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biology > unit 1 - biological molecules > Flashcards

unit 1 - biological molecules Flashcards

1
Q

what is hydrolysis?

A
  1. breaks a chemical bonds between two molecules;
  2. using water
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2
Q

what is a condensation reaction?

A
  1. creates a chemical bond
  2. removing a molecule of water
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3
Q

glycogen - glycogen structure (3)

A
  1. polysaccharide of a-glucose
  2. joined by glycosidic bond
  3. branched structure
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4
Q

glycogen - glycogen compared with cellulose (4)

A
  1. cellulose is made up of b-glucose (monomers) and glycogen is made up of a-glucose (monomers)
  2. cellulose molecule has straight chain and glycogen is branched
  3. cellulose molecule has straight chain and glycogen is coiled
  4. glycogen has 1,4 and 1,6 glycosidic bonds and cellulose has only 1,4 glycosidic bonds
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5
Q

glycogen - glycogen structure related to function (5)

A
  1. insoluble (in water), so doesn’t affect water potential
  2. branched/coiled/a-helix, so makes molecule compact
  3. polymer of a-glucose so provides glucose for respiration
  4. branched/more ends for fast breakdown/enzyme action
  5. large molecule so cant cross the cell membrane
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6
Q

starch - relate 3 properties to its function (6)

A
  1. insoluble
  2. don’t affect water potential
  3. helical
  4. compact
  5. large molecule
  6. cannot leave cell
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7
Q

test for reducing sugar

A
  1. heat with benedicts reagent
  2. colour change from blue to brick- red
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8
Q

test for non reducing sugar

A
  1. heat with benedicts reagent and no colour change
  2. boil with acid (HCL) and then neutralise with (NaHCO3)
  3. re-heat with benedicts reagent and colour change from blue to brick-red
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9
Q

test for starch

A
  1. add iodine in potassium iodide solution
  2. colour change from brown to blue-black
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10
Q

how are triglycerides formed

A
  1. one glycerol and three fatty acids
  2. condensation reaction and removal of three molecules of water
  3. ester bonds formed
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11
Q

phospholipids compared with triglycerides (8)

A
  1. both contain ester bonds (between glycerol and fatty acids
  2. both contain glycerol
  3. fatty acids on both may be saturated or unsaturated
  4. both are insoluble in water
  5. both contain C,H and O but phospholipids also contain P
  6. triglyceride has three fatty acids and phospholipid has two fatty acids and phosphate group
  7. triglyceride are hydrophobic/non-polar and phospholipids have hydrophillic/polar and hydrophobic region
  8. phospholipid form bilayer but triglycerides dont
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12
Q

describe how an ester bond is formed in a phospholipid molecule

A
  1. condensation reaction
  2. between glycerol and fatty acid
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13
Q

test for a lipid

A
  1. mix sample with ethanol then water
  2. white milky emulsion
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14
Q

protein - protein structure (70

A
  1. polymer of amino acids
  2. joined by peptide bonds
  3. formed by condensation
  4. primary structure is order of amino acids
  5. secondary structure is folding of polypeptide chain due to hydrogen bonding into alpha helix or beta pleated sheet
  6. tertiary structure is 3D folding due to hydrogen and bonding and ionic/disulphide bonds between r-groups
  7. quarternary structure is more than one polypeptide chains
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15
Q

test for a protein

A
  1. add biuret reagent to the sample
  2. colour change to lilac
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16
Q

enzymes - induced fit model (3)

A
  1. before reaction active site is not complementary
  2. shape of active site changes as substrate binds/ as e-s complex forms
  3. stressing in the bonds in substrate lead to reaction
17
Q

enzymes - increased temperature and reaction rate (4)

A
  1. particles have more kinetic energy
  2. therefore they move more
  3. so there are more collisions between substrates and active sites
  4. so more ES complexes form
18
Q

enzymes - denaturation (5)

A
  1. heat above optimum temperature breaks hydrogen bonds
  2. this causes the tertiary structure to unfold
  3. so the active site changes shape
  4. substrate can no longer bind to the active site, as its no longer complementary
  5. fewer ES complexes form
19
Q

enzymes - effect of changes in ph

A
  1. ionic bonds holding tertiary structure break
  2. active site distorts and substrate no longer binds to active site
  3. charges on amino acids in active site affected
  4. fewer ES complexes form
20
Q

enzymes - concentration of substrate (2)

A
  1. increase in concentration of product slows as substrate is used up
  2. until no substrate left
21
Q

enzymes - competitive vs non competitive inhibition (2)

A
  1. competitive inhibitor binds to active site of enzyme but non-competitive inhibitor binds at allosteric site
  2. competitive inhibitor does not change shape of active site but non-competitive does
22
Q

describe DNA replication (6)

A
  1. DNA helicase breaks hydrogen bonds and unwinds double helix
  2. both strands act as templates
  3. free DNA nucleotides line up in complementary pairs
  4. DNA polymerase joins nucleotides of new strands
  5. forming phosphodiester bonds
  6. each new DNA molecule consists of one old and one new strand of DNA
23
Q

describe the structure of DNA (5)

A
  1. polymer of nucleotides
  2. each nucleotide formed from deoxyribose, phosphate group and nitrogenous base
  3. phosphodiester bonds between nucleotides
  4. double helix held by hydrogen bonds
  5. hydrogen bonds between complementary base pairs
24
Q

describe and explain how the structure of DNA allows accurate replication (4)

A
  1. two strands therefore semi-conservative replication possible
    2.hydrogen bonds hold strands together
  2. hydrogen bonds are weak allow strands to separate
  3. bases exposed act as template can be copied
  4. DNA one parent strand and one new strand
  5. A+T, C+G
25
Q

describe how a phosphodiester bond is formed between two nucleotides in a DNA molecule (3)

A
  1. condensation reaction
  2. between phosphate and deoxyribose
  3. catalysed by DNA polymerase
26
Q

ATP - uses and properties as an energy source (5)

A
  1. releases relative small amount of energy/little energy lost as heat
  2. releases energy instantaneously
  3. phosphorylates other compounds, making them more reactive
  4. can be rapidly re-synthesised
  5. does not leave cells
27
Q

ATP - structure compared with DNA nucleotide (3)

A
  1. ATP has ribose and DNA has deoxyribose
  2. ATP has 3 phosphates and DNA nucleotide has one phosphate
  3. base is always adenine in ATP and bases vary in DNA nucleotide (A,C,G or T)
28
Q

water - properties that make water important for organisms (6)

A
  1. metabolite in condensation/ hydrolysis/photosynthesis/respiration
  2. A solvent so metabolic reactions can occur
  3. high heat capacity so buffers changes in temperature
  4. large latent heat of vaporisation so provides a cooling effect (through evaporation)
  5. cohesion between water molecules so supports columns of water in plants
  6. cohesion between water so produces surface tension supporting organisms

biology (8 decks)

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