Energy and Enzymes

Question 1

metabolism

Answer 1

sum of all chemical reactions in one organism

extract energy from nutrients

synthesize or breakdown molecules

Question 2

catabolism

Answer 2

reactions that release energy by breaking down molecules (exergonic)

Question 3

anabolism

Answer 3

reactions that require energy to build molecules *endergonic

Question 4

energy

Answer 4

capacity to do work

Question 5

chemical work

Answer 5

making and breaking chemical bonds, building and breaking molecules

Question 6

kinetic work

Answer 6

move ion, molecules, large stuff in and out of the cell, move a cell through a tissue of the body

Question 7

kinetic energy

Answer 7

energy of motion

ex: moving Na+ across the membrane down its concentration gradient
rolling a ball down a hill

Question 8

potential energy

Answer 8

stored energy aka energy that’s about to happen

ex: ball poised at the top of the hill
disequilibrium of Na+ ready to move down its concentration gradient

Question 9

thermal energy

Answer 9

heat

Question 10

chemical energy

Answer 10

potential energy in food or storage molecules

Question 11

energy transformations

Answer 11

constant changes of energy from one form to another

potential energy–>kinetic energy
chemical energy –>thermal energy

Question 12

thermodynamics

Answer 12

study of energy transformations

Question 13

1st law

Answer 13

energy can be neither created nor destroyed just converted from one form to another

Question 14

2nd law

Answer 14

every energy transfer or transformation increases entropy

Question 15

entropy

Answer 15

energy lost when trying to convert from one form to another

results in unusable energy

Question 16

intermediates

Answer 16

molecules involved in reactions that have many steps

A+B–>C–>D–>E

Question 17

exergonic reaction

Answer 17

when you break a bond, energy is released

Question 18

endergonic reaction

Answer 18

when you make a new bond, energy is required

Question 19

where do we get energy for endergonic reactions?

Answer 19

o we can couple an endergonic and exergonic reaction at the same place/time. Use energy from one to fuel the other
o we can store energy as potential energy in electrons carried on nucleotides (NADH, FADH2)
o These energy transfer molecules carry the energy until it can be used in the ADP-ATP conversion
o Side note: ATP forms the bridge between endergonic and exergonic reactions

Question 20

Cellular reactions

Answer 20

• Often reversible
o Often different enzymes are required for each direction-another level of control!
o Either catabolic or anabolic
o A+b←→C +D

Question 21

activation energy

Answer 21

energy needed to start a reaction

energy required to bring two molecules close together

Question 22

enzymes

Answer 22

proteins that catalyze or speed up reactions

Question 23

substrate

Answer 23

ligand

molecule that the enzyme acts on

Question 24

co-factor

Answer 24

another binding partner that may control the enzyme

enzymes get too powerful so in order to maintain homeostasis so we need a co-factor to control enzyme activity

keep enzyme inactive, activate when needed

Question 25

active site

Answer 25

grooves or pockets in the 3-D protein where enzymes bind their substrates

made up of amino acids

Question 26

enzyme-substrate complex

Answer 26

a temporary molecule including the enzyme and substrates

Question 27

steps to catalyze a reaction

Answer 27

o Enzyme binds substrate forms enzyme-substrate complex
• A temporary molecule including the enzyme and substrates
o Chemical reaction occurs—enzyme is not bound to product
o Enzyme releases product
• E+S→ES→EP→E+P
• Lactase and lactose form a lactose-lactase complex, then forms an enzyme product complex, then it will release them back into their monomers
o While enzyme is bound, it cannot produce more substrate

Question 28

enzyme function

Answer 28

• Each enzyme molecule has a single active site
• Once a substrate molecule is bound, the active site is “taken” temporarily
• At the end of the reaction, the products are released and the enzyme is ready to bind to a new substrate

Question 29

turnover number

Answer 29

number of molecules of substrate that the enzyme can process per second

all enzymes have it

Question 30

turnover number is determined by its

Answer 30

affinity

Question 31

affinity

Answer 31

strength that a protein has towards its ligand

enzyme has towards its substrate

Question 32

more molecules will be passed if your affinity is

Answer 32

LOWER

Question 33

binding

Answer 33

occurs when a set of noncovalent interactions tie the proteins together

Question 34

affinity proteins

Answer 34

hemoglobin
can bind CO2, H+, and CO
has a stronger affinity for CO than O2

Question 35

if affinity is stronger

Answer 35

turnover rate decreases

Question 36

an active site will demonstrate more specificity and a higher affinity for its ligand when

Answer 36

the site of interaction is more complex

Question 37

inhibitor

Answer 37

if an inhibitor has a higher affinity for the enzyme than the substrate, there will be a powerful inhibition

Question 38

affinity of the enzyme for its substrate determines

Answer 38

turnover number

Question 39

saturation

Answer 39

what happens when an enzyme is operating at its turnover number

reached when each molecule is bound to a substrate and you cannot increase the rate of reaction

Question 40

competitive inhibitor

Answer 40

something that binds to a substrate’s active site

both molecules are competing for that active site

Question 41

allosteric inhibitor

Answer 41

binds to a separate site enzyme, which changes the shape of the substrate active site so substrate can no longer bind

low affinity

Question 42

competitive inhibition

Answer 42

both the inhibitor and the substrate bind to the same active site

due to turnover number, this reduces enzyme activity

if binding of inhibitor has higher affinity than substrate, this can eliminate enzyme activity

Question 43

beta blockers

Answer 43

• Binds to the epinephrine receptor and blocks it
• Has a higher affinity than epinephrine
• Reduces the rate at which our cells can bind to epinephrine
• Effects: lowers heart rate
• Nervous effects don’t happen
• Tamoxifen

Question 44

feedback inhibition

Answer 44

product of the pathway acts as an inhibitor to the first steps of the pathway

ex: • Highlevel of testosterone, it inhibits the first enzyme, leads to fewer testosterone molecules being produced
• When we fall short with testosterone, it unhibits and then the regular amount of testosterone will continue to be produced

Question 45

phosphorylation

Answer 45

addition of a phosphate group

Question 46

kinases

Answer 46

enzymes that add phosphate groups

Question 47

phosphatases

Answer 47

enzymes that remove phosphate groups

Question 48

lysozyme

Answer 48

o Cuts polysaccharide chains on bacterial cell walls by hydrolysis
o These chains are relatively stable until lysozyme binds and bends the substrate, altering the molecular shape and making it vulnerable to water