwb3JlIG9yIGEgdHVubmVsLiBJdCBhbGxvd3MgbW9sZWN1bGVzIHRvIHBhc3MgdGhyb3VnaC4gV2hhdCwgaW4gdGhpcyBkaWFncmFtLCBsb29rcyBsaWtlIGEgdHVubmVsPw==[Qq]

[f]WWVzLiBHwqBpcyBwb2ludGluZyB0byBhIHByb3RlaW4gY2hhbm5lbC4=

Cg==

[Qq]

[q]In the diagram below, which letter represents cholesterol?

[c]IEHCoCDCoCDCoA==[Qq][c]IETCoCDCoA==[Qq][c]RSDCoCDC oCDCoCA=[Qq][c]SC1JIMKgIMKgIA==[Qq][c]Rw==

Cg==[Qq]

[f]Tm8uIEEgaXMgcG9pbnRpbmcgdG8gYSBwaG9zcGhvbGlwaWQuwqBDaG9sZXN0ZXJvbCBpcyBhIGxpcGlkLiBJdCYjODIxNztzIHVzdWFsbHkgcmVwcmVzZW50ZWQgYXMgYSBncm91cCBvZiBmdXNlZCByaW5ncyBlbWJlZGRlZCBpbiB0aGUgbWVtYnJhbmUuIFdoYXQsIGluIHRoaXMgZGlhZ3JhbSwgZml0cyB0aGF0IGRlc2NyaXB0aW9uPw==[Qq]

[f]Tm8uIEQgaXMgcG9pbnRpbmcgdG8gYSBtZW1icmFuZSBjYXJib2h5ZHJhdGUuIMKgQ2hvbGVzdGVyb2wgaXMgYSBsaXBpZC4gSXQmIzgyMTc7cyB1c3VhbGx5IHJlcHJlc2VudGVkIGFzIGEgZ3JvdXAgb2YgZnVzZWQgcmluZ3MgZW1iZWRkZWQgaW4gdGhlIG1lbWJyYW5lLiBXaGF0LCBpbiB0aGlzIGRpYWdyYW0sIGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=[Qq]

[f]WWVzLiBFIGlzIHBvaW50aW5nIHRvIGEgbW9sZWN1bGUgb2YgY2hvbGVzdGVyb2wu[Qq]

[f]Tm8uIEgtSSBpcyBwb2ludGluZyB0byB0aGUgcGhvc3Bob2xpcGlkIGJpbGF5ZXIuIMKgQ2hvbGVzdGVyb2wgaXMgYSBsaXBpZC4gSXQmIzgyMTc7cyB1c3VhbGx5IHJlcHJlc2VudGVkIGFzIGEgZ3JvdXAgb2YgZnVzZWQgcmluZ3MgZW1iZWRkZWQgaW4gdGhlIG1lbWJyYW5lLiBXaGF0LCBpbiB0aGlzIGRpYWdyYW0sIGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=[Qq]

[f]Tm8uIEfCoGlzIHBvaW50aW5nIHRvIGEgcHJvdGVpbiBjaGFubmVsLsKgQ2hvbGVzdGVyb2wgaXMgYSBsaXBpZC4gSXQmIzgyMTc7cyB1c3VhbGx5IHJlcHJlc2VudGVkIGFzIGEgZ3JvdXAgb2YgZnVzZWQgcmluZ3MgZW1iZWRkZWQgaW4gdGhlIG1lbWJyYW5lLiBXaGF0LCBpbiB0aGlzIGRpYWdyYW0sIGZpdHMgdGhhdCBkZXNjcmlwdGlvbj8=

Cg==

[Qq]

[q]In the diagram below, which letter represents a phospholipid?

[c]IEHCoCDC oCDCoA==[Qq][c]IETCoCDCoA==[Qq][c]RSDCoCDCoCDCoCA=[Qq][c]SC1JIMKgIMKgIA==[Qq][c]Rw==

Cg==[Qq]

[f]WWVzLiBBIGlzIHBvaW50aW5nIHRvIGEgcGhvc3Bob2xpcGlkLg==[Qq]

[f]Tm8uIEQgaXMgcG9pbnRpbmcgdG8gYSBtZW1icmFuZSBjYXJib2h5ZHJhdGUuIMKgWW91IGNhbiBpZGVudGlmeSBwaG9zcGhvbGlwaWRzIGluIHNldmVyYWzCoHdheXM6IDEpIHRoZXkgbWFrZSB1cCB0aGUgbWFpbiBzdHJ1Y3R1cmUgb3IgZnJhbWV3b3JrIG9mIHRoZSBtZW1icmFuZS4gMikgVGhleSYjODIxNztyZSBvcmdhbml6ZWQgaW50byBhIGJpbGF5ZXIsIHdpdGjCoHRoZSB0YWlscyBmYWNpbmcgaW53YXJkIGFuZCB0aGUgaGVhZHMgZmFjaW5nIG91dHdhcmQuIDMpIFRoZXkgaGF2ZSBhICYjODIyMDtoZWFkJiM4MjIxOyBhbmQgYSAmIzgyMjA7dGFpbC4mIzgyMjE7[Qq]

[f]Tm8uIEUgaXMgcG9pbnRpbmcgdG8gYSBtb2xlY3VsZSBvZiBjaG9sZXN0ZXJvbC7CoFlvdSBjYW4gaWRlbnRpZnkgcGhvc3Bob2xpcGlkcyBpbiBzZXZlcmFswqB3YXlzOiAxKSB0aGV5IG1ha2UgdXAgdGhlIG1haW4gc3RydWN0dXJlIG9yIGZyYW1ld29yayBvZiB0aGUgbWVtYnJhbmUuIDIpIFRoZXkmIzgyMTc7cmUgb3JnYW5pemVkIGludG8gYSBiaWxheWVyLCB3aXRowqB0aGUgdGFpbHMgZmFjaW5nIGlud2FyZCBhbmQgdGhlIGhlYWRzIGZhY2luZyBvdXR3YXJkLiAzKSBUaGV5IGhhdmUgYSAmIzgyMjA7aGVhZCYjODIyMTsgYW5kIGEgJiM4MjIwO3RhaWwuJiM4MjIxOw==[Qq]

[f]Tm8sIGJ1dCB5b3UmIzgyMTc7cmUgY2xvc2UuIEgtSSBpcyBwb2ludGluZyB0byB0aGUgcGhvc3Bob2xpcGlkIA==YmlsYXllcg==LiDCoEZpbmQgd2hhdCYjODIxNztzIHBvaW50aW5nIHRvIGEgc2luZ2xlIHBob3NwaG9saXBpZCBtb2xlY3VsZS4=[Qq]

[f]Tm8uIEfCoGlzIHBvaW50aW5nIHRvIGEgcHJvdGVpbiBjaGFubmVsLsKgWW91IGNhbiBpZGVudGlmeSBwaG9zcGhvbGlwaWRzIGluIHNldmVyYWzCoHdheXM6IDEpIHRoZXkgbWFrZSB1cCB0aGUgbWFpbiBzdHJ1Y3R1cmUgb3IgZnJhbWV3b3JrIG9mIHRoZSBtZW1icmFuZS4gMikgVGhleSYjODIxNztyZSBvcmdhbml6ZWQgaW50byBhIGJpbGF5ZXIsIHdpdGjCoHRoZSB0YWlscyBmYWNpbmcgaW53YXJkIGFuZCB0aGUgaGVhZHMgZmFjaW5nIG91dHdhcmQuIDMpIFRoZXkgaGF2ZSBhICYjODIyMDtoZWFkJiM4MjIxOyBhbmQgYSAmIzgyMjA7dGFpbC4mIzgyMjE7

Cg==

[Qq]

[q]Membranes allow certain molecules to pass through but not others. In other words, membranes are [hangman] [hangman].

[c]c2VsZWN0aXZlbHk=[Qq]

[c]cGVybWVhYmxl

Cg==

[Qq]

[q]The dynamic model of cell membrane structure which involves phospholipids, proteins, cholesterol, and carbohydrates in constant motion in the membrane is the [hangman] [hangman] model.

[c]Zmx1aWQ=[Qq]

[c]bW9zYWlj[Qq]

[q]In the diagram below, membrane proteins like the ones at 1, 5, and 6, all of which are embedded in the phospholipid bilayer, are known as [hangman] proteins.

[c]aW50ZWdyYWw=

Cg==

[Qq]

[q]In the diagram below, membrane proteins like the ones at 1 and 6, both of which span the width of the phospholipid bilayer, are known as [hangman] proteins.

[c]dHJhbnNtZW1icmFuZQ==

Cg==

[Qq]

[q]In the diagram below, the molecule shown at 7 is a lipid, but not a phospholipid. Its function is to stabilize the membrane at high temperatures and to keep it fluid at low temperatures. This molecule must be [hangman].

[c]Y2hvbGVzdGVyb2w=

Cg==

[Qq]

[q]Because of the way that it’s positioned in the membrane, you can tell that protein #3 must be a [hangman] protein.

[c]cGVyaXBoZXJhbA==[Qq]

[x]

[restart]

[/qwiz]

6. Cell Membranes Rap

7. Cell Membranes Rap, Karaoke Version

What’s Next?

Proceed to Topics 2.5-2.7, 2.9: Membrane Transport (the next tutorial in AP Bio Unit 2)