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Biology OCR A > 2.2 Biological molecules > Flashcards

2.2 Biological molecules Flashcards

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1
Q

What is a covalent bond?

A

Two atoms sharing a pair of electrons

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2
Q

What is a condensation reaction?

A

The addition of two molecules with the removal of water

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3
Q

What is a hydrolysis reaction?

A

The separation of two molecules by adding water

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4
Q

What is a molecule made up of 2 monomers called?

A

A dimer

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5
Q

What is a chain of monomers called?

A

A polymer

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6
Q

What are carbohydrate molecules (C,H and O) monomers and polymers?

A
  • monosaccharides (e.g glucose)
  • Polysaccharides (e.g starch)
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7
Q

What are proteins (C,H,O,N and S) monomers and polymers?

A
  • amino acids
  • polypeptide and proteins
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8
Q

What are nucleic acids (C,H,O,N and P) monomers and polymers?

A
  • nucleotides
  • DNA and RNA
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9
Q

What is a hydrogen bond?

A

A bond between hydrogen atoms and oxygen, commonly found in water with 2 hydrogens (+) bonded to one oxygen (-) atom. This can become polarised.

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10
Q

What are the properties of water?

A
  • liquid
  • density
  • solvent
  • cohesion and surface tension
  • specific heat capacity
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11
Q

Why is liquid a good property of water?

A
  • provides habitat for living things
  • major component of tissues in organisms
  • reaction medium for chemical reactions
  • effective transport medium (e.g blood)
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12
Q

Why is the density of water a good property?

A

Ice becomes less dense than water when it cools, making it a suitable habitat for animals in the winter, as well as insulating the heat.

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13
Q

Why is being a solvent a good property of water?

A
  • Water molecules are slightly charged meaning they can react with charged molecules
    ^ 70% of the cytoplasm is water so can react better
  • ions can be transported while dissolved in water
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14
Q

Why is cohesion and surface tension a good property of water?

A
  • Water can be transported in the vascular bundles in plants
  • insects like pond skaters can walk on water
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15
Q

Why is a high specific heat capacity a good property of water?

A
  • provides a stable environment as more energy is required to break H bonds so high SHC, meaning temperature remains the same
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16
Q

What is a monosaccharide?

A

The simplest carbohydrate which can exist in straight chains or in ring or cyclic forms as a hexose sugar

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17
Q

What is a hexose sugar?

A

A sugar containing 6 carbon atoms

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18
Q

What is an isomer?

A

One of two or more compounds that have same atoms but different chemical structure

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19
Q

What are the two glucose isomers?

A

alpha glucose and beta glucose

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20
Q

What disaccharides do α-glucose + α-glucose form?

A

maltose

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21
Q

What disaccharides do α-glucose + fructose form?

A

sucrose

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22
Q

What disaccharides do β-glucose + α-glucose form?

A

lactose

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23
Q

What disaccharides do β-glucose + β-glucose form?

A

cellobiose

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24
Q

What bond is formed between two monosaccharides?

A

a glycosidic bond

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25
Q

Which molecule is on top in an α-glucose?

A

The Hydrogen

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26
Q

Which molecule is on top in a β-glucose?

A

The OH group

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27
Q

How many carbons and oxygens does ribose have?

A

5 carbons
5 oxygens
C5H10O5

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28
Q

How many carbons and oxygens does deoxyribose have?

A

5 carbons
4 oxygens
C5H10O4

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29
Q

What type of sugar are alpha and beta glucose?

A

Hexose

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30
Q

What type of sugar are ribose and deoxyribose?

A

Pentose

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31
Q

What is α-glucose role in the body?

A

Energy source
Component of starch and glycogen

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32
Q

What is β-glucose role in the body?

A

Energy source
Component of cellulose for structural support in plant cell walls

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33
Q

What is ribose role in the body?

A

RNA, ATP and NAD

34
Q

What is deoxyribose role in the body?

A

DNA

35
Q

Why are polysaccharides good energy stores?

A
  • glycogen (animals) and starch (plants) are compact
  • glycogen is held in a chain that can be easily hydrolysed and ‘snipped off’
  • branched chains can be hydrolysed easier, amylase enzyme for 1-4 bonds and glucosidase for 1-6 bonds
  • less soluble than monosaccharides, if soluble excess water would diffuse in from the water potential
36
Q

What is the structure of amylose (in plants)?

A

glycosidic bonds 1-4, hydrogen bonds hold a spiral shape with the hydroxyl groups on the inside making it less soluble

37
Q

What is the structure of amylopectin (in plants)?

A

glycosidic bonds 1-4 and 1-6, spiral shape held together by hydrogen bonds

38
Q

What is the structure of glycogen (in animals)?

A

glycosidic bonds 1-4 and 1-6, chains small so don’t coil but branches make it more compact.

39
Q

What is cellulose ?

A

an insoluble fibrous homopolysaccharide made from up to 15000 β-glucose molecules found in the cell walls of plants (structural polysaccharide)

40
Q

What is a microfibril?

A

A group of 60-70 chains of cellulose

41
Q

What is a macrofibril?

A

400 microfibrils

42
Q

Why is cellulose good for plant cell walls?

A
  • macrofibrils and microfibrils are strong
  • glycosidic bonds are strong so cannot be digested
  • space between microfibrils for water and ions to pass through (fully permeable)
  • cannot burst when turgid
  • macrofibril can be reinforced with waxes like cutin and suberin for waterproof
43
Q

What makes up bacterial cell walls?

A

peptidoglycan made from long polysaccharide chains side by side connected by a small peptide chain

44
Q

What are exoskeletons made out of?

A

chitin

45
Q

What are lipids made out of?

A

large amounts of carbon and hydrogen but little oxygen

46
Q

Why are lipids insoluble?

A

They are not charged so cannot attract water molecules

47
Q

What are the 3 main lipids?

A

triglycerides, phospholipids and steroids (macromolecules)

48
Q

What is triglyceride structure (overall)?

A

glycerol and fatty acids

49
Q

What is glycerol?

A

An alcohol with 3 carbons and 3 OH groups

50
Q

What are fatty acids?

A

A carboxyl group (-COOH) on one end with a hydrocarbon tail

51
Q

What does saturated mean?

A

no carbon = carbon bonds

52
Q

What is the structure of a triglyceride?

A

One glycerol bonded to 3 fatty acids (because there are 3 OH groups)

53
Q

What is an ester bond?

A

The bond formed from the condensation reaction of glycerol and fatty acids, carbon bonded with a single bond oxygen and a double bond oxygen

54
Q

What are the functions of triglycerides?

A

Energy source (respiration)
Energy store (insoluble)
Insulation (adipose tissue)
Buoyancy (fat < water density)
Protection (of organs)

55
Q

What is the structure of a phospholipid?

A

A glycerol with 2 fatty acids (with even carbon atoms) and a phosphate group

56
Q

What is a micelle phospholipid structure?

A

A sphere shape with the hydrophobic fatty acid tails on the inside and the hydrophilic phosphate on the outside

57
Q

What is a phospholipid bilayer?

A

2 rows of hydrophobic fatty acid tails facing inwards and hydrophilic phosphate heads facing outwards

58
Q

What is the function of a phospholipid bilayer?

A

20-80% of all plant and animal membranes are made from this structure

59
Q

Why is phospholipid bilayer a good membrane?

A
  • individual phospholipids can move but only in a way that the tails will not touch water, providing stability
  • Selectively permeable that only allows small and non-polar molecules to move through
60
Q

What is cholesterols structure?

A

4 carbon-based rings or isoprene units

61
Q

What is the function of cholesterol?

A

The hydrophobic molecule can sit in the hydrophobic tails of the phospholipid bilayer and regulate the fluidity of the membrane, not too fluid or too stiff

62
Q

What hormones contain cholesterol?

A

testosterone, oestrogen and vitamin D

63
Q

What are proteins?

A

large polymers made up of long chains of amino acids

64
Q

What is the function of proteins?

A
  • Structural components in animals, e.g muscles
  • Tendency to adopt specific shapes being important in enzymes, antibodies and some hormones
  • Used in membranes
65
Q

What is the structure of amino acids?

A

amino group (-NH2) at one end and carboxyl (-COOH) group at the other, with an R group and a carbon and hydrogen molecules

66
Q

What bond is formed between amino acids?

A

peptide bonds (covalent)

67
Q

What are 2 amino acids joined together called?

A

a dipeptide

68
Q

What is a chain of amino acids called?

A

a polypeptide

69
Q

What structure is the sequence of amino acids in a chain called?

A

Primary structure

70
Q

What structure is a helix made up of the chain of amino acids called?

A

Secondary structure

71
Q

What structure is the shape made from the coils folded called?

A

tertiary structure

72
Q

What structure is the protein molecule made from many polypeptide chains?

A

Quaternary structure

73
Q

What bonds hold amino acid chain shapes?

A

Hydrogen bonds, ionic bonds, disulfide bonds (amino acid cysteine) and hydrophobic and hydrophilic interactions

74
Q

What is a fibrous protein?

A

Regular repetitive sequences of amino acids and are usually insoluble in water e.g collagen, elastin and keratin

75
Q

What is a globular protein?

A

Specifically shapes (spherical) protein that have hydrophobic R groups on the inside making the protein soluble e.g enzymes, hormones and haemoglobin

76
Q

for globular and fibrous proteins look at the sheet or pages 70-71 in the textbook

A

i literally cannot be asked to copy down these two pages bc we already did them, sorry :(

77
Q

What is the quantitative test for reducing sugars?

A

Using the benedict’s solution and a colorimeter (reed filter) to create a calibration curve

78
Q

how’s ur day going :)

A

daily affirmation: you are awesome

79
Q

What is the structure and function of collagen?

A
  • Three chains of amino acids wound in a triple helix
    -artery, tendons, bones and connective tissue
80
Q

What is the structure and function of keratin?

A
  • Matrix structure with a superhelical twist, rich in cysteine and disulfide bridges between its polypeptide chains, and also has hydrogen bonds
  • Found in fingernails, hair, horns, hoofs, claws, fur and feathers.
  • Impermeable barrier and strong protection
  • prevents entry of water-borne pollutants
81
Q

What is the structure and function of elastin?

A
  • Short repeated sequences of 3 to 9 amino acids
  • Cross linking and coiling structure
  • Skin stretches around bones and muscles
  • lungs to inflate and deflate
  • blood vessels stretch and recoil, helping maintain the pressure
82
Q

What is the structure and function of haemoglobin?

A

Quaternary structure of 4 polypeptide chains; 2 alpha and 2 beta globin
Haem group on the outside made up of an iorn ion
Carries ocygen from the lungs to tissue by attaching to the 4 haem groups

Biology OCR A (18 decks)

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