Biochemistry

Question 1

How are enzyme affinity and Km related?

Answer 1

As Km increases, enzyme affinity decreases

Question 2

How do you determine carbohydrate configuration?

Answer 2

Locate the highest number stereocenter and determine if it is R or S.

R = D sugar

S = L sugar

Question 3

Define active and passive transport.

Answer 3

Active is transport against a concentration gradient and passive is with a concentration gradient.

Question 4

What are fatty acids degraded to during Beta oxidation and what is their fate?

Answer 4

Fatty acids are degraded to acetyl CoA which then enter the citric cycle

Question 5

What are catalytic turnover and catalytic efficiency with respect to K_m and k_cat?

Answer 5

Catalytic turnover is the rate at which an enzyme-bound substrate is converted into a product.

Higher k_cat = higher turnover

Enzyme efficiency is a measure of enzyme specificity and indicates the rate of catalysis at low [S].

Enzyme efficiency = k_cat/K_m

Question 6

Where in the cell do fatty acid oxidation and synthesis occur?

Answer 6

• Fatty acid oxidation occurs int he mitochondria where it undergoes beta-oxidation.
• Fatty acid synthesis occurs int he cytosol when excess acetyl-CoA is converted into malonyl-CoA and then linked to other acyl units to form fatty acids.

Question 7

What are the general steps of the localized inflammatory response?

Answer 7

Phospholipase enzymes release arachidonic acid which through several steps is converted to prostaglandin. Prostaglandin then acts as autocrine and paracrine signals.

Question 8

Which nucleotides are purines?

Answer 8

Adenine and Guanine

Question 9

Which nucleotides are pyrimidines?

Answer 9

Cytosine, Thymine, Uracil

Question 10

What happens to disulfide bonds in oxidizing and reducing environments?

Answer 10

Disulfide bonds are formed in oxidizing environments and broken in reducing environments.

Question 11

Which enzymes in the pentose phosphate pathway produce NADPH?

Answer 11

Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase

Question 12

What are the 3 assumptions for Michaelis- Menten kinetics?

Answer 12

• Free ligand approximation: [S] is constant
• Steady State: [ES] remains constant
• Irreversibility

These 3 assumptions mean that during an experiment only the initial rate should be used for each [S] and that all [S] should be much larger than [E].

Question 13

How many atoms are in the rings of ketoses and aldoses?

Answer 13

Ketoses are 5 member rings and aldoses are 6 member rings.