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A Level Biology > Biological molecules (Topic 1) > Flashcards

Biological molecules (Topic 1) Flashcards

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1
Q

describe a biochemical test to show a solution contains non-reducing sugars

A
  1. perform the reducing sugar test if negative then
  2. heat with acid and neutralise
  3. heat with benedict’s solution
  4. red precipitate formed if present
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2
Q

explain the arrangement of phospholipids in a cell surface membrane

A

hydrophobic tails point away from water and hydrophilic heads point to water

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3
Q

describe how an ester bond is formed in a phospholipid molecule

A

through a condensation reaction between glycerol and fatty acid

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4
Q

state the property of water that helps prevent temperature increase in a cell

A

high specific heat capacity

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5
Q

how does waters high specific heat capacity prevent temperature increase in a cell

A

it buffers change in temperatures

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6
Q

explain how a phosphodiester bond is formed between two nucleotides within a DNA molecule and what catalyses the reaction

A

condensation reaction between phosphate and deoxyribose that is catalysed by DNA polymerase

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7
Q

describe how the separation of the two DNA stands occurs

A

•DNA helicase
•breaks H bonds between base pairs

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8
Q

where is amylase produced

A

pancreas
salivary glands

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9
Q

where is maltase produced

A

small intestine

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10
Q

why does an enzyme only catalyse one reaction

A
  1. active site of enzyme has specific shape
  2. only the substrate can bind to it
  3. to form an enzyme substrate complex
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11
Q

describe how the structure of glycogen is related to its function (4 marks)

A
  1. branched so compact
  2. polymer of glucose so easily hydrolysed
  3. branched so faster hydrolysis
  4. insoluble so not easily lost from cell
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12
Q

what enzyme breaks bonds between amino acids?

A

endopeptidase

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13
Q

all carbohydrates contain the elements….

A

carbon
hydrogen
oxygen

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14
Q

glucose is a _____ sugar

A

hexose

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15
Q

the two types of glucose are….

A

alpha
beta

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16
Q

which type of glucose has the OH group joined above the H?

A

beta

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17
Q

which type of glucose has the OH group joined below the H?

A

alpha

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18
Q

how are disaccharides formed?

A

by joining 2 monosaccharides through a condensation reaction

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19
Q

what bonds are formed when a disaccharide is formed?

A

glyosidic

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20
Q

what is released when disaccharides are formed?

A

water

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21
Q

sucrose is formed from…

A

glucose and fructose

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22
Q

maltose is formed from…

A

two alpha glucose

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23
Q

lactose is formed from…

A

glucose and galactose

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24
Q

what is the test for reducing sugars?

A
  1. heat sample with benedicts reagent
  2. sample forms brick red precipitate
  3. if reducing sugar present
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25
Q

polysaccharides form when…

A

more than two monosaccharides are joined by a condensation reaction

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26
Q

what is amylose formed from?

A

lots of alpha glucose molecules

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27
Q

polysaccharides are broken down by…

A

hydrolysis

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28
Q

plants store excess glucose as….

A

starch

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29
Q

when a plant needs more energy it….

A

breaks down starch to release glucose

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30
Q

starch is a mixture of two polysaccharides which are:

A

amylose
amylopectin

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31
Q

is starch soluble in water?

A

no

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32
Q

why is it important for starch to be insoluble in water?

A

so that it doesn’t affect water potential and water doesn’t move into the cells via osmosis causing them to swell

33
Q

animals store excess glucose as…

A

glycogen

34
Q

what are the benefits of glycogen being branched?

A

stored glucose can be released quickly

35
Q

what is the benefit of glycogen being compact?

A

good for storage

36
Q

cellulose is made of….

A

long, unbranched chains of beta glucose

37
Q

cellulose chains are held together by __ bonds. to form strong fibres called….

A

hydrogen bonds
microfibrils

38
Q

cellulose provides….

A

structural support for cell walls

39
Q

what is the test for starch?

A
  1. add iodine dissolved in potassium iodide solution to the sample
  2. if starch is present sample turns from browny-orange to blue-black
40
Q

lipids are made from…

A

proteins and carbohydrates

41
Q

triglycerides contain…

A

glycerol
3 fatty acids

42
Q

fatty acids have ____ tails and ______ heads

A

hydrophobic
hydrophilic

43
Q

saturated fatty acids don’t have….

A

double carbon bonds

44
Q

unsaturated fatty acids have….
which cause….

A

double carbon bonds
the chain to kink

45
Q

what kind of reaction forms triglycerides?

A

condensation reaction

46
Q

phospholipids consist of…

A

a phosphate group
glycerol
2 fatty acids

47
Q

2 properties of triglycerides…

A
  • insoluble in water
  • long hydrocarbon tails with lots of chemical energy
48
Q

what is the emulsion test for lipids?

A
  1. shake substance with ethanol then pour it into water
  2. lipid will show up as a milky solution
49
Q

proteins are made of….

A

one or more polypeptides

50
Q

amino acid functional groups are

A

NH2 and COOH

51
Q

dipeptides and polypeptides are formed by…

A

condensation reactions

52
Q

the bonds between amino acids are called…

A

peptide bonds

53
Q

primary protein structure is…

A

the sequence of amino acids in the polypeptide chain

54
Q

secondary protein structure is…

A

hydrogen bonds form between amino acids to make alpha helix or beta pleated sheet

55
Q

tertiary protein structure is…

A

hydrogen bonds, ionic bonds and disulfide bridges form to fold and coil them further

56
Q

quaternary protein structure is….

A

the way polypeptide chains are assembled together

57
Q

what is the test for proteins?

A
  1. add NaOH solution TO THE SMAPLE
  2. add copper (II) sulfate solution
  3. if present solution turns purple
58
Q

enzymes are…

A

biological catalysts

59
Q

what are the models for enzyme action?

A

lock and key
induced fit

60
Q

how can you measure enzyme activity?

A

how fast product is made
how fast the substrate is broken down

61
Q

what factors effect enzyme activity?

A

temperature
pH
substrate concentration
enzyme concentration

62
Q

what are competitive inhibitors?

A

they bind to the active site of the enzyme so no substrate can bind to the enzyme

63
Q

what are non competitive inhibitors?

A

molecules that fit onto the molecule away from the active site causing a positive change in the enzymes active site

64
Q

nucleotide consist of…

A

a phosphate
pentose sugar
nitrogenous base

65
Q

nucleotide chains join together to form_______ via a ________ reaction. This forms a ________ bond. The chain of phosphates and sugars is known as the ______ backbone

A

polynucleotides
condensation
phosphodiester
sugar-phosphate

66
Q

the sugar in RNA is…

A

ribose

67
Q

the sugar in DNA is….

A

deoxyribose

68
Q

how many hydrogen bonds form between adenine and thymine?

A

2

69
Q

how many hydrogen bonds form between cytosine and guanine?

A

3

70
Q

polynucleotide strands run _____ to each other

A

anti parallel

71
Q

DNA is replicated by…..

A

semi-conservative repliaction

72
Q

the 4 steps of DNA replication are:

A
  1. DNA helicase breaks H bonds, separating strands
  2. Free nucleotides are attracted by complementary bases
  3. Condensation reaction catalysed by DNA polymerase
  4. Two strands are produced
73
Q

in the experiment which proves semi-conservative replication light nitrogen…

A

settles at the top of the tube

74
Q

in the experiment which proves semi-conservative replication heavy nitrogen…

A

settles at the bottom of the tube

75
Q

in the experiment which proves semi-conservative replication the tube…

A

has one band midway in the tube

76
Q

give the 5 properties of water….

A
  1. its a metabolite
  2. has high latent heat of vaporisation
  3. resists temp changes
  4. is a good solvent
  5. strong cohesion between water molecules
77
Q

ATP consists of…

A

an adenine base
a ribose sugar
3 phosphate groups

78
Q

give the reaction for resynthesis of ATP

A

ADP + P –> ATP
catalysed by ATPase

79
Q

give the equation for when energy is broken down

A

ATP –> ADP + P
catalysed by ATP hydrolase

A Level Biology (19 decks)

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