Lecture 14

Question 1

Uses of energy in living things

Answer 1

1. movement
2. metabolism
3. response to stimuli

Question 2

Energy undergoes transitions in forms

Answer 2

1. potential energy
2. kinetic energy
3. mechanical, chemical, electrical

Question 3

Properties of energy

Answer 3

1. first law of thermodynamics

2. second law of thermodynamics

Question 4

first law of thermodynamics

Answer 4

1. total energy remains constant in a closed system

2. energy cannot be created or destroyed

Question 5

second law of thermodynamics

Answer 5

1. in an isolated system, any change causes the quantity of concentrated, useful energy to decrease
2. energy is converted from more useful to less useful forms
3. organization of matter and energy

Question 6

organization of matter and energy

Answer 6

1. concentrated energy is more ordered (complex) chemically

2. entropy

Question 7

Entropy

Answer 7

all processes in an isolated system result in an increase in randomness

Question 8

Free energy

Answer 8

the portions of a system’s energy that is able to perform work when temperature is uniform throughout the system

Question 9

what does free energy provide

Answer 9

a criterion for measuring spontaneity of a system

Question 10

Where is energy stored in

Answer 10

the chemical bonds of biological molecules

dehydration synthesis

Question 11

How is this stored energy released so work can be accomplished

Answer 11

hydrolysis reaction

Question 12

What are energy releasing chemical reactions

Answer 12

exergonic

Question 13

exergonic chemical reactions

Answer 13

1. high energy reactants -> low energy products

Question 14

Endergonic reactions

Answer 14

low energy reactants -> high energy products

Question 15

A cell does three main kinds of work

Answer 15

1. mechanical
2. transport
3. chemical

Question 16

mechanical work

Answer 16

1. beating of cilia
2. contraction of muscle cells
3. movement of chromosomes

Question 17

transport work

Answer 17

pumping substances across membranes against the direction of spontaneous movement

Question 18

chemical work

Answer 18

driving endergonic reactions such as the synthesis of polymers from monomers

Question 19

In most cases, what is the immediate source of energy that powers cellular work

Answer 19

ATP

Question 20

ATP

Answer 20

a type of nucleotide consisting of the nitrogenous base adenine, the sugar ribose, and a chain of three phosphate groups

Question 21

How can the bonds between phosephate groups be broken

Answer 21

by hydrolysis

Question 22

What does the hydrolysis of the end phosphate group form

Answer 22

adenosine diphosphate

Question 23

what does the hydrolysis of the end phosphate group release

Answer 23

7.3 kcal of energy per mole of ATP under stnadard conditions

Question 24

ATP ->

Answer 24

ADP + Pi

Question 25

ATP is a renewable resource

Answer 25

adding a PO4- group to ADP

Question 26

ATP adding a PO4- group to ADP

Answer 26

catabolic reactions in the cell provide energy for addition

Question 27

In a working muscle cell the entire pool of ATP is recycled once each minute

Answer 27

over 10 million ATP consumed and regenerated per second per cell

Question 28

Whad does regeneratio, an endergonic process, require

Answer 28

an investment of energy: delta G = 7.3 kcal/mol

Question 29

What do chemical reactions in living organisms need to be

Answer 29

catalyzed

Question 30

catalyst

Answer 30

a chemical agent that changes the rate of a reaction without being consumed by the reaction

Question 31

enzyme

Answer 31

a catalytic protein

Question 32

What do enzymes regulate

Answer 32

the movement of molecules through metabolic pathways

Question 33

Activation energy

Answer 33

the amount of energy necessary to push the reactants over an energy barrier

Question 34

at the summit of activation energy

Answer 34

the molecules are at an unstable point, a transition state

Question 35

The difference between free energy of the products and the free energy of the reactants

Answer 35

delta G

Question 36

Enxyme speed reactions by lowering EA

Answer 36

the transition state can then be reached even at moderate temperatures

Question 37

Enzymes do not grange delta G

Answer 37

1. it hastens reactions that would occur eventually | 2. enzyme selectivity etermines which chemical processes occurs

Question 38

Enzyme regulation

Answer 38

1. synthesis 2. active/inactive forms 3. feedback inhibition 4. allosteric regulation 5. competitive inhibition 6. non-competitive inhibitors 7. cofactors 8. cooperativity

Question 39

feedback inhibition

Answer 39

metabolic pathway is turned off by its end product

Question 40

the end product of feedback inhibition

Answer 40

acts as an inhibitor of an enzyme in the pathway

Question 41

if the product of feedback inhibition is abundant

Answer 41

the pathway is turned off

Question 42

if the product of feedback inhibition is rare

Answer 42

the pathway is active

Question 43

what has a major impact on reaction rate

Answer 43

temperature

Question 44

as temperature increases...

Answer 44

collisions between substrates and active sites occur more frequently as molecules move faster

Question 45

each enzyme has an...

Answer 45

optimal temperature

Question 46

what also influences shape and therefor reaction rate

Answer 46

pH

Question 47

optimal pH for most enzymes

Answer 47

6-8