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Biology A Level AQA > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

Which disaccharide is not a reducing sugar?

A

Sucrose

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2
Q

Which monomers make up lactose?

A

a-glucose and galactose

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3
Q

Which monomers make up maltose?

A

a-glucose and a-glucose

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4
Q

Which monomers make up sucrose?

A

a-glucose and fructose

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5
Q

What are the two polymers that make up starch?

A

Amylose and amylopectin

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6
Q

Which covalent bonds are present in carbohydrates?

A

Glycosidic bonds

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7
Q

Which covalent bonds are present in proteins?

A

Peptide bonds

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8
Q

Which covalent bonds are present in lipids?

A

Ester bonds

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9
Q

Which covalent bonds are present in nucleic acids?

A

Phosphodiester bonds

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10
Q

Which monomers makes up cellulose?

A

b-glucose

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11
Q

Which monomers makes up glycogen?

A

a-glucose

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12
Q

What physical features are found in amylose?

A

a-glucose, helix (coiled) shape and 1,4 glycosidic bonds

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13
Q

What physical features are found in amylopectin?

A

a-glucose, branched chain (every ~20 monomers) and 1,4 + 1,6 glycosidic bonds

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14
Q

What are the physical features found in glycogen?

A

a-glucose, branched (every ~10 monomers) and 1,4 + 1,6 glycosidic bonds

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15
Q

What is the main role of glycogen?

A

Mid-term energy storage in animals

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16
Q

What is the main role of starch?

A

Energy storage in plants

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17
Q

What is electronegativity?

A

Measuring an atom’s pull on a shared pair of electrons

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18
Q

What occurs due to oxygens high electronegativity in water?

A

Partial charges (oxygen is slightly negative, hydrogens are slightly positive), causing water to be polar

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19
Q

What is cohesion?

A

‘Stickiness’ between water molecules

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20
Q

What is adhesion?

A

‘Stickiness’ between water molecules and other polar molecules eg. Xylem wall

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21
Q

What does hydrophobic mean?

A

Not soluble in water (will not dissolve)

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22
Q

What does hydrophilic mean?

A

Soluble in water (will dissolve)

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23
Q

Why is water used as a transport medium?

A

It is a universal solvent and a metabolite

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24
Q

What does thermostable mean?

A

Temperature is not going to fluctuate much: buffers changes in temperature

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25
Q

Define large latent heat of vapourisation

A

Takes a large amount of thermal energy to evaporate

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26
Q

What is the reducing sugars test?

A

Add Benedict’s solution and heat in water bath, if positive colour changes from blue to red

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27
Q

What is the non-reducing sugars test?

A

Negative result for reducing sugars test, add HCl to solution and boil, then add sodium hydrogen carbonate to neutralise and repeat reducing sugars test

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28
Q

What is the test for starch?

A

Add iodine solution, if positive colour changes from yellow to blue/black

29
Q

What is the test for proteins?

A

Add Biuret’s reagent, if positive colour changes from blue to purple

30
Q

What are the two main types of lipids?

A

Triglycerides and phospholipids

31
Q

Are lipids soluble in water?

A

No as they are hydrophobic - they are only soluble in other organic solvents eg. Alcohols

32
Q

What are the components of triglycerides?

A

1 glycerol and 3 fatty acid chains

33
Q

What are saturated fatty acids?

A

Straight chains with only single c-c bonds

34
Q

What are unsaturated fatty acids?

A

Bent chains with single c-c bonds and double c=c bonds

35
Q

Which fatty acid type has high melting and boiling points?

A

Saturated fatty acids as they fit closer together in a regular pattern and form stronger associations between the molecules, so they have higher melting and boiling points

36
Q

What is formed in the condensation reaction of 1 glycerol and 3 fatty acids?

A

Produces 1 triglyceride, 3 water molecules are released and 3 ester bonds are formed

37
Q

What physical part has a phospholipid got that a triglyceride doesn’t?

A

A phosphate molecule on the glycerol (but therefore only 2 fatty acid chains)

38
Q

Describe the charge of phospholipids

A

The phosphate group on the molecule is charged so therefore is hydrophilic (head) and the fatty acid chains are uncharged and are therefore hydrophobic (tails)

39
Q

Where are phospholipids found?

A

Plasma membranes in a ‘phospholipid bilayer’ due to their bipolar nature

40
Q

What is the test for lipids?

A

Mix the sample being tested with alcohol, shake the tube thoroughly, add cold water and shake gently, if positive then a milky-white emulsion is formed

41
Q

What is the monomer found in proteins?

A

Amino acids

42
Q

What is the polymer for a protein called?

A

Polypeptide chain

43
Q

What are the 4 types of amino acids?

A

Hydrophilic, charged/ionic, hydrophobic and thiol (sulphur)

44
Q

What is a dipeptide?

A

2 amino acids joined by a peptide bond

45
Q

What is the primary structure of proteins?

A

Sequence of amino acids in the polypeptide chain

46
Q

What is the secondary structure of proteins?

A

Weak hydrogen bonds are formed between the slightly positive N-H group and the slightly negative C=O group of another amino acid. This forms either an alpha helix (coil) or beta pleated sheets

47
Q

What is the tertiary structure of proteins?

A

Further folding of polypeptide chain to give very specific 3D structure. Types of bonding that could be formed are hydrogen bonds, hydrophobic interactions, disulphide bridges and ionic bonds

48
Q

What is the quaternary structure of proteins?

A

Same bonding types as in tertiary, but between more than one polypeptide chain and/or non-protein ‘prosthetic’ groups

49
Q

What are the two types of proteins?

A

Globular and fibrous

50
Q

Describe the characteristics of globular proteins

A

They are hydrophilic, they are spherical and have a compact structure, used in metabolic processes eg. Enzymes and haemoglobin

51
Q

Describe characteristics of fibrous proteins

A

Fibre like - long chains which run parallel to each other, linked by many cross-bridges so are very strong and stable eg. Collagen

52
Q

How many polypeptide chains does haemoglobin have?

A

4

53
Q

How many polypeptide chains does collagen have?

A

3

54
Q

What are enzymes?

A

Globular proteins that act as biological catalysts

55
Q

What are catalysts?

A

Substances that increase the rate of a chemical reaction and are not used up

56
Q

What are anabolic reactions?

A

‘Building’ reactions using energy

57
Q

What are catabolic reactions?

A

‘Breaking down’ reactions that release energy

58
Q

What is an enzyme-substrate complex?

A

Complex formed when a substrate bunds to the active site of an enzyme

59
Q

What does sucrase do?

A

Catalyses the hydrolysis of sucrose

60
Q

What does sucrose synthase do?

A

Catalyses condensation of sucrose

61
Q

What biological molecule are enzymes?

A

Globular proteins

62
Q

Why are enzymes very specific to one reaction?

A

The binding of the substrate to the active site of the enzyme is very specific - substrate must be complimentary to active site

63
Q

What is the induced fit model?

A

As the complimentary substrate binds to the active site, the active site changes shape slightly to better fit the substrate. The ES complex that is formed puts strain/stress on the bonds causing bonds to break/make + form products. When products leave the active site it returns to its original shape

64
Q

How do enzymes speed up the rate of reactions?

A

They lower the activation energy (Ea)

65
Q

What is activation energy?

A

Minimum energy required to get a reaction going

66
Q

What factors affect enzyme activity?

A

Temperature, pH, enzyme concentration + substrate concentration

67
Q

What are enzyme inhibitors?

A

Substances that directly/indirectly affect the functioning of the active site of a specific enzyme therefore preventing substrate binding, so no ES complex formed and therefore decreases the rate of reaction

68
Q

What are competitive inhibitors?

A

Similar shape/structure to substrate so can also bind to active site, so substrate competes with inhibitor for the active site. Not permanent

69
Q

What are non-competitive inhibitors?

A

Binds to allosteric site of enzyme, which causes change in tertiary structure of enzyme, therefore changing shape of active site and it is no longer complementary to substrate. May be permanent

Biology A Level AQA (14 decks)

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