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biological molecules Flashcards

1
Q

condensation reaction definition

A

reaction that occurs when two molecules are joined together with the removal of water

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2
Q

hydrolysis reaction definition

A

reaction that occurs when a molecule is split into 2 smaller molecules with the addition of water

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3
Q

monomer definition

A

a small molecule which binds to many other identical molecules to form a polymer

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4
Q

polymer definition

A

a large molecule made from many smaller molecules called monomers

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5
Q

hydrogen bond definition

A

a weak interaction that can occur whenever molecules contain a slightly negatively charged atom bonded to a slightly positively charge hydrogen atom

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6
Q

where can hydrogen bonds form?

A

between chains of monomers

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7
Q

are hydrogen or covalent bonds weaker?

A

hydrogen bonds

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8
Q

what is a macromolecule?

A

a large molecule

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9
Q

4 examples of macromolecules

A

carbohydrates, proteins, nucleic acids, lipids

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10
Q

carbohydrate chemical elements

A

carbon, hydrogen and oxygen

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11
Q

carbohydrate monomer

A

monosaccharide e.g. glucose

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12
Q

carbohydrate polymer

A

polysaccharide e.g. glycogen

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13
Q

protein chemical elements

A

carbon, hydrogen, oxygen, nitrogen ( and sulfur )

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14
Q

protein monomer

A

amino acid

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15
Q

protein polymer

A

polypeptide (protein) e.g. haemoglobin

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16
Q

nucleic acid chemical elements

A

carbon, hydrogen, oxygen, nitrogen, phosphorus

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17
Q

nucleic acid monomer

A

nucleotide

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18
Q

nucleic acid polymer

A

DNA or RNA

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19
Q

lipids chemical elements

A

carbon, hydrogen, oxygen

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20
Q

lipids polymer?

A

NOT A POLYMER

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21
Q

calcium chemical symbol

A

Ca 2+

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22
Q

sodium chemical symbol

A

Na +

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23
Q

potassium chemical symbol

A

K +

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24
Q

hydrogen chemical symbol

A

H +

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25
Q

ammonium chemical symbol

A

NH4 +

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26
Q

nitrate chemical symbol

A

NO3 -

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27
Q

hydrogen carbonate chemical symbol

A

HCO3 -

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28
Q

chloride chemical symbol

A

Cl-

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29
Q

phosphate chemical symbol

A

PO4 3-

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30
Q

hydroxide chemical symbol

A

OH-

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31
Q

hydrogen functions

A

regulation of blood pH, involved in transport of CO2
involved in ATP formation in photosynthesis and respiration

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32
Q

ammonium functions

A

needed for production of nitrates by nitrifying bacteria
production in deamination of amino acids

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33
Q

calcium functions

A

nerve transmission and muscle contraction
cofactor in blood clotting (prothrombin to thrombin)
bone formation

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34
Q

sodium functions

A

nerve transmission
affects reabsorption of water in kidney

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35
Q

potassium functions

A

nerve transmission
in guard cells as part of opening mechanism in stomata

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36
Q

nitrate functions

A

absorbed by root hair cells
used as source of nitrogen in plants to make amino acids

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37
Q

phosphate functions

A

bone formation, component of phospholipids
component of ATP and nucleic acids

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38
Q

hydrogen carbonate functions

A

regulation of blood PH
involved in transport of CO2

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39
Q

chloride functions

A

cofactor for amylase enzyme
chloride shift in RBC

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40
Q

hydroxide function

A

regulation of blood pH

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41
Q

polar molecule definition

A

a molecule that has an uneven charge distribution (partial positive and negative charges which do not cancel out)

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42
Q

what type of bonds are between water molecules

A

hydrogen bonds

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43
Q

what type of bonds are within water molecules

A

covalent bond

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44
Q

is hydrogen electropositive or electronegative

A

electropositive

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45
Q

is oxygen electropositive or electronegative

A

electronegative (bc greater pull on electron)

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46
Q

electropositive symbol

A

𝛿+

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47
Q

electronegative symbol

A

𝛿-

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48
Q

properties of water due to hydrogen bonds

A

liquid at room temp
density changes
solvent for polar molecules
water & non-polar molecules reactions
cohesion & surface tension
high specific heat capacity
high latent heat of vaporisation
water is a reactant

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49
Q

why is water liquid at room temperature?

A

the hydrogen bonds between H2O molecules make it more difficult for them to escape and become a gas

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50
Q

water is suitable for ‘what’ because it is liquid at room temperature?

A

provides a habitat e.g. lakes, rivers, seas
be a major component of tissues
be a reactions medium for chemical reactions
be an effective transport medium e.g. blood

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51
Q

explain water’s change in density with temperature

A

cooling of water allows maximum number of hydrogen bonds to form so water molecules space out to allow this and water expands as it breezes. Therefore ice is less dense than water and floats. This creates currents.

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52
Q

why are water’s changes in density useful

A

the currents created allow circulation of water.
a layer of ice will float to the top of water and insulate a pond against extreme temperatures, decreasing heat loss so aquatic organisms have a stable environment
ice floats so provides land for terrestrial animals

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53
Q

why is water a good solvent?

A

water molecules cluster around charged parts of solute molecules or ions and keep them apart bc water is polar

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54
Q

water is useful for ‘what’ because it is a good solvent?

A

molecules can move around in solvent and react together
molecules and ions can be transported when dissolved
good for removal of water e.g. urea in urine

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55
Q

what happens to non-polar molecules when surrounded by water?

A

they are pushed together, allowing hydrophobic reactions to occur

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56
Q

what do hydrophobic reactions allow for

A

tertiary structure of proteins to form
phospholipid bilayer to form

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57
Q

how do the properties of water enable globular proteins to be soluble?

A

water can form hydrogen bonds with the hydrophilic groups of the amino acids in these proteins

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58
Q

how does cohesion work?

A

water molecules are attracted together as a result of hydrogen bonds

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59
Q

how does surface tension work?

A

at the surface of water, water molecules are all hydrogen bonded to the water molecules beneath, giving the surface of the water the ability to resist force applied to it

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60
Q

uses of cohesion and surface tension?

A

columns of water are pulled up xylem in the transpiration stream
insects e.g. pond skaters can walk on water
jellyfish keep shape in water because molecules not easily compressed so this gives jellyfish support

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61
Q

what is water’s specific heat capacity

A

HIGH : 4.2 kJ of energy required to raise the temp of 1kg of water by 1C

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62
Q

why does water have a high specific heat capacity

A

hydrogen bonds restrict movement of water molecules and therefore a large amount of energy is needed to raise the temperature

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63
Q

uses of water’s high specific heat capacity

A

water does not warm up or cool down easily (high thermal stability)
water keeps a stable temperature, giving aquatic organisms a stable environment in which to live
gases remain soluble in water e.g. oxygen for aerobic respiration of organisms

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64
Q

what is high latent heat of vaporisation

A

as water molecules are held together by hydrogen bonds, relatively large amounts of heat energy are needed for water to evaporate. this energy helps the molecules to break away form each other

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65
Q

why is water’s high latent heat of vaporisation useful?

A

helps keep temperature stable
cools organisms e.g. mammals sweating and plants’ perspiration

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66
Q

when is water used as a reactant?

A

hydrolysis reactions e.g. digestion (catabolic)
raw material of photosynthesis (anabolic)

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67
Q

why is it useful that water is transparent?

A

aquatic organisms can photosynthesise

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68
Q

what does the wavelength of light do as depth of water increases

A

it varies

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69
Q

carbohydrates general formula

A

Cx(H2O)y

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70
Q

types of carbohydrates with short definition and example

A

monosaccharides= single sugars (short chains or ring) e.g. glucose
disaccharides= double sugars e.g. maltose
polysaccharides=many sugars joined together (branched/unbranched chains) e.g. glycogen

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71
Q

monosaccharides general formula

A

(CH2O)n n=between 3 and 9

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72
Q

monosaccharides properties

A

soluble in water because of polar -OH group
insoluble in non-polar solvents
tastes sweet

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73
Q

monosaccharides molecular formula

A

shows number of each atom

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74
Q

monosaccharides structural formula

A

shows arrangement of atoms

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75
Q

monosaccharides isomers

A

molecules with the same molecular formula but different structural formulae e.g. alpha and beta glucose

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76
Q

alpha glucose molecular formula

A

C6H12O6

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77
Q

alpha glucose functions

A

energy source
component of (monomer for) glycogen and starch (energy stores)

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78
Q

alpha glucose structure

A

H on top

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79
Q

beta glucose molecular formula

A

C6H12O6

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80
Q

beta glucose functions

A

energy source
component of cellulose (provides structural support to cells)

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81
Q

beta glucose structure

A

H on bottom

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82
Q

ribose molecular formula

A

C5H10O5

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83
Q

ribose functions

A

component of RNA
component of ATP

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84
Q

ribose structure

A

two OH groups at bottom

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85
Q

deoxyribose molecular formula

A

C5H10O4

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86
Q

deoxyribose function

A

component of DNA

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87
Q

deoxyribose structure

A

OH group bottom left
H bottom right

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88
Q

name of a C=O group

A

carbonyl group

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89
Q

name of an O-H group

A

hydroxyl group

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90
Q

name of a H-C=O group

A

aldehyde group

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91
Q

what is special about a hydroxyl group?

A

it is polar so makes glucose/ other molecules soluble in water

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92
Q

property of glucose thanks to its polarity? what does this make it useful for

A

freely soluble in water
therefore soluble in blood plasma and can be transported to cells for uptake

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93
Q

functions of water?

A

transport
chemical reactions
temperature control
support
movement
reproduction

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94
Q

how is water useful for reproduction?

A

sexually reproducing organisms sometimes use water to bring gametes together for fertilisation
in mammals the foetus develops in a water-filled sac, which provides physical and thermal stability
bryophytes release antherozoids (male gametes) in moist conditions, which use flagella to swim to oospheres(female reproductive cells) by chemotaxis.

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95
Q

how is water useful for movement?

A

nastic movements (do not involve growth towards a stimulus) depend on osmotic flow of water e.g. open/close of flowers or the snap of a Venus fly trap
organisms such as earthworms and leeches use hydrostatic skeletons to move around. longitudinal and circular muscles contract against the watery fluid of the coelom

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96
Q

how is water useful for support

A

plants gain turgidity, which is essential to maintain the maximum surface area, so maximum light is absorbed for maximum photosynthesis and for maintenance of aerial plant parts for increased seed dispersal
water filled tissues contribute to skeletal support. organisms with hydrostatic skeletons need water for the fluid in the coelom against which muscles can act
for aquatic organisms, water provides support through buoyancy and pressure

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97
Q

how is water useful for temperature control

A

high SHC so water acts as an essential buffer for organisms maintaining a constant body temp for enzyme-controlled reactions to work at optimum temp & regulate metabolism
high latent heat of vaporisation means heat is released when water evaporates, which is a cooling mechanism to keep a stable temp
water remains liquid over a huge temp range, which is essential for metabolism and useful for aquatic organisms which avoid freezing

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98
Q

how is water useful in chemical reactions

A

combination of thermal stability & solvent properties make water an ideal environment for them reactions. all enzyme reactions of photosynthesis, respiration, excretion e.t.c. occur in solution

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99
Q

when does water act as a reactant

A

photosynthesis
hydrolytic reactions e.g. digestive enzymes when digesting starch, proteins, lipids

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100
Q

how is water useful for transport in plants

A

uptake of minerals by plants from soil across root hair cells
transpirations stream
water-based movement of sugars and amino acids in phloem occur in solution
many essential metabolites dissolve completely e.g. glucose, amino acids, vitamins and minerals
larger molecule such as proteins are transported as colloids
transpiration stream held together by cohesion and adhesion (mols bind to side of xylem); these give rise to capillarity in tubes of small diameter
low viscosity so flows easily e.g. in xylem

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101
Q

why are monosaccharides well-suited to their role as an energy source?

A

large number of carbon-hydrogen bonds

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102
Q

why is water useful for transport in animals?

A

all transport fluids in animals are water-based e.g. blood plasma and cytoplasm
many essential metabolites dissolve completely e.g. glucose, amino acids, vitamins and minerals
larger molecule such as proteins are transported as colloids
low viscosity so flows easily

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103
Q

how are disaccharides formed

A

formed by 2 monosaccharides combing together in a condensation reaction, forming a glycosidic bond

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104
Q

disaccharides general formula

A

C12H22O11 (2 hexoses subtract H2O)

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105
Q

disaccharides properties

A

taste sweet
soluble in water because of the polar -OH group
some are reducing sugars (donate electrons) e.g. maltose, lactose, cellulose
some are non-reducing sugars e.g. sucrose

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106
Q

disaccharides examples

A

maltose
sucrose
lactose
cellubiose

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107
Q

is maltose reducing or non-reducing?

A

reducing

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108
Q

maltose monomers

A

formed from 2 alpha glucose molecules

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109
Q

maltose function

A

found in germinating seeds where it is broken down into glucose for respiration

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110
Q

is sucrose reducing or non-reducing?

A

non-reducing and therefore less reactive

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111
Q

sucrose monomers

A

alpha glucose and fructose

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112
Q

sucrose functions

A

how plants transport their sugar in translocation
less reactive as it is a non-reducing sugar

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113
Q

is lactose reducing or non-reducing?

A

reducing

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114
Q

lactose monomers

A

beta galactose and alpha glucose

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115
Q

lactose function

A

sugar found in milk

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116
Q

is cellubiose reducing or non-reducing?

A

reducing

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117
Q

cellubiose monomers

A

2 beta glucose molecules

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118
Q

cellubiose function

A

formed as an intermediate during cellulose production

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119
Q

enzyme for condensation reaction for synthesis of a disaccharide

A

glycogen synthase

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120
Q

bond formed in condensation reaction for synthesis of a disaccharide

A

glycosidic

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121
Q

condensation reaction for synthesis of a disaccharide description

A

2 hydroxyl (-OH) groups line up alongside each other.
one combines with a hydrogen atom of the other to form a water molecule.
this allows an oxygen bridge to form between them
this forms a disaccharide

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122
Q

enzyme for the hydrolysis of a disaccharide

A

maltase

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123
Q

hydrolysis of a disaccharide description

A

a water molecule is used to split the disaccharide during digestion by providing a hydroxyl group (-OH) and a hydrogen (H), which help the glycosidic bond to break

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124
Q

reducing agent definition

A

a chemical species that ‘donates’ an electron to an electron recipient , reducing the recipient.
it is oxidised

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125
Q

oxidising agent definition

A

a substance that ‘accepts’ or ‘receives’ an electron from a reducing agent, therefore oxidising it.
it is reduced.

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126
Q

in terms of hydrogen, oxygen and electrons, oxidation is….

A

loss of hydrogen
gain of oxygen
loss of electrons

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127
Q

in terms of hydrogen, oxygen and electrons, reduction is ….

A

gain of hydrogen
loss of oxygen
gain of electrons

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128
Q

are all monsaccharides and disaccharides reducing sugars?

A

all monosaccharides are reducing sugars
some disaccharides are reducing sugars

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129
Q

how do you know if a sugar is reducing or non-reducing?

A

any sugar containing a hemiacetal is a reducing sugar

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130
Q

how can you test for a reducing sugar?

A

it tests positive with Benedict’s solution (blue to orange/brick red)

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131
Q

which compound does Benedicts reagent contain?

A

copper (II) sulfate

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132
Q

positive test for Benedicts

A

an insoluble brick-red precipitate is formed

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133
Q

why is an insoluble brick-red precipitate formed which a reducing sugar and Benedicts?

A

copper ions are reduced by the sugar by gaining electrons from it
as a result, copper (II) oxide is produced
Cu 2+ gains an electron to become Cu +
reducing sugar is oxidised to form a carboxylic acid

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134
Q

what is a qualitative test?

A

positive or negative result
tells us if a particular substance is present

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135
Q

what is a quantitative test?

A

tells us how much (concentration) of a substance is present

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136
Q

what is a semi-quantitative test?

A

involving less than quantitative accuracy e.g. could have estimated concentration by comparing colour change with the colour change of a known concentration

137
Q

safety precautions for reducing sugar test

A

wear eye protection
if you get chemicals in your eyes, flush for 20 minutes with eye wash
wash any chemical off skin

138
Q

step-by-step how to test for reducing sugar
is it qualitative,quantitative or semmi-quantitative

A

add 5cm Benedicts reagent and stir with glass rod
heat in water bath at 80C for 9 minutes
positive result= green/yellow/orange/brick-red precipitate
negative= blue
semi-quantitative

139
Q

how to use commercially manufactures glucose test strips
use?
what are the positive/negative results?

A

dip strip in solution and compare with calibration card
testing urine of diabetics
pos= shows 1000mg/dl
neg= shows 0mg/dl

140
Q

how to test for a non-reducing sugar?

A

carry out a normal reducing sugar test (negative with sucrose, so proves absence of RS)
take sample and boil with 1cm HCl with antibumping granules and point away from yourself
cool solution
add sodium hydrogen carbonate powder to neutralise
carry out reducing sugar test again (positive with sucrose to prove presence of non-RS)

141
Q

basis of non-reducing sugar test

A

a disaccharide can be hydrolysed into constituent monosaccharides by boiling with hydrochloric acid
this frees up ‘reducing groups’
e.g. sucrose id hydrolysed into glucose and fructose (both RS)

142
Q

expected result with RS and NRS tests for glucose, sucrose and a mixture of the two

A

glucose: positive for both, and the same colour for both
sucrose: negative for RS, positive for NRS
mixture: positive for RS, larger positive result for NRS (if both brick red, w/ no visible difference, filter and measure mass of ppt or use colorimeter on supernatant)

143
Q

why do you use excess Benedicts in the RS test?

A

ensures all sugar reacts withe the benedicts reagent
therefore mass of ppt is proportional to conc of glucose, ensuring calibration curve is accurate

144
Q

why is the reducing sugar content of fruit juice likely to be different from the glucose content?

A

not all the sugar present in the juice will be glucose
most fruit juice also contain high conc of fructose
fructose will react with the Benedicts to give a greater mass of ppt
therefore when interpolating from the glucose calibration curve, the estimate is for the conc of RS,not an accurate estimate for the conc of glucose

145
Q

what does a colorimeter measure in a quantitative analysis of the RS test?
how does absorbance relate to glucose conc?

A

the absorbance of orange light by the supernatant
little glucose present= high absorbance reading (low transmission reading)(very blue, lots of unreacted Cu2SO4)
high conc of glucose= low absorbance reading (high transmission reading)(no colour, little unreacted Cu2SO4)

146
Q

equation for calculating volume of stock solution required

A

total volume wanted/ conc of stock solution x conc wanted

147
Q

controlled variables when using a calibration curve to estimate unknown glucose conc.s

A

vol. of glucose solution (0.5cm)
vol. of Benedicts(5cm)
temp of WB (80C)
time in WB (9 mins)
type of filter paper(fine grade)
colour of filter in colorimeter (orange or red)
same solution used to 0 colorimeter (distilled water)

148
Q

precautions when measuring mass of precpitate

A

avoid spills
stir before filtering (less ppt left in tube)
wash out tube and pour washings through filter
use same quality-fine grade filter paper
record mass of filter paper at start
dry filter paper to constant mass

149
Q

what is it referred to as when you find the concentration of a substance in a sample by comparing it with known standards

A

an assay

150
Q

glycosidic bond definition

A

a bond formed between 2 monosaccharides by a condensation reaction

151
Q

polysaccharide defintion

A

polymers which consist of hundreds/thousands of monosaccharides joined together by condensation reactions, resulting in the formation of glycosidic bonds

152
Q

homopolysaccharide definition and 4 examples

A

made up of one type of monosaccharide only
e.g. starch, cellulose, glycogen, callose

153
Q

heteropolysaccharide definition and an example

A

made up of more than one type of monosaccharide
e.g. hyaluronic acid

154
Q

4 properties of polysaccharides which make them good energy stores

A

hold glucose molecules in chains, so individual molecule can be removed easily
glycogen and starch are compact
glycogen and amylopectin are branched
polysaccharides are insoluble

155
Q

why is it useful that polysaccharides hold glucose molecules in chains?

A

individual molecules can be removed in hydrolysis reactions when required so the rest of the chain can remain if not needed

156
Q

why is it useful that glycogen and starch are compact?

A

it makes them dense granules so they don’t occupy a large amount of space

157
Q

why is it useful that glycogen and amylopectin are branched?

A

they are more compact
offers chance for lots of glucose molecules to be snipped off by hydrolysis at the same time when lots of energy is required quickly

158
Q

what enzyme breaks 1,4-glycosidic links?

A

amylase

159
Q

what enzyme breaks 1,6-glycosidic linkages?

A

glucosidase

160
Q

why are polysaccharides insoluble?

A

they are large macromolecules and the regions which could form hydrogen bonds with the water are hidden away inside the molecule

161
Q

why is it useful that polysaccharides are insoluble?

A

they can be stored without dissolving, so will not change the water potential of the cell or affect osmosis

162
Q

starch monomer

A

alpha glucose

163
Q

starch components

A

amylose
amylopectin

164
Q

amylose monomer

A

alpha glucose

165
Q

what bonds are within amylose

A

1,4-glycosidic bonds

166
Q

amylose structure; why?

A

an amylose helix because a coil is a more compact shape
6 glucose molecules per turn
hydrogen bonds hold helix together

167
Q

amylopectin monomer

A

alpha glucose

168
Q

amylopectin vs amylose : structure

A

amylopectin is branched and shorter

169
Q

amylopectin bonds?

A

1,4-glycosidic bonds in the chains
1,6-glycosidic bonds between chains

170
Q

amylopectin structure

A

main chain forms a spiral joined by hydrogen bonds

171
Q

formation of starch?

A

amylose helix becomes entangle din amylopectin to form very large starch grains

172
Q

where are starch grains found?

A

chloroplasts, seeds and storage organs (e.g. tubers)

173
Q

where is glycogen found?

A

animals = liver and muscle cells
fungi

174
Q

glycogen bonds

A

1,4-glycosidic bonds in main chain
1,6-glycosidic bonds connecting branches

175
Q

differences between amylopectin and glycogen

A

glycogen tend to be even more branches and compact but have shorter 1,4 chains so less tendency to coil

176
Q

glycogen monomer

A

alpha glucose

177
Q

advantage of glycogen having more branches

A

glucose is released more quickly

178
Q

cellulose monomer & details

A

beta glucose
every other beta glucose is rotated 180 degrees

179
Q

cellulose bonds

A

1,4-glycosidic bonds between beta glucose molecules
hydrogen bonds between (-OH) groups of molecules
hydrogen bonds between cellulose straight chains which run in parallel to each other

180
Q

advantage of hydrogen bonds between (-OH) groups of molecules in cellulose

A

stops the molecule spiralling so they are held in straight chains

181
Q

advantage of hydrogen bonds between cellulose straight chains which run in parallel to each other in cellulose

A

increased stability

182
Q

structure of cellulose fibres

A

many microfibrils held in bundles by hydrogen bonding make up macrofibrils

183
Q

cellulose cell wall structure

A

typically has several layers of fibres running in different directions, giving a high tensile strength
other polysaccharides such as pectins cross link with cellulose fibres to create the cell wall’s glue-like matrix structure

184
Q

cellulose cell wall 6 properties

A

very high tensile strength because of glycosidic and hydrogen bonds
can withstand large turgor pressure in cells (due to osmosis) so the cell won’t burst
supports plant (hydrostatic skeleton)
freely permeable (bc of space between macrofibrils) so water and solutes can reach the plasma membrane
insoluble because its a large macromolecule
can be reinforced with other substances to support or waterproof, such as lignin and Suberin
arrangement of macrofibrils determines the growth and change of cell shape e.g. guard cells

185
Q

why can humans not digest cellulose

A

humans don’t produce cellulase so cannot break down cellulose
therefore it is the fibre of our food

186
Q

can ruminants digest cellulose?

A

yes, ruminants e.g. cows have symbiotic bacteria Ian their stomachs which digest cellulose

187
Q

elements in lipids

A

carbon, hydrogen and oxygen

188
Q

proportion of hydrogen and oxygen in lipids

A

higher proportion of hydrogen compared to oxygen

189
Q

types of lipids

A

most common= triglycerides e.g. fats and oils
derivatives e.g. phospholipids, waxes, steroids (cholesterol)

190
Q

what are true lipids

A

esters of fatty acids and alchohol

191
Q

properties of lipids

A

insoluble in water, soluble in organic solvents e.g. ethanol
high in energy

192
Q

why are lipids insoluble in water

A

because they are non-polar

193
Q

lipids energy per gram compared to carbohydrates

A

34kJ/g
carbs= 17kJ/g

194
Q

why are lipids high in energy

A

they are rich in C-H bonds

195
Q

general formula of a fatty acid

A

R.COOH

196
Q

what group does a fatty acid contain

A

carboxyl (carboxylic) acid group -COOH

197
Q

what is stearic acid an example of; is It saturated/unsaturated and why

A

example of a fatty acid
saturated because it contains the maximum number of hydrogens and no double C-C bonds

198
Q

unsaturated fatty acid description and example

A

fatty acid with one or more carbon double bond, causing a kink in the chain
linoleic acid

199
Q

polyunsaturated vs monounsaturated

A

poly= more than 1 carbon double bond
mono= only 1 carbon double bond

200
Q

do unsaturated fatty acids have higher or lower melting points and why?

A

double bonds make fatty acids melt more easily (lower MPs) so they are more likely to be liquid at room temperature

201
Q

examples of saturated and unsaturated lipids

A

saturated: butter, lard
unsaturated: oils e.g. sunflower oil

202
Q

how is a triglyceride formed?

A

by joining a glycerol molecule to 3 fatty acid molecules.
each fatty acid molecule joins via a condensation reaction

203
Q

type of bond formed between fatty acid and hydroxyl group on glycerol

A

ester

204
Q

process of triglyceride formation name

A

esterification

205
Q

functions of triglycerides

A

energy source
energy store
insulation
buoyancy
protection

206
Q

why are triglycerides useful as energy sources?

A

ester bonds can be hydrolysed to form glycerol and 3 fatty acids, which can be used in respiration to release more energy than the respiration of sugars
respiration of a lipid produces more water than that of carbohydrates

207
Q

how do camels use triglycerides as a water source?

A

they store fat in their humps and respire it to release lots of water

208
Q

why are triglycerides suitable as energy stores?

A

insoluble so can be stored without affecting the water potential of cells
high energy density

209
Q

how much energy do triglycerides yield compared to carbohydrates?

A

about twice as much

210
Q

why do triglycerides have a high energy density?

A

they have a greater proportion of hydrogen atoms compared to carbohydrates
they have lots of C-H bonds

211
Q

examples of triglycerides used as insulators

A

heat insulator= whales have blubber (adipose tissue) which decreases heat loss to the surroundings
electrical insulator= fatty myelin sheath around some neurones speeds up conduction of impulses

212
Q

why are triglycerides used for buoyancy

A

fat is less dense than water, so it allows aquatic organisms to keep afloat e.g. frogs

213
Q

where/why are triglycerides used for protection

A

fat around delicate organs e.g. kidneys acts as a shock absorber

214
Q

what are waxes & an example

A

lipid derivatives
e.g. Suberin

215
Q

what are waxes composed of

A

large alcohols attached to fatty acids (larger than triglyceride)

216
Q

where are triglycerides used for waterproofing and why

A

in the waxy cuticle to prevent water loss

217
Q

what are phospholipids and what are they made from

A

lipid derivatives
made from triglycerides

218
Q

how are phospholipids formed?

A

a condensation reaction between and OH group on a phosphoric acid molecule (H3PO4) and one of the three -OH groups on the glycerol forms an ester bond

219
Q

how are phospholipids similar to triglycerides?

A

one of the fatty acids on a triglyceride is replaced by a phosphate group

220
Q

amphipathic meaning & nature of phospholipids

A

phosphate group= polar and hydrophilic bc of -OH group
rest of molecule is non-polar and hydrophobic

221
Q

what happens when phospholipids are mixed with water

A

they may form a layer with heads in the water and tails sticking up or may form micelles (heads facing outwards and hydrophobic tails facing inwards)

222
Q

description of phospholipid membrane and why

A

phospholipids form a bilayer- tails pointing inwards (hydrophobic so move away from water and interact with each other) and heads pointing outwards ( hydrophilic so move towards water extracellularly and intracellularly)

223
Q

properties of phospholipid bilayer and why

A

increased stability because the phospholipids are free to move in the layer but will not flip sides
semi permeable so small and non-polar molecules can move through the tails

224
Q

which molecules can pass through the phospholipid bilayer

A

small and non polar molecules (lipid soluble / hydrophobic0 e.g. oxygen, steroid hormones

225
Q

how does length of phospholipid tails affect fluidity ?

A

interactions between shorter tails are weaker, maintaining fluidity by making the membrane less rigid

226
Q

how does the saturation of the phospholipid tails affect fluidity?

A

unsaturated fatty acid tails have ‘kinks’ so cannot pack as closely together, maintaining fluidity by making the membrane less rigid

227
Q

what is cholesterol and what does it consist of?

A

a steroid alcohol (because of hydroxyl group)
consists of 4 carbon based rings

228
Q

where is cholesterol made in animals

A

all cells, but mainly in the liver because it is used to synthesise bile

229
Q

where is cholesterol derivative in plants?

A

in the membrane
called stigma sterol

230
Q

amphipathic cholesterol?

A

its hydroxyl group in hydrophillic and aligns towards the phosphate heads
the remainder of the molecule is hydrophobic and associates with the phospholipid tails

231
Q

what is cholesterol part of?

A

the bilayer

232
Q

cholesterol functions

A

regulates and maintains fluidity of the membrane
makes up steroid hormones and vitamin d

233
Q

how does cholesterol maintain and regulate the fluidity of the membrane?

A

at high temps it stabilises the membrane and raises the melting point
at low temps it intercalates between the phospholipids and prevents clustering

234
Q

examples of steroid hormones

A

testosterone, oestrogen, aldosterone, cortisol

235
Q

are steroid hormones and vitamin d hydrophobic or hydrophillic?

A

hydrophobic (lipid soluble) so can pass across membranes into cells

236
Q

protein elements

A

carbon, hydrogen, oxygen, nitrogen (and sometimes phosphorus and/or sulfur)

237
Q

what are proteins made up of?

A

amino acids joined by peptide bonds

238
Q

what is the sequence of amino acids in a protein determined by?

A

the sequence of bases in DNA

239
Q

how many different amino acids occur naturally in proteins?

A

20

240
Q

in humans, where do essential and non-essential amino acids come from

A

essential must come from diet
non-essential can be made

241
Q

what do plants need in order to make amino acids?

A

nitrates

242
Q

functions of proteins

A

essential component of cell membranes
all enzymes are proteins (specific shape important)
antibodies are proteins
haemoglobin (oxygen-carrying pigment)
collagen
keratin (hair)
form structural component of animals e.g. muscle (actin and myosin)

243
Q

why are proteins an essential part of cell membranes?

A

act as carriers and pores for active transport and FD

244
Q

uses of antibodies?

A

attack and destroy invading micro-organisms

245
Q

uses of collagen

A

adds strength to many tissues including bones and artery walls

246
Q

the 3 components found in every amino acid which are bonded to the central carbon

A

amino group NH2
carboxyl group COOH
hydrogen atom H

247
Q

how do amino acids differ from one another

A

by the R group

248
Q

what is the simplest R group and which amino acid is it in?

A

H
in glycine

249
Q

what is a zwitterion?

A

a compound with no overall electric charge, which contains separate parts which are positively and negatively charged

250
Q

how are amino acids amphoteric and why is this useful?

A

carboxyl group acts as an acid
amino group acts as a base
means that amino acids can act as buffers

251
Q

what is a buffer?

A

a substance that helps to resist large changes in pH

252
Q

polar R groups on amino acids? examples

A

OH, C=O or N-H
some are positively charged and some are negatively charged

253
Q

example of amino acid which has a basic R group

A

arginine
proton/H+ acceptor e.g. NH2 + -> NH3 +

254
Q

example of an amino acid with an acidic R group

A

aspartic acids
proton/H+ donor e.g. COOH -> COO-

255
Q

what happens when an amino acid is dissolved in water

A

the amino and carboxyl group can ionise
amino group accepts a hydrogen ion to become NH3 +
carboxyl group donates a hydrogen ion to become COO-

256
Q

reaction to form a peptide bond? what enzyme is used?

A

condensation
peptidyl transferase enzymes

257
Q

what type of bond is a peptide bond

A

covalent

258
Q

description of peptide bond formation

A

one amino acid loses a hydroxyl group from its carboxylic acid group
the other amino acid loses a hydrogen atom from its amino group
the C atom of the first amino acid bonds with the N of the second amino acid
1 O and 2 H atoms removed to form water (condensation)

259
Q

what is the name of:
2 linked amino acids
many linked amino acids

A

2=dipeptide
many-polypeptide

260
Q

where are amino acids linked together in living cells

A

on ribosomes

261
Q

how to test for proteins?

A

biuret test (mixture of sodium hydroxide and copper sulphate)

262
Q

what is albumen? observation of biurets with albumen

A

egg white protein
purple layer at the interface. after shaking, uniformly purple
(positive result)

263
Q

observation of biurets with glucose solution

A

blue layer at the interface. after shaking uniformly blue
(negative test)

264
Q

basis of biurets test?

A

a test for peptide bonds
colour formed by a complex between the nitrogen atoms in the peptide chain and the Cu2+ ions

265
Q

how many levels of protein structure and organisation are there?

A

4
but not all proteins have all layers

266
Q

what shape do all proteins have

A

a characteristic and specific 3D shape

267
Q

primary structure of proteins

A

sequence of amino acids held together by peptide bonds

268
Q

what can a change in one amino acid in the primary structure of a protein do?
example

A

completely alter the properties of the protein
e.g. sickle cell anaemia: 1 amino acid substitution in haemoglobin

269
Q

secondary structure of proteins

A

folding of amino acid chain into alpha helix or beta pleated sheet du to hydrogen bonding between amino acids.

270
Q

are hydrogen bonds weak or strong?

A

weak on their own
many together are strong

271
Q

tertiary structure of proteins

A

folding of the secondary structure to a form a precise (specific) 3D shape.

272
Q

what bonds hold together the tertiary structure of a protein?

A

ionic, disulphide, hydrogen, hydrophobic/hydrophillic

273
Q

quaternary structure of proteins

A

a protein which is made up of 2 or more polypeptide chains.

274
Q

what bonds hold together the tertiary structure of a protein?

A

ionic, disulphide, hydrogen , hydrophobic/hydrophillic

275
Q

structure of an alpha helix

A

polypeptide chains coil into a helix with 36 amino acids per 10 turns of the helix.
helix is held together by hydrogen bonds

276
Q

what is a hydrogen bond?

A

a primarily electrostatic force of attraction between an electropositive atom (with a slight positive charge) e.g. hydorgen and a more electronegative atom (with a slight negative charge) e..g nitrogen or oxygen

277
Q

beta pleated sheet structure

A

polypeptide chains fold into a zigzag structure, where one chain folds over on itself, producing a beta pleated sheet.
held together by hydrogen bonds

278
Q

protein tertiary structure in detail

A

when alpha coils and beta pleats start to fold, along with the areas of straight chains of amino acids, this forms the tertiary structure.
very specific 3D shape due to bonds between amino acids which lie close to each other.

279
Q

where do the bonds form in the tertiary structure of a protein?

A

between different types of R groups

280
Q

what kind of bonds do negatively charged R groups form in the proteins tertiary structure?

A

ionic bonds

281
Q

what kind of bonds do uncharged (polar) R groups form in the proteins tertiary structure?

A

hydrophilic
interacting with each other or the water in the cytoplasm

282
Q

what kind of bonds do nonpolar R groups form in the proteins tertiary structure?

A

hydrophobic
interact with each other away from the water in the cytoplasm

283
Q

what does the quaternary structure of a protein describe?

A

how the multiple polypeptides are arranged and held together to make the complete molecule(if it is made up of more than one polypeptide chain)

284
Q

PROTEINS
disulfide bonds description
where do they form?
strength?

A

hydrogen (H2) is removed
disulfide bond forms between R groups of cysteine amino acids
very strong covalent bond

285
Q

PROTEINS
ionic bonds description
where do they form?
strength?
what can they be broken by?

A

electrostatic attraction between oppositely charged R groups
fairly strong
can be broken by changes in pH

286
Q

PROTEINS
hydrogen bonds
strength
where do they form?
what are they broken by?

A

relatively weak, but many form a strong hold
between amine and carbonyl groups
between hydroxyl R groups
between other polar R groups
changes in pH or high temperature can break them

287
Q

PROTEINS
hydrophobic interactions

A

some of the amino acids that make up proteins have nonpolar groups and are therefore hydrophobic. these have a strong tendency to associate with one another inside the interior of the folded protein to avoid water molecules

288
Q

PROTEINS
where do hydrophobic and hydrophilic groups point?

A

hydrophobic R groups point inwards
hydrophilic R groups point outwards and hydrogen bond with water: this makes proteins soluble

289
Q

fibrous proteins primary structure

A

repetitive regular sequence of amino acids

290
Q

fibrous proteins shape

A

long parallel polypeptide chains crosslinked (bonded e.g. H bonds) at intervals to form long fibres
helical

291
Q

fibrous proteins stability

A

stable structure
are therefore strong and unreactive

292
Q

fibrous proteins solubility

A

insoluble

293
Q

fibrous proteins function

A

support and structural functions

294
Q

fibrous proteins examples and where are they found

A

collagen (found in skin and arteries)
elastin (found in skin, arteries and alveoli)
keratin (found in hair, nails, scales)

295
Q

globular proteins primary structure

A

irregular amino acid sequence

296
Q

globular proteins shape

A

folded into a spherical shape

297
Q

globular proteins stability

A

relatively unstable structure

298
Q

globular proteins solubility

A

easily soluble because hydrophilic groups point outwards

299
Q

globular proteins function

A

metabolic functions

300
Q

globular proteins examples and why they are globular

A

enzymes (must be soluble to function)
some hormones e.g. insulin (must be soluble to function, travels in blood)
haemoglobin (carries oxygen in blood)
myoglobin (stores oxygen in muscle cells)

301
Q

why can triglycerides not be described as polymers?

A

not composed of monomers/ repeating subunits

302
Q

how does the lipid content of mycoprotein differ from food that comes from animals?

A

higher ratio of unsaturated to saturated fat
less (overall lipid/fat)
less/no saturated fat
more unsaturated fatty acids

303
Q

haemoglobin:
type of protein
shape
amino acids
bonds
is it conjugated?
quaternary structure?
is it soluble?
does it bind specifically to molecules?
function
found where?

A

globular
spherical
range of amino acids
hydrogen bonds, hydrophobic interactions
yes; haem group
quaternary structure held together by H bonds and hydrophobic interactions. 4 polypeptide chains
yes, soluble
binds to O2, CO2, CO and H+ (therefore acts as buffer)
transports O2 and CO2 in the blood
in red blood cells

304
Q

insulin
type of protein
shape
amino acids
bonds
is it conjugated?
quaternary structure?
is it soluble?
does it bind specifically to molecules?
function
found where?

A

globular
spherical
range of amino acids
hydrogen and disulfide bonds
not conjugated
quaternary structure held together by disulphide bonds. 2 polypeptide chains
yes soluble
binds to receptors on muscles and liver
regulates BGL (decreases it)
produced in pancreas, travels in blood plasma

305
Q

pepsin
type of protein
shape
amino acids
bonds
is it conjugated?
quaternary structure?
is it soluble?
does it bind specifically to molecules?
function
found where?

A

globular
spherical
327 amino acids, most of which are acidic so aren’t affected by stomach acid
disulphide and hydrogen bonds
not conjugated
no quaternary structure; only 1 polypeptide chain
yes soluble
protease enzyme breaks down proteins to peptides
stomach

306
Q

collagen
type of protein
shape
amino acids
bonds
is it conjugated?
is it soluble?
does it bind specifically to molecules?
function
found where?

A

fibrous
fibre
1000 amino acids-long helices. glycine every 3rd amino acid, repetitive
covalent and hydrogen bonds
not conjugated
insoluble
no
high tensile strength, so prevent artery walls from bursting
artery walls, bones, tendons, skin

307
Q

keratin
type of protein
shape
amino acids
bonds
is it conjugated?
is it soluble?
does it bind specifically to molecules?
function
found where?

A

fibrous
fibre
cysteine (disulphide bond)
disulfide and hydrogen bonds
not conjugated
insoluble
no
strong, inflexible and waterproof so acts as barrier
skin, hair, nails, hoofs, scales

308
Q

elastin
type of protein
shape
amino acids
bonds
is it conjugated?
is it soluble?
does it bind specifically to molecules?
function
found where?

A

fibrous
fibre
range of amino acids
covalent crosslinks, hydrophobic interactions, hydrogen bonds
not conjugated
insoluble
no
gives strength and elasticity to skin and alveoli because it can stretch and recoil
artery walls, skin, bladder, alveoli

309
Q

haemoglobin function

A

transports oxygen from the lungs to respiring cells

310
Q

haemoglobin location

A

RBCs; each RBC contains 280 million molecule of Hb

311
Q

haemoglobin molecule structure: how many and which polypeptide chains

A

globular, made up of 4 tightly packed polypeptide chains
2 identical alpha globin chains and 2 identical beta globin chains

312
Q

haemoglobin molecule structure: hydrophobic/philic

A

hydrophobic R groups face inwards; the interactions hold the molecule in a precise 3D shape
hydrophilic R groups point outwards to maintain solubility

313
Q

haemoglobin polypeptide chains’ structure

A

each polypeptide has 8 or 9 sections of a helix
each polypeptide has a haem group, which is permanent but not made of protein (a prosthetic group)
therefore it is a conjugated protein

314
Q

ham group in haemoglobin

A

porphyrin (polymorphyin) group. it is a flat structure with an iron ion (Fe 2+) at the centre. this gives its colour
ham group binds reversibly with a molecule of O2

315
Q

haemoglobin equation

A

Hb+4(O2)<->Hb(O2)4
haemoglobin+oxygen<->oxyhaemoglobin
from a dark purplish colour to a bright red colour
->oxygen associates with Hb to form Hb(O2)4. (loading)
<- oxyhemoglobin dissociates to form Hb and O2 (unloading)

316
Q

insulin basic structure

A

disulphide bonds,
alpha helices
beta pleated sheets

317
Q

insulin shape
why is this important

A

has a specific 3D shape, which is important for binding to complementary receptors

318
Q

how does insulin’s shape relate to its function
(what does it bind to, where, what does this lead to)

A

insulin binds to a tyrosine kinase receptor on its target cells in the liver and muscles
it has a specific shape that is complementary to the target receptor
this leads to other signalling events within the cells, leading to a decrease in BGL

319
Q

validity defintion?

A

an experiment is valid if it is suitably designed to answer the question i.e. variables have been controlled

320
Q

how does the structure of galactose make it suitable for use as a respiratory substrate?

A

the bonds contain energy, which is released when they are broken by respiratory enzymes
H/OH groups can form H bonds with water so galactose is soluble and can move within the cell
AVP

321
Q

why is a covalent bond stronger than a hydrogen bond?

A

covalent bond involves the sharing of electrons between 2 atoms
H bond= electrostatic attraction between electropositive H atom and an electrongeative atom

322
Q

what is the significance of an R group in an amino acid?

A

property of R group gives AA its properties
e.g. determines what bonds it forms and whether it faces in/out

323
Q

difference between polypeptide and protein?

A

polypeptide translated at ribosomes= linear sequence of amino acids
protein= more than 1 chain of amino acids with a complex shape

324
Q

why does keratin in hair contain less disulphide bonds than keratin in nails

A

flexibility increases with decreasing disulfide bonds
hair is more flexible than nails

325
Q

how do the shape of globular proteins contribute to the maintenance of life?

A

signalling molecules e.g. hormones; control body systems by binding to receptors
bind to and carry molecules around the body
AS correct, specific shape for substrate so digest food

326
Q

3 mechanical functions of collagen in the body

A

prevents bursting of artery walls by allowing them to withstand high pressure
in tendons, bones, cartilage, connective tissue

327
Q

how can a colorimeter be used to do a quantitative benedicts test?

A

colorimeter measures absorbance/transmissioon of light by a coloured slution
more conc solution= more light absorbed/less light transmitted
or compare to data table of known concentration

328
Q

what are the 2 parts that make up a carboxylic acid?

A

carboxyl group and hydrocarbon chain

329
Q

why do oils contain unsaturated triglycerides rather than saturated?

A

1 or more C=C double bonds
cause kink/bend in tail
cannot pack closely together
cannot form more H bonds
lower MP

330
Q

2 similarities and 1 difference between phospholipids and sterols

A

BOTH have dual hydrophobic/philic characteristics
BOTH make up plasma membrane
DIFFERENCE sterols are complex alcohol molecules, phospholipids are lipids

331
Q

alpha glucose structure

A

H on top

332
Q

collagen structure

A

high proportion of glycine means chains can lie close to each other
crosslinks between molecules are staggered to avoid weak points

333
Q

collagen properties

A

provides mechanical strength (high tensile strength) due to covalent bonds liking triple helix molecules together
flexible
insoluble

334
Q

keratin properties

A

v strong molecule (lots of disulphide bonds: degree of these determines flexibility)
insoluble
mechanical protection
waterproof (prevents entry of waterborne pollutants)

335
Q

elastin properties

A

strong and can stretch and recoil without breaking
insoluble

336
Q

elastin found where?
why?

A

alveolar walls: allows them to stretch during inhalation and recoil during exhalation to expel air

337
Q

differences between amylose and cellulose?

A

amylose= coiled, cellulose has no coiling
alternate molecules flipped 180 in cellulose but monomers are same orientation in amylose
alpha 1-4 glycosidic bonds in amylose, beta 1-4 glycosidic bonds in cellulose
amylose is granular whereas cellulose is fibrous
H bonds within molecule of amylose, H bonds between adjacent molecules of cellulose

338
Q

which properties of cellulose make it suitable for forming cell walls?

A

high tensile strength
H bonds can form between adjacent fibres

339
Q

why is the ability of water to act as a solvent important for the survival of organisms?

A

reactions medium (e..g metabolic)
transport medium
ionic compounds separate and dissolve in it
can dilute toxic substances
can take in gases e.g. O2

biology (28 decks)

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