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Sai_BiochemFinal > L8 Enzymes > Flashcards

L8 Enzymes Flashcards

1
Q

Enzymes work on biological molecules in 3 ways:

A
  1. Anabolism
  2. Catabolism
  3. Rearrange atoms/ molecules (enantiomers and chiral formations
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2
Q

Enzymes catalyze biological reactions in 2 ways:

A

Specificity and reaction rate

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3
Q

Catalysts work to lower the ______ _____ of chemical reactions, thus accelerating the ______ _______

A

activation energy; reaction rate

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4
Q

What is a substrate?

A

A molecule that will be worked on by an enzyme (starch is the substrate of amylase enzymes)

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5
Q

Drugs and herbs fool the specificity of enzymes by causing ____ ______ of the active site

A

competitive inhibition

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6
Q

Enzymes are made of _____ and incorporate _____ (coenzymes, vitamins, porphyrins, mineral ions) and _____

A

proteins; cofactors; rRNA

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7
Q

(T/F) Enzymes are usually globular in shape

A

true son

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8
Q

Tertiary structures of enzymes include at least one _____ ____ where molecules fit and are transformed

A

active site

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9
Q

Some enzymes do not use ATP because they:

A

Rearrange molecules in orientation, instead of breaking and fusing bonds

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10
Q

Enzyme activity is affected by external factors (6)

A
  1. Presence/ absence of substrates
  2. pH change or other ionic factors
  3. Temp change
  4. Availability of nutrients: ATP, cofactors, coenzymes, ions
  5. Functionality of enzyme
  6. Competitive inhibition of active site (drugs, herbs, etc)
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11
Q

“-ase” indicates:

A

enzyme

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12
Q

Enzymes that remove molecules or atoms from substrates

A

Oxidoreductases

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13
Q

Enzyme that transfers functional groups from one molecule to another, such as moving a phosphate group

A

Transferases

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14
Q

Enzyme that adds water to substreates

A

Hydrolases

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15
Q

Enzymes that work with double bonds

A

Lyases

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16
Q

Enzymes that change the isomeric status of a molecule

A

Isomerases

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17
Q

Enzymes that join or release carbon bonds and requires ATP

A

Ligases

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18
Q

What kind of pathway?

  1. Substrate enters active site of enzyme
  2. Enzyme changes shape as substrate binds
  3. Catalysis
  4. Products leave active site of enzyme
A

Catabolic

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19
Q

A common way that drugs or other molecules stop enzymatic fx is called:

A

Competitive inhibition

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20
Q

Orderly chain of events facilitated by different enzymes:

A

enzyme cascade

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21
Q

Many enzymes are dependent for proper function on non-protein molecules called ________

A

cofactors

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22
Q

An enzyme that does not have its coenzymes present and is NOT functional

A

apoenzyme

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23
Q

An enzyme that has coenzymes present and is fully functioning:

A

holoenzyme

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24
Q

Cofactor is a non-________ molecule that has either a tight or loose affinity to an enzyme and is required for _______ reaction

A

protein; enzymatic

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25
Q

What are the two type of cofactors

A
  1. Prosthetic

2. Coenzymes

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26
Q

What are the 3 most common types of prosthetic groups?

A

Porphyrins, vitamins, metallic ions

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27
Q

What groups are often the limiting factors in nutrition and energy generation that can slow the overall metabolism?

A

Prosthetic groups (esp. porphyrins, vitamins, metallic ions)

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28
Q

Deficiency in vitamins and minerals slow the overall mineral metabolism in organism because:

A

Cellular enzymes revert back to apoenzyme status

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29
Q

Pyruvate dehydrogenase is an example of a:

A

vitamin prosthetic group

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30
Q

Pyruvate dehydrogenase is a _-domain enzyme used to eventually make _ _ _ from _ _

A

6; acetyl coenzyme A; pyruvic acid

31
Q

Pyruvate dehydrogenase is made of:

A
  1. Vitamin B1 (Cofactor thiamine pyrophosphate [TPP])
  2. Magnesium ion
  3. Potassium ions
32
Q

Coenzymes are called ________ b/c they act to donate a part of themselves like a substrate to a reaction happening in an active site

A

cosubstrates

33
Q

These cofactors are rapidly consumed, renewed, and reused

A

Coenzymes

34
Q

2 coenzymes used repeatedly in production of ATP in mitochondrion

A
  1. NAD/NADH or nicotinamide adenine dinucleotide

2. Acetyl coenzyme A (ACA)

35
Q

_ vitamins play a vital role in energy production and can be a limiting factor in nutrition

A

B vitamins

36
Q

NAD has one component:

A

Niacin- Vitamin B3

37
Q

Acetyl coenzyme A has one component:

A

Pantothenic acid- Vitamin B5

38
Q

Other important coenzymes are: (5)

A

ATP, lipoamine, FAD/FADH, Ubiquinone (coenzyme Q10, S-adenyl methionine (Sam-e)

39
Q

ATP splits off a high energy-bonded phosphate in the _____ sites of enzymes to propel the reaction

A

active

40
Q

Genes coding for enzymes are either ______ or ______ by gene expression factors

A

induced or inhibited

41
Q

If the product produced by an enzyme reaches a plateau concentration, this turns off the enzyme. This is called ___ ___ ___ or __ __

A

Negative feedback loop

Allosteric inhibition

42
Q

Enzymes can be modified by addition or subtraction of ________ groups to make the enzyme active or not (e.g. phosphorylation of enzymes will turn on breakdown of glycogen)

A

functional

43
Q

(T/F) pH can activate/ deactivate enzyme

A

true

44
Q

A pre-active enzyme is called a ____ or ____

A

zymogen or proenzyme

45
Q

____ ____ is the enzyme that reduces glutathione disulfide (GSSG) to the sulfhydryl form (reduced glutathione or GSH)

A

glutathione reductase (GSR)

46
Q

What is the most important cellular antioxidant

A

reduced glutathione (GSH)

47
Q

For every molecule of oxidized glutathione (GSSG), __ molecules of NADPH are required to reduce GSSG to GSH

A

2

48
Q

For every ____ and 2 ____ you gain 2 reduced _____molecules that can act as antioxidants scavenging reactive oxygen species (ROS) in the cell

A

GSSH and NADPH; GSH

49
Q

In RBC, a lack of _____ and ______ will allow oxidants to damage and lyse cells, leading to anemia

A

NADPH and GSH

50
Q

Reactive forms of oxygen, such as ______ leak from mitochondrial respiration enzymes and wreak havoc in cells

A

superoxide

51
Q

Superoxides are:

A

oxygen with extra electron 02 -1

52
Q

This can cause mutations in DNA or attack enzymes that make essential molecules:

A

superoxides

53
Q

Combats superoxides:

A

superoxide dismutase (SOD) an enzyme that detoxifies superoxide

54
Q

SOD (superoxide dismutase) ____ superoxide

A

dismutes (reaction where 2 equal but opposite reactions occur on two separate molecules)

55
Q

SOD takes 2 molecules of superoxide, strips the extra ____ off of one, and places it on the other

A

electron

56
Q

The first oxygen forms normal ____ and the other ends up with an extra electron. The one with extra electron picks up a ___ ____ to form hydrogen peroxide (H202)

A

oxygen; dihydrogen oxide (water)

57
Q

Hydrogen peroxide is a toxic compound and must be ____ by an enzyme to be detoxified

A

catalyzed

58
Q

What is the fastest enzyme discovered?

A

Catalase (converts hydrogen peroxide to water and 02)

59
Q

SOD (superoxide dismutase) mutation is connected with __ ___ __ or __ __

A

amyotrophic lateral sclerosis (ALS)

Lou Gehrig’s disease

60
Q

A degenerative disorder that leads to selective death of motor neurons in the brain/ spinal chord leading to paralysis; occurs later in life; tenth of cases are hereditary

A

Amyotrophic lateral sclerosis (ALS) or Lou Gehrig’s disease

61
Q

A group of hemoprotein enzymes (proteins containing an iron porphyrin ring)

A

Cytochrome P450

62
Q

2 fx of cytochrome P450

A
  1. Oxygenate substrates

2. Pass electrons in aerobic respiraton

63
Q

Cytochromes catalyze a plethora of substrates, and so are:

A

nonspecific

64
Q

Cytochrome P450 are found in all mitochondria, as a part of the ___ __ ___ of __ __

A

electron transport chain

oxidative phosphorylation

65
Q

Cytochrome P450 can also be found in the lumen of __ __ in cells, performing ___ functions

A

endoplasmic reticulum

detoxification

66
Q

Cytchromes are ____-associated proteins located either in the inner membrane (___) of mitochondria or in the ___ ___ of cells

A

membrane
cristae
ER

67
Q

Cytochromes metabolize _____ of endogenous and exogenous compounds

A

thousands

68
Q

Cytochrome P450 enzymes are present in all tissues of the body and play impt roles in: (4)

A
  1. Hormone synthesis/ breakdown
  2. Cholesterol synthesis
  3. Vitamin D synthesis
  4. Detox function of LV
69
Q

The liver detoxifies or metabolizes drugs, toxic compounds, all foods, and metabolic products such as ____ (breakdown product of hemoglobin)

A

bilirubin

70
Q

Many drug side effects are due to overuse or inhibition of cytochrome detoxification potential in LV ___

A

hepatocytes

71
Q

__________ are the major enzymes involved in drug metabolism

A

Cytochromes

72
Q

A lot of drugs can affect cytochromes by ___ or ____

A

induction or inhibition

73
Q

Reduced dosage of medications from too rapid metabolism is called:

A

induction

74
Q

Slow breakdown of drugs, causing overdose

A

Inhibition

Sai_BiochemFinal (6 decks)

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