Unit 6a -Metabolism and Enzymes

Question 1

Describe catabolism

Answer 1

• BREAKING DOWN nutrients to smler molecules to produce energy
• energy stored in bonds of ATP molecule, transported where needed

Question 2

Describe anabolism

Answer 2

-BUILDING UP
stored energy is used to assemble new molecules from sm components produced from catabolism

Question 3

What are the storage forms of energy? 3

Answer 3

ATP, NADH, FADH2

Question 4

Describe the 3 stages of catabolism in simplified terms and steps

Answer 4

 Stage 1: the gastrointestinal tract
 digestion in the lumen of the GI tract
 Stage 2: the cytosol
 anaerobic respiration in the cell’s cytosol
 Stage 3: the mitochondria
 aerobic respiration in cell mitochondria

Question 5

Describe catabolism in stage 1

Answer 5

Occurs in GI tract
Food is broken down in stomach, digested contents pass to sm intestine to further break down by enzymes
-hydrolysis
carbs broken down to monosaccs
fats broken to fatty acids + glycerol
proteins broken down to amino acids

Nutrient molecules absorbed by cells that line sm intestine, nutrients pass to blood or lymph, carried to organs/tissue, or to liver for more metabolism

Question 6

Describe catabolic metabolism stage 2

Answer 6

occurs in cytosol
process of anaerobic respir catabolizes nutrients
acetyl coA transported thru cytoplasm to mitocchondria

Question 7

Describe catabolic metabolism stage 3

Answer 7

Occurs in mitochondria
aerobic respir involves attachment of inorganic PO4 to a molecule of ADP to form ATP
ATP used by cell to carry energy
Catabolic pathways of proteins, carbs, and fats transfer energy stored in nutrients to ATP

Question 8

Describe the ATP-ADP cycle

Answer 8

ATP -> Motion Active Transport biosynthesis -> ADP -> Oxidation of fuel molecules -> repeats

Question 9

Describe anabolic metabolism

Answer 9

 A biosynthetic process
 Growing cells need additional proteins:
 for the expanded cell membranes
 to perform many other vital functions
 Replacement molecules must be manufactured continuously
 metabolic turnover

Question 10

Describe dehydration synthesis

Answer 10

Important part of anabolism - the effect is opposite of hydrolysis
-monosaccs assembles to form chains of poly saccs [1 mono + 1 mono = 1 disacc + water]
-fat molecules formed from connection of glycerol + fatty acids
proteins created from chains of amino acids

Question 11

Can an enzyme react with more than one particle? Explain why or why not

Answer 11

no, each enzyme only reacts with 1 molecule (substrate) to produce a new molecule (product)

Question 12

What is an active site?

Answer 12

region of enzyme that binds to the substrate

Question 13

What do enzyme names end in? Are they altered by reactions

Answer 13

-ase, not altered by reactions

Question 14

Give an example of how an enzyme is named. What about transfer enzymes? Explain

Answer 14

Named for substrate it acts upon = lactase breaks down lactose

Transferases move a part of a molecule to another molecule.
EX. phosphotransferasse moves a phosphate group

Question 15

Describe catalytic efficiency of enzymes. Give an example of it

Answer 15

enzymes act as catalyst to speed up reactions by lowering activation energy

increased rate of reaction is essential to life.
EX. CO2, wast product of respiration must be moved out of body. Carbonic anhydrase combines CO2 w/ water to form carbonic acid and bicarbonate ions

Question 16

What is a cofactor? Give examples

Answer 16

Assistance of a nonprotein cofactor in order to complete a reaction.

EX. iron, zinc, copper, magnesium, potassium, calcium ions

Question 17

Describe what co-enzymes are. Give some examples

Answer 17

nonprotein organic molecules that may also ac as cofactors - are often vitamins
may be temp or perma bound to enzyme

EX. nicotinamide Adenine dinucleotide (NAD), acetyle-coenzyme A (acetyl CoA), Flavin adenine dinucleotide (FAD)

Question 18

Bonus: What are the abbreviations for NAD, Acetyle CoA and FAD

Answer 18

nicotinamide Adenine dinucleotide (NAD), acetyle-coenzyme A (acetyl CoA), Flavin adenine dinucleotide (FAD)

Question 19

What factors affect enzyme activity?

Answer 19

Enzyme concen.
Effect rate is directly proportional (/)
Substrate concentration (/-)
Rate increases until enzyme is saturated
Temp [/]
Rate increases until denaturation of enzyme
pH [u but upside down]
Many enzymes max activity at pH near 7, most denature at high pH extremes except pepsin, optimum pH is 1.5

Question 20

What is the name of enzymes affected by temperature?

Answer 20

thermolabile enzymes

Question 21

What is a enzyme inhibitor

Answer 21

any substances that can decrease the rate of an enzyme-catalyzed reaction

Question 22

What are the two categories of enzyme inhibitors/

Answer 22

irreversible + reversible

Question 23

Describe what an irreversible inhibitor is. Give 3 examples

Answer 23

• Forms covalant bond w/ a functional group of the enzyme - renders enzyme inactive

EX. Cyanide ion - blocks mitochondrial e+ transport train, stops aerobic cellular respiration, antidote - Sodium thiosulfate
EX. Heavy metals - murcery + lead, combines with sulfhydryl groups on enzymes to cause neuro damage, treated w/ chelating agents
EX. Antibiotics - Penicillin, inhibits enzymes essential to life processes of bacteria - interferes with transpeptidase needed for bacterial cell wall construction

Question 24

Describe reversible inhibitor

Answer 24

Reversibly binds to an enzyme so it can be removed.

2 types: competitive and noncompetitive

Question 25

Explain what an competitive inhibitor does? What happens? Give an example of one

Answer 25

Competes w/ substrate for binding at active site of enzyme. Reversed by increasing conc of normal substrate. Compete is won by most concentrated molecule

Molecular structure similar to substrate of enzyme

EX. Sulfa drugs - folic acid need by bacteria is synth from p-aminobenzoic acid, resembles sulfanilamid

Sulfanilamide competes for active site = synth of folic acid slowed or stopped, bacteria prevent from multiplying

Question 26

Describe a non competitibe inhibitor. What does it do? give an example of it

Answer 26

Binds to enzyme at location other than normal active site
no resemblance to normal enzyme substrate
interaction causes 3-D shape of enzyme + active site to change
enzyme no longer binds to normal substrate or it binds improperly so reaction is not catalyzed
more substrate does not reverse inhibition

EX. isoleucine feedback inhibitor

Question 27

List the summar of enzyme inhibitor tree

Answer 27

inhibitor
[binds to enzyme] |
irreversible inhibitor | Reversible inhibitor
(cyanides, heavy metals) |
end——————————
[binds to active site] {binds not at active site]
competitive inhibitor Non compete inhibitor
sulfa drugs isoleucine feedback
ethanol inhib

Question 28

What are the three control mechanisms of regulating enzyme activity?

Answer 28

activation of zymogens
allosteric regulation
genetic control

Question 29

Describe what activation of zymogens are

Answer 29

Enzymes may be synthesizes as inactive precursors called zymogems or proenzymes
-stored in inactive state
- when needed zymogen is released and activated @ loc. of reaction
-activation usually involved cleavage of peptide bonds of zymogen

Question 30

List some examples of zymogens and what their function is

Answer 30

Zymogen Active Enzyme Funct
Trypsinogen Trypsin Digest of proteins
Prothrombin thrombin Blood clotting
Proelastase elastase digest of proteins

Question 31

Explain what allosteric regulation is

Answer 31

A combination of enzyme w/ compound that changes 3-d shape - compound called modulator

modulators may be activators to increase activity, inhibitors to decrease activity

Often loc. at key control points in cellular processes

Question 32

Give and explain an example of allosteric regulation

Answer 32

synthesis of isoleucine

5 steps
product isoleucine binds to enzyme at first step, inhibits enzyme activity
no excess isoleucine is produces
when isoleucine lvls lower, enzyme will be more active and more isoleucine synthesized

Question 33

What is feedback inhibition?

Answer 33

a process in which the end product of a pathway inhibits an earlier step in
the process

Question 34

What is enzyme induction? Give an example of it

Answer 34

synthesis of an enzyme in
response to cellular need

Allows an organism to adapt to enviro changes

EX. Regulation of gluconeogenesis
- Activity of PEP carboxykinase increased during fasting, starvation and diabetes mellitus due to enzyme induction by glucagon

Question 35

What can be used to clinically detect cell damage or uncontrolled growth?

Answer 35

Blood serum lvls of specific enzymes

Question 36

List some enzymes in clinical diagnosies? Which ones are important for diagnosing diseases of heart, liver, panceas and bone?

Answer 36

 Alkaline phosphatase – liver or bone disease
 Amylase – pancreatic diseases
 Lipase – acute pancreatitis
 Alanine transaminase – hepatitis
 Aspartate transaminase – hepatitis or heart
attack

Question 37

Describe what an isozyme is

Answer 37

a slightly different form of the same
enzyme produced by different tissues
 Have similar catalytic properties but different
physical properties
 Assays for isozymes can pinpoint location and
type of disease more accurately