Exam 2

Question 1

Cofactors may be

Answer 1

Metal ions or organic molecules referred to as coenzymes

Question 2

Understand that an enzyme affects the free energy along the path of a chemical rxn…

Answer 2

But not the overall free energy change

Question 3

What parameter on the free energy profile of a rxn is altered by a catalyst such as an enzyme?

Answer 3

The activation energy

Question 4

The enzyme has a higher affinity for the transition state intermediate than…

Answer 4

The substrate and will bind the transition state intermediate more tightly than the substrate

Question 5

Enzyme complementary to substrate

Answer 5

Change in G cat > change in G uncat

Question 6

Enzyme complementary to transition state

Answer 6

Change in G cat < change in G uncat

Question 7

General acid base catalysis

Answer 7

Proton transfer

Question 8

Specific acid base catalysis

Answer 8

Using the H in H30 for acid and H in OH for base

Question 9

Metal ion catalysis and the three roles

Answer 9

Na, K, and Mg, Mn, Cu, Zn, Fe, Ni
1. Orienting a substrate into the active site by coordination
2. Polarizing a bond and/or stabilizing a negatively charged intermediate
3. Assisting in reversible oxidation-reduction reactions.

Question 10

Covalent catalysis

Answer 10

Tetrahedral intermediate
Nucleophile
Electrophile

Question 11

Nucleophiles

Answer 11

Partial negative charge looking for positive charge like -O, -S, -C, -N, hydroxide ion

Question 12

Electrophiles

Answer 12

Partial positive looking for negative charge like carbon atom of a carbonyl group double bonded to oxygen, a proton (H)

Question 13

Rate = v = k[A]1

Answer 13

First order reaction

Question 14

What is the kinetic effect of the enzyme on a reaction?

Answer 14

Speeds up the reaction

Question 15

V = k [A][B] is what order reaction

Answer 15

1+1 =2 (if there’s no number, assume 1)

Question 16

V=k (what order reaction and what does it look like?)

Answer 16

Zero order
Straight line

Question 17

V=k[A] (what order reaction and what does it look like?)

Answer 17

First order
Straight line upwards

Question 18

V=k[A][B] (what order reaction and what does it look like?)

Answer 18

Second order
Curved line upwards

Question 19

Km is the substrate concentration

Answer 19

That produces an initial rate of 1/2 Vmax

Question 20

The larger the Km…and example

Answer 20

Weaker the binding affinity
Km= 100uM

Question 21

Strongest burning Km affinity

Answer 21

Km is low (1uM)

Question 22

R-X irreversible inhibitor

Answer 22

Forms covalent/ionic interactions with enzyme and renders the enzyme permanently inactive

Question 23

Competitive inhibition

Answer 23

Inhibitor competes with the substrate for an active site

Question 24

Uncompetitive inhibition

Answer 24

The inhibitor combines only with ES and not with the free enzyme

Question 25

Non competitive inhibition

Answer 25

Usually interacts with both the E and the ES complex

Question 26

Carbohydrates

Answer 26

Compounds that have aldehyde or ketone function groups and multiple hydroxyl groups

Question 27

Aldehyde has

Answer 27

C double bonded to O with 1 R group and H

Question 28

Ketone has

Answer 28

A C double bonded to O with two R groups attached

Question 29

Aldotriose (what branch and how many carbons)

Answer 29

Aldoses Three carbons

Question 30

Aldotetrose

Answer 30

Aldoses 4 carbons

Question 31

Ketotetrose

Answer 31

Ketoses 4 carbons

Question 32

When OH is pointing up it’s in what form

Answer 32

Beta form

Question 33

When OH is pointing down it’s in what form

Answer 33

Alpha form

Question 34

Pyrannose

Answer 34

5 carbons

Question 35

Furanoses

Answer 35

4 carbons

Question 36

Chitin has what linkage

Answer 36

Beta (1-4)

Question 37

Starch has what linkage

Answer 37

Alpha (1-4) with a reducing end and non reducing end

Question 38

Amylopectin has 1 branch

Answer 38

Every 25th glucose (low) Alpha (1-6 branch) glycosidic linkage Alpha (1-4 branch) main chain of glucose Plants

Question 39

Glycogen has 1 branch

Answer 39

For every 10th glucose (high) Alpha (1-6) in branching Alpha (1-4) in main chain Animals

Question 40

Glycoproteins

Answer 40

Proteins that have covalent bonded carbohydrate units attached to them 1. Proteins with attached carbohydrates 2. Carbohydrates are monosacc 3. Can have o glycosidic bonds to Ser/Thr 4. Can have n glycosidic bonds to Asn

Question 41

Covalent linkages between carbohydrates has 2 types of bonds

Answer 41

O glycosidic bonds between hydroxyl groups and serine/threonine N-glycosidic bonds between side chain amide nitrogen of asparagine

Question 42

Glycosaminoglycans

Answer 42

1. Repeating disaccharide units 2. Negatively charged Uronate or Sulfer ester

Question 43

Proteoglycans

Answer 43

1. Proteins with attached glycosaminoglycans (negative) 5. The trisaccharide linker (Gal-Gal-Xyl) is attached to Ser via an O glycosidic bond