Maris Exam 1

Question 1

How are Wnt genes shut off?

Answer 1

Adenomatous polyposis coli (APC) along with active GSK3 and active CK1 bind to unstable beta-catenin and lead to degradation

Question 2

What occurs when Wnt is present?

Answer 2

Binds to its cell receptor, Frizzled, and activates along LRP
Leads to Ck1gamma and GSK3 to bind to active LRP
Dishevelled binds to activated Frizzled and Axin
APC cannot bind to beta-catenin

Question 3

When beta-catenin is stable what occurs?

Answer 3

Translocates into nucleus where it displaces Groucho from LEF1/TCF of transcription of Wnt genes
Initiates transcription with LEF1/TCF

Question 4

What is Km?

Answer 4

The substrate concentration at which the rate of the reaction is halfway to its max
1/2 Vmax

Question 5

What is Vmax?

Answer 5

The fastest possible rate of reaction

Question 6

What is [S]?

Answer 6

Inc the rate of rxn up to a max value

Vmax

Question 7

When [S] increases do does the ______ until ____ is reached.

Answer 7

Rate of rxn, Vmax

Question 8

[S] at 1/2 Vmax is _____.

Answer 8

Km

Question 9

What can [E] do?

Answer 9

Bind to a substrate to allow Vmax to be attained faster and be more active

Question 10

What do motor protein do?

Answer 10

Cause filaments to exert some kind of tension or slide against one another

Question 11

What processes to motor proteins drive?

Answer 11

Muscle contraction
Ciliary binding
Cell division

Question 12

How does Dynein move?

Answer 12

Toward the minus end of the microtubule

Toward from centrosome

Question 13

How does Kinesin move?

Answer 13

Toward the positive end of the microrubule
Away from centrosome
Spindle formation and chromosome segregation

Question 14

Which motor proteins have head with ATPase activity?

Answer 14

Both Dynein and Kinesin

Question 15

What do the tails of motor proteins do?

Answer 15

Bind cargo and go on a microtubule adventure

Question 16

What are is the way splicing occurs?

Answer 16

In each rxn one phosphodiester bond is exchanged for another

Question 17

What is the first step where splicing occurs?

Answer 17

2’-OH of the branch site A attacks the G of the 5’ splice sit
Freed 5’ end of the intron is joined to the A at the branch site

Question 18

What is the second step where splicing occurs?

Answer 18

The newly liberated 3’-OH of the exon attacks the 3’ splice site
The exons are then joined and the introns are liberated in a lariat fashion

Question 19

Is energy consumed in splicing reactions?

Answer 19

No because the number of bonds doesn’t change

Question 20

Does a spliceosome require energy?

Answer 20

Yes a lot!