A pedigree chart showing inheritance of cystic fibrosis.

Here’s a human example. The pedigree chart at left shows  how the boy in the bottom right corner inherited a genetic disease from his parents.  parents in the top row both are both carriers for a genetic disease. Being a carrier means that they have one copy of the gene that causes this disease, but also another normal version of the gene. What’s a gene? It’s a piece of DNA that specifies a trait. Because they each have one normal version of this gene, the parents don’t have the disease, because their cells have that one correct gene which gives them the instructions they need to perform their normal functions. However, each time the parents make egg cells or sperm cells, there’s a one-in-two chance that they’ll pass the gene for the disease on to their offspring.

The disease is called cystic fibrosis: it primarily involves compromised lung function, but it has effects all throughout the body, significantly shortening lifespan. The gene for cystic fibrosis codes for a defective transport protein in cell membranes.

Two of the children in the pedigree above (represented by the half-shaded circle and square on the left of the bottom row) inherited only one copy of the defective gene, so they’re also carriers. One child (represented by the empty circle in the bottom row) inherited two normal versions of the gene. The fourth child (represented by the shaded square on the right) had the bad luck to inherit a defective DNA message from his mother and his father. With two copies of this defective DNA, he’ll suffer from cystic fibrosis.

 CAP labeled diagrams

[qwiz]

[h]Positive Gene Regulation in Prokaryotes: cAMP and CAP

[i]

[q labels = “top”]

 

[l]CAP binding site

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

[f*] Excellent!

[l]Catabolite Activator Protein

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

[f*] Excellent!

[l]glucose

[fx] No. Please try again.

[f*] Excellent!

[l]lactose

[fx] No. Please try again.

[f*] Correct!

[l]operator

[fx] No. Please try again.

[f*] Correct!

[l]Promoter

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

[f*] Excellent!

[l]regulatory gene

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

[f*] Good!

[l]regulatory protein

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

[f*] Excellent!

[l]RNA polymerase

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

[f*] Great!

[l]structural genes

[fx] No. Please try again.

[f*] Correct!

 

 

[q labels = “top”]

 

[l]CAP binding site

[fx] No. Please try again.

[f*] Good!

[l]Catabolite Activator Protein (inactive)

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

[f*] Good!

[l]Catabolite Activator Protein (active)

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

[f*] Great!

[l]lactose

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

[f*] Excellent!

[l]operator

[fx] No. Please try again.

[f*] Excellent!

[l]Promoter

[fx] No. Please try again.

[f*] Good!

[l]regulatory gene

[fx] No. Please try again.

[f*] Correct!

[l]regulatory protein

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

[f*] Great!

[l]RNA polymerase

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

[f*] Great!

[l]structural genes

[fx] No. Please try again.

[f*] Correct!

[l]cAMP

[fx] No. Please try again.

[f*] Great!

[/qwiz]

STOP PASTING HERE

LABELS

[l]CAP binding site

[l]Catabolite Activator Protein

[l]glucose

[l]lactose

[l]operator

[l]Promoter

[l]regulatory gene

[l]regulatory protein

[l]RNA polymerase

[l]structural genes

[qwiz]

[q labels = “top”]

 

[l]CAP binding site

[fx] No. Please try again.

[f*] Good!

[l]Catabolite Activator Protein (inactive)

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

[f*] Good!

[l]Catabolite Activator Protein (active)

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

[f*] Great!

[l]lactose

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

[f*] Excellent!

[l]operator

[fx] No. Please try again.

[f*] Excellent!

[l]Promoter

[fx] No. Please try again.

[f*] Good!

[l]regulatory gene

[fx] No. Please try again.

[f*] Correct!

[l]regulatory protein

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

[f*] Great!

[l]RNA polymerase

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

[f*] Great!

[l]structural genes

[fx] No. Please try again.

[f*] Correct!

[l]cAMP

[fx] No. Please try again.

[f*] Great!

[/qwiz]