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biological molecules Flashcards

1
Q

what is a monomer?

A

small/identical/similar molecules can be joined together through condensation reactions to form larger molecules (polymers)

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2
Q

what is a polymer?

A

large molecules made from joining 3 or more identical or similar monomers together

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3
Q

condensation reactions:

A

joins two or more monomer units together with the removal of water molecule and the formation of a chemical bond

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4
Q

anabolic reaction:

A

condensation reaction

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5
Q

hydrolysis reaction:

A

the addition of one molecule of water to break the chemical bond between two molecules

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6
Q

catabolic reaction:

A

hydrolysis reaction

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7
Q

examples of monomers:

A

monosaccharides (alpha and beta glucose)
amino acids
nucleotides

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8
Q

examples of polymers:

A

polysaccharides (starch, glycogen, cellulose)
proteins (haemoglobin, enzyme)
polynucleotide/nucleic acid (DNA, RNA)

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9
Q

monomer of carbohydrates:

A

monosaccharides

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10
Q

what elements do carbohydrates contain?

A

carbon, hydrogen, oxygen

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11
Q

general formulae of carbohydrate:
ratio of H:O in molecule

A

(CH2O)n where n is 3 to 7

H:O ratio 2:1

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12
Q

formula of a monosaccharide:

A

C6H12O6

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13
Q

4 examples of monosaccharide:

A

alpha glucose
beta glucose
galactose
fructose

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14
Q

how to draw alpha glucose:

A

penguin - both OH groups down

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15
Q

how to draw beta glucose:

A

eqyptian
left OH down, right OH up

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16
Q

formula of disaccharide:

A

C12H122O11

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17
Q

bond formed between disaccharides:

A

glycosidic bond

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18
Q

how do you form maltose?
and where is it found?

A

alpha glucose + alpha glucose
found in germinating seeds

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19
Q

how do you form lactose?
and where is it found?

A

alpha glucose + galactose
found in milk of lactating mammals

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20
Q

how do you form sucrose?
and where is it found?

A

alpha glucose + fructose
transported in phloem of plants

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21
Q

after digestion of polysaccharides and disaccharides into monosaccharides, what happens?

A

it is absorbed and used in the body,
e.g respiratory substances during respiration or used to make components or cell membrane

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22
Q

2 types of polysaccharides molecules:

A

storage or structural

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23
Q

what is the storage molecule in humans?

A

glycogen

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24
Q

what is the storage molecules in plants?

A

starch

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25
Q

what is the structural molecules in plants?

A

cellulose

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26
Q

what is an isomer?

A

molecules with the same molecular formula but have different arrangement of atoms

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27
Q

starch amylose:
structure and function:

A

carbon 1:4 glycosidic bond so long linear chains of alpha glucose which coils into a helix,

compact so good for storage,
insoluble so doesn’t affect water potential,
large so doesn’t leave/diffuse out of cell

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28
Q

how do plant cells store glucose?

A

as starch
(made up of 2 polysaccharides called amylose and amylopectin)

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29
Q

starch amylopectin:
structure and function:

A

carbon 1:4 and 1:6 glycosidic bonds,
branched chains of alpha glucose with many terminal ends,

so large surface area for rapid hydrolysis by enzymes to release glucose to be used in respiration,

insoluble so doesn’t affect water potential,
large so doesn’t leave/diffuse out of cell

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30
Q

where is glycogen stored?

A

in liver and muscle cells

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31
Q

glycogen:
structure and function:

A

long branched chains of alpha glucose,
bonded by carbon 1:4 and 1:6 glycosidic bonds,

more shorter chains, so more highly branched and large surface area,
for rapid hydrolysis by enzymes to release glucose to be used in respiration,

insoluble so doesn’t affect water potential,
large so doesn’t leave/diffuse out of cell

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32
Q

how do animals store excess glucose?

A

as glycogen

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33
Q

cellulose:

A

long striaght unbranched chains of beta glucose,
joined together by many weak hydrogen bonds to form microfibrils,
provides rigidity/support/strength to cell wall

many weak hydrogen bonds provide strength in large numbers

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34
Q

every other beta glucose molecule is

A

rotated 180 degrees so the OH group is adjacent to each other on C1 and C4 to form 1:4 glycosidic bonds

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35
Q

examples of reducing sugars

A

alpha glucose,
beta glucose,
maltose,
lactose,
fructose,
galactose

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36
Q

examples of non-reducing sugars:

A

sucrose

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37
Q

what is the test for a reducing sugar

A

Benedict’s test

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38
Q

Benedict’s test for reducing sugar:

A

add equal volumes of Benedict’s reagent to sample,
heat to 95 degrees in an electric water bath,
red precipitate shows reducing sugar is present,

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39
Q

what is a precipitate?

A

solid suspended in solution

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40
Q

Benedict’s test for non-reducing sugar:

A

complete Benedict’s test and observe a negative result (blue),
add HCl to sugar solution and heat to 95 degrees in an electric water bath to hydrolyse glycosidic bonds,
then neutralise with alkali (sodium hydrogen carbonate),
add equal volumes of Benedict’s reagent and heat to 95 degrees,
red precipitate shows non-reducing sugar is present

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41
Q

what type is the Benedict’s test?

A

semi-quantitative test
range of colours but no conc of sugars

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42
Q

what type is a colorimeter?

A

quantitative test
increasing conc of sugars will produce increasing mass of precipitates

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43
Q

how to make Benedict’s test quantitative?

A

filter, dry and weight precipitate

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44
Q

how does a colorimeter work?

A

measures the intensity of light transmitted through a solution,
increased precipitate = reduced transmission
absorbance and transmission are indirectly proportional

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45
Q

how to calibrate a colorimeter?

A

add distilled water and set absorption to 0

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46
Q

rules for using a colorimeter:

A

samples should always be shaken before tested,
zero the colorimeter before use,
use same absorbance/transmission filter,
use same volume for reducing

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47
Q

test for starch:

A

add potassium iodide to sample,
turns from orange to blue/black shows starch is present

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48
Q

describe how to use a calibration curve to find concentration of an unknown solution

A

make upseveral known concentrations of a reducing sugar,
carry out benedict’s test on each one,
use a colorimeter to measure the absorbance/transmission of each one,
plot curve of absorbance on y axis, known conc. on X
read off from absorbance of unknown conc. Using curve

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49
Q

two types of lipids:

A

triglyceride and phospholipid

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50
Q

what is a lipid?

A

a macromolecule

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51
Q

how is triglycerides formed?

A

condensation reaction of one molecule of glycerol and three molecules of fatty acids
joined by 3 ester bonds
and loss of 3 water molecules

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52
Q

what is triglyceride used primarily as?

A

a storage molecule

53
Q

the whole molecule of a triglyceride is..

A

hydrophobic

54
Q

saturated fatty acids:
melting point and state at room temp?

A

no double bonds between carbon atoms within hydrocarbon chains,
high MP and solid at room temp
straight chain molecules with many contact points

55
Q

saturated fatty acids are found in

A

animal fats

56
Q

unsaturated fatty acids:
melting point and state at room temp?

A

double bonds between carbon atoms within hydrocarbon chains,
low MP and liquid at room temp
kinked molecules with fewer contact points

57
Q

unsaturated fatty acids are found in

A

plant oils

58
Q

what are phospholipids used for?

A

primary component of all membranes

59
Q

what are phospholipids made from?

A

condensation reaction between one molecule of glycerol, one molecule of phosphate and 2 fatty acid molecules

60
Q

what is the charge of phosphate group?

A

negative charge (polar)

61
Q

what is the charge of fatty acids?

A

no charge (non-polar)

62
Q

phospholipid heads

A

hydrophilic,
are water facing,
in contact with water on both sides
attracts water - soluble

63
Q

fatty acid tails:

A

hydrophobic,
face inwards away from water
repels water - insoluble

64
Q

properties of phospholipids:

A

form bilayer in cell membrane
form a double layer with heads
membrane acts as barrier
allowing diffusion of non polar/ small molecules
centre of bilayer is hydrophobic so water soluble substances cannot easily pass through
tails = waterproofing

65
Q

properties of triglycerides:

A

low energy to mass ratio so good energy store,

insoluble in water so doesn’t affect water potential,

slow conductor of heat, so thermal insulator,

less dense than water,

high H:O ratio so good source of water,

hydrocarbon chain contains a lot of chemical energy, which is released when broken down,

protects organs by storing around them

66
Q

emulsion test for lipids:

A

crush/grind sample
add ethanol and shake
then add water and shake
cloudy white emulsion shows lipid is present

67
Q

what is the bond and monomer of proteins?

A

peptide bond,
amino acids

68
Q

what groups does the amino acid contain?

A

amine group,
variable side chain,
carboxyl group

69
Q

R groups can be

A

positive
negative
hydrophilic
hydrophobic

70
Q

primary structure of protein:

A

number and sequence of amino acids in a polypeptide chain
only peptide bonds

71
Q

secondary structure of protein:

A

coiling/folding of polypeptide chains due to weak hydrogen bonds into alpha helixes and beta pleated sheets,

only bond between O atoms on carboxyl group and H atoms on amine group,

weak hydrogen bonds provide strength in large numbers

72
Q

tertiary structure of protein:

A

further folding of polypeptide chain into specific 3D complex shape held together by ionic bonds, disulphide bridges and weak hydrogen bonds

73
Q

ionic bonds
disulphide bridges
weak hydrogen bonds

A

ionic bonds between oppositely charged R groups,

disulphide bridges between S atoms on cysteine amino acids

weak hydrogen atoms between H and O

74
Q

quaternary structure of protein:

A

two or more polypeptide chains joined together

haemoglobin - 4 polypeptide chain, globular, spherical chain, functional proteins

collagen - 3 polypeptide chain, fibrous, rope like strands twisted, structural proteins

75
Q

dipeptides:

A

condensation of two or more amino acids, with removal of molecule of water and formation of peptide bond

76
Q

polypeptides:

A

condensation of 3 or more amino acids

77
Q

protein:
increasing the temperature

A

increases the kinetic energy of the molecules making them vibrate more, this breaks the weak hydrogen bonds in secondary and tertiary structure

78
Q

protein:
changing the pH of environment

A

breaks ionic bonds between R groups in the tertiary structure
as bonds break, specific tertiary structure is lost
= denaturation - permanent change

79
Q

biuret test for protein:

A

add equal volumes of biuret solution to sample in test tubes,
if protein is present, changes from blue to purple

(enzymes are proteins = positive result)

80
Q

function of DNA:

A

holds genetic information in all living organisms cells

81
Q

structure of DNA:

A

phosphate group attached to carbon 5 of
deoxyribose sugar
nitogrenous organic base
adenine, thymine, guanine, cytosine

double helix structure with 2 polynucleotide chains joined together by many weak hydrogen bonds between complementary base pairings

82
Q

function of RNA:

A

transfers genetic information from DNA to the ribosome where translation occurs to make protein

83
Q

structure of RNA:

A

phosphate group attached to carbon 5 of
ribose sugar
nitogrenous organic base
adenine, uracil, guanine, cytosine

nucleotide forms a single strand
shorter than most DNA polynucleotide chains

84
Q

polynucleotide:

A

3 or more identical/similar nucleotides by covalent bonds to form a larger polymer/polynucleotide chain by condensation reactions

forms a phosphodiester bond between the phosphate group of the nucleotide to the 3rd carbon of the next nucleotide

there is a covalent bond and makes sugar phosphate backbone of nucleic acid very strong and stable

85
Q

what are purines

A

adenine and guanine

86
Q

what are pyrimadines

A

thymine cytosine and uracil

87
Q

dna consists of 2 anti parallel strands:

A

each end of the molecule is labelled with a 3’ end and a 5’end indicating when carbon is involved in phosphodiester bond
on the complementary strand, top is 3’end and bottom is 5’end

88
Q

DNA polymerase only has a complimentary end to the

A

5’end of the molecule

89
Q

process of semi conservative replication:

A

DNA helicase attaches and moves along the DNA molecule,
unwinding the DNA and breaking hydrogen bonds between complementary bases,
the strands separate - each strand acts as a template,
DNA polymers joins adjacent nucleotides via condensation reactions forming phosphodiester bonds in a 5’ end to 3’ end direction,
the new DNA molecule contains an original and new strand that is identical to original strand

90
Q

adaptations of DNA:
long/large molecule

A

stores a lot of information

91
Q

adaptations of DNA:
helical/coiled structure

A

so compact

92
Q

adaptations of DNA:
base sequence

A

allows info to be stored
codes amino acids and therefore proteins

93
Q

adaptations of DNA:
double stranded

A

replication can only occur semi conservatively,
as each strand acts as a template

94
Q

adaptations of DNA:
hydrogen bonds between bases are weak

A

allows for easy strand separation for semi conservative replication

95
Q

adaptations of DNA:
many weak hydrogen bonds

A

so DNA is a strong/stable molecule

96
Q

adaptations of DNA:
sugar phosphate backbone and double helix

A

provides strength and stability,
protects the bases,
protects the hydrogen bonds in between bases

97
Q

adaptations of DNA:
complimentary base pairings

A

allows for accurate replication/identical copies are made

98
Q

ATP - adenine triphosphate

A

3 phosphate groups
ribose sugar
nitrogenous organic base adenine

99
Q

2 uses of ATP:

A

provides energy for active transport/muscle contraction/protein synthesis

  • phosphorylation of molecules to lower activation energy, make substrate more reactive, activates enzymes by altering tertiary structure
100
Q

why is ATP useful?

A

releases relatively small amounts of energy,
releases energy instantaneously,
phosphorlaytes other compounds making them more reactive,
can be rapidly resynthesised,
is not lost from/does not leave cell

101
Q

ATP condensation ADP + Pi -> ATP

A

catalysed by ATP synthase,
produces H2O
requires energy to add Pi to ADP creating a high energy bonds
(occurs during photosynthesis and respiration)

102
Q

ATP hydrolysis ATP -> ADP + Pi

A

catalysed by ATP hydrolase
requires H2O
bond between 2nd and 3rd Pi breaks releasing small manageable energy

103
Q

water as a solvent:

A

polar molecules dissolve in solvent = universal solvent
major component of cytoplasm as it allows chemical and enzymes to dissolve so chemical reactions can occur,
can dissolve other substances like gases urea ammonia

104
Q

water
high specific heat capacity

A

requires a lot of heat energy to heat because of hydrogen bonds,
higher heat capacity in water than air = more energy required to heat water than air,
habitats in H2O resist fluctuations in temp,
so organisms enzymes always have optimum temp to work,
organisms mainly made of water so can maintain a consistent body temp,

105
Q

water
latent heat of vapourisarion

A

takes a lot of heat energy to break H bonds,
lots of body heat required to evaporate all amounts of sweat = lowers body temp

106
Q

water as metabolite

A

water is used and produced in many chemical reactions,
hydrolysis reaction and photosynthesis reactions use water,
condensation reaction and respiration reactions produce water,

chemical reactions take place in aqueous medium
and enzymes and substrates dissolve so can react

107
Q

water
cohesion and surface tension:

A

water molecules stick together by weak bonds = cohesion,
provides surface tension at an air water surface so small organisms can be supported,
allows water to be pulled up narrow tubes - xylem

108
Q

other properties of water:

A

when water freezes, it becomes less dense,
ice forms habitats for animals,
insulates the water below and stops freezing,

not easily compressed so provide support in plants, hydro skeleton in worms

light can penetrate through in plants underwater so plants can photosynthesise

109
Q

where are inorganic ions found?

A

in extracellular fluid and in cytoplasm

110
Q

function of H+ ions and OH- ions

A

affects acidity of solution

H+ used in respiration to provide energy to make ATP
H+ used in photosynthesis to provide energy to make ATP

111
Q

function of Fe2+/Fe3+

A

structural component of Hb
to allow transport of O2 to respiring tissues

112
Q

function of sodium ions:

A

used in co transport of glucose and amino acids from lumen of small intestine into intestinal epithelial cell

also used in nervous conduction

113
Q

function of phosphate ions:

A

component of phospholipid, ATP, DNA, RNA

114
Q

function of nitrates NO3 -
and nitrites NO2 -

A

taken up plant roots from soil
used in making amino acids

115
Q

function of chloride:

A

used in regulating water potential in small intestine

116
Q

what are enzymes?

A

globular proteins soluble - act as biological catalysts
which increase rate of reaction but remain unchanged (not used up)

117
Q

how do enzymes increase rate of reaction?

A

(products can only form when all bonds are broken which required activation energy)

by lowering activation needed for reaction
stresses/distorts/weakens bonds in substrate when forming an enzyme substrate complex
- allows reaction to work at lower temp

118
Q

enzyme have a

A

specific tertiary structure which is specifically complementary shaped active site to substrate

which allows substrate to bind and form enzyme substrate complex

119
Q

lock and key model:

A

active site is rigid and doesn’t change shape,
substrate binds to active site,
substrate fits exactly into active site - they are complementary,
products are formed and no longer fit in active site so are released,
enzymes free to take part in another reaction

120
Q

induced fit model:

A

substrate enters enzyme active site and binds to form enzyme substrate complexes,
binding of substrate induced a change in shape of active site,
change in shape of specific 3D structure stresses/distorts bonds within substrate molecules
which lowers activation energy of reaction,
when substrate leaves, active site returns to original shape

121
Q

effect of temperature on enzymes:
at optimum temp:

A

optimum temperature increases KE of enzyme and substrate = more likely to collide successfully = rate of reaction increases = more enzyme substrate complexes form per second

122
Q

effect of temperature on enzymes:
above optimum temp:

A

above temp = atoms vibrate faster within amino acid structure of enzyme = more KE = weak hydrogen bonds and ionic bonds between R groups of amino acids to break = change in specific tertiary structure = change in active site = denatured as no longer complimentary and cannot catalyse anymore reactions

123
Q

effect of pH on enzymes:

A

change from optimum =
change on thr charge on R groups of amino acids and ionic bond in tertiary broken = active site changes shape
= substrate can no longer fit
= less/no enzyme substrate complexes formed and rare of reaction decreases
= denatured enzymes

124
Q

describe and explain the effect of substrate concentration on enzyme action:

A

as substrate conc increases, the rate of reaction increases then plateaus

when substrate conc is low, the rate of reaction is low as there is less collisions = fewer enzyme substrate complexes form per second, substrate is limiting factor

the rate of reaction shows no further increase even when the substrate conc increases as the enzyme active sites are all saturated, enzyme conc is now limiting factor

125
Q

effect of enzyme concentration on enzyme action:

A

LOW ENZYME CONC:
too few enzyme molecules to allow all substrate molecules to find an active site at one time,
all enzyme active sites are saturated,
enzyme conc is limiting factor,

MEDIUM ENZYME CONC:
twice as many enzyme molecules available,
twice as many ESC can form per second,
enzyme conc is limiting factor,

HIGH ENZYME CONC:
addition of further enzyme molecules has no effect on as there are already enough active sites for all available substrate conc,
no increase in rate of reaction,
all substrate has been converted to product

126
Q

process of product formation:

A
  • initial rate of reaction is high, because lot of substrate molecules,
    soa lot of enzyme substrate complexes can form, therefore a lot of product formed (initially)
  • rate of product formation plateaus
    because no substrate is left for reaction so fewer ESC form
127
Q

what is an inhibitor?

A

substances which decrease the rate of reaction

128
Q

how does a competitive inhibitor work?

A
  • similar structure to substrates,
  • bind to active site and prevent substrate from binding temporarily,
  • fewer enzyme substrate complexes form per second
  • reduce rate of reaction so fewer products are formed per second,
  • longer for all substrates to eventually form products
129
Q

how does a non-competitive inhibitor work?

A
  • bind to a site on enzyme away from active site - allosteric site,
  • causes a conformational change to shape of active site so substrate cannot bind,
  • binding can be temporary or permanent,
  • if detached from one enzyme it is free to bind to another enzyme,
  • fewer enzyme substrate complexes formed-> rare of reaction decreases
    so fewer product formed.
    same effect as reducing total no. of enzymes

key definitions (9 decks)

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