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Flashcards in Biochemistry Deck (81)
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1

What are the laws of thermodynamics?

1st - energy is neither created or destroyed - just converted from one form to another
2nd - No energy conversion is 100% efficient, some of the produced energy will always be unavailable

2

What are the principles of the following common reactions;
Esterification
Condensation
Hydrolysis

Esterification - Water is a bi-product
Condensation - Water is removed
Hydolysis - Water is added

3

what is meant by entropy?

Randomness/ Disorder
(things tend towards disorder)

4

What are exergonic and endergonic reactions?

An exergonic reaction is one in which the total free energy of the products is less than the total free energy of the reactants. This is a NEGATIVE change and can occur SPONTANEOUSLY.
An endergonic reaction is one in which the total free energy of the products i s more than the total free energy of the reactants. This is a POSITIVE change which REQUIRES ENERGY to proceed.

5

What are the standard conditions?

298K temperature
1 Atmosphere pressure
1M concentration of reactants

6

Are +ve or -ve deltaG changes favourable or unfavourable?

+ve = UNFAVOURABLE
-ve = FAVOURABLE

7

Define the terms glycolysis and glyconeogenesis

GLYCOLYSIS- The breakdown of glucose to generate ATP
GLYCONEOGENESIS - Making glucose from non-carbohydrate sources

8

What is meant by an amphipathic molecule?

It is both hydrophilic and hydrophobic

9

What is Ka

The acid dissociation constant - it measure how readily an acid donates or accepts
The higher the dissociation constant, the stronger the acid

10

What is a buffer solution?

A solution which resists changes in pH when small amounts of acid or alkali are added

11

In which direction is the coding strand synthesised in DNA replication? What direction is the template strand synthesised in?

Coding - 5' to 3' direction
Template - 3' to 5'

12

What are the functions of the following in DNA replication ?
DNA polymerase
Primase
DNA helicase

DNA polymerase - elongates both strands
Primase - synthesises a primer
DNA helicase - unwinds the double helix

13

What is the lagging strand in DNA replication composed of?

Okazaki fragments

14

What is significant about the 'TATA box'?

This is the point at which transcription is about to start

15

What is TBP and what is its function?

It is the TATA box binding protein.
It binds DNA and indicates where transcription should start.

16

What are the 5 important steps during transcription?

RNA polymerase binging
DNA chain separation
Transcription Initiation
Elongation
Termination

17

To which end of the strand is the poly (A) tail added and what is its purpose?

Added to the 3' end - it is added for stability

18

What is Vmax?

The maximum velocity that can possibly be obtained by that enzyme

19

What is Km? What does it mean if this value is high or low?

The amount of substrate that is required for the enzyme to work to 50% of its max
High Km - Lots of substrate is required by the enzyme
Low Km - The enzyme only requires a small amount of substrate

20

In terms of the Lineweaver- Burk plot, describe the slope of the line and where it intersects the x and y axis

The slope = Km/Vmax
Vmax = The intersection with the y axis
Km = The intersection with the x axis

21

How does competitive and non-competitive inhibition affect Vmax and Km?

Competitive inhibition does not change Vmax but varies Km
Non-compeitive inhibition causes Vmax to vary but does not affect Km

22

What is ANABOLISM?

ASSIMILATION OF MOLECULES
REQUIRES ENERGY
= ENDERGONIC AND REDUCTIVE

23

What is CATABOLISM?

BREAKDOWN OF MOLECULES
RELEASES ENERGY
=EXERGONIC AND OXIDATIVE

24

What are the three control points in glycolysis?

Hexokinase - regulates entry of glucose
Phosphofructokinase - regulates rate of flow
Pyruvate kinase - regulates product exit

25

How many times does the TCA cycle turn for each molecule of glucose consumed?

TWICE

26

What effect does a surplus of substrates or products have on the rate of the TCA cycle?

surplus of substrates - accelerated the rate of the TCA cycle
surplus of products - slows the TCA cycle

27

What does the standard redox potential(E'o) of a reduced substance measure?

How readily that substrate donates an electron in comparison with hydrogen

28

Would a higher affinity for electrons than H2 suggest a positive or negative E'o?

POSITIVE

29

Would a lower affinity for electrons than H2 suggest a positive or negative E'o?

NEGATIVE

30

How man molecules of ADP are converted to ATP per glucose molecule in glycolysis?

4