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Flashcards in Biochemistry Deck (107):
1

What is a covalent bond?

The sharing of electron pairs

2

What is an ionic bond?

Attraction of opposite charges

3

What is a hydrogen bond?

Sharing of a hydrogen atom

4

What are Van der Wall interactions?

Electron interactions of non-polar substances

5

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

More likely

6

What is a condensation reaction?

When water is removed

7

What is a hydrolysis reaction?

When water is added

8

What is lactose made up of?

Galactose and glucose

9

What is sucrose made up of?

Glucose and fructose

10

Which glucose linkages are found in cellulose?

Beta 1,4

11

Which glucose linkages are found in glycogen?

Alpha 1,4 and occasionally alpha 1,6

12

Give examples of a disaccharide

Lactose, maltose, cellobiose, sucrose

13

Give examples of a polysaccharide

cellulose and glycogen

14

First law of thermodynamics

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

15

Second law of thermodynamics

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

16

What is Gibbs free energy law?

ΔG = ΔH - TΔS

17

What is the equation for a change in free energy?

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

18

What is enthalpy?

Heat content

19

What is entropy?

Disorder

20

What is an exergonic reaction?

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

21

What is an endergonic reaction?

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

22

Is ΔG in exergonic +ve or -ve?

Negative

23

Is ΔG in endergonic +ve or -ve?

Positive

24

Catabolism

Break down of complex molecules

25

Anabolism

Assembly of complex molecules from smaller ones

26

Glycolysis

Break down of glucose into pyruvate

27

Gluconeogynesis

Makes glucose from pyruvate

28

4 Types of amino acid

Non-polar = hydrophobic
Polar = uncharged
Basic
Acidic

29

Acids

Proton donators

30

Bases

Proton acceptors

31

Zwitterions

Amino acids with no net charge

32

What are the two forms of tertiary protein structures?

Fibrous - parallel
Globular - spherical shape

33

Interactions present in a tertiary structure

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

34

Which amino acid forms disulphide bridges?

Cystine

35

Where does DNA replication and transcription take place?

Nucleus

36

Where does translation take place?

Cytoplasm

37

Nucleoside

Base + sugar

38

Nucleotide

Nucleoside + phosphate group

39

Which carbon is the base and phosphate connected to?

Base = carbon 1
Phosphate = Carbon 5

40

Purines

Adenine and guanine

41

Pyridemines

Thymine, uracil and cytosine

42

How many bonds between A and T?

2

43

How many bonds between C and G?

3

44

What is the catalyst for DNA replication?

DNA polymerase

45

Which direction does DNA polymerase work?

3' to 5' direction

46

What is the most abundant type of RNA?

Ribosomal

47

What synthesises all RNA?

Pol II

48

Transcription

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

49

Where is a TATA box usually found?

25 nucleotides before transcription starts

50

What is the function of a TATA box binding protein?

Provides a landing platform for further transcription factors and RNA polymerase

51

Translation

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

52

Degenerate

Many codons code for one amino acid

53

Unambiguous

Each codon codes for only one amino acid or a stop

54

Which enzyme binds amino acids to their tRNA molecule?

Aminoacyl-tRNA synthase

55

What is the initiation tRNA?

UAC

56

Stop codons

UAA, UAG and UGA

57

Point mutation

Change in single base in DNA

58

Silent mutation

No effect on protein function

59

What do free ribosomes do?

Make proteins for the nucleus, mitochondria, cytosol

60

What do bound ribosomes do?

Make proteins for the plasma membrane, ER and golgi body

61

Apoenzyme

An enzyme without a co-factor

62

Holoenzyme

An enzyme with a co-factor

63

Example of a co-factor

zinc, ion, copper (in stable transition state)

64

Isoenzymes

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

65

Phosphorylation

Converts enzymes into an active or inactive form

66

Km

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

67

Which axis does Km cross?

x axis intersection

68

Which axis does Vmax cross?

y axis intersection

69

Vmax

The maximum velocity of a reaction

70

What does a low Km mean?

The enzyme only needs a little substrate

71

What does a high Km mean?

The enzyme needs a lot of substrate

72

Is competitive inhibition reversible or irreversible?

Reversable

73

What happens to Vmax and Km in competitive inhibition?

Km changes, Vmax doesn't

74

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

Vmax changes, Km doesn't

75

What kind of curve is formed bye an allosteric enzyme?

Sigmoidal curve - not hyperbola

76

Anabolism

Oxidised precursor + electrons = reduced biosynthetic product

77

What are the two qualities of an anabolic reaction?

Endergonic and reductive

78

Catabolism

Reduced fule - electrons = oxidised product

79

What are the two qualities of a catabolic reaction?

Exergonic and oxidative

80

Terminal electron acceptor

Oxygen

81

What are the four fates of glucose?

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

82

Where does glycolysis take place?

Cytoplasm

83

Where does the Kreb's cycle take place?

Matrix of the mitochondria

84

Where does the cytochrome system take place?

Cristae of the mitochondria

85

Which two ways are glucose transported into a cell?

Via an Na+/glucose symporter
Passive facilitated diffusion glucose transporter

86

Where do GLUT receptors work?

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

87

What are the steps of glycolysis?

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

88

What are the control points of glycolysis?

Hectokinase, Phosphofrucktokinase and pyruvate kinase

89

How does AMP increase glycolysis?

By allosterically increasing phosphofructokinase

90

What three substances inhibit glycolysis?

ATP, citrate and H+

91

How is NAD+ regenerated?

Through the metabolism of pyruvate

92

How does pyruvate enter the matrix?

H+ conc. gradient
H+/pyruvate symport by facilitated diffusion

93

What catalyses the conversion of pyruvate into Acetly-CoA?

Pyruvate dehydrogenase complex

94

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

Succinate dehydrogenase

95

Net yield from each molecule of glucose

4 ATP
10 NADH and H+
2 FADH2
2 CO2

96

What is the energy from proton flow used for?

Phosphorylation of ADP to ATP

97

2 transport modes of NADH

Glycerol-3-phosphate
Malate-asparate shuffle

98

Phosphorylate transfer potential

Free energy change for the hydrolysis of ATP

99

Electron transfer potential

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

100

2 stages of oxidative phosphorylation

Electron transport
ATP synthesis

101

Cytochromes

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

102

Which complexes pump H+ ions?

I, III and IV

103

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

Inter-membrane space not the matrix

104

Is the matrix negative or positive?

Negative

105

Chemicals which inhibit oxidative phosphorylation

Cyanide, CO and azide

106

P/O ratio

Measurement of the coupling of ATP synthase to electron transport

107

Yield of ATP from 1 mole of glucose

30-32