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Flashcards in Biochemistry Deck (107)
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1
Q

What is a covalent bond?

A

The sharing of electron pairs

2
Q

What is an ionic bond?

A

Attraction of opposite charges

3
Q

What is a hydrogen bond?

A

Sharing of a hydrogen atom

4
Q

What are Van der Wall interactions?

A

Electron interactions of non-polar substances

5
Q

If an atom is more electronegative is it more or less likely to attract bonded electrons towards it?

A

More likely

6
Q

What is a condensation reaction?

A

When water is removed

7
Q

What is a hydrolysis reaction?

A

When water is added

8
Q

What is lactose made up of?

A

Galactose and glucose

9
Q

What is sucrose made up of?

A

Glucose and fructose

10
Q

Which glucose linkages are found in cellulose?

A

Beta 1,4

11
Q

Which glucose linkages are found in glycogen?

A

Alpha 1,4 and occasionally alpha 1,6

12
Q

Give examples of a disaccharide

A

Lactose, maltose, cellobiose, sucrose

13
Q

Give examples of a polysaccharide

A

cellulose and glycogen

14
Q

First law of thermodynamics

A

Energy is neither created nor destroyed, just converted from one form to another

15
Q

Second law of thermodynamics

A

When energy is converted from one form to another, some energy becomes unavailable to do work

16
Q

What is Gibbs free energy law?

A

ΔG = ΔH - TΔS

17
Q

What is the equation for a change in free energy?

A

ΔG = (Energy of products) - (Energy of reactants)

18
Q

What is enthalpy?

A

Heat content

19
Q

What is entropy?

A

Disorder

20
Q

What is an exergonic reaction?

A

The free energy at the end of the reaction is less than the free energy at the start - energy has left the system

21
Q

What is an endergonic reaction?

A

The free energy available at the end of the reaction is more than at the start

22
Q

Is ΔG in exergonic +ve or -ve?

A

Negative

23
Q

Is ΔG in endergonic +ve or -ve?

A

Positive

24
Q

Catabolism

A

Break down of complex molecules

25
Q

Anabolism

A

Assembly of complex molecules from smaller ones

26
Q

Glycolysis

A

Break down of glucose into pyruvate

27
Q

Gluconeogynesis

A

Makes glucose from pyruvate

28
Q

4 Types of amino acid

A

Non-polar = hydrophobic
Polar = uncharged
Basic
Acidic

29
Q

Acids

A

Proton donators

30
Q

Bases

A

Proton acceptors

31
Q

Zwitterions

A

Amino acids with no net charge

32
Q

What are the two forms of tertiary protein structures?

A

Fibrous - parallel

Globular - spherical shape

33
Q

Interactions present in a tertiary structure

A

Covalent disulphide bridges
Hydrophobic interactions
H-Bonds
Van der Val Forces

34
Q

Which amino acid forms disulphide bridges?

A

Cystine

35
Q

Where does DNA replication and transcription take place?

A

Nucleus

36
Q

Where does translation take place?

A

Cytoplasm

37
Q

Nucleoside

A

Base + sugar

38
Q

Nucleotide

A

Nucleoside + phosphate group

39
Q

Which carbon is the base and phosphate connected to?

A
Base = carbon 1
Phosphate = Carbon 5
40
Q

Purines

A

Adenine and guanine

41
Q

Pyridemines

A

Thymine, uracil and cytosine

42
Q

How many bonds between A and T?

A

2

43
Q

How many bonds between C and G?

A

3

44
Q

What is the catalyst for DNA replication?

A

DNA polymerase

45
Q

Which direction does DNA polymerase work?

A

3’ to 5’ direction

46
Q

What is the most abundant type of RNA?

A

Ribosomal

47
Q

What synthesises all RNA?

A

Pol II

48
Q

Transcription

A

Making an RNA molecule from a DNA molecule template i.e. it synthesises mRNA using Pol II

49
Q

Where is a TATA box usually found?

A

25 nucleotides before transcription starts

50
Q

What is the function of a TATA box binding protein?

A

Provides a landing platform for further transcription factors and RNA polymerase

51
Q

Translation

A

Where the anticodons in tRNA form base pairs with the codons in mRNA - both consist of three nucleotides

52
Q

Degenerate

A

Many codons code for one amino acid

53
Q

Unambiguous

A

Each codon codes for only one amino acid or a stop

54
Q

Which enzyme binds amino acids to their tRNA molecule?

A

Aminoacyl-tRNA synthase

55
Q

What is the initiation tRNA?

A

UAC

56
Q

Stop codons

A

UAA, UAG and UGA

57
Q

Point mutation

A

Change in single base in DNA

58
Q

Silent mutation

A

No effect on protein function

59
Q

What do free ribosomes do?

A

Make proteins for the nucleus, mitochondria, cytosol

60
Q

What do bound ribosomes do?

A

Make proteins for the plasma membrane, ER and golgi body

61
Q

Apoenzyme

A

An enzyme without a co-factor

62
Q

Holoenzyme

A

An enzyme with a co-factor

63
Q

Example of a co-factor

A

zinc, ion, copper (in stable transition state)

64
Q

Isoenzymes

A

Enzymes which both catalyse the same reaction but do it in a slightly different way from each other

65
Q

Phosphorylation

A

Converts enzymes into an active or inactive form

66
Q

Km

A

The substrate conc. where the initial reaction rate is half the maximal

67
Q

Which axis does Km cross?

A

x axis intersection

68
Q

Which axis does Vmax cross?

A

y axis intersection

69
Q

Vmax

A

The maximum velocity of a reaction

70
Q

What does a low Km mean?

A

The enzyme only needs a little substrate

71
Q

What does a high Km mean?

A

The enzyme needs a lot of substrate

72
Q

Is competitive inhibition reversible or irreversible?

A

Reversable

73
Q

What happens to Vmax and Km in competitive inhibition?

A

Km changes, Vmax doesn’t

74
Q

What happens to Vmax and Km in non-competitive inhibition?

A

Vmax changes, Km doesn’t

75
Q

What kind of curve is formed bye an allosteric enzyme?

A

Sigmoidal curve - not hyperbola

76
Q

Anabolism

A

Oxidised precursor + electrons = reduced biosynthetic product

77
Q

What are the two qualities of an anabolic reaction?

A

Endergonic and reductive

78
Q

Catabolism

A

Reduced fule - electrons = oxidised product

79
Q

What are the two qualities of a catabolic reaction?

A

Exergonic and oxidative

80
Q

Terminal electron acceptor

A

Oxygen

81
Q

What are the four fates of glucose?

A

Stored as glycogen, starch etc.
Oxidised to pyruvate
Fermented to Lactate
Oxidised via the pentose-phosphate pathway to make ribose-5-phosphate

82
Q

Where does glycolysis take place?

A

Cytoplasm

83
Q

Where does the Kreb’s cycle take place?

A

Matrix of the mitochondria

84
Q

Where does the cytochrome system take place?

A

Cristae of the mitochondria

85
Q

Which two ways are glucose transported into a cell?

A

Via an Na+/glucose symporter

Passive facilitated diffusion glucose transporter

86
Q

Where do GLUT receptors work?

A

GLUT 1 and 3 = Brain
GLUT 2 = liver
GLUT 4 = Muscle and fat
GLUT 5 = Gut

87
Q

What are the steps of glycolysis?

A

Glucose > Fructose-1,6-biophosphate > 2 triode phosphate > 2 pyruvate

88
Q

What are the control points of glycolysis?

A

Hectokinase, Phosphofrucktokinase and pyruvate kinase

89
Q

How does AMP increase glycolysis?

A

By allosterically increasing phosphofructokinase

90
Q

What three substances inhibit glycolysis?

A

ATP, citrate and H+

91
Q

How is NAD+ regenerated?

A

Through the metabolism of pyruvate

92
Q

How does pyruvate enter the matrix?

A

H+ conc. gradient

H+/pyruvate symport by facilitated diffusion

93
Q

What catalyses the conversion of pyruvate into Acetly-CoA?

A

Pyruvate dehydrogenase complex

94
Q

Which enzyme is not located in the mitochondria matrix for the TCA cycle?

A

Succinate dehydrogenase

95
Q

Net yield from each molecule of glucose

A

4 ATP
10 NADH and H+
2 FADH2
2 CO2

96
Q

What is the energy from proton flow used for?

A

Phosphorylation of ADP to ATP

97
Q

2 transport modes of NADH

A

Glycerol-3-phosphate

Malate-asparate shuffle

98
Q

Phosphorylate transfer potential

A

Free energy change for the hydrolysis of ATP

99
Q

Electron transfer potential

A

Redox potential of a compound - how readily it donates an electron

100
Q

2 stages of oxidative phosphorylation

A

Electron transport

ATP synthesis

101
Q

Cytochromes

A

Proteins which contain a harm group as a functional co-factor

102
Q

Which complexes pump H+ ions?

A

I, III and IV

103
Q

Where is there a higher concentration of protons in the mitochondria?

A

Inter-membrane space not the matrix

104
Q

Is the matrix negative or positive?

A

Negative

105
Q

Chemicals which inhibit oxidative phosphorylation

A

Cyanide, CO and azide

106
Q

P/O ratio

A

Measurement of the coupling of ATP synthase to electron transport

107
Q

Yield of ATP from 1 mole of glucose

A

30-32