Quiz 4

Question 1

Definition: Heme

Answer 1

• Cofactors in many different proteins

- The most important hemes are: hemoglobin, myoglobin and cytochromes

Question 2

Definition: Cytochromes

Answer 2

Electron transfer proteins involved in metabolism

Question 3

Definition: Porphyrin

Answer 3

• The ring that surrounds the iron ion in a heme

- May be covalently attached via chemical groups to the protein backbone

Question 4

What is allostery?

Answer 4

-It is when a protein has multiple binding sites, and if a ligand binds to the first site (the allosteric site) and it changes the conformation of the protein, this is allostery

Question 5

Lock and key hypothesis

Answer 5

Enzymes and the molecules that they interact with are generally a perfect fit for each other in order to make sure that there is a high specificity

Question 6

Induced fit hypothesis

Answer 6

Upon initial binding, enzymes undergo some level of modification to optimize interaction

Question 7

True or false: Enzymes change the position of equillibrium

Answer 7

False - Enzymes just increase the rate of change. The ratio of change of X to Y and Y to X stay the same

Question 8

True or false: As K’eq becomes larger, the more positive Delta G’o becomes

Answer 8

False - As K’eq becomes larger, Delta G’o becomes more negative (and therefore a more favorable reaction)

Question 9

As Ka becomes (larger/smaller), the binding affinity increases

Answer 9

Larger

Question 10

As Kd becomes (larger/smaller), the binding affinity increases

Answer 10

Smaller

Question 11

What is myoglobin’s main function?

Answer 11

It is an excellent storer of oxygen, and provides oxygen to cells in low-oxygen conditions

Question 12

What is hemoglobin’s main function?

Answer 12

It transports oxygen. It becomes saturated in the lungs and is the primary source of oxygen for cells– easily gives it up to any cell needing it