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biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are polymers

A

large, complex molecules made of long chains of monomers (e.g most carbohydrates)

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2
Q

what are monomers

A

small, basic molecular units (e.g monosaccharides, amino acids, nucleotides)

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3
Q

what elements do all carbohydrates contain

A

C (carbon), H (hydrogen), O (exygen)

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4
Q

what are monosaccharides

A

sugar that can be hydrolysed to give a simpler sugar (e.g glucose, fructose, galactose)

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5
Q

what is glucose

A

hexose sugar (monosaccharide with 6 carbon atoms in each molecule) , with two types (alpha and beta) which are isomers (molecules with same molecular formula, but atoms connected in a different way)

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6
Q

alpha

A

H at top, HO at bottom (same as other side)

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7
Q

beta

A

OH at top, H at bottom

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8
Q

what is a condensation reaction

A

when 2 molecules join together with the formation of a new chemical bond, and a water molecule released when bond is formed

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9
Q

condensation reaction example

A

two alpha glucoses joined together to form maltose (disaccharide), a glycosidic bond and a water molecule

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10
Q

glucose +… = disaccharide examples

A

2 alpha glucose = maltose
glucose + fructose = sucrose
glucose + galactose = lactose

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11
Q

what are disaccharides

A

2 monosaccharides joined by a condensation reaction

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12
Q

what is hydrolysis reaction

A

break down of the chemical bond between monomers using a water molecule

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13
Q

hydrolysis reaction example

A

carbohydrates broken down into monosaccharides using a water molecule

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14
Q

what is the test for sugars

A

Benedicts test

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15
Q

types of sugars

A

reducing (all monosaccharides and some disaccharides) and non-reducing (do not have an OH group attached to carbon atom)

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16
Q

test for reducing sugars

A

1) add benedicts reagent (blue) to sample
2)heat in a water bath thats been brought to the boil
positive = coloured precipitate (solid particles suspended in solution)
(none) blue-green-yellow-orange-red (most)

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17
Q

test for non-reducing

A

1)break down into monosaccharides by adding silute hydrochloric acid
2) heating in a water bath thats been brought to the boil
3)neutralise with sodium hydrogencarbonate
4)carry out same test as for reducing sugars
positive = coloured precipitate blue-red

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18
Q

what are polysaccharides

A

more than 2 monosaccharides joined by condensation reactions (e.g starch, glycogen, cellulose)

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19
Q

polysaccharide formation example

A

lots of alpha glucose joined with glycosidic bonds to form amlyose and water

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20
Q

starch function

A

plants store of excess glucose

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21
Q

starch structure

A

mixture of the polysaccharides amylose and amylopectin, insoluble in water (so doesn’t affect water potential, so water doesn’t enter cells through osmosis and cells don’t swell as a result = good for storage)

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22
Q

amylose

A

long, unchained branch of alpha glucose, coiled structure (due to angles of glycosidic bonds) = compact and good for storage

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23
Q

amylopectin

A

long, branched chain of alpha glucose, enzymes can break glycosidic bonds easily (due to side branches) = glucose can be released quickly

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24
Q

what is the test for starch

A

iodine test

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25
Q

the test for starch

A

1)add idoine dissolved in potassium iodide solution to sample
positive = colour change from browny-orange ti blue-black

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26
Q

glycogen function

A

animals store of excess glucose

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27
Q

glycogen structure

A

lots of side branches = glucose can be released quickly, long, compact = good for storage

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28
Q

cellulose function

A

structure in plant cell walls

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29
Q

cellulose structure

A

long, unbranched chains of beta glucose, straight chains (due to the bonds), hydrogen bonds linked to form microfibrils (making it strong= good for structural support)

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30
Q

what are triglycerides

A

kind of lipid

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31
Q

triglyceride structure

A

one molecule of glycerol with three fatty acids (forming hydrocarbon tail, which is insoluble in water (hydrophobic))

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32
Q

fatty acid structure

A

carbon atom in centre, attached to HO on the bottom left, O on bottom left with double bond, and variable R group hydrocaron tail on the right

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33
Q

triglyceride formation

A

condensation reaction between fatty acid and glycerol molecule, with the formation of an ester bond and a water molecule ( occurs 3 times total, one for each fatty acid)

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34
Q

types of fatty acids

A

saturated or unsaturated - difference is hydrocarbon tails (R groups)

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35
Q

saturated fatty acid

A

don’t have double bonds between carbon atoms (fatty acid is ‘saturated’ with hydrogen

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36
Q

unsaturated fatty acid

A

at least one double bond between carbon atoms, causing a kink in the chain

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37
Q

what are phospholipids

A

lipids found in the cell membrane

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38
Q

phospholipid structure

A

glycerol attached to 2 fatty acids (hydrophobic hydrocarbon tail) and a phosphate group (hydophilic)

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39
Q

triglyceride structure - function

A

energy storage molecules (long hydrocarbon tails contain lots of energy so lots is released when broken down, and they’re insoluble so doesn’t affect water potential and water doesn’t enter through osmosis)

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40
Q

triglyceride droplets

A

clump to form insoluble molecules as hydrophocib fatty acids face inwards

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41
Q

phospholipid structure - function

A

make up bilayer of cell membranes (hydrophobic tails and hydrophilic heads form a double later where water passes on either side, but can’t pass easily through it

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42
Q

what is the bilayer job

A

control what enters and leaves a cell

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43
Q

test for lipids

A

emulsion test

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44
Q

emulsion test

A

1) shake test substance with ethanol for a minute (suntil it dissolves)
2) pour solution into water
positive = milky emulsion - more milky means more fat

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45
Q

what are proteins

A

long chains of amino acids (amino acids = monomers) , one or more polypeptides joined together

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46
Q

what are dipeptides

A

2 amino acids joined together

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47
Q

what are polypeptides

A

more than 2 amino acids joined together

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48
Q

amino acid structure

A

C (carbon) attached to a carboxyl group (COOH), amino group (NH2) and R group (variable R group)

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49
Q

polypeptide formation

A

condensation reaction, amino acids join to form peptide bonds and a water molecule

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50
Q

protein structural levels

A

primary, secondary, tertiary, quaternary

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51
Q

primary structure

A

sequence of amino acids in the polypeptide chain

52
Q

secondary structure

A

hydrogen bonds form between amino acids making it coil into an alpha helix, or fold into a beta pleated sheet

53
Q

tertiary structure

A

more bonds form (hydrogen, ionic, disulfide bridges) so chain is coiled and folded further , for single polypeptide chain proteins its the final 3D structure

54
Q

what are ionic bonds

A

attractions between negative and positive chrges on the molecules

55
Q

what are disulfide bridges

A

bonds formed when 2 molecules of cysteine come close together (sulfur atoms in each bond to each other)

56
Q

quaternary structure

A

the way that several different polypeptide chains are held together by bonds, for proteins with more than 1 polypeptide chain its the final 3D structure

57
Q

protein functions

A

enzymes, antibodies, transport proteins, structural proteins

58
Q

proteins as enzymes

A

roughly spherical (due to tight folding), soluble, often have roles in metabolism (e.g digestive enzymes)

59
Q

proteins as antibodies

A

involved in immune response. made up of 2 light (short) and 2 heavy (long) polypeptide chains bonded together, have variable regions

60
Q

proteins as transport proteins

A

(a.k.a channel proteins) present in cell membranes, contain hydrophobic and hydrophilic amino acids (= protein folds up to form channel), transport ions and molecules across membranes

61
Q

proteins as structural proteins

A

physically strong, consist of long polypeptide chains lying parallel with cross-links between them (e.g keratin - hair and nails, collagen - connective tissue)

62
Q

test for proteins

A

biuret test

63
Q

biuret test

A

1) add sodium hydroxide solution (to make alkaline)
2) add copper sulfate solution
positive = solution turns purple from blue
negative = solution stays blue

64
Q

what are enzymes

A

biological catalysts (for metabolic reactions) at a cellular level and for the organism as a whole, have an active site, can affect structures of an organism

65
Q

what are catalysts

A

substance that speeds up a chemical reaction without being used up in the reaction itself

66
Q

enzyme action

A

can be intracellular (within cells) or extracellular (outside cells)

67
Q

how enzymes work

A

lower activation energy which speeds up the rate of a reaction by forming an enzyme-substrate complex with the complimentary substrate

68
Q

enzyme in a joining reaction

A

being attached to the enzyme brings the substances close together, reducing repulsion meaning they can bond more easily

69
Q

enzyme in a breakdown reaction

A

fitting into the active site puts strain on the bonds in the substrate, so they break up more easily

70
Q

what is activation energy

A

certain amount of energy that needs to be supplied to the chemicals before the reaction can start (usually heat)

71
Q

enzyme-substrate models

A

lock and key, induced fit

72
Q

lock and key model

A

substrate fits into the enzyme as it is complimentary to the shape (enzyme is unchanged after reaction)

73
Q

induced fit model

A

the substrate changes the active site shape to fit the substrate (active shape changes back once substrate is broken down)

74
Q

active site shape

A

determined by tertiary structure (so if its altered, active site will change and substrate won’t fit) (e.g mutation in gene in primary structure = different tertiary structure)

75
Q

factors that affect enzyme action

A

temperature, pH, enzyme/substrate concentration, inhibitors

76
Q

temperature on enzyme action

A

higher temperature = faster rate up to a certain point

high temp. means molecules vibrate faster, so collide more with more energy so more likely to react) (become denatured

77
Q

denatured due to temperature

A

particles vibrate more, which breaks bonds that hold enzyme in shape, so active site changes shape and can’t form an enzyme-substrate complex so can’t function as a catalyst

78
Q

pH on enzyme action

A

optimum pH = fastest rate (lower/higher = denatured) (e.g pepsin optimum pH is 2, and is found in stomach which has acidic conditions)

79
Q

denatured due to pH

A

above and below pH = H+ and OH- ions mess up the ionic and hydrogen bonds in tertiary structure, so changes shape

80
Q

concentration of enzyme on enzyme action

A

more enzyme conc = faster rate (more likely to collide, so reaction rate increases) up to certain point if substrate is limited (as no more substrate will be available)

81
Q

concentration of substrate on enzyme action

A

higher substrate conc = faster rate (more likely collisions so more complexes formed, so faster rate) up to a certain point (all active sites will be full so will be saturated) initial rate = fastest

82
Q

types of inhibitors

A

competitive and non-competitive

83
Q

competitive inhibitors

A

similar shape to substrate, bind to active site but no reaction takes place (blocks active site)

84
Q

concentration of competitive inhibitors

A

high conc of inhibitor = take up nearly all active sites
high conc of subtrate = chance of substrate forming enzyme-substrate complex before inhibitor fills it increases, so rate of reaction increases

85
Q

non-competitive inhibitors

A

bind to enzyme away from active site and change the structure meaning active site changes shape, and substrate can’t bind

86
Q

concentration of non-competitive inhibitors

A

doesn’t change the rate

87
Q

what is DNA

A

deoxyibonucleic acid

88
Q

DNA function

A

used to store genetic information (all instructions an organism needs to grow and develop)

89
Q

DNA structure

A

nucelotide (pentose sugar = dexoyribose, nitrogen containing organic base = adenine thymine cytosine and guanine, phosphate group)

90
Q

what is a nucleotide

A

type of biological molecule, monomers of DNA and RNA, contain pentose sugar, phosphate group, organic base

91
Q

what does organic mean

A

contains carbon

92
Q

what is RNA

A

ribonucleic acid

93
Q

RNA function

A

transfer genetic information from DNA to ribosomes

94
Q

RNA structure

A

nucleotide (pentose sugar = ribose, nitrogen containing organic base = adenine uracil guanine and cytosine, phosphate group)

95
Q

what are polynucleotides

A

polymer of nucleotides (that have joined via condensation reaction)

96
Q

condensation reaction between nucleotides

A

between phosphate group of one and pentose sugar of other, forms phosphodiester bond and water molecule = sugar-phosphate backbone

97
Q

phosphodiester bond

A

phosphate group and 2 ester bonds

98
Q

double helix DNA

A

anitparallel strands twisted , joined by hydrogen bonds in complementary base pairing

99
Q

complementary base pairing

A

adenine-thymine (2 hydrogen bonds) , cytosine-guaning (3 hydrogen bonds)`

100
Q

single chain RNA

A

relatively short, single polynucleotide chain

101
Q

DNA carrying genetic code

A

doubted as it has a relatively simple composition, until 1953. double helix structure determined by Watson and Crick

102
Q

DNA replication

A

semi-conservative replication

103
Q

semi-conservative replication method

A

1) DNA helicase breaks hydrogen bonds between bases to seperate strands
2) free nucleotides bind to the complimentary bases on the template strand
3) free nucleotides are joined together by enzyme DNA polymerase with phosphodiester bonds
4) 2 identical strands of DNA are made, containing half of the original DNA and half of the new DNA

104
Q

enzyme DNA polymerase

A

moves in opposite ways (due to being complimentary to the 3’ (3 prime) end) so starts at 3’ and ends at 5’ (opposite ends on each strand)

105
Q

semi-conservative replication discovery

A

designed by Watson and Crick, validated by Meselson and Stahl

106
Q

validation of semi-conservative replication

A

1) N15 - heavy -DNA strand placed in centrifuge (settled at bottom of centrifuge tube)
2)N15 placed in N14 - light -broth
3)left to replicate
4)new strands placed in centrigue, and settled mid-way up the tube showing it was a combination
if it was conservative = new strand would have settled at top (light) and bottom (heavy) of tube

107
Q

water structure

A

2 hydrogen, 1 oxygen joined by shared electrons

108
Q

water atom charges

A

polar
oxygen = delta negative (unshared negative electrons give a slight negative charge) which attracts the
hydrogen = shared negative electrons mean the other side of the hydrogen atom are slightly positive)

109
Q

water functions

A

transport, metabolite, solvent, temperature control

110
Q

water for transport

A

cohesive (molecules stick together) due to being polar, = flows, so good for transport (e.g in columns up the xylem) and high surface tension when in contact with air, so can form droplets (e.g sweat, to evaporate)

111
Q

water as a metabolite

A

metabolic reactions = condensation/hyrolysis, so release or require water molecules

112
Q

water as a solvent

A

polar, so surround ionic substances (negative attracted to positive and vice versa) (e.g salt), meaning substance dissolves

113
Q

water as temperature control

A

1) high latent heat of vaporisation - takes lots of energy to break hydrogen bonds, so lots of energy used up when it evaporates = cools substance down
2) can resist changes in temperature - hydrogen bonds can absorb a lot of energy (has high specific heat capacity) which stops rapid temperature changes

114
Q

what is ATP

A

adenosine triphosphate

115
Q

ATP structure

A

nucleotide derivative - nucleotide base adenine, pentose sugar ribose, three phosphate groups

116
Q

ATP function

A

immediate source of energy in a cell (energy stored in high energy phosphate group)

117
Q

ATP energy release

A

hydrolysis reaction (ATP - ADP & Pi with break of the phosphate bond using a water molecule, catalysed by enzyme ATP hydrolase)

118
Q

what is ADP

A

adenosine diphosphate

119
Q

ATP energy used

A

uses ADP and Pi, occurs during respiration and photosynthesis, creates ATP, catalysed by enzyme ATP dynthase

120
Q

what is an ion

A

atom/group of atoms that has an electrical charge
positive charge = cation
negative = anion

121
Q

what is an inorganic ion

A

doesn’t contain carbon (e.g ions in solution in cytoplasms of cells and body fluid of organisms

122
Q

important ions

A

iron, hydrogen, sodium, phosphate

123
Q

iron ions

A

Fe2+ - important part of haemoglobin (binds the oxygen in the haemoglobin and becomes Fe3+, until the oxygen is released) (also the centre of each polypeptide chain)

124
Q

hydrogen ions

A

H+ - determine pH which affects enzyme controlled reactions, more H+ present = lower pH

125
Q

sodium ions

A

Na+ - co-transport for glucose and amino acids across membranes

126
Q

phosphate ions

A

PO43- - when attached to another molecule = phosphate group, the bonds between these store energy in ATP, essential part of ATP, DNA and RNA

Biology aqa AS (7 decks)

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