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module 2 > biological molecules > Flashcards

biological molecules Flashcards

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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
what is the structure of glycogen?
lots of branches - stored glucose released quick compact molecule - good for storage
25
what is the polysaccharide cellulose used for?
component in cell walls in plants
26
what is cellulose made up of?
beta glucose
27
what is the structure of cellulose?
long + unbranched + straight chains - beta glucose molecules bond chains linked by hydrogen bonds - microfibrils ( strong fibres )
28
what is the structure of amylopectin?
long + branched chain of alpha glucose side branches glycosidic bonds between 1-4 + 1-6
29
explain the properties of amylopectin?
branches - allow the enzymes that break down the molecules to easily get glycosidic bonds easily so glucose can be released quickly
30
what are triglycerides?
lipids macromolecules - complex molecules + big molecular mass carbon + hydrogen + oxygen
31
what do triglycerides have attached to it?
3 fatty acids
32
describe fatty acids?
have 'long tails' - hydrocarbons tails are 'hydrophobic' - repel water molecules tails make lipids insoluble in water all have different hydrocarbon tails
33
how are triglycerides synthesised?
by formation of ester bond between each fatty acid + glycerol molecule ( esterification )
34
how is each ester bond formed?
condensation reaction
35
how do triglycerides break down?
when ester bonds are broken by hydrolysis
36
what are saturated + unsaturated fatty acids?
saturated - no double bond between carbon atoms + saturated with hydrogen unsaturated - at least 1 double bond between carbon atoms
37
what are phospholipids + how do they differ from triglycerides?
macromolecules 1 fatty acid replaced with phosphate group phosphate group - hydrophilic - attracts water molecules
38
what are triglycerides used for?
energy storage molecules in plants + animals
39
explain the properties of triglycerides from its structure?
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
what are phospholipids used for?
in cell membrane of eukaryotes + prokaryotes - phospholipid layer
41
explain the properties of phospholipids from its structure?
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
what is the structure of cholesterol?
hydrocarbon ring attached to hydrocarbon tail ring - polar hydroxyl group attached
43
what is cholesterol used for?
regulating fluidity of cell membrane by interacting with phospholipid bilayer - eukaryotic cells
44
explain the properties of cholesterol from its structure?
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
what are proteins?
polymers
46
what are amino acids in proteins?
monomers
47
how is a dipeptide + polypeptide formed?
dipeptide - 2 amino acids join polypeptide - more than 2 amino acids join
48
what are proteins made up of?
1 or more polypeptides ( lots of amino acids joined )
49
what is the structure of all amino acids?
carboxyl group ( -COOH ) amino group ( -NH2 ) attached to carbon atom
50
whats the difference between all amino acids?
the variable group ( R )
51
what elements make up amino acids?
carbon + oxygen + hydrogen + nitrogen sometimes sulfur
52
how are amino acids joined together?
linked by peptide bonds - dipeptides + polypeptides condensation reaction releases molecule of water reverse adds water molecule to break peptide bond - hydrolysis
53
what is the primary structure of a protein?
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
what is the secondary structure of a protein?
hydrogen bonds form between amino acids nearby coils into alpha helix / folds into beta pleated sheet
55
what is the tertiary structure of a protein?
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
what is the quaternary structure of a protein?
how proteins from more than 1 polypeptide chain are assembled e.g haemoglobin is made of 4 polypeptide chains 3D structure
57
what bonds hold primary structure together?
peptide bonds
58
what bonds hold secondary structure together?
hydrogen bonds
59
what bonds hold tertiary structure together?
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
what bonds hold quaternary structure together?
determined by tertiary structure so influenced by all the bonds
61
how does a globular protein form + what does this make them?
hydrophobic + hydrophilic interactions in protein's tertiary structure soluble so easily transported in fluids
62
what are the 3 globular proteins + their functions?
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
what are fibrous proteins?
structural proteins unreactive + insoluble + strong
64
what are the 3 fibrous proteins + their functions?
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
what is the role of calcium? ( cation )
involved in transmission of nerve impulses involved in release of insulin cofactor for enzymes helps with bone formation
66
what is the role of sodium? ( cation )
generates nerve impulses muscle contraction regulates fluid balance
67
what is the role of potassium? ( cation )
generates nerve impulses muscle contraction regulates fluid balance activates the enzymes for photosynthesis
68
what is the role of hydrogen? ( cation )
affects PH of substances - more H+ ions so creates acid important for photosynthesis reactions
69
what is the role of ammonium? ( cation )
absorbed from soil by plants important source of nitrogen
70
what is the role of nitrate? ( anion )
absorbed from soil by plants important source of nitrogen
71
what is the role of hydrogencarbonate? ( anion )
acts as a buffer - maintains PH of blood
72
what is the role of chloride? ( anion )
involved in 'chloride shift' - maintains PH of blood in gas exchange cofactor for enzyme amylase involved in some nerve impulses
73
what is the role of phosphate? ( anion )
involved in photosynthesis + respiration needed for synthesis of biological molecules: nucleotides, phospholipids, calcium phosphate
74
what is the role of hydroxide? ( anion )
affects PH of substances - more OH- ions so creates alkali
75
what is an inorganic ion?
an ion without carbon
76
test for reducing sugars?
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
test for non reducing sugars?
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
test for glucose?
test strips coated in reagant present - colour change
79
test for starch?
iodine present - blue black
80
test for proteins?
biuret test: add sodium hydroxide solution - makes it alkaline add copper sulfate present - purple not present - stays blue
81
test for lipids?
emulsion test: shake substance with ethanol pour solution in water present - milky emulsion
82
how does a calorimeter work?
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
how do you measure the concentration of a glucose solution?
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
how do you make calibration curve?
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
how does a biosensor work?
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
how do glucose biosensors work?
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
2 types of chromotography?
paper thin layer
88
what is the mobile + stationary phase + what are they in each type?
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
what is the basic principle of chromatography for both?
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
how do you identify unknown amino acids with chromatography?
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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