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A-level Biology > Chapter 3 - Biological Molecules > Flashcards

Chapter 3 - Biological Molecules Flashcards

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1
Q

what is a polymer

A

long chain molecules made up by the linking of multiple monomers in a repeating pattern

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2
Q

what is a condensation reaction

A

a reaction which joins monomers by chemical bonds and it involves the elimination of a water molecule

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3
Q

what is hydrolysis

A

when water is added to break a chemical bond between two molecules

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4
Q

what chemical elements make up carbohydrates

A

carbon, hydrogen and oxygen
general formula: Cx(H2O)x

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5
Q

what chemical elements make up lipids

A

carbon, hydrogen and oxygen

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6
Q

what chemical elements make up proteins

A

carbon, hydrogen, oxygen, nitrogen and sulfur

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7
Q

what chemical elements make up nucleic acids

A

carbon, hydrogen, oxygen, nitrogen and phosphorous

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8
Q

structure of water (polar)

A
  • each hydrogen shares a pair of e- with oxygen
  • e- closer to oxygen as it has a greater affinity for them
  • oxygen δ- and hydrogen δ+
  • molecule is polar as it has two charged regions
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9
Q

how do hydrogen bonds occur between water molecules

A

the δ- charge on the oxygen attracts the δ+ hydrogen on another water molecule

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10
Q

high boiling point of water

A
  • has a high specific heat capacity due to many stable hydrogen bonds between molecules
  • large amount of energy required to break the bonds
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11
Q

why is ice less dense than water

A

below 4oC hydrogen bonds fix the positions of H2O molecules further apart than in liquid state

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12
Q

cohesion of water molecules
give eg

A

water molecules attract each other and move as one mass
eg. plants draw water up from roots/ surface tension

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13
Q

adhesion of water

A

water molecules are attracted to other surfaces

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14
Q

water as a coolant

A

high specific heat capacity buffers temperature changes on chemical reactions eg. for enzymes that may denature

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15
Q

other uses of water

A

habitat

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16
Q

what is a hexose monosaccharide,

A

has 6 carbons

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17
Q

types of glucose

A

alpha and beta

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18
Q

alpha glucose

A

OH on carbons 1 and 4 on same plane
down on carbon1

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19
Q

beta glucose

A

OH on carbons 1 and 4 on opposite planes
up on carbon1

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20
Q

solubility of glucose

A

polar due to OH groups so hydrogen bonds can form with water
dissolved in cytosol of cell

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21
Q

type of bond between monosaccharides

A

glycosidic

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22
Q

general condensation reaction of sugars

A

monosaccharides —> disaccharide + h2o

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23
Q

which carbons does a glycosidic bond form between usually

A

1 and 4

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24
Q

glucose + glucose

A

maltose

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25
Q

glucose + fructose

A

sucrose

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26
Q

glucose + galactose

A

lactose

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27
Q

examples of hexose monosaccharides

A

glucose, fructose and galactose

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28
Q

what is a pentose monosaccharide

A

sugars that contain 5 carbons

29
Q

examples of pentose sugar + explain

A

ribose: sugar present in RNA nucleotides
deoxyribose: sugar present in DNA nucleotides

30
Q

how do polysaccharides break down into simpler sugars

A

hydrolysis reactions

31
Q

what 2 polysaccharides make up starch

A

amylose and amylopectin

32
Q

what is starch

A

chemical energy store of glucose made in photosynthesis for plants

33
Q

structure of amylose

A

alpha glucose joined by 1,4-glycosidic bonds
coiled chain in helix stabilised by hydrogen bonding
helix shape = compact and less soluble than glucose

34
Q

structure of amylopectin

A

alpha glucose joined by 1,4-glycosidic bonds and some 1,6-glycosidic bonds
branched structure due to 1,6 bonds

35
Q

structure of glycogen

A

alpha glucose 1,4 and 1,6-glycosidic bonds
more branching so more compact as animals have higher metabolism

36
Q

what is the benefit of branched polysaccharide chains

A

free ends for glucose to break off quicker

37
Q

structure of cellulose

A

beta glucose molecules 1,4-glycosideic bonds, alternate molecules rotate 180 degrees due to position of OH groups
straight chain

38
Q

how do cellulose chains join together

A

form hydrogen bonds with eachother forming microfibrils that join to make macrofibrils that join to form insoluble fibres in plant cell walls

39
Q

What are triglycerides made up of

A

1 glycerol 3 fatty acids

40
Q

What is the synthesis of triglycerides called, what type of reaction is it

A

Esterification, condensation

41
Q

‘Equation’ for esterification

A

Glycerol + 3fatty acids -—-> triglyceride + 3H2O

42
Q

Name of bond between fatty acids and glycerol

A

Ester bond

43
Q

How much water does the hydrolysis of a triglyceride require

A

3 molecules

44
Q

Saturated fat (triglyceride)

A

No C=C bonds in fatty acids

45
Q

Saturated fat (triglyceride)

A

No C=C bonds in fatty acids

46
Q

Monounsaturated fatty acid

A

1 C=C bond in fatty acid

47
Q

Polyunsaturated fat

A

More than one C=C bond in fatty acid

48
Q

Structure of phospholipid

A
  • hydrophilic polar phosphate head
  • 2 hydrophobic non polar fatty acid tails
49
Q

Cholesterol function

A

Stabilise cell membranes and regulate membrane fluidity

50
Q

Primary structure of protein

A

The sequence of amino acids in the polypeptide chain

51
Q

Secondary structure of a protein

A

The folding of a polypeptide chain into an alpha helix or beta pleated sheet by hydrogen bonding

52
Q

Tertiary structure of a protein

A

The 3D folding of a polypeptide chain by interactions between R-groups

53
Q

Interactions between side groups of tertiary protein structure

A

Hydrogen bonds
Ionic bonds
Discúlpate bridges
Hydrophobic interactions
Hydrophilic interactions

54
Q

Quaternary protein structure

A

2 or more polypeptide chains joined together

55
Q

Globular protein structure

A

Globe shaped
Hydrophilic side groups
Water soluble

56
Q

Types of globular protein

A

Insulin
Protease
Haemoglobin

57
Q

Properties of insulin and protease as globular proteins

A

Can diffuse through cells to bind to specific receptors

58
Q

What is a conjugated protein

A

Containing a non-amino acid part in its structure (prosthetic group)

59
Q

Haemoglobin

A

Globular, conjugated
4 haem groups (prosthetic) that contain iron

60
Q

Structure of fibrous proteins

A

Proteins made up of strands and fibres
Hydrophobic side groups
Insoluble in water

61
Q

Types of fibrous proteins and their functions

A
  • collagen: strengthens tendon, bones and blood vessel walls
  • elastin: increase flexibility in cartilage eg. Alveoli and artery walls
  • keratin: strengthens hair, skin and nails
62
Q

Biuret test

A
  • Biuret (NaOH and CuSO4) added to sample, mixed and left
  • if protein present, colour change from blue to purple
63
Q

Iodine test

A
  • iodine dissolved in potassium iodide
  • added and mixed into sample
  • if starch present colour change from yellow/ brown to purple/ black
64
Q

Emulsion test

A
  • mix sample with ethanol then water and shake
  • if lipid present a white emulsion will form
65
Q

Benedict’s test for reducing sugars

A
  • sample in boiling tube
    -add equal volume Benedicta solution
  • heat gently in water bath
  • reducing sugar present colour change ( red precipitate)
66
Q

Example of reducing sugar

A

Maltose and lactose

67
Q

What to do if testing a solid sample

A

Grind up with water

68
Q

Test for non-reducing sugars

A
  • Benedicts test (negative)
  • hydrolyse by boiling with dilute hydrochloride acid
  • Benedicta test positive
69
Q

Example of non reducing sugar

A

Sucrose

A-level Biology (16 decks)

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