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Biology resit > Biological molecules > Flashcards

Biological molecules Flashcards

1
Q

What are most carbohydrates?

A

Polymers

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2
Q

What are polymers?

A

Large, complex molecules composed of long chains of monomers

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3
Q

What are examples of monomers?

A

Monosaccharides, amino acids and nucleotides

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4
Q

What 3 elements do all carbohydrates contain?

A

Carbon, hydrogen and oxygen

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5
Q

What is glucose?

A

Glucose is a hexose sugar which is a monosaccharide with 6 carbon atoms

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6
Q

What are the two type of glucose?

A

Alpha and beta

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7
Q

What is the difference between alpha and beta glucose?

A

The hydrogen and OH groups are reversed

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8
Q

What is a condensation reaction?

A

When 2 molecules join together with formation of a new chemical bond and a water molecule is released

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9
Q

What bond is formed between monosaccharides as water is released?

A

Glycosidic bond

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10
Q

What is formed when 2 monosaccharides join together?

A

Disaccharide

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11
Q

Glucose+Glucose=?

A

Maltose

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12
Q

Glucose+fructose=?

A

Sucrose

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13
Q

Glucose+galactose=?

A

Lactose

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14
Q

Hydrolysis?

A

When water is added to a disaccharide and glycosidic bond is broken

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15
Q

When are polysaccharides formed?

A

When more than two monosaccharides are joined together by condensation reaction.

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16
Q

What is the main energy storage material in plants?

A

Starch

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17
Q

Why is starch stored?

A

Cells get energy from glucose so the plant stores excess glucose as starch so when the plant needs energy it breaks down the starch to release glucose.

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18
Q

What two polysaccharides is starch a mixture of?

A

Amylose and Amylopectin

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19
Q

What is amylose?

A

A long, unbranched chain of alpha glucose. The angles of the glycosidic bonds gives it a coiled structure which makes it compact which is good for storage because you can fit more into a small space

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20
Q

What is amylopectin?

A

A long, branched chain of alpha glucose. It’s side branches allow enzymes that break down molecule to get at glycosidic bonds easier. This means glucose can be broken down easier

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21
Q

Is starch soluble or insoluble?

A

Starch is insoluble

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22
Q

Why is it good that starch is insoluble?

A

Because it’s insolubility means water potential is not affected, so water can’t enter cells by osmosis which would make them swell. This makes it good for storage

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23
Q

What is the main energy storage material in animals?

A

Glycogen.

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24
Q

Why is glucose a good storage molecule?

A

It is similar to amylopectin because it has side branches but it has many more than amylopectin which is key in animals for fast glucose release. It is also very compact molecule so it is good for storage

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25
Q

What is the major component of cell walls in plants?

A

Cellulose

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26
Q

What is cellulose made up of?

A

Long, unbranched chains of beta glucose

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27
Q

What happens when beta glucose bond?

A

They form straight cellulose chains

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28
Q

Why is cellulose a good component of cell walls in plants?

A

Cellulose chains are linked together by weak hydrogen bonds to form strong fibres called microfibrils. The strong fibres means cellulose provide structural support for cells.

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29
Q

Triglycerides?

A

They are a type of lipid which has one glycerol with 3 fatty acids attached to it.

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30
Q

Fatty acid molecules?

A

Have long tails made of hydrocarbons. The tails are hydrophobic. These tails make lipids insoluble in water. All fatty acids have same basic structure, but the hydrocarbon tail varies.

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31
Q

What are lipids soluble in?

A

They are soluble in organic substances such as alcohols and acetones

32
Q

What are the two main groups of lipids?

A

Triglycerides and phospholipids

33
Q

What is one example of the roles lipids have?

A

They have a role in the cell membranes. Phospholipids contribute to the flexibility of membranes and the transfer of lipid-soluble substances

34
Q

What are other roles lipids might have?

A
  • Source of energy when oxidised
  • Waterproofing because they are insoluble in water e.g plants having waxy lipid cuticles that conserve water
  • Insulation because fat is a slow conductor of heat
  • Protection, fat is normally stored around delicate organs such as a kidney
35
Q

What bond is formed between the fatty acids and the glycerol in triglycerides?

A

An ester bond.

36
Q

What are the two kinds of fatty acids and what is the difference?

A

Saturated and unsaturated. The difference is in the “r” group (hydrocarbon tails)

37
Q

What is a saturated fatty acid?

A

When there is no double bonds between the carbon atoms.

38
Q

What is an unsaturated fatty acid?

A

Have at least one double bond between carbon atoms which cause a kink

39
Q

How many different types of hydrocarbons are there?

A

70

40
Q

Definition of hydrophobic?

A

Repels from water

41
Q

Definition of hydrophilic?

A

Attracted to water

42
Q

What is the difference between phospholipids and triglycerides?

A

One of the fatty acids in triglycerides is replaced by a phosphate group in phospholipids

43
Q

Why are triglycerides good energy storage molecules?

A
  • They have long hydrocarbon tails of the fatty acids which contain a lot of chemical energy which means loads of energy can be released when broken down. Because of this lipids contain about twice as much energy per gram as carbohydrates.
  • They are insoluble so they do not affect the water potential of the cell and cause water to enter the cells by osmosis. This leads to triglycerides clumping together as insoluble droplets in cells because the fatty acids tails are hydrophobic causing the tails to face inwards shielding themselves from water with glycerol heads
44
Q

Why do phospholipids make up the bilayer of cell membranes?

A
  • Phospholipids heads are hydrophilic and there tails hydrophobic so they form a double layer with there heads facing out towards the water on either side.
  • The centre of the bi-layer is hydrophobic so water soluble substances cannot easily pass through. The membrane acts as a barrier
45
Q

Definition of polar?

A

Molecules that have 2 ends that behave differently in this way are said to be polar.

46
Q

What are proteins made up of?

A

Long chains of amino acids

47
Q

When is a dipeptide formed?

A

When two amino acids join together

48
Q

When is a polypeptide formed?

A

When more than two amino acids join together

49
Q

What is the difference between amino acids?

A

Different variable groups

50
Q

How may types of amino acids are there?

A

20

51
Q

How are polypeptides formed?

A

Through the condensation reaction

52
Q

What are the bonds formed between amino acids called?

A

Peptide bonds

53
Q

When does the reverse reaction of the condensation reaction of amino acids happen?

A

During digestion

54
Q

How many structural levels do proteins have?

A

4

55
Q

What are the 4 levels of protein in order?

A

Primary, secondary, tertiary and quaternary.

56
Q

Primary structure definition?

A

The sequence of amino acids in the polypeptide chains.

57
Q

Secondary structure definition?

A

Polypeptide chain doesn’t remain flat and straight. Hydrogen bond form between amino acids in the chain. This makes it automatically coil into alpha helix or fold into beta pleated sheet

58
Q

Tertiary structure definition?

A

Amino acids are coiled further. More bonds form between different parts of the polypeptide chain including hydrogen and hydrogen bonds. Disulphide bridges also form whenever 2 molecules of the amino acid cysteine come closer together the sulphur atom in the other. For proteins made from a single polypeptide chain, the tertiary structure forms final 3D structure

59
Q

Quaternary structure definition?

A

Some proteins are made of several different polypeptide chains held together by bonds. The quaternary structure is the way these polypeptide chains are assembled together. For proteins made from more than one polypeptide chains the quaternary structure is the proteins final 3D structure.

60
Q

Enzymes structure and functions?

A

They are usually spherical in shape due to the tight folding of polypeptide chains They’re soluble and often have roles in metabolism E.G some enzymes break down large food molecules.

61
Q

Antibodies structure and functions?

A

Are involved in the immune response. They’re made up of two light polypeptide chains and two heavy polypeptide chains bonded together. Antibodies have variable regions which have amino acids sequences which vary greatly

62
Q

Transport proteins structure and functions?

A

An example of transport proteins is channel proteins which are present in cell membranes. Channel proteins contain hydrophobic and hydrophilic amino acids which cause the proteins to fold up and form a channel. These proteins transport molecules and ion across membranes.

63
Q

Structural proteins structure and functions?

A

Are physically strong. They consist of long polypeptide chains lying parallel to each other with cross-links between them. Structural proteins include keratin and Collagen.

64
Q

What are enzymes?

A

They are a biological catalyst

65
Q

Where does enzyme action happen?

A

Enzyme action can be intracellular or extracellular.

66
Q

Definition of catalyst?

A

Is a substance that speeds up chemical reactions without being used up in the reaction

67
Q

What levels do enzymes catalyse metabolic reactions?

A

At a cellular level (respiration) and for the organisms as a whole (digestion in mammals)

68
Q

Structure of enzyme?

A

They have an active site which has a specific shape. The active site is the part of the enzyme where the substrate molecules bind to.

69
Q

How does an enzyme speed up the rate of reaction?

A

By lowering the activation energy

70
Q

Activation energy definition?

A

A certain amount of energy needed to be supplied to the chemicals before the reaction will start

71
Q

What is the main type of activation energy and how does enzymes deal with it?

A

The main type of activation energy is normally heat and enzymes normally lower the temperature

72
Q

What is an enzyme-substrate complex?

A

It is when a substrate fits into the active site of an enzyme.

73
Q

Why does the enzyme-substrate complex lower activation energy?

A
  • Two substrate molecules need to be joined being attached to the enzyme holds them close together, reducing any repulsion between molecules so they can bond easier
  • If the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate , so the substrate molecule breaks up more easily.
74
Q

What model did early scientists studying enzyme action come up with?

A

The lock and key model

75
Q

Why did scientists have to change the lock and key model?

A

Because they realised that although the enzyme and substrate have to fit together but the new evidence showed that the enzyme substrate complex changed shape slightly to complete the fit.

76
Q

What was the model called which improved on the ideas of the lock and key model?

A

Induced fit model.

Biology resit (9 decks)

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