Fundamentals Of Biochemical Rxns Flashcards Preview

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Flashcards in Fundamentals Of Biochemical Rxns Deck (66):
1

Release energy

Exergonic

2

Consume energy

Endergonic

3

A series of biochemical reactions

Metabolism

4

DeltaG = 0

Equilibrium

5

DeltaG < 0

Spontaneous; exergonic/energy producing

6

DeltaG > 0

Non-spontaneous; endergonic/energy consuming

7

Keq = ?

Ratio of product to substrate

8

Keq dependent on concentration of products & reactants

Le Chatelier’s Principle

9

Most important type of reaction to preserve life

Acid-base

10

Normal body pH = ?

7.37 - 7.43

11

DeltaG’ = ?

-RTlnKeq

12

When ATP breaks down into ADP + Pi, how much energy is released? (Same as thioester)

-7.3 kcal/mol

13

When ATP breaks down to AMP and PPi, how much energy is released?

-10.99 kcal/mol

14

When PPi is broken down, how much energy is produced?

-4.0 kcal/mol

15

Endergonic reaction coupled to exergonic reaction to make the former happen; must share a common intermediate

Coupled reactions (input of energy)

16

The first 3 steps of _____ are coupled and irreversible rxns controlled by mass action

Glycolysis

17

Transfer of an atom to a multiple bond or elimination of an atom to form a multiple bond

Addition/elimination reaction

18

Replacement of a functional group with another

Substitution reaction

19

Shifting of a functional group within a molecule

Rearrangement reaction

20

Transfer of an electron from one molecule to another

Oxidation-reduction reactions

21

Involve molecules that donate protons (acids) and accept protons (bases)

Acid-base reactions

22

Loses a proton

Conjugate base

23

Gains a proton

Conjugate acid

24

The kidneys remove H+ from blood in the form of ____ and reabsorb HCO3-

NH4+

25

Blood pH < 7.37

Acidosis

26

Hypoventilation leads to an increase in the concentration of CO2 in blood, called respiratory acidosis. This shifts the reaction to the:

Left

27

Hyperventilation leads to a decrease in the concentration of CO2 in the blood. As a result, the reaction shifts to the:

Right

28

How do enzymes increase reaction rate?

They lower the activation energy for the reaction

They DO NOT alter DeltaG

29

Transfer electrons from a donor (reducing agent) to an acceptor (oxidizing agent)

ex: lactate dehydrogenase

Oxidoreductases

30

What are 6 examples of oxidoreductases?

Dehydrogenase, oxidases, peroxidases, reductases, monooxygenases, dioxygenases

31

Transfer a functional group between molecules

Transferases

32

Rearrange/isomerize molecules

Isomerases

33

Add or remove atoms to or from a double bond

Lyases (synthases)

34

Form C-O, C-S, C-N, or C-C bonds with the hydrolysis of ATP

Ligases (synthetases)

35

Cleave bonds via the addition of water

Hydrolases

36

Substrate is a perfect fit for active site

Lock and key hypothesis

37

Binding induces conformational changes in active site

Induced fit hypothesis

38

Metal ions, essential trace elements, interact with enzyme via noncovalent interaction and stabilize the active site

Cofactors

39

Small organic molecules, derived from vitamins

Can be co-substrates or prosthetic

Coenzymes

40

Cytochrome c oxidase, ferroxidase, superoxide disputable, lysyl oxidase, and tyrosinase all have ___ as a metal ion

Cu

41

Heme proteins cytochromes, catalases, and peroxidases all have ____ as a metal ion

Fe

42

ATPases, adenylate cyclase, and kinases all have ___ as a metal ion

Mg

43

Glutathione peroxidase uses ____ as a metal ion

Se

44

Superoxide disputable, collagenase, alcohol dehydrogenase, alkaline phosphate, transcription factors, and carbonic anhydrase all have ____ as a metal ion

Zn

45

This protein requires both Copper (Cu) and Zinc (Zn)

Superoxide dismutase (antioxidant): binds the free radical of molecular oxygen

46

Temporary association

Ex: NAD+ ..loosely associated, leaves in a changed form (NADH, reduced; also reverse)

Co-substrate

47

Permanent association; almost a part of the enzyme

Ex: FAD, FMN, heme

Prosthetic

48

What is the ideal temp for enzymes?

37 degrees C

49

What is the ideal pH for enzymes?

4-8

EXCEPT gastric enzymes such as pepsin

50

Phosphorylation and dephosphorylation are both examples of:

Covalent modifications

51

Pumps H+ into lumen where it combines with Cl- to form HCl

Found in parietal cells lining gastric lumen

Proton pump

52

Proton pump inhibitors may cause

Hypochlorhydria

53

Resemble substrate; compete with substrate binding by binding to active site; can be overcome by increasing the substrate concentration

Competitive inhibitor

54

Binds to E and ES (enzyme-substrate intermediate) at site other than substrate binding site

Non-competitive inhibitor

55

Only binds to ES complex; site other than substrate binding site

Uncompetitive inhibition

56

In competitive inhibition, what happens to Vmax and Km?

There is no effect on Vmax

Km increases (decreased affinity because the active site is blocked)

There is also a larger substrate concentration needed to achieve 1/2Vmax

57

In non-competitive inhibition, what happens to Vmax and Km?

Vmax decreases because the reaction is not proceeding

Km is unchanged because the active site is still available

58

In uncompetitive inhibition, whaat happens to Vmax and Km?

Vmax and Km decrease by the same factor

59

How are metalloenzymes inhibited?

The cofactors (like Mg2+ and Zn2+) are chelated

Chelating agent ex: ethylene diamine tetraacetic acid (EDTA)

60

Describe chelating agents for lead poisoning

Lead is involved in heme biosynthesis....heme is a conenzyme for hemoglobin. Lead poisoning is treated by administering EDTA-CA with dimercoprol; lead has a higher affinity for EDTA than Ca does, so it displaces it and binds to the EDTA. Then, this is excreted out

61

Destruction or covalent modification of the key functional groups of amino acids in an enzyme; irreversible loss of function

Enzyme inactivation

62

In enzyme inactivation, what happens to Vmax and Km?

There is a decrease in Vmax

Km is unchanged

THIS IS THE SAME AS NON-COMPETITIVE INHIBITION

63

Activity modulated by noncovalent binding of a metabolite to a site other than the catalytic site; affects substrate binding by inducing conformational changes

Usually r/t the first reaction or rate limiting step

Last product usually negative effector; “feedback inhibition”

Alllosteric enzymes

64

Same catalytic function, different primary sequence

Include markers of MI such as CK-MB, AST, LDH-1, although these are nonspecific

Isozymes

65

A protein complex which is pertinent to heart muscle contraction

Ca2+ binding causes a conformational change, transmitted to tropomyosin, allowing myosin to bind to actin filaments —> muscle contraction

Max sensitivity 10-24 hours after onset of acute MI

CTn-1

Troponin

66

Inactive precursor of enzyme; need proselytizing breakdown (cleavage of a specific peptide bond) to become active

Form of enzyme regulation: we don’t want digestive enzymes to be chewing up things all over our body, but rather want them to become active when there is food to digest

Proenzymes (zymogen)