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a-level biology > 2.1.2 Biological Molecules > Flashcards

2.1.2 Biological Molecules Flashcards

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1
Q

monomer

A

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

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2
Q

polymer

A

a larger molecule made up of monomers chemically bonded together

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3
Q

covalent bond

A

strong bond formed when electrons are shared between 2 atoms

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4
Q

condensation reaction

A

occurs when 2 molecules are joined together with the removal of water
a covalent bond is formed

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5
Q

hydrolysis reaction

A

splitting a polymer apart with the addition of water
a covalent bond is broken

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6
Q

chemical elements of carbohydrates

A

carbon, hydrogen, oxygen

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7
Q

monomer of carbohydrates

A

monosaccharide (eg. glucose)

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8
Q

polymer of carbohydrates

A

polysaccharide (eg. glycogen)

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9
Q

chemical elements of proteins

A

carbon, hydrogen, oxygen, nitrogen (sulfur)

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10
Q

monomer of proteins

A

amino acid

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11
Q

polymer of proteins

A

polypeptide (eg. haemoglobin)

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12
Q

polypeptide

A

many amino acids joined together by peptide bonds

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13
Q

chemical elements of nucleic acids

A

carbon, hydrogen, oxygen, nitrogen, phosphorus

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14
Q

monomer of nucleic acids

A

nucleotide

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15
Q

polymer of nucleic acids

A

DNA
RNA

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16
Q

chemical elements of lipids

A

carbon, hydrogen, oxygen

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17
Q

chemical symbol for calcium ion

A

Ca 2+

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18
Q

functions of Ca 2+

A

nerve transmission
muscle contraction
bone formation
cofactor in blood clotting

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19
Q

chemical symbol for sodium ion

A

Na+

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20
Q

functions of Na+

A

nerve transmission
affects reabsorption of water in kidneys

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21
Q

chemical symbol for a potassium ion

A

K+

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22
Q

functions of K+

A

nerve transmission
in guard cells as a part of the stomatal opening mechanism

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23
Q

chemical symbol for hydrogen ion

A

H+

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24
Q

functions of H+

A

involved in ATP formation in photosynthesis & respiration

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25
Q

chemical symbol for ammonium

A

NH4 +

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26
Q

functions of NH4 +

A

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

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27
Q

chemical symbol for nitrate

A

NO3 -

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28
Q

functions of NO3 -

A

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

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29
Q

chemical symbol for hydrogen carbonate

A

HCO3 -

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30
Q

functions of HCO3-

A

involved in the transport of CO2
regulation of blood pH

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31
Q

chemical symbol for chloride

A

Cl-

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32
Q

functions of Cl-

A

cofactor for amylase enzyme
chloride shift in red blood cells

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33
Q

chemical symbol for phosphate

A

PO4 3-

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34
Q

functions of PO4 3-

A

bone formation
component of ATP and nucleic acids
component of phospholipids

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35
Q

chemical symbol for a hydroxide ion

A

OH-

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36
Q

functions of OH-

A

regulation of blood pH

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37
Q

polar molecule

A

uneven charge distribution
partial positive and negative charges which do not cancel out

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38
Q

structure of water

A

covalent bonds within one molecule. hydrogen bonds between the molecules

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39
Q

water is a liquid at room temperature

A

provide a habitat
a major component of tissues
reactions medium for chemical reactions
effective transport medium

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40
Q

properties of water

A

chemical:
polar molecule - uneven charge distribution
hydrogen bonds between water molecules
hydrogen bonds are weak, large number of bonds collectively strong
physical:
ice insulates water below/ice freezes
liquid water is more dense than solid water (ice)
solvent for polar molecules
cohesion
adhesion
high surface tension
transparent

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41
Q

water is more dense than ice

A

ice floats so ponds are insulated against extreme temperatures which decreases heat loss - aquatic organisms have a stable environment
ice creates another habitat for animals e.g. polar bear

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42
Q

structure of ice vs water

A

ice: open lattice structure, hydrogen bonds are stable
water: hydrogen bonds break and reform

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43
Q

water is a solvent for polar molecules

A

molecules can move around in a solution and react together
molecules and ions can be transported when dissolved
removal of waste

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44
Q

water and non-polar molecules allow hydrophobic interactions to occur

A

allows tertiary structure of proteins to form
allows phospholipid bilayer to form

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45
Q

cohesion

A

the attraction of water molecules to one another

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46
Q

surface tension (of water)

A

the surface of water’s ability to resist force

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47
Q

cohesion and surface tension enables

A

columns of water to be pulled up the xylem
insects to walk on water

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48
Q

water has a high specific heat capacity

A

hydrogen bonds restrict the movement of water molecules so a large amount of energy is required to raise the temperature

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49
Q

high specific heat capacity of water means

A

water does not warm up or cool down easily
water keeps a stable temperature, giving aquatic organisms a stable environment in which to live
gases remain soluble in water

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50
Q

water has a high latent heat of vaporisation

A

hydrogen bonds mean large amounts of energy are required for water to evaporate

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51
Q

high latent heat of vaporisation in water

A

helps keep temperature stable and cool organisms
plants are cooled in transpiration

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52
Q

general formula for carbohydrates

A

Cx(H2O)y

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53
Q

types of carbohydrates

A

monosaccharides, disaccharides, polysaccharides

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54
Q

functions of carbohydrates

A

energy source
energy store
structural role
part of larger molecules

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55
Q

general formula for monosaccharides

A

(CH2O)n where n = 3-9

56
Q

properties of monosaccharides

A

soluble in water -polar OH groups
insoluble in non-polar solvents
tastes sweet

57
Q

isomers of monosaccharides

A

same molecular formula, different structural formula
e.g. alpha glucose and beta glucose

58
Q

displayed formula of alpha glucose

A

OH group is below the plane of the axis

59
Q

role of alpha glucose

A

energy source
component of starch and glycogen - acts as an energy store

60
Q

displayed formula of beta glucose

A

OH group is above the plane of the axis

61
Q

role of beta glucose

A

energy source
acts as a component in cellulose - provides structural support in plant cell walls

62
Q

displayed formula of ribose

A

4 OH groups

63
Q

role of ribose

A

component of RNA and ATP

64
Q

displayed formula of deoxyribose

A

3 OH groups, 1 H off carbon-2

65
Q

role of deoxyribose

A

component of DNA

66
Q

solubility of glucose

A

freely soluble in water - polar
soluble in blood plasma, can be transported to cells for uptake

67
Q

disaccharides

A

formed by two monosaccharides joining together in a condensation reaction
a glycosidic bond is formed

68
Q

general formula for disaccharides

A

C12H22O11

69
Q

maltose

A

alpha glucose + alpha glucose
formed in a condensation reaction with the removal of water

70
Q

sucrose

A

alpha glucose + frictose

71
Q

lactose

A

alpha glucose + beta glucose

72
Q

cellubiose

A

beta glucose + beta glucose

73
Q

reducing agent

A

a chemical species that donates an electron to an electron recipient, reducing the recipient

74
Q

oxidising agent

A

a substance that gains an electron from a reducing agent, oxidising the reducing agent

75
Q

test for reducing sugar

A

add benedict’s solution
heat in water bath

76
Q

positive result for reducing sugar

A

colour change from blue to green-yellow-orange to brick red

77
Q

qualitative

A

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

78
Q

quantitative

A

tells us how much of a substance is present

79
Q

why is excess benedict’s used when testing for reducing sugar

A

to ensure all sugar will react

80
Q

equation for volume of stock solution required

A

(total volume wanted/conc. of stock solution) x conc. wanted

81
Q

validity

A

it is suitably designed to answer the question being asked
testing what is being tested

82
Q

polysaccharides

A

polymers which consist of hundreds or thousands of monosaccharides
joined by condensation reactions resulting in glycosidic bonds

83
Q

examples of polysaccharides

A

cellulose, glycogen, starch, callose

84
Q

starch

A

polymer of alpha glucose
made up of two components, amylose and amylopectin

85
Q

amylose

A

1,4 glycosidic bonds
between carbon-1 and carbon-4

86
Q

amylose helix

A

coil = more compact shape
held together by hydrogen bonds

87
Q

properties of lipids

A

insoluble in water
high in energy

88
Q

differences between saturated and unsaturated fatty acids

A

S: single C-C bonds, max. hydrogens, solid at room temperature, high melting point
U: 1 < double C=C bond, not max. carbons, low melting point

89
Q

structure of a triglyceride

A

3 fatty acids, 1 glycerol

90
Q

functions of triglycerides

A

energy source
energy store
insulation
buoyancy
protection

91
Q

triglyceride as an energy source

A

ester bonds can be hydrolysed to form 1 glycerol and 3 fatty acids
used in respiration and release energy

92
Q

triglyceride as an insoluble energy store

A

can be stored without affecting the water the water potential of cells

93
Q

triglycerides as an energy store: high energy density

A

they have a greater proportion of hydrogen atoms compared to carbohydrates

94
Q

triglycerides as a heat insulator

A

whales have blubber (adipose tissue)

95
Q

triglycerides as an electrical insulator

A

fatty myelin sheath around some neurones. insulates and increases conduction speed of impulses

96
Q

triglycerides - buoyancy

A

fat is less dense than water
aquatic organisms can float. eg. frogs

97
Q

triglycerides - protection

A

fat acts as a shock absorber around delicate organs

98
Q

test for lipids

A

emulsion test

99
Q

structure of a saturated fatty acid

A

no double bonds

100
Q

structure of an unsaturated fatty acid

A

at least one double C=C bond

101
Q

simplified structure of a phospholipid

A

hydrophilic phosphate head
hydrophobic fatty acid tail

102
Q

structure of a phospholipid

A
103
Q

amphipathic

A

both hydrophobic and hydrophobic parts

104
Q

phospholipid fatty acid tails

A

non-polar
hydrophobic
move away from water and interact with each other

105
Q

phospholipid phosphate heads

A

polar
hydrophilic
interact with water extracellularly and intracellularly

106
Q

structure of cholesterol

A
107
Q

function of cholesterol

A

regulates and maintains the fluidity of the membrane

108
Q

cholesterol at high temperatures

A

it stabilises the membrane and raises the melting point

109
Q

cholesterol at low temperatures

A

it intercalates between the phospholipids and prevents clustering

110
Q

without cholesterol, the bilayer is too hot

A

too fluid/flexible
won’t hold shape

111
Q

functions of proteins

A

an essential component of cell membranes
antibodies
enzymes
form structural components of animals

112
Q

structure of an amino acid

A

amine group, carboxylic group, hydrogen atom, R group

113
Q

a zwitterion

A

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

114
Q

a buffer

A

a substance that helps to resist large changes in pH

115
Q

basis of the test for protein

A

a test for peptide bonds
colour formed by a complex between the nitrogen atoms in the peptide chain and the Cu 2+ ions

116
Q

primary structure of a protein

A

sequence of amino acids held together by peptide bonds

117
Q

secondary structure of a protein

A

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

118
Q

tertiary structure of a protein

A

folding of the secondary structure to form a specific (3D) shape. 4 different types of bonding/interactions can hold this shape together

119
Q

two types of secondary structure of a protein

A

alpha helix
beta pleated sheet

120
Q

quaternary structure of a protein

A

a protein which is made up of 2 or more polypeptide chains. 4 different types of bonding/interactions can hold this shape together

121
Q

examples of fibrous proteins

A

keratin, elastin, collagen

122
Q

examples of globular proteins

A

antibodies, hormones, enzymes

123
Q

4 different types of bonding/interactions in protein structure

A

ionic
disulfide
hydrogen
hydrophilic/hydrophobic

124
Q

primary structure of a fibrous protein

A

repetitive regular sequence of amino acids

125
Q

primary structure of a globular protein

A

irregular amino acid sequence

126
Q

shape of fibrous protein

A

long parallel polypeptide chains cross-linked at intervals from long fibres

127
Q

shape of globular proteins

A

folded into a spherical shape

128
Q

stability of fibrous proteins

A

stable structure - unreactive

129
Q

solubility of fibrous protein

A

insoluble

130
Q

solubility of globular proteins

A

easily soluble - hydrophilic R groups point outwards

131
Q

stability of globular proteins

A

relatively unstable structure

132
Q

function of fibrous proteins

A

support + structural functions

133
Q

function of globular proteins

A

metabolic functions

134
Q

properties of collagen

A

provides high mechanical strength due to covalent bonds linking triple helix molecules together
flexible and insoluble
found in the outer wall of artery where it prevents bursting under high pressure

135
Q

properties of elastin

A

strong and can stretch and recoil without breaking
insoluble
found in alveolar walls where it allows them to stretch during inhalation and recoil during exhalation to expel air
found in blood vessel walls, skin

136
Q

properties of keratin

A

very strong molecule - lots of disulfide bonds, the degree of these determines flexibility
insoluble
mechanical protection
waterproof
found in hair, skin, nails, claws, hoofs, scales, horns, fur, feathers

a-level biology (26 decks)

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