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module 2 > biological molecules > Flashcards

biological molecules Flashcards

1
Q

how is water a polar molecule? ( H2O )

A

shared negative hydrogen electrons attracted to oxygen

other side of each hydrogen - slight positive charge

unshared negative electrons on oxygen - slight negative charge

partial positive + negative charge

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2
Q

what does water having a high specific heat capacity mean?

A

a lot of energy needed raise temp - hydrogen bonds between water molecules absorb a lot of energy ( not enough for water )

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3
Q

how is water having a high heat capacity helpful?

A

water doesn’t experience rapid temp changes
good habitat

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3
Q

what does water having a high latent heat of evaporation mean?

A

lots of heat needed to break hydrogen bonds
lots of energy used up when it evaporates

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4
Q

how is water having a high latent heat of evaporation helpful?

A

good for cooling things like mammals

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5
Q

what does water being cohesive mean?

A

good attraction between the molecules - polar
helps water flow

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6
Q

how is water’s cohesion helpful?

A

easily transported up plant stems in transpiration stream

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7
Q

how is water a good solvent?

A

polar

slight negative end of water molecule attracted to positive ion .etc
ions get completely surrounded by water molecules - dissolve

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8
Q

why is ice less dense than water?

A

water molecules further apart in ice - each forms 4 hydrogen bonds to other water molecules

lattice structure

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9
Q

how is ice being less dense than water useful?

A

ice forms insulating layer
organisms in water beneath don’t freeze

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10
Q

3 elements that make up a carbohydrate?

A

carbon + hydrogen + oxygen

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11
Q

monosaccharide?
disaccharide?
polysaccharide?

A

single sugar unit
2 monosaccharides joined
more than 2 monosaccharides

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12
Q

why is glucose a hexose monosaccharide?

A

six carbon atoms

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13
Q

what is the difference between alpha and beta glucose?

A

their OH groups are reversed

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14
Q

what is ribose?

A

a pentose monosaccharide

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15
Q

how are monosaccharides formed?

A

glycosidic bonds

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16
Q

what happens in a condensation reaction?

A

hydrogen atom on a monosaccahride bonds to an OH group on other
releases molecule of water ( lost )

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17
Q

what happens in a hydrolysis reaction?

A

molecule of water reacts with glycosidic bond
breaks glycosidic bond
( reverse of condensation )

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18
Q

what is the polysaccharide starch used for?

A

energy storage material in plants
broken down to release glucose - energy

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19
Q

what is starch made up of?

A

2 polysaccharides of alpha glucose
amylose + amylopectin

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20
Q

what is the structure of amylose?

A

long + unbranched chain of alpha glucose
angles of glycosidic bonds give a coiled structure
glycosidic bonds between carbons 1-4

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21
Q

explain the properties of amylose?

A

good for storage - compact
insoluble so water doesn’t enter cells by osmosis ( don’t swell )

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22
Q

what is the polysaccharide glycogen used for?

A

energy storage material in animals

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23
Q

what is glycogen made up of?

A

a polysaccharide of alpha glucose

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24
Q

what is the structure of glycogen?

A

lots of branches - stored glucose released quick
compact molecule - good for storage

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25
Q

what is the polysaccharide cellulose used for?

A

component in cell walls in plants

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26
Q

what is cellulose made up of?

A

beta glucose

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27
Q

what is the structure of cellulose?

A

long + unbranched + straight chains - beta glucose molecules bond

chains linked by hydrogen bonds - microfibrils ( strong fibres )

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28
Q

what is the structure of amylopectin?

A

long + branched chain of alpha glucose
side branches
glycosidic bonds between 1-4 + 1-6

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29
Q

explain the properties of amylopectin?

A

branches - allow the enzymes that break down the molecules to easily get glycosidic bonds easily
so glucose can be released quickly

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30
Q

what are triglycerides?

A

lipids
macromolecules - complex molecules + big molecular mass
carbon + hydrogen + oxygen

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31
Q

what do triglycerides have attached to it?

A

3 fatty acids

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32
Q

describe fatty acids?

A

have ‘long tails’ - hydrocarbons

tails are ‘hydrophobic’ - repel water molecules

tails make lipids insoluble in water

all have different hydrocarbon tails

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33
Q

how are triglycerides synthesised?

A

by formation of ester bond between each fatty acid + glycerol molecule
( esterification )

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34
Q

how is each ester bond formed?

A

condensation reaction

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35
Q

how do triglycerides break down?

A

when ester bonds are broken by hydrolysis

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36
Q

what are saturated + unsaturated fatty acids?

A

saturated - no double bond between carbon atoms + saturated with hydrogen

unsaturated - at least 1 double bond between carbon atoms

37
Q

what are phospholipids + how do they differ from triglycerides?

A

macromolecules

1 fatty acid replaced with phosphate group
phosphate group - hydrophilic - attracts water molecules

38
Q

what are triglycerides used for?

A

energy storage molecules in plants + animals

39
Q

explain the properties of triglycerides from its structure?

A

tails - lots of chemical energy - energy released when broken so lipids have x2 energy as carbohydrates

insoluble - don’t cause water to enter by osmosis + don’t swell

bundle together as insoluble droplets as tails hydrophobic

tails face inwards - shield from water with glycerol heads

40
Q

what are phospholipids used for?

A

in cell membrane of eukaryotes + prokaryotes - phospholipid layer

41
Q

explain the properties of phospholipids from its structure?

A

phospholipid heads - hydrophilic

tails - hydrophobic

double layer with heads facing out towards water on each side

centre of bilayer - hydrophobic - soluble substances can’t easily pass through membrane

42
Q

what is the structure of cholesterol?

A

hydrocarbon ring attached to hydrocarbon tail

ring - polar hydroxyl group attached

43
Q

what is cholesterol used for?

A

regulating fluidity of cell membrane by interacting with phospholipid bilayer - eukaryotic cells

44
Q

explain the properties of cholesterol from its structure?

A

small + flattened shape - fit in between phospholipid molecules in membrane

bind to tails of phospholipids at high temps - packed closely together - membrane less fluid

prevents phospholipids from packing closely together at low temps - increases membrane fluidity

45
Q

what are proteins?

A

polymers

46
Q

what are amino acids in proteins?

A

monomers

47
Q

how is a dipeptide + polypeptide formed?

A

dipeptide - 2 amino acids join
polypeptide - more than 2 amino acids join

48
Q

what are proteins made up of?

A

1 or more polypeptides
( lots of amino acids joined )

49
Q

what is the structure of all amino acids?

A

carboxyl group ( -COOH )
amino group ( -NH2 ) attached to carbon atom

50
Q

whats the difference between all amino acids?

A

the variable group ( R )

51
Q

what elements make up amino acids?

A

carbon + oxygen + hydrogen + nitrogen
sometimes sulfur

52
Q

how are amino acids joined together?

A

linked by peptide bonds - dipeptides + polypeptides

condensation reaction releases molecule of water

reverse adds water molecule to break peptide bond - hydrolysis

53
Q

what is the primary structure of a protein?

A

sequence of amino acids in polypeptide chain

each protein has a different sequence

one change to an amino acid - changes structure of whole protein

54
Q

what is the secondary structure of a protein?

A

hydrogen bonds form between amino acids nearby

coils into alpha helix / folds into beta pleated sheet

55
Q

what is the tertiary structure of a protein?

A

coiled / folded chain of amino acids is further coiled / folded

more bonds form between parts of polypeptide chain

proteins made from 1 polypeptide chain- 3D structure

56
Q

what is the quaternary structure of a protein?

A

how proteins from more than 1 polypeptide chain are assembled
e.g haemoglobin is made of 4 polypeptide chains
3D structure

57
Q

what bonds hold primary structure together?

A

peptide bonds

58
Q

what bonds hold secondary structure together?

A

hydrogen bonds

59
Q

what bonds hold tertiary structure together?

A

ionic bonds - negatively charged R groups and postively charged R groups

disulfide bonds - 2 molecules of amino acid cysteine come close + the sulfur in one bonds to sulfur in other

hydrophobic + hydrophilic interactions - hydrophobic R groups come close so clump and hydrophilic R groups pushed to outside affecting how protein folds up

hydrogen bonds - between slightly positively charged hydrogen atoms in R groups + slightly negatively charged hydrogen atoms in other R groups
( polypeptide chain )

60
Q

what bonds hold quaternary structure together?

A

determined by tertiary structure so influenced by all the bonds

61
Q

how does a globular protein form + what does this make them?

A

hydrophobic + hydrophilic interactions in protein’s tertiary structure
soluble so easily transported in fluids

62
Q

what are the 3 globular proteins + their functions?

A

haemoglobin - carries oxygen in red blood cells
conjugated protein - protein with a non protein group attached ( prosthetic group )
4 polypeptide chains has a prosthetic group - haem - contains iron for oxygen to bind to

insulin - hormone secreted by pancreas + regulates blood glucose level
soluble - transported in blood to tissues
2 polypeptide chains held by disulfide groups

amylase - enzyme catalyses breakdown of starch
single chain of amino acids
alpha helix + beta pleated sheets - secondary structure

63
Q

what are fibrous proteins?

A

structural proteins
unreactive + insoluble + strong

64
Q

what are the 3 fibrous proteins + their functions?

A

collagen - in animal connective tissues
( bone + skin + muscle )
strong molecule
minerals can bind to protein - increases rigidity

keratin - in external structures of animals
( skin + hair + nails )
flexible - skin or hard / tough - nails

elastin - in elastic connective tissue
( skin + large blood vessels + some ligaments )
tissues can return to original shape after being stretched

65
Q

what is the role of calcium?
( cation )

A

involved in transmission of nerve impulses
involved in release of insulin
cofactor for enzymes
helps with bone formation

66
Q

what is the role of sodium?
( cation )

A

generates nerve impulses
muscle contraction
regulates fluid balance

67
Q

what is the role of potassium?
( cation )

A

generates nerve impulses
muscle contraction
regulates fluid balance
activates the enzymes for photosynthesis

68
Q

what is the role of hydrogen?
( cation )

A

affects PH of substances - more H+ ions so creates acid
important for photosynthesis reactions

69
Q

what is the role of ammonium?
( cation )

A

absorbed from soil by plants
important source of nitrogen

70
Q

what is the role of nitrate?
( anion )

A

absorbed from soil by plants
important source of nitrogen

71
Q

what is the role of hydrogencarbonate?
( anion )

A

acts as a buffer - maintains PH of blood

72
Q

what is the role of chloride?
( anion )

A

involved in ‘chloride shift’ - maintains PH of blood in gas exchange
cofactor for enzyme amylase
involved in some nerve impulses

73
Q

what is the role of phosphate?
( anion )

A

involved in photosynthesis + respiration
needed for synthesis of biological molecules: nucleotides, phospholipids, calcium phosphate

74
Q

what is the role of hydroxide?
( anion )

A

affects PH of substances - more OH- ions so creates alkali

75
Q

what is an inorganic ion?

A

an ion without carbon

76
Q

test for reducing sugars?

A

add benedict’s to sample
heat in water bath
positive - precipitate - blue to brick red
higher concentration of reducing sugar = further colour change
negative - non reducing sugar present

77
Q

test for non reducing sugars?

A

add dilute hydrochloric acid + heat in water bath
neutralise with sodium hydrogencarbonate
carry out benedict’s
positive - coloured precipitate
negative - stays blue - no sugar

78
Q

test for glucose?

A

test strips coated in reagant
present - colour change

79
Q

test for starch?

A

iodine
present - blue black

80
Q

test for proteins?

A

biuret test:
add sodium hydroxide solution - makes it alkaline
add copper sulfate
present - purple
not present - stays blue

81
Q

test for lipids?

A

emulsion test:
shake substance with ethanol
pour solution in water
present - milky emulsion

82
Q

how does a calorimeter work?

A

measures the strength of coloured solution by seeing how much light passes through
measures absorbance
the more concentrated the colour of solution - the higher the absorbance

83
Q

how do you measure the concentration of a glucose solution?

A

serial dilution technique:
make 5 serial dilutions with a dilution factor of 2:

line up 5 test tubes

add 10 cm of intial 40 Mm glucose solution to first test tube + 5 cm distilled water to other 4

draw 5 cm of solution from first test tube + add to distilled water in 2nd test tube + mix ( now 10 cm of solution half as concentrated as solution in first test tube - 20 Mm )

repeat 3x to give solutions of 10, 5, 2.5

84
Q

how do you make calibration curve?

A

do benedict’s test on each solution

remove any precipitate

measure absorbance with calorimeter

make calibration curve with absorbance against glucose concentration

test unknown solution in same way as known + use curve to find its concentration

85
Q

how does a biosensor work?

A

uses a biological molecule ( enzyme ) to detect a chemical

molecule produces a signal that is converted into an electrical signal by transducer ( part of biosensor )

electrical signal processed

86
Q

how do glucose biosensors work?

A

determines concentration of glucose in a solution

uses enzyme glucose oxidase + electrodes
enzyme catalyses oxidation of glucose at electrodes

creates a charge + becomes electrical signal

electrical signal processed to work out initial glucose concentration

87
Q

2 types of chromotography?

A

paper
thin layer

88
Q

what is the mobile + stationary phase + what are they in each type?

A

mobile - molecules can move
mobile phase is the liquid solvent in both

stationary - molecules can’t move
paper - chromatography paper
thin layer - thin layer of solid ( glass / layer of solid / plastic plate )

89
Q

what is the basic principle of chromatography for both?

A

mobile phase moves over stationary phase

components of each mixture spend different amounts of time in each phase

ones that spend longer in mobile - travel further

90
Q

how do you identify unknown amino acids with chromatography?

A

draw pencil line near bottom of chromatography paper + put concentrated spot of the mixture of amino acids on it
( roll paper into cyclinder with spot on outside so it stands up )

add small amount of solvent ( butanol, glacial ethanoic acid, water ) to beaker
dip bottom of paper into it ( not spot )
cover with lid to stop solvent evaporating

different amino acids move with solvent

when solvent nearly reached top take paper out + mark solvent front with pencil

amino acids not coloured so spray with ninhydrin solution to turn them purple to see it

use Rf values to identify separated molecules

module 2 (3 decks)

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