Lecture 7: enzyme structure and function

Question 1

Enzymes

Answer 1

a class of protein that catalyze specific chemical reactions

Question 2

chemical reaction

Answer 2

the breaking and making of chemical bonds leading to changes in the composition matter

Question 3

forms of energy in Biology

Answer 3

potential energy of position

kinetic energy of motion aka cellular work

Question 4

Potential energy of position

Answer 4

• covalent chemical bonds
• concentration gradients
• electrical charge differences

Question 5

kinetic energy of motion aka cellular work

Answer 5

• active transport of molecules across a membrane
• chemical reactions that reorganize matter into higher energy states
• mechanical motion of items

Question 6

Types of cellular work

Answer 6

transport work
mechanical work
chemical work

Question 7

phosphoanghydride bond

Answer 7

(of ATP) releases energy that powers cellular work

Question 8

metabolism

Answer 8

the sum total of all chemical reactions occurring in a biological system

Question 9

anabolic reactions

Answer 9

join simple molecules to form more complex ones, endergonic, require energy to form higher energy products

Question 10

catabolic reactions

Answer 10

break down complex molecules, exergonic, release stored energy in the reactants

Question 11

ATP is a…

Answer 11

RNA nucleotide

Question 12

what is required to initiate an energy releasing chemical reaction, like the combustion of Methane?

Answer 12

energy

Question 13

energy barrier

Answer 13

(aka activation energy) inhibits exergonic reactions

Question 14

How do enzymes catalyze reactions?

Answer 14

by lowering the activation energy

Question 15

What changes the shape of enzymes?

Answer 15

interactions between substrates and enzymes

Question 16

Which interactions are sensitive to pH, temperature, and force and why?

Answer 16

hydrogen bonding, ionic bonds, and hydrophobic interactions

because they are weak bonds

Question 17

enzyme active sites have….

Answer 17

specific patterns of shape and charge that bind with the substrate

Question 18

cofactors

Answer 18

inorganic ions that bind to enzymes and initiate transition state molecule

Question 19

coenzymes

Answer 19

adds or removes chemical groups from enzymes

Question 20

prosthetic groups

Answer 20

covalently bond non-amino acids components of enzymes

Question 21

rate of reaction w/o enzymes

Answer 21

-the reaction rate without enzymes is directly proportional to the concentration of the substrate

Question 22

rate of reaction w/ an enzyme

Answer 22

once the reaction rate with an enzyme reaches a maximum, the rate is unaffected by increased concentration of the substrate

Question 23

on a reaction rate graph, where is the rate of the reaction equal to zero?

Answer 23

at the origin

Question 24

Collision Theory

Answer 24

as the density of the substrate increases, the rate of the reaction increases due to the collisions

Question 25

graph of rate of reaction / enzyme concentration

Answer 25

directly proportional

Question 26

point of saturation

Answer 26

the point at which adding more concentration does not affect reaction rate

Question 27

rate of reaction =

Answer 27

amount of product/time

Question 28

amount of product/time graph

Answer 28

• the slope of the line is equal to 0 at 0% substrate

- the rate of reaction is about equal at the highest substrate concentrations

Question 29

enzyme denaturation

Answer 29

after an optimal temperature, when temperate is increased, non covalent bonds break and the activity of the enzyme decreases

Question 30

irreversible inhibition

Answer 30

1. inhibitor covalently binds to side chain in the active site
2. the enzyme is permanently inactivated

Question 31

reversible chemical inhibitors

Answer 31

• noncompetitive

- competitive

Question 32

competitive inhibitors

Answer 32

• slow the rate of reaction by occupying active sites of enzymes
• competes with natural substrate for active sites
• as substrate concentration increases, the active site becomes saturated with the substrate and the effect of the inhibitor is decreased

Question 33

noncompetitive inhibitor

Answer 33

• binds at a site distinct from the active site

- this causes allosteric change in the shape of the enzyme that decreases the maximum enzyme function

Question 34

allosteric regulation

Answer 34

• changes the shape of the enzyme
  1. phorsphylation: covalent addition of phosphate group (kinase)
  2. non-covalent binding of other molecules at regulatory site

Question 35

2 classes of enzymes

Answer 35

1. kinase- covalently binds phosphate

2. phosphatase- removes phosphate group