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Biology > Biological molecules > Flashcards

Biological molecules Flashcards

1
Q

What four carbon-based compounds are all living organisms made up of?

A

Carbohydrates, proteins, lipids and nucleic acid

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2
Q

What is the name of the process where monomers are joined together to form polymers?

A

Polymerisation

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3
Q

What happens during a condensation reaction?

A

Two monomers are combined to form a single molecule and a molecule of water is removed each time a sub-unit is added.

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4
Q

What is a hydrolysis reaction?

A

The breaking down of polymers into their constituent monomers by the addition of water molecules ( the bonds that join the monomers are broken ).

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5
Q

Give three examples of monomers

A

Monosaccharides, amino acids, nucleotides

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6
Q

Give three examples of polymers

A

Polysaccharides, polypeptides (protein), polynucleotides (DNA)

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7
Q

Define monosaccharide

A

A single monomer

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8
Q

Define disaccharide

A

A combined pair of monosaccharides

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9
Q

Define polysaccharide

A

A large number of combined monosaccharides

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10
Q

Give three examples of monosaccharides

A

Glucose, galactose and fructose

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11
Q

How are disaccharides formed?

A

By the condensation of two monosaccharides

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12
Q

What is the name of the bond formed between monosaccharides?

A

Glycosidic bond

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13
Q

Give three examples of disaccharides

A

Maltose, sucrose, lactose

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14
Q

What does glucose + glucose form?

A

Maltose + water

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15
Q

What does glucose + fructose form?

A

Sucrose + water

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16
Q

What does glucose + galactose form?

A

Lactose + water

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17
Q

Name the three chemical elements contained in carbohydrates

A

Carbon, hydrogen, oxygen

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18
Q

Describe the two main functions of carbohydrates in living organisms

A
  • They store energy in plants and animals
  • They provide a structural role in plant cell walls
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19
Q

What are some examples of carbohydrates?

A

Monosaccharides, disaccharides, polysaccharides

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20
Q

How is the structure of starch suited to its role?

A
  • Starch is insoluble so doesn’t draw water put of cells by osmosis or diffuse out of cells
  • Has a compact structure meaning lots can be stored in a small space
  • Can be hydrolysed to form alpha-glucose which is easily transported and used in respiration
  • Has branched ends which can be acted on simultaneously meaning glucose monomers are released rapidly
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21
Q

What is the main role of starch?

A

Energy storage in plants

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22
Q

What monomer is starch made up of?
Describe the structure of starch
State the glycosidic bonds in starch

A
  • alpha glucose
  • branched, helical, compact
  • 1-4, 1-6
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23
Q

What monomer is cellulose made up of?
Describe the structure of cellulose
State the glycosidic bonds in cellulose

A
  • beta glucose
  • unbranched and straight
  • 1-4
24
Q

What monomer is glycogen made up of?
Describe the structure of glycogen
State the glycosidic bonds in glycogen

A
  • alpha glucose
  • highly branched
  • 1-4, 1-6
25
Q

Where is glycogen stored?

A

In the muscles and liver

26
Q

What is the main role of glycogen?

A

Energy storage in animals and bacteria

27
Q

Explain how starch and glycogen differ in structures

A
  • Glycogen has shorter chains than starch
  • Glycogen is more highly branched than starch
28
Q

How is the structure of glycogen suited to its role?

A
  • Glycogen is insoluble so it doesn’t draw water into cells by osmosis or diffuse out of cells
  • Has a compact structure meaning lots can be stored in a small space
  • Glycogen is highly branched so has lots of ends that can be acted on simultaneously by enzymes to break down glycogen to form glucose monomers
29
Q

Why is it important that glycogen is more highly branched than starch?

A
  • As glycogen is more highly branched, it can be broken down more rapidly than starch can be into its constituent alpha glucose monomers which are used in respiration
  • This is important as glycogen is used for energy storage in animals and starch is used for energy storage in plants
  • Animals are more active than plants and so have a higher metabolic rate and therefore respiratory rate meaning they will use up the glucose monomers faster than starch will which is why its important that the monomers can be replaced faster in glycogen due to it being more highly branched
30
Q

What is the main role of cellulose?

A

To provide support and rigidity for plant cell walls

31
Q

How does cellulose prevent cells from bursting?

A

By exerting an inward pressure that stops any further influx of water

32
Q

How is the structure of cellulose suited to its role?

A
  • The OH groups occur on both sides of the molecule allowing it to form hydrogen bonds with other chains on both sides
  • Made up of beta glucose so forms long straight unbranched chains which provides a lot of support to the plant
  • Has straight unbranched chains that run parallel to one another which allows hydrogen bonds to form cross-linkages with adjacent chains which add collective strength
  • Cellulose molecules are grouped together to form microfibrils which are then grouped together to form fibres which provides a considerable amount of strength
33
Q

How does starch keep its helical structure?

A

The OH groups are pointing inwards which allows the hydrogen bonds that hold the helix structure in shape to form.

34
Q

List three roles that apply to lipids

A
  • Source of energy
  • Insulation
  • Waterproofing
35
Q

Name the bond found in triglycerides between a fatty acid and glycerol?

A

Ester bond

36
Q

What is a triglyceride made up of?

A

3 fatty acids and glycerol

37
Q

What is the difference between a saturated fatty acid and an unsaturated fatty acid?

A

A saturated fatty acid contains no carbon-carbon double bonds whilst an unsaturated fatty acid contains one or more carbon-carbon double bonds

38
Q

What are phospholipids made up of?

A

2 fatty acids, glycerol and a phosphate molecule

39
Q

Why are lipids better than carbohydrates for long-term energy storage?

A
  • Lipids provide twice as many calories as the same mass of carbohydrates
  • So it is a lighter storage molecule ( which is a significant advantage for mobile organisms )
40
Q

What is the difference between fatty acids and phosphate molecules relationship with water?

A

Fatty acids are hydrophobic and so keep away from water whilst phosphate molecules are hydrophilic and so interact with water

41
Q

How many different types of amino acids are there?

A

20

42
Q

What are amino acids made up from?

A
  • Central carbon atom
  • Amine group ( NH2 )
  • Carboxyl group ( COOH )
  • Hydrogen atom
  • R (variable) group - each amino acid has a different R group
43
Q

Name the bond formed between amino acids

A

Peptide bond

44
Q

What is the primary structure of a protein?

A
  • The sequence of amino acids in a polypeptide chain
  • Determines the shape and function of a protein
45
Q

What is the secondary structure of a protein?

A

The polypeptide chain is twisted into a 3D shape (e.g alpha-helix, beta-pleated sheet)

46
Q

What is the tertiary structure of a protein?

A
  • Where the protein is twisted and folded more to give the complex 3D structure of a protein
47
Q

Name the bonds that maintain the tertiary structure of a protein

A
  • Disulphide bonds ( fairly strong so not easily broken )
  • Ionic bonds ( easily broken by change in pH )
  • Hydrogen bonds ( numerous but easily broken )
48
Q

What is the quaternary structure of a protein?

A

Where individual polypeptide chains are linked together

49
Q

Define activation energy

A

The minimum amount of energy required for a reaction to take place

50
Q

What is the functional region of an enzyme called?

A

Active site

51
Q

Describe and explain the induced fit model of enzyme action

A
  • Proposes that the the active site forms as the enzyme and substrate interact
  • This suggests that the enzyme is flexible and can mould itself around the substrate
  • As the enzyme changes shape, it puts a strain on the substrate molecule which distorts bonds in the substrate and consequently lowers the activation energy
52
Q

What 2 conditions need to be met for an enzyme to work?

A
  • The enzyme has to come into physical contact with its substrate
  • The active site of the enzyme must be complementary to the substrate
53
Q

List 4 factors that affect the rate of enzyme action

A
  • Enzyme concentration
  • Substrate concentration
  • pH
  • Temperature
54
Q

How does enzyme concentration affect the rate of enzyme action?

A
  • As long as there is an excess of substrate, an increase in the enzyme concentration will lead to a proportionate increase in the rate of reaction
  • If there is not sufficient substrate to supply all the enzyme’s active site, increasing the enzyme concentration will have no effect on the rate of reaction
55
Q

How does substrate concentration affect the rate of enzyme action?

A
  • As long as there is an excess of enzymes, an increase in the substrate concentration will lead to a proportionate increase in the rate of reaction
  • As more substrate is added, the active sites gradually become filled until all of them are working as fast as they can which means the addition of more substrate will have no effect on the rate of enzyme action
56
Q

How does pH affect the rate of enzyme action?

A
  • Each enzyme has an optimum pH, at which it works the fastest
  • An increase or decrease in pH reduces the rate of enzyme action
  • Change in pH alters the charges on the amino acids which make up the active site which means the substrate can no longer be attached
  • If the change in pH is extreme then the enzyme becomes denatured (the bonds maintaining the tertiary structure break) and the active site changes shape meaning enzyme-substrate complexes can no longer form which reduces the rate of enzyme action
57
Q

How does temperature affect the rate of enzyme action?

A
  • An increase in temperature increases the kinetic energy of the molecules meaning molecules move around more rapidly and collide with each other more often meaning more enzyme-substrate complexes form and rate of enzyme action increases
  • Above a certain temperature the enzyme will denature and no longer be functioning

Biology (17 decks)

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