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Biology need to knows⚠️ > Carbohydrates, Proteins & Lipids > Flashcards

Carbohydrates, Proteins & Lipids Flashcards

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1
Q

Describe the structure structure of carbohydrates

A
  • organic compounds containing carbon, hydrogen and oxygen
  • in carbohydrates the basic unit is a monosaccharide
  • monosaccharide + monosaccharide = disaccharide
  • many monosaccharides = polysaccharide
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2
Q

What are monosaccharides?

A

Small organic molecules and the building blocks for the larger carbohydrates

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3
Q

How many carbon atoms does a triose sugar have?

A

3

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4
Q

Define the term isomer

A

Same formula but different structural arrangement e.g alpha and beta glucose

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5
Q

Name some of the functions of monosaccharides

A
  • source of energy
  • building blocks for larger molecules
  • intermediates for reactions
  • constituents of nucleotides
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6
Q

What are disaccharides?

A

Two monosaccharide units bonded with the formation of glycosidic bind and the elimination of water

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7
Q

Glucose + glucose =

Glucose + fructose =

Glucose + galactose =

A

Maltose

Sucrose

Lactose

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8
Q

What is the test for reducing sugars?

A

Benedict’s test

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9
Q

How do you carry out the Benedict’s test for reducing sugars?

A

1) add equal volumes of the reagent to the solution
2) boil
3) colour change from blue to brick red

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10
Q

Test for non reducing sugars

A

1) add solution to HCL
2) boil
3) neutralise with alkali (sodium hydrogencarbonate)
4) add Benedict’s reagent
5) colour change from blue to brick red

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11
Q

What is another way to detect sucrose?

A

1) add sucrase enzyme
2) hydrolysed sucrose into glucose and fructose
3) add Benedict’s reagent

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12
Q

What are polysaccharides?

A

Large complex polymers formed from large numbers of monosaccharide units

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13
Q

Why is glucose converted to starch?

A
  • insoluble so has no osmotic effect
  • cannot diffuse out of the cell
  • compact molecule that can be stored in a small space
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14
Q

What are the two polymers that starch is made up of?

A

Amylose and amylopectin

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15
Q

What is the structure of amylose?

A
  • linear, unbraced
  • alpha 1,4 glycosidic bonds
  • this is repeated forming a chain which coils into a helix
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16
Q

What is the structure of amylopectin?

A
  • 1,4 & 1,6 glycosidic bonds

- branched

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17
Q

What is the test for starch called?

A

Iodine test

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18
Q

How do you test for starch?

A

1) add iodine

2 colour change from brown to blue/black

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19
Q

What is the main storage in animals?

A

Glycogen

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20
Q

Describe the structure of glycogen?

A
  • alpha 1,4 and 1,6 glycosidic bonds

- more branched than amylopectin

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21
Q

Where is cellulose found?

A

Plant cell walls

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22
Q

Describe the structure of cellulose

A
  • long parallel chains of beta glucose
  • better 1,4 glycosidic bonds
  • adjacent glucose molecules rotated 180 degrees
  • hydrogen bonds form
  • molecules become tightly crosslinked to form microfibrils
  • bundles of microfibrils = fibres
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23
Q

Where in chitin found?

A
  • exoskeleton of insects

- fungal cell walls

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24
Q

Describe the structure of chitin

A
  • beta 1,4 glycosidic bonds
  • adjacent molecules rotated 180 degrees
  • long parallel chains
  • linked together by hydrogen bonds forming microfibrils
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25
Q

What are groups derived from amino acids added called?

A

Heteropolysaccharides

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26
Q

What do elements lipids contain, briefly describe their relative proportions?

A

Carbon, hydrogen and oxygen

But in proportion to carbon and hydrogen they contain much less oxygen

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27
Q

Describe some properties of lipids

A
  • non poplar
  • insoluble on water
  • dissolve on organic solvents (such as proanone and alcohols)
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28
Q

How are triglycerides formed?

A

1 glycerol molecule and 3 fatty acid molecules join together during a condensation reaction and 3 molecules of water are removed and ester bonds are formed

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29
Q

What is an ester bond?

A

An oxygen atom joining two atoms one of which is a carbon atom attached by a double bond to an oxygen atom

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30
Q

What is an unusual property of phospholipids?

A

Each molecule has one end that is soluble in water, (in the glycerol group, the phosphate and the choline and so has a lot of oxygen atoms)

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31
Q

What part of a phospholipid is hydrophilic?

A

The phosphate group

32
Q

What does a phospholipid consist of?

A

1 Glycerol molecule + 2 fatty acid molecules

- (this is the polar head of the molecule)

33
Q

Why are the fatty acid tails non-polar?

A

The fatty acid tails do not have any oxygen atoms and do not interact with water so they are hydrophobic and non-polar

34
Q

What are waxes?

A

Lipids and melt above 45°.

- they have a waterproofing role in both animals, such as insect exoskeleton and plants, in the leafs cuticle

35
Q

Define saturated

A
  • If the hydrocarbon chain has only single carbon-carbon bonds
  • all the carbon atoms are linked to the maximum possible number of hydrogen atoms
36
Q

Describe the structure and state of saturated lipids

A
  • the fatty acid chain is a straight zig-zag
  • the molecules can align readily so the fats are solid
  • remain semi-solid at body temperature and so are useful for storage in mammals
    •animal lipids often contain saturated fatty acids
37
Q

Define unsaturated

A
  • if any carbon-carbon bond is not a single bond

- not bonded to maximum number of hydrogen atoms

38
Q

Describe the structure and shape of unsaturated lipids

A
  • the molecules cannot align uniformly
  • the lipid does not solidify readily
  • unsaturated lipids are oils which are liquid at room temperature
    •plant lipids are often unsaturated and occur as oils
39
Q

What is a monounsaturated lipid?

If a lipid contains many carbon-carbon double bonds it is called?

A
  • a lipid with one carbon-carbon double bond

- polyunsaturated

40
Q

Roles of Phospholipids: (BE)

A
  • In BIOLOGICAL MEMBRANES

* ELECTRICAL INSULATION- the myelin sheath that surrounds the axons of nerve endings

41
Q

Roles of Triglycerides: (MPET)

A
  • METABOLIC WATER-water released during chemical reactions in the body (triglycerides produce a lot of metabolic water when oxidised)
  • PROTECTION-fat is often stored around delicate internal organs (e.g. The kidneys) to protect against physical damage
  • ENERGY RESERVES-in both plants and animals because lipids contain more carbon-hydrogen bonds than in carbohydrates
  • THERMAL INSULATION-when stored under the skin lipids insulate against heat loss in the cold or head gain when it’s very hot
42
Q

Roles of Waxes: (W)

A

• WATERPROOFING-in terrestrial organism, waxes reduce water loss such as in the insect exoskeleton and in cuticle of plants

43
Q

Test for fats and oils- the emulsion test

A

1) the sample is mixed with ethanol (it dissolves any lipids present
2) it is shaken with equal volumes of water
3) the dissolved lipids come out of solution because they are insoluble I water
4) they form an emulsion making the sample cloudy white

44
Q

What are the main causes of heat disease?

A
  • fatty deposits in the coronary arteries (atherosclerosis)
  • high blood pressure (hypertension)
  • a diet high in saturated fats
  • smoking
  • lack of exercise
  • ageing
45
Q

How are lipoproteins made?

A

When food has been absorbed at the small intestine lipids and proteins combine to make lipoproteins which travel around the body in the bloodstream

46
Q

What happens if your diet is high in saturated fats ?

A
  • (LDL) build up and cause harm
  • fatty material (atheroma) gets deposited in the coronary arteries restricting blood flow therefore oxygen delivery to the heart
  • can result in angina and if the vessel is completely blocked a myocardial infarction of heart attack occurs
47
Q

What happens if your diet has a high proportion of unsaturated fats?

A
  • the body has a high proportion of HDL which carries harmful fats away to the liver for disposal
  • the higher the proportion of HDL to LDL in a persons blood the lower their risk of cardiovascular and coronary heart disease
48
Q

How do proteins differ from carbohydrates?

A
  • In addition to carbon, hydrogen and oxygen they always contain nitrogen
  • many proteins also contain sulphur and some contain phosphorus
49
Q

Proteins are polymers made of monomers called…

A

Amino acids

50
Q

What are the chains of amino acids called?

A

Polypeptides

51
Q

Around how many amino acids are used to make up proteins?

A

20

52
Q

The proteins shape is determined by…

A

The specific sequence of amino acids in the chain

53
Q

Describe the basic structure that all amino acids have

A
  • Amine group-NH2 at one end of the molecule called N terminal
  • Carboxyl group-COOH at the other end of the molecule called the C-terminal
  • A hydrogen atom
  • R group (which is different in each amino acid)
54
Q

The amino group is alkaline, acidic or basic?

A

Basic

55
Q

How does a zwitterion form?

A
  • The amino group is basic
  • At pH7, the pH of the cell it gains a H and becomes positively charged
  • the carboxyl group is acidic and at pH7 it looses an H becoming negatively charged
  • this is a zwitterion
56
Q

How does a peptide bond form?

A

The amino group of one amino acid e
Reacts with the carboxyl group of another with the elimination of water. The bond that is formed from the condensation reaction is a peptide bond and the resulting compound is a dipeptide

57
Q

Describe the primary structure of proteins:

A

•the order of amino acids in a polypeptide chain

  • can be joined together in any number order and combination so there are many possible polypeptide
  • the primary structure is determined by the base sequence on one strand of the DNA molecule
58
Q

Describe the secondary structure of proteins:

A

•the shape that the polypeptide chain forms as a result of hydrogen bonding in the peptide bonds along the chain
- causes long polypeptide chain to be twisted into a 3D shape
- coils/ spirals to form alpha helix or folds to form beta pleated sheet
-

59
Q

Secondary structure of Keratin

Secondary structure of silk

A
  • keratin has a high proportion of alpha helix

- silk has a high proportion of beta pleated sheet

60
Q

Describe the tertiary structure of proteins:

A

• further folding of the secondary structure into a more complex 3D shape which is maintained by:

  • hydrogen bonds
  • ionic bonds
  • disulphides bridges
  • hydrophobic interactions
61
Q

Describe the quaternary structure of proteins:

A
  • Many polypeptide chains joined together

- they many be associated with non-protein groups and form large complex molecules such as haemoglobin

62
Q

What are the two main types of proteins?

A

Globular & Fibrous proteins

63
Q

Are fibrous proteins soluble in water?

A

No they are insoluble

64
Q

Describe the shape of fibrous proteins

A
  • Fibrous proteins have Long, thin molecule

- the polypeptides are in parallel chains or sheets with many cross-linkages forming long fibres e.g keratin

65
Q

What kind of functions do fibrous proteins have?

A

Structural functions e.g in bone

66
Q

Properties of fibrous proteins

A

Strong and tough

67
Q

What is the fibrous protein in hair?

A

Keratin

68
Q

What is collagens function?

A

To provide strength and toughness in tendons

69
Q

Describe the structure of collagen

A
  • A single fibre (sometimes called tropocollagen) consists of three identical polypeptide chains twisted around each other like a rope
  • the three chains are linked by hydrogen bonds making the molecule very stable
70
Q

Describe the shape of globular proteins

A

Compact and folded into spherical molecules this makes them soluble in water

71
Q

Give some examples of globular proteins

A

Enzymes, antibodies, plasma proteins and hormones

72
Q

Describe the structure of haemoglobin

A

4 folded polypeptide chains at the centre of which is the iron containing prosthetic group (haem)

73
Q

What is the test for proteins called?

A

The biuret test

74
Q

Briefly describe how you would test for proteins

A

1) add a few drops of biuret reagent (sodium hydroxide and copper sulphate)
2) the sodium hydroxide and copper sulphate react to make copper hydroxide which interacts with the peptide bonds present in the protein to make biuret which is purple

75
Q

Why is the test qualitative?

A

The more concentrated the protein the darker the purple colour

76
Q

What is the problem at low protein concentrations

A

The colour is difficult to detect by eye

77
Q

What could help you to overcome the problem of low protein concentration?

A

A colorimeter gives an estimate of relative concentration of proteins present in a sample

To detect the concentration of a specific protein, a biosensor would be required

Biology need to knows⚠️ (18 decks)

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