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MTC > Enzymes and Energy > Flashcards

Enzymes and Energy Flashcards

MTC wk 5

1
Q

What is enthalpy?

A

heat content

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2
Q

what is change in enthalpy? (delta H)

A

amount of heat absorbed/released during a reaction

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3
Q

What is entropy?

A

the measure of chaos: how much thermal energy per unit of temperature is UNavaliable.

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4
Q

What is the calculation for Gibbs Free Energy?

A

G= enthalpy - Temp x entropy

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5
Q

What is Gibbs Free Energy?

A

Change in free energy

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6
Q

Describe exergonic reactions.

A

The energy of the reactants is higher than the products: energy released

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7
Q

Describe endogonic reactions.

A

The energy of the reactants is lower than the products: energy is added.

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8
Q

How do cells attain energy?

A

from chemical bonds of organic molecules (oxidation)

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9
Q

What is oxidation?

A

removal of electrons from an atom

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10
Q

what is reduction?

A

addition of electrons to an atom

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11
Q

What is a REDOX reaction?

A

The simultaneous occurrence of oxidisation and reduction

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12
Q

What happens to C-H bonds in an oxidization reaction?

A

the number of them decrease

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13
Q

what happens to a C-H bond in reduction?

A

the number of them increase

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14
Q

What are the electron carriers?

A

NADH, NADPH and FADH

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15
Q

What do the electron carriers do and become?

A

Carry hydride ions, pass them onto a donor atom and become oxidised (NAD+, NADH+ and FAD+)

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16
Q

what is the reaction for ATP?

A

ATP + H2O –> ADP + P + free energy

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17
Q

what does ATP do?

A

Captures and transfers free energy by phosphorylating other molecules

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18
Q

is the conversion of ADP –> ATP exo or endergenic?

A

Endergonic

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19
Q

what are the three basic steps of a basic enzyme catalysed reaction?

A

Binding of a substrate- E + S <–> ES

Conversion of bound substrate to bound product ES <–> EP

Release of product EP <–> E + P

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20
Q

What do enzymes lower and what do they NOT change?

A

Lower energy barrier for reactions

final equilibrium and Gibs Free energy does not change

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21
Q

What does Glucokianse catalyse?

A

the transfer of P from ATP to C6 of glucose

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22
Q

What are two general ways that drugs can impact enzymatic activity?

A

Drugs can inhibit or activate it

Alter V or Km

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23
Q

what is the Michaelis-Menten Equations

A

Describes rate of enzymatic reactions by relating reaction rate (V) to substrate concentration (S)

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24
Q

What is Km?

A

Affinity constant

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25
Q

What can sulfa drugs do that impact enzymatic activity?

A

inhibit folic acid synthesis is essential for the metabolism and growth of disease-causing bacteria

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26
Q

What happens to Km and S when competitive inhibition occurs?

A

Increase S= decreased inhibitor action

Km higher

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27
Q

What do Non-competitive inhibitors do to enzymes?

A

react with enzymes and alter its structure and activity.

less activity = slow reaction rate

28
Q

what happens when increase in entropy?

A

increased disorder

29
Q

Describe the nature of catabolic reactions.

A

bonds broken, disorder and negative Gibbs Free Eneregy

30
Q

Describe the nature of anabolic reactions.

A

bonds created, more order and positive Gibbs Free Energy

31
Q

What do you need for a negative Gibbs Free?

A

negative delta H (exergonic)

32
Q

what do you need for a positive Gibbs Free?

A

positive delta H (endergonic)

33
Q

What occurs in Cellular Respiration (reference glucose bonds)

A

Energy in glucose bonds is broken down and used to create other compounds.

6C6h12O6 + 6O2 –> 6CO2 + 6H20 + energy

oxidization

34
Q

What is the difference between NADP+ and NADPH?

A

NADP+ = oxidised form
NADPH = reduced as H added to the nicotinamide ring

35
Q

What is the structure of NADPH?

A

Two phosphates attached to ribose with added H on the nicotinamide ring

36
Q

What is the chemical reaction for Flavin Adenine Dinucleotide.

A

Succinate <-Succinate dehydrogenase-> Fumarate

succinate dehydrogenease= FAD–> FADH2

37
Q

How much can enzymes speed reactions by?

A

10^6 - 10^17

38
Q

How do enzymes lower energy barriers for reactions?

A

bring substarte, coenzyme and metals to enzyme –> change shape

39
Q

Describe the graph that represents Michaelis-Menten Kinetics

A

Reaction rate (v) (vertical axis) vs Substrate concentration

40
Q

What does Km tell us?

A

Concentration of substrate = velocity that is 1/2 maximal velocity

41
Q

what does a low Km tell us?

A

high affinity

42
Q

Decribe the Km of isomers Hexokinase 1 vs Glucokinase (in liver)

A

Hexokinase: Km= 0.05 = high affinity for glucose = low glucose concentartion

glucokinase =Km= 5-6 low affinity for glucose = needs a High glucose concentration

43
Q

what are the units for reaction velocity? (Vmax units)

A

Vmax units = umol/min/mg protein

44
Q

How can we analyse the impact of drugs on enzymes?

A

use lineweaver-burk plots

45
Q

What does the lineweaver-burk plot determine and what is the formula?

A

Determines Km and Vmax

1/v = km/Vmax (1/{s} + 1/Vmax

46
Q

What is the impact of increases [S] in Competitive inhibition?

A

decrease inhibitors actions

47
Q

In competetive inhibition, can the same Vmax be reached with more [S]?

A

Yes

48
Q

Describe what happens to V, Vmax and [S] in non-competitive inhibition.

A

V is lower (slower rate of reaction) = less product
increasing [S] NOT stop inhibition
Vmax desceases

49
Q

What is the impact on Vmax and Km with competitive inhibition?

A

Same Vmax will be met (despite inc [s])

Km will be higher

50
Q

What are allosteric enzymes?

A

enzymes that have an additional binding site for effector molecules. Not an active site.

51
Q

Why are allosteric enzymes important for regulating the entire metabolic pathway?

A

They provide inhibitory and stimulatory responses. So will inhibit to slow down process that are not needed and allow for extra binding sites if need to have an increased reaction.

52
Q

What is the function and common features of a activation-transfere coenzyme?

A

Functions
-participate directly in catalysis by forming a covalent
bond
-
features
Two groups in the coenzyme:
* Forms a covalent bond (functional group)
* Binds tightly to the enzyme (binding group)

53
Q

what is an example of an activation-transfer coenzyme?

A

Thiamine pyrophosphate

54
Q

Where is the highest energy phosphate on ATP found?

A

The bonds between phosphate groups, especially the second and third.

55
Q

Why is there a higher level of glucose but not glycogen in the liver for a patient with a glucokinase mutation?

A

Glucokinase is not functioning correctly = glucose not broken into glycogen correctly = as glycogen is the store of glucose in the blood, the body does not recognise that it has glucose in it. Thus the BG levels will contain to rise rather than raise and plateau.

56
Q

What happens to the Km, Substrate concentration and V-Max in a patient with glucokinase mutation?

A

Km will increase as the body needs a higher substrate concentration to absorb the glucose, and V-max stays the same.

57
Q

What is the importance of Mg2+ in ATP hydrolysis?

A

Activator of hydrolysis and increases metabolic state

58
Q
  1. How can Positive Delta G reactions go in the forward direction
A

high reactants and low product levels

59
Q

What is the name of the enzyme that breaks down alcohol?

A

aldehyde dehydrogenase.

60
Q

what are isozymes and an example?

A

enzymes that catalyze the same type of reaction but are created by different genes and have different molecular shapes.

creatine kinase

61
Q

What is the difference between NADH and NADPH?

A

NADPH has a phosphate group which alters its shape.

NADPH= anabolic (energy added)
NADH= catabolic (energy released)

62
Q

what is the role of thiamine? What can be caused when

A

enzymatic cofactor in alcohol metabolism. heart and over issues

63
Q

What is the highest energy phosphate found in ATP?

A

Alpha and beta phosphate (2nd and 3rd)

64
Q

What promotes the forward direction of glycolysis? (Glucose-6-phosphate –> Glucose 1-phosphate)

A

Delta is positive = non-spontaneous = needs energy

[subrate] high enough and products low enough

65
Q

If the Delta G is negative =

A

spontaneous

66
Q

f delta G is positive =

A

non-spontaneous

67
Q

Which parto of the enzyme catalyst has the product inhibition?

A

first

MTC (14 decks)

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