1. Watch this video
2a. Some useful concepts and terms that didn’t make it into the video
- Euchromatin: loosely packed (often acetylated) DNA that is transcribed into RNA and translated into protein.
- Heterochromatin: tightly packed (often methylated) DNA that is NOT transcribed
1. Nuclear membrane. 2. Euchromatin 3. Heterochromatin 4. Nucleolus - Euchromatin: loosely packed (often acetylated) DNA that is transcribed into RNA and translated into protein.
2b. Study this summary
Why Gene Regulation in Eukaryotes is Complex (especially when compared to prokaryotic gene regulation
- Eukaryotic genomes are much larger than prokaryotic genomes (4 billion base pairs in humans, vs. 3 million in E. coli).
- Multicellular eukaryotes (e.g., humans, lizards, jellyfish) have trillions of cells with the same DNA, but each tissue expresses specific genes based on its function (e.g., muscle vs. skin cells). How do cells know which genes to express?
- Eukaryotic genes are not contiguous but interrupted by non-coding DNA stretches called introns. How do cells “know” to express the coding DNA, but not the intron?
Mechanisms of Eukaryotic Gene Regulation:
- Epigenetic modifications of DNA.
- Changes in DNA expression through reversible chemical modifications without altering the DNA sequence.
- Methylation: Adds a methyl group to DNA, silencing gene transcription.
- Acetylation: Loosens DNA-histone complexes, enabling transcription.
- Drives tissue differentiation (e.g., skin cells vs. muscle cells).
- Some epigenetic changes can be passed to future generations (intergenerational transmission).
- Transcription Regulation:
- Involves regulatory DNA sequences and regulatory proteins:
- Promoters: Sites where RNA polymerase binds.
- Enhancers: Increase the likelihood of transcription.
- Activators, DNA-bending proteins, and transcription factors work together to enable RNA polymerase to transcribe genes.
- Involves regulatory DNA sequences and regulatory proteins:
- Coordination of Gene Expression:
- Different tissues can share common regulatory sequences.
- Example: Testosterone regulates gene expression in both neck (mane) and muscle tissues in male lions, causing tissue-specific effects.
RNA Processing in Eukaryotes:
- Introns and Exons:
- Introns: Non-coding sequences removed during RNA splicing.
- Exons: Coding sequences spliced together to form mRNA for translation.
- Alternative Splicing:
- Allows exons to be combined in various ways, producing multiple protein variants from one gene.
- Increases phenotypic variation.
- Post-Transcriptional Modifications:
- 5′ GTP Cap:
- Protects mRNA from degradation.
- Aids in nuclear export and ribosome binding.
- 3′ Poly-A Tail:
- Enhances mRNA stability and delays breakdown.
- 5′ GTP Cap:
Role of Small RNAs:
- MicroRNAs (miRNAs):
- Regulate gene expression post-transcriptionally.
- Form RNA silencing complexes that either pause translation or degrade mRNA so that it can no longer be translated.
- Result: Altered gene expression without modifying DNA.
Why This Matters:
- Eukaryotic Gene Regulation:
- Ensures genes are expressed in the right place, at the right time, and in response to environmental or developmental signals.
- Essential for understanding processes like development, tissue specialization, and cellular responses.
3. Master these flashcards
[qdeck style=”width: 650px !important; min-height: 400px !important;” bold_text=”false” ]
[h] Eukaryotic Gene Regulation: Key Concepts
[q] Why is gene regulation in eukaryotes more complex than in prokaryotes?
[a]
– Eukaryotic genomes are much larger (e.g., 4 billion base pairs in humans vs. 3 million in E. coli).
– Multicellular eukaryotes have trillions of cells with the same DNA, but each tissue expresses specific genes based on its function.
– Eukaryotic genes are interrupted by non-coding introns, requiring cells to selectively express coding DNA.
[q] What are introns and exons?
[a]
– Introns: Non-coding sequences removed during RNA splicing.
– Exons: Coding sequences spliced together to form mRNA for translation.
[q] What is alternative splicing, and why is it important?
[a]
– Combines exons in different ways, producing multiple protein variants from one gene.
– Increases phenotypic variation in eukaryotes.
[q] What are two types of epigenetic modifications?
[a]
1. Methylation: Adds methyl groups to DNA, silencing transcription.
2. Acetylation: Loosens DNA-histone complexes, enabling transcription.
[q] How do epigenetic modifications affect gene expression?
[a]
– Drive tissue differentiation (e.g., skin vs. muscle cells).
– Some changes are reversible and can be passed to future generations.
[q] What is the role of promoters and enhancers in transcription regulation?
[a]
– Promoters: Sites where RNA polymerase binds to initiate transcription.
– Enhancers: Increase the likelihood of transcription by interacting with activators and other proteins.
[q] How is gene expression coordinated across different tissues?
[a]
– Shared regulatory sequences enable coordination.
– Example: Testosterone regulates different genes in neck (mane) and muscle tissues in male lions.
[q] What are the post-transcriptional modifications of mRNA in eukaryotes?
[a]
1. 5′ GTP Cap:
– Protects mRNA from degradation.
– Assists in nuclear export and ribosome binding.
2. 3′ Poly-A Tail:
– Enhances mRNA stability and delays breakdown.
[q] What is the role of small RNAs like microRNAs (miRNAs) in gene regulation?
[a]
– Regulate gene expression post-transcriptionally.
– Form RNA silencing complexes that either pause translation or degrade mRNA.
– Alter gene expression without modifying DNA.
[q] Why is eukaryotic gene regulation important?
[a]
– Ensures genes are expressed in the right place, at the right time, and in response to signals.
– Crucial for processes like development, tissue specialization, and cellular responses.
[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” dataset_id=”AP_Bio_Flashcards_2022|18d2436940d10″ question_number=”220″ topic=”6.3.Transcription_and_RNA_Processing”] What is pre-mRNA? Describe some of the post-transcriptional modification that has to happen to pre-mRNA in eukaryotes before it can be translated into protein.
[a] In eukaryotic cells, pre-mRNA (2) is what’s transcribed from a protein-coding gene. Before it can be translated into protein, pre-mRNA is processed with addition of a 5’ GTP cap (“g”), a 3’ poly-A tail (j), excision of introns (“f”) and splicing together of exons.
[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” topic=”6.3.Transcription_and_RNA_Processing” dataset_id=”AP_Bio_Flashcards_2022|173d636aaee002″ question_number=”221″] What is the function of the 5′ GTP cap and the 3′ poly-A-tail that’s added to mRNA during eukaryotic RNA processing?
[a]
The 5’ GTP cap (“g”) protects the mRNA from breakdown by enzymes in the cytoplasm, and also assists the mRNA in leaving the nucleus and binding with a ribosome. The 3’ poly-A tail (j) makes the mRNA more stable and delays its enzymatic breakdown in the cytoplasm.
[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” dataset_id=”AP_Bio_Flashcards_2022|18c962fbeb910″ question_number=”222″ topic=”6.3.Transcription_and_RNA_Processing”] Describe, on a big picture level, how transcription is regulated in eukaryotes.
[a] Eukaryotes possess regulatory DNA sequences that interact with regulatory proteins to control transcription. These sequences include promoters (d) and enhancers (a). Interactions between activator proteins (b), DNA bending proteins (f), mediator proteins (g), and general transcription factors (h) enable RNA polymerase (i) to bind, making transcription possible. (Note that letter “e” is a “proximal control element.” For AP Bio, don’t worry about it!)
[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” topic=”6.3.Transcription_and_RNA_Processing” dataset_id=”AP_Bio_Flashcards_2022|ac507a8247bd” question_number=”223″]Explain how organization of eukaryotic genetic material into introns and exons can increase phenotypic variation.
[a] Through alternative splicing, exons can be spliced together in alternative ways allowing for the production of multiple protein versions from the same mRNA transcript.
[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” dataset_id=”AP_Bio_Flashcards_2022|18b2d4c8bad10″ question_number=”225″ topic=”6.4.Translation”] How are transcription and translation different in prokaryotes and eukaryotes?
[a] In prokaryotes (1), transcription and translation are coupled: protein synthesis begins while transcription of mRNA is still taking place. In eukaryotes (2), the processes of transcription and translation are spatially and temporally separate: transcription occurs in the nucleus, and translation is in the cytoplasm.
In prokaryotes, a single mRNA can code for multiple proteins within a specific metabolic pathway; in eukaryotes, the mRNA codes for only a single polypeptide. In eukaryotes, pre-mRNA is modified before translation occurs (the details of which are covered in another card).
[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” dataset_id=”AP_Bio_Flashcards_2022|18658f7e1c110″ question_number=”233″ topic=”6.5.Regulation_of_Gene_Expression”] What are transcription factors?
[a]
Transcription factors (5) are proteins that bind to DNA at or near a gene’s promoter (1). Transcription factors play a regulatory role, enhancing or inhibiting gene expression by promoting or inhibiting the binding of RNA polymerase (6)
[x][restart]
[/qdeck]
4. Tackle these quizzes
4.1. DNA Packaging (Euchromatin and Heterochromatin)/ Epigenetic Modifications of DNA
[qwiz]
[h]DNA packaging
[i]
[q labels = “top”]
[l]Acetyl group
[fx] No, that’s not correct. Please try again.
[f*] Correct!
[l]DNA
[fx] No. Please try again.
[f*] Excellent!
[l]histone
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]histone tail
[fx] No. Please try again.
[f*] Excellent!
[l]nucleosome
[fx] No. Please try again.
[f*] Correct!
[l]Transcribable DNA
[fx] No. Please try again.
[f*] Excellent!
[l]Untranscribable DNA
[fx] No. Please try again.
[f*] Correct!
[q labels = “top”]
[l]euchromatin
[fx] No. Please try again.
[f*] Excellent!
[l]heterochromatin
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]nuclear membrane
[fx] No. Please try again.
[f*] Excellent!
[l]nucleolus
[fx] No, that’s not correct. Please try again.
[f*] Correct!
[q labels = “top”]
[l]active/transcribed DNA
[fx] No. Please try again.
[f*] Correct!
[l]inactive/untranscribed DNA
[fx] No. Please try again.
[f*] Correct!
[l]ribosome assembly site
[fx] No. Please try again.
[f*] Great!
[l]RNA must cross this to be transcribed
[fx] No. Please try again.
[f*] Correct!
[q labels = “top”]
[l]Acetyl group
[fx] No. Please try again.
[f*] Good!
[l]histone
[fx] No. Please try again.
[f*] Excellent!
[l]histone tail
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]methyl group
[fx] No. Please try again.
[f*] Correct!
[l]Transcribable DNA
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]Untranscribable DNA
[fx] No, that’s not correct. Please try again.
[f*] Good!
[q labels = “top”]
[l]acetyl group
[fx] No, that’s not correct. Please try again.
[f*] Excellent!
[l]euchromatin
[fx] No, that’s not correct. Please try again.
[f*] Excellent!
[l]heterochromatin
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]methyl group
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]RNA polymerase
[fx] No. Please try again.
[f*] Great!
[q]The differences between muscle tissue and eye-lens tissue are not about differences in the [hangman] in these tissues. That’s because almost all cells in a eukaryotic organism are genomically [hangman]. The difference, in other words, isn’t genetic, but [hangman].
[c]RE5B[Qq]
[c]ZXF1aXZhbGVudA==[Qq]
[c]ZXBpZ2VuZXRpYw==[Qq]
[q] In the diagram below, which number is pointing to a histone?
[textentry single_char=”true”]
[c]ID M=[Qq]
[f]IEV4Y2VsbGVudC4gTnVtYmVyICYjODIyMDszJiM4MjIxOyBpcyBwb2ludGluZyB0byBhIGhpc3RvbmUu[Qq]
[c]IDc=[Qq]
[f]IFlvdSYjODIxNztyZSBleHRyZW1lbHkgY2xvc2UuICYjODIyMDs2JiM4MjIxOyBpcyBhIGdyb3VwIG9mIGhpc3RvbmVzIG9yZ2FuaXplZCBpbnRvIGEgbnVjbGVvc29tZS4gQ2hvb3NlIGEgbnVtYmVyIHRoYXQmIzgyMTc7cyBqdXN0IHBvaW50aW5nIHRvIG9uZSBoaXN0b25lLg==[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIaXN0b25lcyBtYWtlIHVwIG51Y2xlb3NvbWVzIChzaG93biBhdCAmIzgyMjA7Ni4mIzgyMjE7KS4gVGhlIGhpc3RvbmVzIGhhdmUgdGFpbHMgKHNob3duIGF0ICYjODIyMDs1JiM4MjIxOykgdGhhdCBjYW4gYmUgdXNlZCB0byBtb2RpZnkgdGhlIGRlbnNpdHkgb2YgRE5BIHBhY2thZ2luZy4=[Qq]
[q] In the diagram below, which number is showing DNA that’s available for transcription?
[textentry single_char=”true”]
[c]ID c=[Qq]
[f]IEV4Y2VsbGVudCEgJiM4MjIwOzcmIzgyMjE7IHNob3dzIEROQSB0aGF0JiM4MjE3O3MgYXZhaWxhYmxlIGZvciB0cmFuc2NyaXB0aW9uLg==[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBGaW5kIEROQSAoaW5kaWNhdGVkIGJ5ICYjODIyMDsxJiM4MjIxOykgdGhhdCYjODIxNztzICYjODIyMDtyZWxheGVkIGVub3VnaCB0byBiZSBhY2Nlc3NlZCBieSBtb2xlY3VsZXMgbGlrZSBSTkEgcG9seW1lcmFzZSwgbWFraW5nIHRyYW5zY3JpcHRpb24gcG9zc2libGUu[Qq]
[q] In the diagram below, which number is showing an acetyl group?
[textentry single_char=”true”]
[c]ID g=[Qq]
[f]IEdvb2Qgd29yay4gJiM4MjIwOzgmIzgyMjE7IGlzIGFuIGFjZXR5bCBncm91cCwgYXNzb2NpYXRlZCB3aXRoIGhpc3RvbmUgbW9kaWZpY2F0aW9uIHRoYXQgYWxsb3dzIHRyYW5zY3JpcHRpb24u[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLg==[Qq]
[c]ICo=[Qq]
[f]IE5vLiBGaW5kIHNvbWV0aGluZyB0aGF0JiM4MjE3O3MgYm9uZGVkIHdpdGggb25lIG9mIHRoZSBoaXN0b25lIHRhaWxzIChzaG93biBhdCAmIzgyMjA7NSYjODIyMTspLCBhbGxvd2luZyB0aGUgRE5BIHRvIHVuY29pbCBhbmQgYmVjb21lIGF2YWlsYWJsZSBmb3IgdHJhbnNjcmlwdGlvbi4=[Qq]
[q] In the diagram below, which LETTER is showing euchromatin?
[textentry single_char=”true”]
[c]IE I=[Qq]
[f]IE5pY2Ugam9iLiBCIGlzIHNob3dpbmcgZXVjaHJvbWF0aW4u[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLg==[Qq]
[c]ICo=[Qq]
[f]IE5vLiBMb29rIGZvciBhIGxldHRlciB0aGF0JiM4MjE3O3MgYXNzb2NpYXRlZCB3aXRoIGxvb3NlbHkgY29pbGVkIEROQS4=[Qq]
[q] In the diagram below, which LETTER is showing heterochromatin?
[textentry single_char=”true”]
[c]IE E=[Qq]
[f]IE5pY2Ugam9iLiAmIzgyMjA7QSYjODIyMTsgaXMgdGlnaHRseSBwYWNrZWQgaGV0ZXJvY2hyb21hdGluLg==[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IFNvcnJ5LCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBMb29rIGZvciBhIGxldHRlciB0aGF0JiM4MjE3O3MgYXNzb2NpYXRlZCB3aXRoIHRpZ2h0bHkgY29pbGVkIEROQS4=[Qq]
[q] In the diagram below, which number represents methyl groups?
[textentry single_char=”true”]
[c]ID Q=[Qq]
[f]IE5pY2UuICYjODIyMDs0JiM4MjIxOyByZXByZXNlbnRzIG1ldGh5bCBncm91cHMu[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBMb29rIGZvciBhIG51bWJlciBpbmRpY2F0aW5nIHNvbWV0aGluZyB0aGF0IGNoZW1pY2FsbHkgbW9kaWZpZXMgRE5BIGFuZCBoaXN0b25lIHByb3RlaW5zIGluIGEgd2F5IHRoYXQgY2F1c2VzIEROQSB0byBiZWNvbWUgdGlnaHRseSBwYWNrZWQgaGV0ZXJvY2hyb21hdGluLg==[Qq]
[q] In the diagram below, which number represents an acetyl group?
[textentry single_char=”true”]
[c]ID Y=[Qq]
[f]IE5pY2UuICYjODIyMDs2JiM4MjIxOyByZXByZXNlbnRzIGFjZXR5bCBncm91cHMuIEFjZXR5bCBncm91cHMgbW9kaWZ5IGhpc3RvbmVzIGluIGEgd2F5IHRoYXQgY2F1c2VzIEROQSB0byB1bmNvaWwsIG1ha2luZyBnZW5lcyBhdmFpbGFibGUgZm9yIHRyYW5zY3JpcHRpb24u[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IFNvcnJ5LCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50OiBhY2V0eWwgZ3JvdXBzIG1vZGlmeSBoaXN0b25lJiM4MjE3O3MgaW4gYSB3YXkgdGhhdCBhbGxvd3MgRE5BIHRvIHVuY29pbCwgbWFraW5nIGdlbmVzIGF2YWlsYWJsZSBmb3IgdHJhbnNjcmlwdGlvbi4=[Qq]
[q] The functional group associated with silencing DNA is the [hangman] group.
[c]IG1ldGh5bA==[Qq]
[q] In female mammals, one of the two X chromosomes in every cell becomes deactivated, and can be seen as a piece of [hangman] called a [hangman]body.
[c]IGhldGVyb2Nocm9tYXRpbg==[Qq]
[c]IGJhcnI=[Qq]
[q] The functional group associated with activating DNA so that it can be transcribed is the [hangman] group.
[c]IGFjZXR5bA==[Qq]
[/qwiz]
4.2. Control of Gene Expression through Transcription
6. Quiz: Eukaryotic RNA Processing and Control of Eukaryotic Transcription
[qwiz random = “true” style=”width: 650px !important; min-height: 400px !important;” ]
[h]Eukaryotic RNA Processing
[i]
[q] In the diagram below, letters “a” and “b” both represent [hangman] elements, which are binding sites within an [hangman].
[c]Y29udHJvbA==
[c]ZW5oYW5jZXI=[Qq]
[q] In the diagram below, which letter indicates intron DNA (don’t worry about superscripts)?
[textentry single_char=”true”]
[c]IG U=[Qq]
[f]IE5pY2Ugam9iLiBUaGUgaW50cm9uIEROQSAoYXQgJiM4MjIwO2UmIzgyMjE7KSBiZWNvbWVzIFJOQSBpbiB0aGUgcHJlLVJOQSwgYnV0IHRoZW4gY3V0cyBjdXQgb3V0IGFzIG1STkEgaXMgZm9ybWVkLg==[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLsKgVGhlIGludHJvbiBETkEgY29kZXMgZm9yIFJOQSB0aGF0IGdldHMgY3V0IG91dCBvZiB0aGUgcHJlLVJOQSBiZWZvcmUgaXQgZ2V0cyBtYWRlIGludG8gbVJOQS4gJiM4MjIwO0YmIzgyMjE7IHJlcHJlc2VudHMgdHdvIFJOQSBzZWdtZW50cyB0aGF0IGhhdmUgYmVlbiBjdXQgb3V0JiM4MjMwO3NvIGp1c3Qgd29yayB1cCBmcm9tIHRoZXJlIGFuZCB5b3UmIzgyMTc7bGwgaGF2ZSB0aGUgYW5zd2VyLsKg[Qq]
[q] In the diagram below, pre-mRNA (still with introns) is represented by the number
[textentry single_char=”true”]
[c]ID I=[Qq]
[f]IEF3ZXNvbWUuICYjODIyMDsyJiM4MjIxOyBpcyBwcmUtbVJOQS4=[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBTcGxpY2VkIG91dCBSTkEgaW50cm9ucyBjYW4gYmUgc2VlbiBhdCAmIzgyMjA7Zi4mIzgyMjE7IA==TG9vayBmb3IgUk5BIHRoYXQgc3RpbGwgY29udGFpbnMgaW50cm9ucy7CoA==wqA=[Qq]
[q] In the diagram below, messenger RNA is represented by the number
[textentry single_char=”true”]
[c]ID M=[Qq]
[f]IEdvb2Qgd29yay4gJiM4MjIwOzMmIzgyMjE7IGlzIG1lc3NlbmdlciBSTkEu[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBSTkEgaW50cm9ucyBjYW4gYmUgc2VlbiBpbiBudW1iZXLCoCAmIzgyMjA7Mi4mIzgyMjE7IA==TG9vayBmb3IgUk5BIGluIHdoaWNoIHRoZSBpbnRyb25zIGhhdmUgYmVlbiBzcGxpY2VkIG91dC4=[Qq]
[q] In the diagram below, the protective, 5′ GTP cap is at
[textentry single_char=”true”]
[c]IG c=[Qq]
[f]IEV4Y2VsbGVudC4gJiM4MjIwO0cmIzgyMjE7IGlzIHRoZSA1JiM4MjQyOyBHVFAgY2FwLg==[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBHVFAgaXMgYXR0YWNoZWQgdG8gbVJOQSwgYW5kIGl0IGhhcyAzIHBob3NwaGF0ZSBncm91cHMuwqA=[Qq]
[q]In the diagram below, which number represents eukaryotic transcription and translation?
[textentry single_char=”true”]
[c]ID I=[Qq]
[f]IEV4Y2VsbGVudC4gJiM4MjIwOzImIzgyMjE7IGlzIGV1a2FyeW90aWMgdHJhbnNjcmlwdGlvbiBhbmQgdHJhbnNsYXRpb24u[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBSZW1lbWJlciB0aGF0IGluIGV1a2FyeW90ZXMsIFJOQSBoYXMgdG8gYmUgcHJvY2Vzc2VkIGJlZm9yZSBpdCBjYW4gYmUgdHJhbnNsYXRlZC4gSW4gcHJva2FyeW90ZXMsIHRoYXQmIzgyMTc7cyBub3QgbmVjZXNzYXJ5LsKg[Qq]
[q]In the diagram below, which number represents pre-mRNA?
[textentry single_char=”true”]
[c]IG I=[Qq]
[f]IEV4Y2VsbGVudC4gJiM4MjIwO2ImIzgyMjE7IGlzIHByZS1tUk5BLg==[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBQcmUtbVJOQSBjb250YWlucyBpbnRyb25zIGFuZCBsYWNrcyBhIDUmIzgyNDI7IGNhcCBhbmQgYSBwb2x5LUEgdGFpbC7CoA==[Qq]
[q labels = “top”]
[l]introns
[f*] Excellent!
[fx] No. Please try again.
[l]mRNA
[f*] Correct!
[fx] No. Please try again.
[l]poly-A tail
[f*] Great!
[fx] No, that’s not correct. Please try again.
[l]pre-mRNA
[f*] Good!
[fx] No. Please try again.
[q labels = “top”]
[l]Alternative splicing
[f*] Great!
[fx] No. Please try again.
[l]pre-mRNA
[f*] Great!
[fx] No, that’s not correct. Please try again.
[l]transcription
[f*] Excellent!
[fx] No, that’s not correct. Please try again.
[l]translation
[f*] Great!
[fx] No. Please try again.
[q multiple_choice=”true”] Which of the statements below most closely matches what’s being depicted in the following diagram?
[c]IEV2ZXJ5IEROQSBnZW5lIGhhcyBvbmUgY29ycmVzcG9uZGluZyBwcm90ZWluIHByb2R1Y3Qu[Qq]
[f]IE5vLiBMb29rIGF0ICYjODIyMDtELCYjODIyMTsgJiM4MjIwO0UsJiM4MjIxOyBhbmQgJiM4MjIwO0YsJiM4MjIxOyBhYm92ZS4gVGhyZWUgcHJvdGVpbnMgY29tZSBmcm9tIG9uZSBnZW5lLg==[Qq]
[c]IE11bHRpcGxlIHByb3RlaW5zIGNhbiBiZS Bwcm9kdWNlZCBmcm9tIG9uZSBnZW5lLg==[Qq]
[f]IEV4YWN0bHkuIEJ5IHNodWZmbGluZyBvciBkZWxldGluZyBleG9ucywgYWx0ZXJuYXRpdmUgc3BsaWNpbmcgYWxsb3dzIG11bHRpcGxlIHByb3RlaW5zIHRvIGJlIGNyZWF0ZWQgZnJvbSBvbmUgY29kaW5nIEROQS4=[Qq]
[c]IFByb2thcnlvdGVzIGhhdmUgbW9yZSBmbGV4aWJpbGl0eSBpbiBob3cgZ2VuZXMgYXJlIGV4cHJlc3NlZCB0aGFuIGRvIGV1a2FyeW90ZXM=[Qq]
[f]IE5vLiBUaGF0JiM4MjE3O3MgcHJvYmFibHkgbm90IHRydWUgKGp1c3QgY29uc2lkZXIgdGhlIGFsdGVybmF0aXZlIHNwbGljaW5nIHNob3duIGFib3ZlKSwgYW5kLCBpdCYjODIxNztzIG5vdCBkZXBpY3RlZCBpbiB0aGUgaW1hZ2UgYWJvdmUu[Qq]
[c]TW9kaWZpY2F0aW9uIG9mIEROQSBmcm9tIGNlbGwgdG8gY2VsbCB3aXRoaW4gYSBldWthcnlvdGljIG9yZ2FuaXNtIGNhbiBlbmhhbmNlIHBoZW5vdHlwaWMgZGl2ZXJzaXR5Lg==[Qq]
[f]Tm8uIE5vdGUgdGhhdCBpdCYjODIxNztzIG5vdCB0aGUgRE5BIHRoYXQmIzgyMTc7cyBiZWluZyBtb2RpZmllZC4gVGhlIG1vZGlmaWNhdGlvbiBvY2N1cnMgYWZ0ZXIgdHJhbnNjcmlwdGlvbiwgYW5kIGl0IGludm9sdmVzIFJOQS4=[Qq]
[q] In the diagram below, 5 is a general [hangman] factor.
[c]IHRyYW5zY3JpcHRpb24=[Qq]
[f]IEdyZWF0IQ==[Qq]
[q] In the diagram below, number 2 is a [hangman] box.
[c]IFRBVEE=[Qq]
[f]IEdyZWF0IQ==[Qq]
[q] In the diagram below, number 1 is the [hangman].
[c]IHByb21vdGVy[Qq]
[f]IEdvb2Qh[Qq]
[q] In the diagram below, numbers 5, 6, and 7, arrayed at a gene’s promoter, is called a(n) [hangman] initiation complex.
[c]IHRyYW5zY3JpcHRpb24=[Qq]
[f]IEV4Y2VsbGVudCE=[Qq]
[q] In the diagram below, the three DNA elements indicated by “a” together make up an [hangman]. Another word for this same structure is a regulatory [hangman].
[c]IGVuaGFuY2Vy[Qq]
[f]IEV4Y2VsbGVudCE=[Qq]
[c]IHN3aXRjaA==[Qq]
[f]IEdyZWF0IQ==[Qq]
[q] In the diagram below, the two deleted RNA segments labeled as f1 and f2 must be [hangman]. Once these are removed (and a few other modifications are made), the result (shown at “3”) is [hangman] RNA.
[c]IGludHJvbnM=[Qq]
[f]IEV4Y2VsbGVudCE=[Qq]
[c]IG1lc3Nlbmdlcg==[Qq]
[f]IEV4Y2VsbGVudCE=[Qq]
[q] In the diagram below, “c” is a control element. Letter “a” is an [hangman]. The molecule that’s binding with “c” is an [hangman].
[c]IGVuaGFuY2Vy[Qq]
[f]IEV4Y2VsbGVudCE=[Qq]
[c]IGFjdGl2YXRvcg==[Qq]
[f]IEV4Y2VsbGVudCE=[Qq]
[q] In the diagram below, “d” is the [hangman]. Letter “f” is a DNA [hangman] protein. Letter “g” is a group of mediator proteins, and “h” is a group of general [hangman] factors. When all of these assemble on the promoter, RNA [hangman] can finally bind and transcribe the gene.
[c]IHByb21vdGVy[Qq]
[f]IENvcnJlY3Qh[Qq]
[c]IGJlbmRpbmc=[Qq]
[f]IENvcnJlY3Qh[Qq]
[c]IHRyYW5zY3JpcHRpb24=[Qq]
[f]IEdvb2Qh[Qq]
[c]IHBvbHltZXJhc2U=[Qq]
[f]IEdyZWF0IQ==[Qq]
[q labels = “top”]
[l]Activators
[fx] No. Please try again.
[f*] Good!
[l]Control Elements
[fx] No. Please try again.
[f*] Good!
[l]DNA Bending protein
[fx] No. Please try again.
[f*] Correct!
[l]Enhancer
[fx] No, that’s not correct. Please try again.
[f*] Correct!
[l]Mediator Proteins and Transcription Factors
[fx] No. Please try again.
[f*] Great!
[l]Promoter
[fx] No. Please try again.
[f*] Good!
[l]RNA polymerase
[fx] No, that’s not correct. Please try again.
[f*] Great!
[x][restart]
[/qwiz]
4.3. Coordinated Control of Gene Expression
Reading the passage below will help you on the following quiz:
How plants coordinate a variety of genes in response to drought-induced stress
One example of coordinated gene expression involves how plants respond to stress induced by drought. To survive, plants must produce a variety of proteins simultaneously.
To do this, inactive transcription factors (shown at “a”, below) have to respond to stress by changing to an activated form (at “b”). This activation may involve phosphorylation or another type of conformational change.
Once activated, these transcription factors will bind with any promoter that has, as part of its structure, a matching regulatory nucleotide sequence. In the diagram above, you can see three genes, each of which has a promoter (d) containing what’s called a “dehydration response element” (indicated by “c”). The binding of the transcription factor with this element allows RNA polymerase (g) to bind, producing each gene’s RNA (at “e”). This mRNA then gets translated into a variety of proteins (at “f”).
[qwiz random = “true” style=”width: 650px !important; min-height: 400px !important;”]
[h]Coordinated Control of Eukaryotic Transcription
[q] In the diagram below, the stress is drought. The drought response element is indicated by
[textentry single_char=”true”]
[c]IG M=[Qq]
[f]IE5pY2Ugam9iLiBUaGUgZHJvdWdodCByZXNwb25zZSBlbGVtZW50IGlzIGluZGljYXRlZCBieSAmIzgyMjA7Yy4mIzgyMjE7[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBJdCYjODIxNztzIHBhcnQgb2YgdGhlIHByb21vdGVyIHJlZ2lvbiBvZiB0aGUgZ2VuZXMuwqA=[Qq]
[q] In the diagram below, an activated transcription factor is represented by
[textentry single_char=”true”]
[c]IG I=[Qq]
[f]IE5pY2Ugam9iISBMZXR0ZXIgJiM4MjIwO2ImIzgyMjE7IGluZGljYXRlcyBhbiBhY3RpdmF0ZWQgdHJhbnNjcmlwdGlvbiBmYWN0b3Iu[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBUaGUgYWN0aXZhdGVkIHRyYW5zY3JpcHRpb24gZmFjdG9yIGNhbiBiaW5kIHdpdGggKG9yIG5lYXIpIHRoZSBwcm9tb3RlciByZWdpb24u[Qq]
[q] In the diagram below, RNA polymerase is represented by
[textentry single_char=”true”]
[c]IG c=[Qq]
[f]IEV4Y2VsbGVudCEgUk5BIHBvbHltZXJhc2UgaXMgcmVwcmVzZW50ZWQgYnkgJiM4MjIwO2cuJiM4MjIxOw==[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IFNvcnJ5LCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBUaGUgYWN0aXZhdGVkIHRyYW5zY3JpcHRpb24gZmFjdG9yIGNhbiBiaW5kIHdpdGggKG9yIG5lYXIpIHRoZSBwcm9tb3RlciByZWdpb24u[Qq]
[q] In the diagram below, messenger RNA is represented by
[textentry single_char=”true”]
[c]IG U=[Qq]
[f]IEV4Y2VsbGVudCEgTWVzc2VuZ2VyIFJOQSBpcyByZXByZXNlbnRlZCBieSAmIzgyMjA7ZS4mIzgyMjE7[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLg==[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBMZXR0ZXIgJiM4MjIwO2cmIzgyMjE7IHJlcHJlc2VudHMgUk5BIHBvbHltZXJhc2UmIzgyMTc7cyByb2xlLiBJdCB0cmFuc2NyaWJlcyBETkEgaW50byBSTkEuIElmICYjODIyMDtnJiM4MjIxOyBpcyBSTkEgcG9seW1lcmFzZSwgdGhlbiBtUk5BIG11c3QgYmUgJiM4MjMwOw==[Qq]
[q] In the diagram below, estrogen would be
[textentry single_char=”true”]
[c]IE Y=[Qq]
[f]IENvcnJlY3QhICYjODIyMDtGJiM4MjIxOyByZXByZXNlbnRzIGVzdHJvZ2VuLg==[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBMb29rIGZvciBhIGhvcm1vbmUgdGhhdCYjODIxNztzIGNvbWluZyBmcm9tIG91dHNpZGUgdGhlIGNlbGwsIHRoZW4gZGlmZnVzaW5nIGludG8gdGhlIGN5dG9wbGFzbSB0aHJvdWdoIHRoZSBjZWxsIG1lbWJyYW5lLg==[Qq]
[q] In the diagram below, a mobile estrogen receptor before it has bound to estrogen would be represented by
[textentry single_char=”true”]
[c]IE c=[Qq]
[f]IENvcnJlY3QhICYjODIyMDtHJiM4MjIxOyByZXByZXNlbnRzIGEgbW9iaWxlIGVzdHJvZ2VuIHJlY2VwdG9yIGJlZm9yZSBpdCBiaW5kcyB3aXRoIGVzdHJvZ2VuLg==[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBMb29rIGZvciBhIHJlY2VwdG9yIHRoYXQgY2FuIGJpbmQgd2l0aCBlc3Ryb2dlbiAod2hpY2ggaXMgcmVwcmVzZW50ZWQgYnkgJiM4MjIwO0YuJiM4MjIxOyk=[Qq]
[q] In the diagram below, which letter represents the estrogen-receptor complex acting as a transcription factor?
[textentry single_char=”true”]
[c]IG k=[Qq]
[f]IENvcnJlY3QhICYjODIyMDtJJiM4MjIxOyBzaG93cyBhbiBlc3Ryb2dlbi9yZWNlcHRvciBjb21wbGV4IGludGVyYWN0aW5nIHdpdGggRE5BLCBhY3RpbmcgYXMgYSB0cmFuc2NyaXB0aW9uIGZhY3Rvci4=[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IFNvcnJ5LCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBMb29rIGZvciBhIHJlY2VwdG9yIGJvdW5kIHRvIGVzdHJvZ2VuLCBpbnRlcmFjdGluZyB3aXRoIEROQS4=[Qq]
[q] In the diagram below, which letter represents the part that’s translating the transcription product into protein?
[textentry single_char=”true”]
[c]IE w=[Qq]
[f]IENvcnJlY3QhIExldHRlciAmIzgyMjA7TCYjODIyMTsgc2hvd3MgYSByaWJvc29tZS4gdGhlIHJpYm9zb21lIGlzIHRyYW5zbGF0aW5nIFJOQSAodGhlIHRyYW5zY3JpcHRpb24gcHJvZHVjdCkgaW50byBwcm90ZWlu[Qq]
[c]IEVudGVyIHdvcmQ=[Qq]
[f]IFNvcnJ5LCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3Qu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBUaGUgdHJhbnNjcmlwdGlvbiBwcm9kdWN0IGlzIFJOQSAoZmlyc3Qgc2hvd24gYXQgJiM4MjIwO0smIzgyMjE7KS4gV2hhdCYjODIxNztzIHRyYW5zbGF0aW5nIHRoZSBSTkEgaW50byBwcm90ZWluPw==[Qq]
[q] A key idea represented below is that the action of genes can be [hangman] if these genes share common [hangman] sequences.
[c]IGNvb3JkaW5hdGVk[Qq]
[c]IHJlZ3VsYXRvcnk=[Qq]
[x][restart]
[/qwiz]
4.4. Post-transcriptional control of gene expression through micro-RNAs
[qwiz]
[h] RNA Interference
[q multiple_choice=”true”]
[l]miRNA
[f*] Excellent!
[fx] No. Please try again.
[l]mRNA degradation
[f*] Great!
[fx] No, that’s not correct. Please try again.
[l]DNA
[f*] Good!
[fx] No, that’s not correct. Please try again.
[l]precursor miRNA
[f*] Good!
[fx] No. Please try again.
[l]Blocked translation
[f*] Good!
[fx] No. Please try again.
[q multiple_choice=”true”] The type of RNA with a regulatory function is
[c]IG1STkE=[Qq]
[f]IE5vLiBtUk5BIGlzIG1lc3NlbmdlciBSTkEuIEl0IGdldHMgdHJhbnNsYXRlZCBpbnRvIHByb3RlaW4u[Qq]
[c]IG1p Uk5B[Qq]
[f]IENvcnJlY3QuIG1pUk5BIGlzIG1pY3JvUk5BLCBhbmQgaXRzIHJvbGUgaXMgcmVndWxhdGluZyB0cmFuc2xhdGlvbi4=[Qq]
[c]IHRSTkE=[Qq]
[f]IE5vLiB0Uk5BIGlzIHRyYW5zZmVyIFJOQS4gSXRzIHJvbGUgaXMgdG8gYnJpbmcgYW1pbm8gYWNpZHMgdG8gdGhlIHJpYm9zb21lIGR1cmluZyBwcm90ZWluIHN5bnRoZXNpcy4=[Qq]
[q] In the diagram below, the RNA-induced silencing complex is represented by the letter
[textentry single_char=”true”]
[c]IE k=[Qq]
[f]IE5pY2UhICYjODIyMDtJJiM4MjIxOyByZXByZXNlbnRzIHRoZSBSTkEtaW5kdWNlZCBzaWxlbmNpbmcgY29tcGxleC4=[Qq]
[c]ICo=[Qq]
[f]IE5vLiBGaW5kIG1pUk5BIHRoYXQmIzgyMTc7cyBhdHRhY2hlZCB0byBhIHByb3RlaW4sIHdoaWNoIGlzIGluIHR1cm4gYXR0YWNoZWQgdG8gdGhlIHJpYm9zb21lLg==[Qq]
[q] In the diagram below, the RNA-induced silencing complex is represented by the letter
[textentry single_char=”true”]
[c]IE k=[Qq]
[f]IE5pY2UhICYjODIyMDtJJiM4MjIxOyByZXByZXNlbnRzIHRoZSBSTkEtaW5kdWNlZCBzaWxlbmNpbmcgY29tcGxleC4=[Qq]
[c]ICo=[Qq]
[f]IE5vLiBGaW5kIG1pUk5BIHRoYXQmIzgyMTc7cyBhdHRhY2hlZCB0byBhIHByb3RlaW4sIHdoaWNoIGlzIGluIHR1cm4gYXR0YWNoZWQgdG8gdGhlIHJpYm9zb21lLg==[Qq]
[q] In the diagram below, a silenced ribosome is represented by the letter
[textentry single_char=”true”]
[c]IE Y=[Qq]
[f]IEdvb2Qgam9iISAmIzgyMjA7RiYjODIyMTsgcmVwcmVzZW50cyBhIHJpYm9zb21lIHRoYXQmIzgyMTc7cyBiZWVuIHNpbGVuY2VkIGJ5IFJOQSBpbnRlcmZlcmVuY2Uu[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBJbiB0aGlzIGRpYWdyYW0sIG1STkEgaXMgcmVwcmVzZW50ZWQgYXMgYSBibHVlLCBzaW5nbGUgc3RyYW5kLiBXaGF0JiM4MjE3O3MgJiM4MjIwO3JlYWRpbmcmIzgyMjE7IHRoZSBtUk5BPw==[Qq]
[q]The phenomenon shown below is called [hangman] [hangman].
[c]Uk5B[Qq]
[c]aW50ZXJmZXJlbmNl[Qq]
[q]The molecule shown at “E” is called an [hangman] (use an abbreviation, like “tRNA”).
[c]bWlSTkE=[Qq]
[q] In the diagram below, mature miRNA is represented by the letter
[textentry single_char=”true”]
[c]IE U=[Qq]
[f]IEF3ZXNvbWUhICYjODIyMDtFJiM4MjIxOyByZXByZXNlbnRzIGEgbWF0dXJlIG1pUk5BLCByZWFkeSB0byBmb3JtIGFuIFJOQS1pbmR1Y2VkIHNpbGVuY2luZyBjb21wbGV4IGFuZCBibG9jayB0cmFuc2xhdGlvbi4=[Qq]
[c]ICo=[Qq]
[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBJbiB0aGlzIGRpYWdyYW0sIHByZS1taVJOQSBpcyByZXByZXNlbnRlZCBieSB0aGUgbGV0dGVyICYjODIyMDtDLiYjODIyMTsgV2hpY2ggbGV0dGVyIHdvdWxkIHNob3cgYSBwcm9jZXNzZWQgZm9ybSBvZiAmIzgyMjA7Qz8mIzgyMjE7[Qq]
[/qwiz]
What’s Next?
Please proceed to our next tutorial: Mutation