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Principles: biochemistry > Introduction to Biochemistry > Flashcards

Introduction to Biochemistry Flashcards

1
Q

Carbon can form 4 _____ bonds

A

covalent

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2
Q

the less oxidised the molecule the ____ energy contained in the bonds.

A

more

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3
Q

alkane (in fats) has ____ energy in its bonds than carbon dioxide (final product of catabolism)

A

more

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4
Q

what is the glycosidic bond in lactose?

A

galactose beta 1-4- glucose

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5
Q

what is the glycosidic bond in maltose?

A

glucose alpha 1,4 - glucose

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6
Q

what is the glycosidic bond in sucrose?

A

glucose alpha 1,2 - fructose

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7
Q

what is the glycosidic bond in cellobiose?

A

glucose beta 1-4- glucose

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8
Q

carbs are made of carbon, hydrogen and oxygen in a ___:___:___ ratio

A

1:2:3

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9
Q

what is the free energy equation involving enthalpy and entropy

A

ΔG = ΔH – TΔS

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10
Q

for a process to occur delta G must be _____

A

negative

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11
Q

an endothermic process with a negative ᐃS can never be _______, for example photosynthesis.

A

spontaneous

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12
Q

ΔG = (energy of the ______) – (energy of the ______)

A

ΔG = (energy of the products) – (energy of the reactants)

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13
Q

exergonic reactions are reactions in which the total free energy of the product(s) is _____ than the total free energy of the reactant(s)

A

less

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14
Q

exergonic reactions can occur +_____

A

spontaneously

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15
Q

endergonic reactions are reactions in which the total free energy of the product(s) is ____ than the total free energy of the reactant(s)

A

more

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16
Q

endergonic reactions cannot occur _____. They need an Input of _____ to proceed.

A

spontaneously, energy

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17
Q

what is the equation for delta G for a given reaction

A

ΔG = ΔGo’ + RTln([C][D]/[A][B])

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18
Q

what is R

A

the universal gas constant

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19
Q

what is T

A

the absolute temperature

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20
Q

what is ΔGo’

A

the change in free energy under standard conditions

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21
Q

ΔG is related to the point of equilibrium: The further towards completion the point of equilibrium is, the ____free energy is released

A

more

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22
Q

ΔG values near ___ are characteristic of readily reversible reactions.

A

zero

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23
Q

When the system is at equilibrium, forwards and backwards reactions are balanced:
ΔG = 0 and therefore
ΔGo’ = -RTlnKeq

A

Keq = [C][D]/[A][B]

(substrate and product concentrations at equilibrium)

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24
Q

reactions with a negative delta Go, i.e. reactions going from high energy reactants to low energy products, are ______

A

favourable

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25
Q

What about reactions with a positive delta G - it all depends on the initial concentrations of the _____

A

reactants

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26
Q

what is the effect of increasing [A][B] relative to [C][D] do the delta G ?

A
  • [C][D]/[A][B] becomes smaller than 1

- the ln of a number smaller than 1 is negative!

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27
Q

many cellular processes are unfavourable and are driven by ____ to highly favourable processes

A

coupling

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28
Q

the breakdown of ATP is a very ____ delta G

A

negative

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29
Q

The negative charges close together in ATP put a ____ (electrostatic repulsion) on the molecule that makes it less ____ than ADP

A

strain, stable

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30
Q

the phosphate parts of ATP are anhydride bonds. These are ___ energy bonds. So when they break energy is _____

A

high, released

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31
Q

what are the two ways to make ATP?

A
  1. using creating phosphate

2. using 2 ADP

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32
Q

what is glycolysis ?

A

Initial breakdown of glucose for the generation of ATP

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33
Q

Reactions close to equilibrium (ΔG close to 0) are not used as _____ points

A

control

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34
Q

hydrogen bonds tend to be ____ in form

A

linear

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35
Q

amphipathic molecules form ____ in water

A

micelles

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36
Q

Proteins and polypeptides in humans are made up from ___ different __-amino acids

A

20, L

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37
Q

what is the one exception to the L amino acids?

A

glycine - it has two of the same group

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38
Q

all amino acids contain an α-carbon bonded to …. 4 things

A

an amino group (-NH2)
a carboxyl group (-COOH)
a hydrogen (-H)
a side chain (-R)

39
Q

D and L form AAs are _______

A

stereoisomers

40
Q

what are the 4 groups of AAs

A
  • non polar, hydrophobic
  • polar, uncharged
  • acidic
  • basic
41
Q

what are the characteristic chains on - non polar, hydrophobic ?

A

mainly hydrocarbons

42
Q

what are the characteristic chains on - polar uncharges?

A

mainly carbonyl and hydroxyl groups, NH

43
Q

what are the characteristic chains on acidic aas?

A

carboxyl grop

44
Q

what are the characteristic chains on basic AAs?

A

ammine

NH3 and

45
Q

what is a peptide bond the linkage of?

A

CO and NH groups with the removal of water

46
Q

peptides have a direction , what is it?

A

from N terminal residue NH3+ to the C-terminal residue COO-

47
Q

peptide bonds have a partial ___ bond character

A

double

48
Q

____ bonds are planar

A

peptide

49
Q

Acids are molecules which can ____ a proton (hydrogen ion, H+)

A

donate

50
Q

Bases are proton _____

A

acceptors

51
Q

H+ conc of 10 -7 has a pH of 7, what is the pH of a H+ conc of 10 -6

A

6

52
Q

the henderson -hasselbach equation Connects the __ of a weak acid with the __ of a solution containing this acid

A

Connects the Ka of a weak acid with the pH of a solution containing this acid

53
Q

what is the quation?

A

pH = pKa + log[A-/HA]

54
Q

the H-H equations lets us calculate the properties of _____ solutions

A

buffer

55
Q

When the concentration of acid is equal to the concentration of conjugate base: pH = ____

A

pKa

56
Q

at their ____value buffers tend to resist a change of pH upon addition of moderate amounts of acid or base

A

pKa

57
Q

Amino acids without charged side groups exist as _____ in neutral solution

A

zwitterions

58
Q

The pH at which a molecule has no net charge is called the —_______ pH, pI

A

isoelectric

59
Q

The ends of proteins can be ____- and therefore proteins can act as _____

A

ionised, buffers

60
Q

give an example of a protein buffer?

A

haemoglobin in blood

61
Q

Proteins can act as buffers because each protein molecule is both a weak _____ and a weak _____. The weakly acidic carboxylic acids counteract ____ pHs while the weakly basic amino groups can counteract ____ pHs.

A

Proteins can act as buffers because each protein molecule is both a weak acid and a weak base. The weakly acidic carboxylic acids counteract rising pHs while the weakly basic amino groups can counteract falling pHs.

62
Q

polypeptides can rotate around the angles between, which two things in the chain?

A

the α carbon and the amino group

the α carbon and the carboxyl group

63
Q

what is the secondary structure of a protein?

A

Hydrogen-bonded three-dimensional arrangements of a polypeptide chain

64
Q

secondary structure considers only the ____ of the polypeptide

A

backbone

65
Q

what are the three types of secondary structures?

A

alpha helix
beta strands and sheets
triple helix

66
Q

Alpha helix is where the ___ group of one amino acid forms a hydrogen bond with the __group of an amino acid four residues away

A

-C-O group of one amino acid forms a hydrogen bond with the -N-H group of an amino acid four residues away

67
Q

how do proline residues break alpha helices?

A

Prolines in alpha helices after the first turn (4th residue) cause a kink in the helix.This kink is caused by proline being unable to complete the H-bonding chain of the helix

68
Q

beta sheets can run in a _____ or anti_____ direction

A

parallel

69
Q

what amino acids occur at turns in the strands? 2

A

glycine and proline

70
Q

beta sheets can be in a zig zag shape in which case they are called Beta ____ sheets

A

pleated

71
Q

Different ______ structure elements can occur within one protein
Example: _______ ______

A

Different secondary structure elements can occur within one protein
Example: phosphoglycerate kinase

72
Q

collagen triple helix is a component of ___ and _____ tissue

A

bone and connective

73
Q

collagen triple helix is made of Three ___-handed helical chains twisted around each other form a ____-handed superhelix

A

Three left-handed helical chains twisted around each other form a right-handed superhelix

74
Q

tropocollagen is a repeating sequence of X-Y-Gly in all strands
X=
Y=

A 
X = any amino acid
Y = proline or hydroxyproline
75
Q

in collagen triple helix there are inter-chain h bonds involving _____ and______

A

hydroxylysine and hydroxyproline

76
Q

______ of collagen occur with age

A

crosslinking

77
Q

scurvy results in weakened collagen, how?

A
  • the enzyme which hydroxylates proline requires ascorbic acid (vitamin C)
  • dietary deficiency of vitamin C results in reduction in hydroxyproline
    results in weakened collagen
78
Q

the tertiary structure of a polypeptide is held together by interactions between the ____ chain - the ‘R’ groups.

A

side

79
Q

what are fibrous proteins?

A

Contain polypeptide chains organized approximately parallel along a single axis

80
Q

fibrous proteins are ____ in water and dilute ___ solutions

A

insoluble, salt

81
Q

give some examples

A
  • keratin of hair and wool

- collagen of connective tissue of animals including cartilage, bones, teeth, skin, and blood vessels

82
Q

what are globular proteins

A

Proteins which are folded to a more or less spherical shape

83
Q

globular proteins tend to be ___ in water and salt solutions

A

soluble

84
Q

in globular proteins most of their polar side chains are on the o____ and interact with the aqueous environment by _____ _____ and___-_____ interactions

A

most of their polar side chains are on the outside and interact with the aqueous environment by hydrogen bonding and ion-dipole interactions

85
Q

give 2 examples of globular proteins

A

myoglobin and haemoglobin

86
Q

give 5 examples of the bonds/forces stabilizing tertiary structures

A
  • Covalent disulphide bonds
  • Electrostatic interactions = salt bridges
  • Hydrophobic interactions
  • Hydrogen bonds
  • Complex formation with metal ions
87
Q

______ side groups are normally located on the outside of proteins

A

Charged (polar) side groups are normally located on the outside of proteins
interact with water

88
Q

Amino acids with hydrophobic side-chains tend to cluster in the ____ of globular proteins

A

centre

89
Q

sickle cell anaemia results from a signle nucleotide sequence meaning that there is a change of ___in the proteins

A

shape

90
Q

Sometimes folding process is aided by other specialised proteins. what are these called/

A

chaperones

91
Q

Detergents, urea, guanidine hydrochloride can disrupt _______ interactions

A

hydrophobic

92
Q

myoglobin contains a _____ haem group

A

prosthetic

93
Q

haemoglobin is composed of __ alpha and )___ beta subunits

A

2

94
Q

how many haem groups are there in haemoglobin?

A

4

Principles: biochemistry (7 decks)

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