Biochemistry Flashcards
(77 cards)
1
Q
Covalent bond
A
share electron pairs
2
Q
Ionic bond
A
attraction of opposite forces
3
Q
Hydrogen bond
A
sharing of an H atom
4
Q
Hydrophobic interactions
A
interaction of hydrophobic substances in the presence of polar substances (e.g. water)
5
Q
Van der waals interactions
A
interaction of electrons of non polar substances
6
Q
Electronegativity
A
attractive force than at atomic nuclei experts on electrons
7
Q
Phosphorylation
A
addition of a phosphate group, P04(3-) –> this can switch an enzyme on or off
8
Q
Acylation
A
addition of acyl group COR
9
Q
Esterification
A
conversion of carboxylic acid to esters in the presence of alcohol
10
Q
OIL RIG
A
oxidation is loss of electrons
reduction is gain of electrons
11
Q
What are the oxidation states of carbon
A
alkane (in fats) alcohol (in carbohydrates) aldehyde carboxylic acid carbon dioxide
12
Q
what is the final product of catabolism
A
carbon dioxide
13
Q
Peptides and proteins consist of
A
amino acids
14
Q
What is a peptide
A
a ‘sort of unit’ derived either from a protein after cleavage or in a lab
15
Q
What is a protein
A
a complete unit, encoded in its entirety as one or several peptides
16
Q
triglycerides, phospholipids and steroids are all members of what group
A
lipids
17
Q
What is meant by nutrients
A
carbohydrates (sugar)
lipids (fats/oils)
proteins (amino acids)
18
Q
What is meant by nutrients
A
carbohydrates
lipids
proteins
19
Q
Lactose
A
galactose-beta-1-4-glucose
20
Q
Sucrose
A
fructose-alpha-1-2-glucose
21
Q
Maltose
A
glucose-alpha-1-4-glucose
22
Q
Cellobiose
A
glucose-beta-1-4-glucose
23
Q
What is the name for the high energy bonds in ATP
A
anhydride bonds
24
Q
How is the strain relieved in ATP
A
by removing phosphate groups
25
Give an example of how ATP is regenerated from a different pathway than the 2ADP ...
creatine phosphate
26
Glucogenesis
making new glucose from non-carbohydrate precursors, such as pyruvate
27
What makes a reaction a useful control point
high delta g - high free energy change
28
What shape are hydrogen bonds
linear
29
Why are there hydrogen bonds between water molecules
- polar
| - bent --> dipole and tetrahedral shape
30
When are micelles formed
when amphipathic molecules are added to water
31
Sodium palmitate forms what when added to water
micelle
32
What type of amino acids are present in the human body
L-type amino acids
33
Describe the basic structure of an amino acid
alpha carbon attached to:
- amino acid group (-NH2)
- carboxyl group (-COOH)
- hyrogen (-H)
- side chain (-R)
34
What is the bond of the protein back bone
peptide bond
35
Describe the peptide bond
formed between the carboxyl group of 1 amino acid to the amino group of another amino acid,
- partial double bond character
- planar
- strong and rigid
36
What direction do amino acids grow?
N-terminal residue to the C-terminal residue (amino acids can be added)
37
pH
measure of the no. of protons in a sol
38
pKa
measure of the acid strength
39
At what value do buffers tend to resits a change of pH on addition of a small amount of acid or base
pKa
40
What is a ZWITTERION
compound with no overall electrical charge, but contains separate parts of which one is +ve and the other is -ve
41
What compound contains two titratable groups
zwitterion
42
Give an example of a protein that acts as a buffer?
haemoglobin in the blood
43
What is meant by the primary structure of a protein
the sequence of amino acids
44
What is meant by the secondary structure of a protein
the shape/structure of the polypeptide back bone
45
What is meant by the tertiary structure of proteins
the 3D structure of the entire polypeptide, including all its side chains
46
What is meant by the quaternary structure
the spatial arrangement of polypeptide chains in a protein with multiple subunits
47
What are the three types of secondary structures
Alpha helix
Beta sheets and strands
Triple helix
48
Polypeptides can rotate around the angles between
- the alpha carbon and the amino group
| - the alpha carbon and the carboxyl group
49
What bond characterises the secondary structure of proteins
hydrogen bond
50
Characters of alpha helix
- rod-like
- one polypeptide chain
- hydrogen bonds between -C-O and -N-H groups of one amino acid with another 4 residues away
51
What breaks alpha helixes
proline
52
Characteristics of beta sheets I
- extended backbone
- 1+ polypeptide chains
- parallel or anti-parallel
- turns between strands
53
Beta pleated sheets
-repeated zigzag structures
54
Example of a protein containing both alpha helixes and protein sheets
phosphoglycerate kinase
55
Characteristics of collagen triple helix
- water-insoluble fibres
- right-handed superhelix
- repeating sequence of X-Y-Gly
- inter-chain H-bonds
- covalent inter- and intra- molecular bonds
56
What is the component of bone and connective tissue as well as being the most abundant protein in verterates
collagen triple helix
57
What is the repeating sequence of the collagen triple helix?
X-Y-Gly
X-amino acid
Y-proline/hydroxyproline
also contains hydroxylysine
58
Bleeding gums are a result of
weakened collagen
59
Covent cross linking increases with
age
| meat from older animals is tougher
60
Ascorbic acid
vitamin C
61
Scurvy : bleeding gums, skin discolouration
```
dietary deficiency of vitamin C
Vitamin C (ascorbic acid) is the enzyme which hydroxylates proline --> hydroxyproline
deficiency of vitamin c results in a reduction of hydroxyproline
WEAKENED COLLAGEN
```
62
Fibrous proteins and globular proteins are examples of
tertiary structures
63
Characteristics of fibrous proteins
- polypeptide chains organised approximately parallel along a single axis
- consist of long fibres or large sheets
- mechanically strong
- insoluble in water and dilute salt solutions
- play an important structural role in nature
64
Examples of fibrous proteins
- keratin of hair and wool
| - collagen of connective tissue of animals including cartilage bones, teeth, skin, and blood vessels
65
Characteristics of globular protein
- proteins which are folded to a more or less spherical shape
- soluble in water and salt solutions
- polar side chains on the outside --> hydrogen bonding and ion-dipole interactions
- substantial sections of alpha-helix and beta-sheet
66
Examples of globular proteins
- myoglobin
| - haemoglobin
67
Forces stabilising tertiary structures
- covalent disulphide bonds
- electrostatic interactions = salt bridges
- hydrophobic interactions
- hydrogen bonds (backbone, side chain)
- complex formation with metal ions
68
Sickle cell anaemia
- single nucleotide sequence change in coding region of the B-chain of haemoglobin A
- results in altered protein,valine instead of glutamic acid
- under low 02 conditions, haemoglobin polymerises, results in rigid, sickle shaped cells
- can block blood flow in capillaries
69
Examples of when proteins spontaneously fold incorectly
Alzheimers
Parkinsons
CJD
70
Specialised proteins which aid in the folding of proteins
chaperones
71
Mad cow disease
caused by infection
72
Creutzfeldt-Jacob disease
caused by spontaneous or inherited mutation
73
Detergents, urea, guanidine hydrochlorine all act to denature proteins by
disrupting hydrophobic interactions
74
Thiol agents, reducing agents all act to denature proteins by
reducing and thereby disrupting disulphide bonds
75
stores oxygen in muscle
myoglobin
76
Haemoglobin
- four subunits
- two alpha and two beta chains
- each contains a ham group
- each subunit can bind one oxygen molecule
77
transports oxygen in blood
haemoglobin
