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Biology Year 1 > 1. Biological Molecules > Flashcards

1. Biological Molecules Flashcards

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1
Q

define monomer
give example

A

smaller units that join together to create larger molecules
e.g monosaccharides (glucose, fructose, galactose), nucleotides, amino acids

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2
Q

define polymer
give example

A

molecules formed when many monomers joined together
e.g DNA/RNA, proteins, polysaccharides

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3
Q

what happens in a condensation reaction

A

a chemical bond between 2 molecules and a molecule of water is produced

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4
Q

what happens in a hydrolysis reaction

A

a water molecule is used to break 2 molecules

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5
Q

what are 3 hexose monosaccharides

A

glucose, fructose, galactose

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6
Q

what formula do all hexose monosaccharides have

A

C6H12O6

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7
Q

what is a monosaccharide

A

the monomers from which larger carbohydrates are made from

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8
Q

what is the bond formed when two monosaccharides react

A

(1/4 or 1/6) glycosidic bond

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9
Q

how are disaccharides formed

A

condensation reaction forms glycosidic bonds between 2 monosaccharides

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10
Q

what formula does maltose, sucrose and lactose all have

A

C12H22O11

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11
Q

what forms maltose

A

2 alpha glucose

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12
Q

what forms sucrose

A

glucose and fructose

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13
Q

what forms lactose

A

glucose and galactose

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14
Q

what is a covalent bond

A

a strong chemical bond where 2 atoms share a pair of electrons

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15
Q

what is an ionic bond

A

a moderate chemical bond from the electrostatic attraction between oppositely charged ions

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16
Q

what is a hydrogen bond

A

a weak chemical bond between the positive charge on a hydrogen atom and the negative charge on the atom of an adjacent molecule.

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17
Q

what is a glycosidic bond

A

a covalent bond between a carbohydrate molecule and a hydroxyl group on another molecule, resulting from a condensation reaction

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18
Q

what is a peptide bond

A

a covalent bond between two amino acids, resulting from a condensation reaction.

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19
Q

what is a phosphodiester bond

A

a covalent bond between two nucleotides via a condensation reaction

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20
Q

what is a dipolar molecule

A

a molecule with equal and opposite charges at each end

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21
Q

structure of an alpha glucose

A

OH alpha below

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22
Q

structure of beta glucose

A

OH beta above

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23
Q

what is glucose

A

a monosaccharide with two isomers: alpha glucose and beta glucose.

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24
Q

what is a carbohydrate

A

a molecule formed of one or more monosaccharides

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25
Q

what is a polysaccharide

A

a molecule formed by the condensation of many monosaccharide units

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26
Q

what is starch

A

a polysaccharide formed by condensation of alpha glucose in plants

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27
Q

what are the 2 types of starch

A

amylose and amylopectin

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28
Q

features of amylose

A

1,4 glycosidic bonds
helix structure with intermolecular H bonds meaning its compact

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29
Q

features of amylopectin

A

1,4 and 1,6 glycosidic bonds
branched structure meaning many terminal/free ends for hydrolysis into glucose

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30
Q

features of starch

A

-insoluble due to no osmotic effect on cells
-large so doesn’t diffuse out of the cell
-compact
-some plants store starch as fruit

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31
Q

what is glycogen

A

a polysaccharide formed by condensation of alpha glucose , containing 1, 4 - and 1,6- glycosidic bonds in mainly animals and bacteria

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32
Q

features of glycogen

A

-1,4 and 1,6 glycosidic bonds
-highly branched structure meaning many -terminal/free ends for hydrolysis into glucose
-insoluble so no osmotic effect and doesn’t diffuse out of cells
-compact

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33
Q

what is cellulose

A

a polysaccharide formed by condensation of beta glucose , containing only 1 , 4 -glycosidic bonds

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34
Q

features of cellulose

A

-polymer of beta glucose so gives rigidity to plant cell walls (prevents bursting under turgor pressure, holds stem up)
-1,4 glycosidic bonds
-straight chain, unbranched molecule
-alternate glucose molecules are rated 180 degrees
-H bonds crosslink between parallel strands from microfibrils meaning makes cell wall strong

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35
Q

benedicts test for reducing sugar

A

-add equal volume of benedicts reagent to sample
-heat mixture
-positive result goes blue to orange/brick red

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36
Q

benedicts test for non reducing sugar

A

-negative result- benedict reagent remains blue
-hydrolyse non reducing sugar by adding HCl and and heat in water bath
-neutralise the mixture using sodium carbonate solution
-test with benedicts test again to observe colour change

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37
Q

concentration of benedicts test from lowest to highest

A

blue (no sugar present), purple, green, yellow, orange, red

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38
Q

how to make benedicts test quantitative

A

filter precipitate at the bottom of the tube and measure the mass to give indication of the quantity of sugars

39
Q

why is benedicts test semi quantitative

A

by observing the colour change on a scale from blue to red it’s possible to estimate the ​concentration of the reducing sugar.

40
Q

test for starch

A

-add iodine solution to sample
-positive result is blue to black

41
Q

how could colorimetry be used to give quantitative results for presence of sugars and starch

A

-make standard solution with known concentrations and record abundance
-plot calibration curve with absorbance on y axis and concentration on x axis
-record abundance of unknown samples and use calibration curve to read off concentration

42
Q

test for lipids

A

-dissolve sample solids in ethanol and shake
-then add equal volume of water and shake
-positive result is milky white emulsion

43
Q

what is a triglyceride

A

A molecule formed by condensation, with
ester bonds joining three fatty acids to one molecule of glycerol

44
Q

what are the 2 types of fatty acids

A

the R group of fatty acid can be saturated or unsaturated

45
Q

features of saturated fatty acids

A

-contains only one C bond
-straight chin molecule so many contact points
-higher melting points means solid at room temp
-found in animal fats

46
Q

features of unsaturated fatty acids

A

-contain double carbon bonds
-kinked molecule so fewer contact points
-lower melting points means liquid at room temp
-found in plant oils

47
Q

features of fatty acid

A

has carboxylic acid at start joining to a hydrocarbon chain, more C-H is more energy storage

48
Q

what are the 2 types of lipids

A

phospholipids and triglycerides

49
Q

functions and structures of triglycerides

A

-high energy to mass ratio so increase in energy storage
-insoluble hydrocarbon chain providing waterproofing
-slow conductor of heat for thermal insulation
-source of water

50
Q

what is a phospholipid

A

A molecule formed by condensation reaction with two fatty acids and a phosphate group bonded to one molecule of glycerol.

51
Q

where is the phosphodiester bond in a phospholipid

A

between phosphahte group and glycerol

52
Q

where is the ester bond in a phospholipid

A

between glycerol and 2 fatty acids

53
Q

what shape does a phospholipid have

A

kinked

54
Q

what is the key feature of a fatty acid and phospahte molecule of a phospholipid

A

-fatty acid repels water so has a hydrophobic tail
-phosphate molecules attracts water so has a hydrophilic head

55
Q

what type of molecule is a phospholipid

A

polar molecule

56
Q

what is the main function of a phospholipid

A

main component of cell membrae

57
Q

importance of phospholipid bilayer

A

contributes to flexibility and transfer of lipids meaning its soluble, also its a barrier

58
Q

what is formed when a phospholipid combines with a carbohydrate and why is it important

A

glycolipid formed and important for cell recognition

59
Q

similarities of phospholipids and triglycerides

A

-both have glycerol backbone
-both attached to mixture of saturated, unsaturated and polysaturated fatty acids
-both formed by condensation reactions

60
Q

differences in phospholipids and triglycerides

A

phospholipids:
-2 fatty acids and 1 phosphate group
-hydrophilic head and hydrophobic tail
-used in cell membrane formation

triglycerides:
-3 fatty acids
-entire molecule is hydrophobic
-used for storage for oxidation to release energy

61
Q

why is water a polar molecule

A

O is more electronegative than H so, attracts the electron density in covalent bond ore strongly. Forms O partially negative and H partially positive

62
Q

5 properties of water

A

Due to polarity and intermolecular H bonds:
-a metabolite for chemical reactions in the body like respiration
-a solvent so metabolic reactions can occur
-high specific heat capacity so buffers change in temperature
-high latent heat of vaporisation so provides cooling effect
-cohesion between water molecules so supports columns of water in plants

63
Q

why is water important for living organisms

A

-solvent for polar molecules during metabolic reactions
-cohesion tension of water molecules in transpiration stream

64
Q

where are inorganic ions found

A

found in cytoplasm and extracellular fluids in high or low concentrations

65
Q

role of H+ ions in body

A

-high concentration of H+ ions means very acidic so low pH
-H+ ions interact with H bonds and ionic bonds in tertiary structure of proteins which can cause them to denature

66
Q

general structure of an amino acid

A

R group, amine group and COOH group

67
Q

test for proteins

A

-add equal volume of food sample to biuret regent in test tube
-shake and leave for 5 mins
-positive result goes from blue to purple

68
Q

how many amino acids are there and how do they differ

A

20
different R group

69
Q

how do dipeptide and polypeptide bonds formed

A

a condensation reaction between 2 amino acids (di) or 3 amino or more amino acids (poly) by the removal of water

70
Q

how many level of protein structures are there

A

4

71
Q

what is the primary structure

A

-specific sequence of amino acids in polypeptide chain
-amino acid arranged in particular order determined by DNA

72
Q

what is the secondary structure

A

-polypeptide folds due to H bonds forming within
-H bonding doesn’t involve R group but forms between O and H atoms on polypeptide backbone
-common structures are alpha helices and beta pleated sheets (3D structure)

73
Q

what is the tertiary structure

A

-further folding into 3D structure caused by bonding of atoms between R groups of diff amino acids
-ionic bonding, hydrogen bonding, disulfide bonding
-forms functional (e.g enzyme) or structral (e.g keratin) proteins

74
Q

what is the quaternary structure

A

-made up of more than 1 polypeptide chains (subunit)
-some are conjugated protein which is a prosthetic group added to it

75
Q

what are enzymes

A

a biological catalyst that increases rate of reactions and the formation of e-s complexes lowers activation energy. specific tertiary structure determines shape of active site, complementary to a specific substrate

76
Q

what is the induced fit model

A

shapes of the enzyme’s active site and its substrate are not exactly complementary, but when the substrate enters the active site, a conformational change enables e-s complexes to form, puts strain on substrate bonds lowering ae

77
Q

5 factors that affect enzymes

A

pH
Temp
Enzymes conc
Substrate conc
Conc of inhibitors

78
Q

how have the models of enzymes changed

A

Initially lock and key model: rigid shape of active site, complementary to only 1 substrate
Current induced fit model: explains why binding at allosteric sites can change active site

79
Q

how do E-S complexes form

A

Substrate held in place by temporary bonds
Bonds form between amino acids of active site and groups on substrate

80
Q

how does temp affect enzymes activity

A

Increase temp increases KE As temp increase H bonds can break
Enzymes and substrates collide more often Shape of enzyme and active site changes
Rate of reaction increases Substrate fits less easily at first then denature

81
Q

how does pH affect enzymes

A

Changes in pH can alter changes on amino acids of active site
Arrangement of active site is partly determined by H bonds between amine and carboxylate group
Bonds break leading to a distortion in shape of active site so substrate can’t attach as no longer complementary
If bonds in tertiary structure break enzyme is denatured

82
Q

how does substrate concentration affect enzymes

A

Increasing substrate conc will increase rate of reaction until maximum rate of reaction

83
Q

how does enzyme con affect enzymes

A

Increasing enzyme conc will increase rate of reaction as long as there’s excess substrates

84
Q

Competitive inhibitors features

A

Similar shape to substrate so binds to active site
Doesn’t stop reaction as only temporary, ES complexes form when inhibitor is released
Increasing substrate conc decreases their effect

85
Q

Non competitive inhibitors features

A

Binds at allosteric site
Can permanently stop reaction as triggers active site to change shape
Increasing substrate conc has no impact on their effect

86
Q

what is the pentose sugar in DNA and RNA

A

DNA: deoxyribose
RNA: ribose

87
Q

what is the structure of a nucleotide

A

phosphate group
pentose sugar
nitrogenous base

88
Q

what is the role of DNA in living cells

A

DNA replication
Holds genetic info
Base sequence of genes codes for functional RNA and amino acids and sequences of polypeptides

89
Q

how do polynucleotides form

A

Condensation reactions between nucleotides form phosphodiester bonds (sugar phosphate backbone)

90
Q

structure of DNA

A

double helix of 2 polynucleotide strands
H bonds between complementary purine and pyrimidine base pairs on opposite strands
Adenine + Thymine
Guanine + Cytosine

91
Q

Which bases are purine and which bases are pyrimidine

A

A & G = 2 ring purine bases
T & C & U = 1 ring pyrimidine bases

92
Q

what are the complementary base pairs in DNA

A

2 H bonds between adenine and thymine
3 H bonds between guanine and cytosine

93
Q

complementary base pairs in RNA

A

2 H bonds between adenine and uracil
3 H bonds between guanine and cytosine

94
Q

relate structure of DNA to its functions

A

Biology Year 1 (4 decks)

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