Chapter 4

Question 1

What does metabolism encompass? And what are these reactions interconnected by?

Answer 1

encompasses all chemical reactions, metabolic pathways

Question 2

Why are enzymes crucial to speed reactions to rates that are compatible with life?

Answer 2

metabolic reactions occur spontaneously but too slow or require too much heat.

Question 3

Enzyme def

Answer 3

biological catalysts that lower the activation energy required for reactions

Question 4

https://prnt.sc/K8jZDS1L8hg_
What is each step in the pathway catalyzed by?
And what are most enzymes

Answer 4

specific enzyme, proteins

Question 5

What is this an example of?
https://prnt.sc/2Xpu4HYsUts2

Answer 5

metabolic pathway

Question 6

What does lowering activation energy do?

Answer 6

enzymes increase nb of molecules with enough energy to react.

Question 7

Transition state def

Answer 7

in-between state where old bonds are being broken and new ones being formed

Question 8

Activation energy def

Answer 8

Amount of energy required for reactants to reach transition state

Question 9

Do enzymes change delta g(overall free energy change)?

Answer 9

No

Question 10

Substrate def

Answer 10

the substance on which an enzyme acts

Question 11

Are enzymes consumed or changed in a reaction?

Answer 11

no

Question 12

General formula of enzyme catalyzing substrate

Answer 12

E + S -> ES -> E + products

Question 13

Active Site def

Answer 13

Pocket or groove on the protein’s surface where substrate binds

Question 14

What type of interactions does substrate binding to active site involve?

Answer 14

non-covalent interaction(H-bonds , ionic bonds)

Question 15

Induced fit def

Answer 15

Enzyme changes shape to fit substrate better
- bring amino acid side chains in position
- enfolds the substrates

Question 16

What happens when substrates are converted to products?

Answer 16

Products are released and active site is available

Question 17

Chemical reaction is triggered by what after reactant moves towards enzyme’s active site?

Answer 17

enzyme

Question 18

What are the ways enzymes lower activation energy?

Answer 18

-Hold substrates in correct orientation
- Induced fit can stress the substrate’s chemical bond and stabilize transition state
- Active site provides microenvironment for specific reaction
- Amino acid side chains can participate directly in reaction

Question 19

Explain how holds in correct orientation

Answer 19

Active site binds substrates in a specific way(induced fit model)

Question 20

Explain how induced fit may stress the substrate’s chemical bonds and stabilize transition state

Answer 20

Bond between reactants easier to break in enzyme substrate complex =>less energy required
https://prnt.sc/m56qPMV9jMOO

Question 21

Explain how active site may provide a microenvironment for a specific reaction

Answer 21

Example: providing an acidic environment or create hydrophobic environment

Question 22

Factors that affect reaction rates

Answer 22

-Substrate concentration
- Enzyme concentration
- Environmental condition(temperature and ph)
- Cofactors or coenzymes

Question 23

Explain substrate concentration effect

Answer 23

more substrate molecules = more collisions with enzyme active sites
- Eventually, all active site are occupied

Question 24

Explain enzyme concentration effect

Answer 24

More active sites available, and is linear assuming there is an excess of substrate

Question 25

Explain how temperature effects reaction rate

Answer 25

Temperature increases frequency of collisions between substrate and active site

Question 26

Do enzymes have a most active temperature range? why can't go higher?

Answer 26

Will denature if too high, causing decrease . Yes

Question 27

Temperature def

Answer 27

Average kinetic energy of molecules

Question 28

Picture of how temperature affects. Click reveal

Answer 28

https://prnt.sc/3EAtVxTY28Nz

Question 29

Explain pH effect

Answer 29

There is an optimal range for activity, for most is 6-8

Question 30

How can pH cause enzyme to denature?

Answer 30

extreme pH affects ionization of amino acid side chain

Question 31

Enzyme inhibitor def

Answer 31

the process by which a molecule (an inhibitor) decreases or stops the activity of an enzyme.

Question 32

2 types of inhibition

Answer 32

Irreversible(attaches by covalent linkage) and Reversible(weak,non-covalent bonds)

Question 33

Why is reversible inhibition important? Give an example

Answer 33

Regulate metabolism in our bodies - Ethanol inhibits enzymes during antifreeze poisoning

Question 34

Types of reversible inhibition

Answer 34

competitive and non-competitive

Question 35

Characteristics of competitive inhibitor

Answer 35

Binds to active site and competes with substrate for binding(resembling substrate) https://prnt.sc/3Earai0DnePH

Question 36

How can you overcome a competitive inhibitor?

Answer 36

Increasing substrate concentration

Question 37

Characteristics of non-competitive inhibitor

Answer 37

Binds not on the active site, which then causes enzyme to change shape, no longer bindable https://prnt.sc/BMB2w4_O6PmF

Question 38

Allosteric enzyme def

Answer 38

Enzymes that have more than one binding site(allosteric and catalytic)

Question 39

Purpose of allosteric enzymes

Answer 39

regulation of metabolic pathways

Question 40

conformations of allosteric enzymes

Answer 40

active,inactive

Question 41

Regulator def

Answer 41

Molecule that binds weakly to allosteric site, inhibitor or activator

Question 42

Allosteric site def

Answer 42

Location where regulator binds to enzyme, located where polypeptides join

Question 43

Allosteric activation def

Answer 43

active site becomes available when a regulatory molecules binds to a different site on enzyme.

Question 44

Allosteric deactivation def

Answer 44

Active site becomes unavailable to the substrates (allosteric regulation)

Question 45

What do allosteric activators and inhibitors do

Answer 45

stabilize active or inactive form of enzyme

Question 46

Cooperativity def

Answer 46

Since enzymes have more than one polypeptide, substrate binding to one active site increases substrate binding to other active sites(change shape of all)