Chapter 8

Question 1

what does an organisms metabolism do?

Answer 1

an organisms metabolism transforms matter and energy

Question 2

what is metabolism?

Answer 2

the totality of an organism’s chemical reactions, an emergent property of life that arises from orderly interactions between molecules

Question 3

how does a metabolic pathway begin and end and what happens each step?

Answer 3

begins with a specific molecule and ends with a product, is catalyzed for every step by a specific enzyme

Question 4

what are catabolic pathways?

Answer 4

catabolic pathways release energy by breaking down complex molecules into simple compounds

Question 5

what is an example of catabolism?

Answer 5

cellular respiration: the breakdown of glucose in the presence of oxygen

Question 6

what is an anabolic pathway?

Answer 6

anabolic pathways consume energy to build complex molecules from simpler ones

Question 7

what is an example of an anabolic pathway?

Answer 7

synthesis of protein from amino acids

Question 8

define energy

Answer 8

energy is the capacity to cause change and exists in various forms

Question 9

what is thermal energy (heat)

Answer 9

kinetic energy associated with random movement of atoms or molecules

Question 10

what is thermodynamics?

Answer 10

the study of energy transformations

Question 11

what happens in an isolated system?

Answer 11

an isolated system is unable to exchange energy with surroundings

Question 12

what happens in an open system?

Answer 12

energy and matter can be transferred between a system and its surroundings

Question 13

first law of thermodynamics?

Answer 13

energy of the universe is constant, cannot be created or destroyed

Question 14

second law of thermodynamics?

Answer 14

during every energy transfer, some energy is unusable and is lost as heat; it increases the entropy (disorder) of the universe

Question 15

what are spontaneous processes?

Answer 15

spontaneous process dont require energy and can happen quick or slow, they increase entropy of the universe

Question 16

what tells us whether a reaction is spontaneous or not?

Answer 16

free energy change

Question 17

what is free energy change Change in G

Answer 17

a living systems free energy is energy that can do work when temperature and pressure are uniform

Question 18

which processes have a negative G?

Answer 18

spontaneous processes have a negative G

Question 19

what is free energy a measure of?

Answer 19

free energy is a measure of a systems instability, its tendency to change to a more stable state

Question 20

free energy in a spontaneous change?

Answer 20

during a spontaneous change, free energy decreases and stability of a system increases

Question 21

define exergonic reaction

Answer 21

an exergonic reaction proceeds with a net release of free energy and is spontaneous

Question 22

define endergonic reaction

Answer 22

an endergonic reaction absorbs free energy from it surroundings and is nonspontaneous

Question 23

group words together with spontaneous

Answer 23

a spontaneous reaction doesn’t require energy, it is catabolic because catabolic reactions lose energy, they are exergonic because they release free energy, a release of free energy means a -G

Question 24

group words together with nonspontaneous

Answer 24

nonspontaneous reactions require energy, anabolic reactions need energy, they are endergonic because it takes in energy which results in a +G

Question 25

are cells in equilibrium?

Answer 25

no because they are open systems and constantly experience a flow of materials

Question 26

what types of work do cells do?

Answer 26

chemical, transport, mechanical

Question 27

what is energy coupling?

Answer 27

cells managing energy resources by energy coupling, the use of an exergonic process to drive an endergonic one

Question 28

what is ATP

Answer 28

ATP is the cell's energy chuttle

Question 29

what is ATP made of?

Answer 29

ATP is made of a ribose (a sugar), adenine (a nitrogenous base), and 3 phosphate groups

Question 30

when is energy released from ATP?

Answer 30

energy is released from ATP when the terminal phosphate bond is broken

Question 31

what does ATP hydrolysis lead to?

Answer 31

ATP hydrolysis leads to a change in protein shape and binding ability

Question 32

How do enzymes speed up metabolic reactions?

Answer 32

enzymes speed up metabolic reactions by lowering energy barriers

Question 33

what is a catalyst

Answer 33

a chemical agent that speeds up a reaction without being consumed by the reaction

Question 34

what is an enzyme

Answer 34

an enzyme is a catalytic protein

Question 35

What is activation energy?

Answer 35

The initial energy needed to start a chemical reaction is called the free energy of activation

Question 36

what is activation energy often supplied in the form of?

Answer 36

activation energy is often supplied in the form of thermal energy that reactant molecules absorb from their surroundings

Question 37

How do enzymes speed up reactions?

Answer 37

enzymes catalyze reactions by lowering the activation energy barrier

Question 38

do enzymes affect the change in free energy?

Answer 38

no, they just hasten reactions that would have already occurred

Question 39

What is a substrate?

Answer 39

a substrate is the reactant that an enzyme acts on

Question 40

What is an enzyme-substrate complex

Answer 40

when the enzyme binds to its substrate

Question 41

what is the active site?

Answer 41

the active site is the region on the enzyme where the substrate binds

Question 42

what is induced fit?

Answer 42

induced fit of a substrate brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction

Question 43

how can the active site lower the activation energy barrier?

Answer 43

by orienting substrates correctly, straining substrate bonds, providing a favorable microenvironment, and covalently bonding to the substrate

Question 44

What can affect an enzymes activity?

Answer 44

environmental factors such as temperature and pH

Question 45

what do optimal conditions do?

Answer 45

optimal conditions favor the most active shape for the enzyme molecule

Question 46

what are cofactors?

Answer 46

cofactors are nonprotein enzyme helpers

Question 47

what are competitive inhibitors?

Answer 47

competitive inhibitors bind to the active site of an enzyme and compete with a substrate

Question 48

what are noncompetitive inhibitors?

Answer 48

they bind to another part of the enzyme, causing the enzyme to change shape and making the active site less effective

Question 49

what is allosteric regulation?

Answer 49

allosteric regulation may either inhibit or stimulate an enzyme's activity

Question 50

when does allosteric regulation occur?

Answer 50

it occurs when a regulatory molecule binds to a protein at one site and affects the proteins function at another site

Question 51

what are allosterically regulated enzymes made from?

Answer 51

made from polypeptide subunits

Question 52

what does binding an activator do?

Answer 52

stabilizes the active form of the enzyme

Question 53

what does binding an inhibtor do?

Answer 53

binding an inhibitor stabilizes the inactive form of the enzyme

Question 54

what is cooperativity?

Answer 54

a type of allosteric regulation that can amplify enzyme activity