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AQA A Level Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

Glucose + _____ makes maltose

A

Glucose + glucose makes maltose

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2
Q

Glucose + fructose makes _____

A

Glucose + fructose makes sucrose

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3
Q

Glucose + _____ make lactose

A

Glucose + galactose makes lactose

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4
Q

What is a reducing sugar?

A

A sugar that donates electrons

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5
Q

Glucose + glucose –> maltose

What type of reaction is this?

A

Condensation

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6
Q

Fill in the blank:
Polymers are molecules made from a large number of _____
joined together.

A

Monomers

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7
Q

Fill in the blank:
Monosaccharides, amino acids and nucleotides are examples of
____.

A

Monomers

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8
Q

A condensation reaction involves the elimination of what molecule?

A

A water molecule

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9
Q

What is hydrolysis?

A

Breaking a chemical bond with water

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10
Q

Two monosaccharides are formed in what type of reaction?

A

A condensation reaction

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11
Q

Two monosaccharides are joined together in a reaction. What type of bond is formed?

A

A glycosidic bond.

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12
Q

Glucose has two isomers: alpha and beta. What is the difference in their structures?

A

In alpha glucose both OH groups are at the bottom/top whereas in beta glucose one OH group on top, one of bottom

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13
Q

Glycogen and starch are formed by the condensation reactions of which glucose isomers?

A

Alpha glucose

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14
Q

Cellulose is formed by the condensation of which glucose isomer?

A

Beta glucose

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15
Q

Triglycerides are formed in what type of reaction?

A

A condensation reaction

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16
Q

Triglycerides are formed in a condensation reaction from which molecules?

A

One molecule of glycerol and three molecules of fatty acid.

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17
Q

The condensation reaction between a glycerol and a fatty acid forms which type of bond?

A

An ester bond

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18
Q

What is the difference between a phospholipid and a triglyceride?

A

In phospholipids, one of the fatty acids of a triglyceride is substituted
by a phosphate-containing group.

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19
Q

What is the general structure of a amino acid?

A

A central carbon with an R group, an H, a carboxylic acid group (COOH) and an amine (NH2) group attached to it.

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20
Q

What is the bond between two amino acids called?

A

A peptide bond

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21
Q

How are peptide bonds formed?

A

A condensation reaction between two amino acids.

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22
Q

How do enzymes catalyse a reaction?

A

By lowering the activation energy

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23
Q

Is starch a monosaccharide, disaccharide or polysaccharide?

A

Polysaccharide

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24
Q

Is sucrose a monosaccharide, disaccharide or polysaccharide?

A

Disaccharide

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25
Q

Is fructose a monosaccharide, disaccharide or polysaccharide?

A

Monosaccharide

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26
Q

Is glycogen a monosaccharide, disaccharide or polysaccharide?

A

Polysccharide

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27
Q

What are the monomers of DNA called?

A

Nucleotides

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28
Q

Nucleotides are formed from three key parts. What are they?

A

A phosphate group, pentose sugar and a nitrogen containing base.

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29
Q

A condensation reaction between two nucleotides form what type of bond?

A

A phosphodiester bond

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30
Q

What are the key components of a DNA nucleotide?

A

A deoxyribose sugar, a phosphate group, and one of the organic bases: adenine, cytosine, guanine or thymine.

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31
Q

What are the key components of a RNA nucleotide?

A

A ribose sugar, a phosphate group, and one of the organic bases: adenine, cytosine, guanine or uracil.

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32
Q

What are three differences between DNA and RNA?

A

DNA has deoxyribose sugar, whereas RNA has ribose sugar
DNA is larger/longer than RNA/RNA is shorter
DNA contains thymine, RNA contains uracil instead
DNA is double stranded, RNA is single stranded

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33
Q

What are 3 features of a fibrous molecule?

A

Insoluble
Roles tend to be structural
Remains as a long chain
Very strong and stable

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34
Q

What are 3 features of a globular molecule?

A 
Compact, spherical
Soluble (hydrophilic side chain)
Not very stable
Range of function
Usually shape specific
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35
Q

How does temperature affect rate of reaction?

A

Increasing temperature increase the kinetic energy of the molecules therefore increasing the number of collisions and so increasing the rate of reaction. However, this only to an extent –> will denature if too hot

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36
Q

How does pH affect rate of reaction?

A

pH can alter tertiary structure and therefore active site, thus halting reactions from occurring.

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37
Q

How does DNA replicate?

A

DNA is unwound
Helicase breaks the H bonds b/wn bases to unwind strands
Free nucleotides H bond w/ exposed complementary bases
DNA polymerase joins nucleotides on 1 strand together to make a new strand forming phosphodiester bonds
Hydrogen bonds b/wn strands reform
Rewinds

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38
Q

Why is DNA replication known as semi-conservative?

A

In each DNA, one strand is old, one strand is new

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39
Q

Why is ATP an ideal short term energy currency? Give three reasons

A

Very quickly broken down (quicker than glucose)
Small amounts released (minimal wastage)
Easy to remake
Can’t move in/out of cells so therefore is always available in the cell

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40
Q

Why is glucose a more ideal long term energy currency than ATP?

A

Glucose releases more energy, and at a slower rate. It is also larger
Carbs can be stored as glycogen

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41
Q

What are the 3 components of an ATP molecule?

A

An adenine molecule, a ribose sugar, and three phosphate groups

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42
Q

The hydrolysis of ATP is catalysed by which enzyme?

A

ATP hydrolase

43
Q

ATP is hydrolysed to what?

A

ADP (adenosine diphosphate) and an inorganic phosphate group (Pi)

44
Q

The inorganic phosphate released in the hydrolysis of ATP can be used to reform ATP. What else can it be used for?

A

To phosphorylate other compounds, often making them more reactive

45
Q

ATP is resynthesised by the condensation of ADP and Pi. This reaction is catalysed by what enzyme?

A

ATP synthase

46
Q

ATP hydrolase catalyses what reaction?

A

The hydrolysis of ATP into ADP and Pi

47
Q

Give 4 key properties of water

A

Water:
Is a metabolite in many metabolic reactions (inc hydrolysis and condensation reactions)
Is an important solvent in which metabolic reactions occur
Has a relatively high specific heat capacity, buffering changes in temp.
Has a relatively large latent heat of vaporisation, providing a cooling effect w/ little loss of water through evaporation
Has a strong cohesion b/wn water molecules; supports columns of water in the tube like transport cells of plants and produces surface tension where water meets air

48
Q

What makes up cell walls in plants?

A

Cellulose

49
Q

Which microscope has the best resolution?

A

TEM

50
Q

What are triglycerides used for?

A

Energy storage

51
Q

What is the structure of a nucleotide?

A

A pentose sugar, an nitrogenous base and a phosphate group

52
Q

What type of bond joins the phosphate group and pentose sugar in a nucleotide?

A

An ester bond

53
Q

What type of bond joins the pentose sugar and the nitrogenous base in a nucleotide?

A

Glycosidic bond

54
Q

What is the name of the monomers that make up DNA?

A

Nucleotides

55
Q

What are the three basic components that make up RNA?

A

Ribose sugar, nitrogenous base and a phosphate group

56
Q

How is DNA adapted for its function?

A

Stable - Able to pass from generation to generation with no change
Strands may be separated to allow replication
Large - able to carry lots of information
Base pairs with helix
Genetic information protected by strong sugar-phosphate backbone

57
Q

What type of bond forms between DNA nucleotides?

A

Phosphodiester

58
Q

What are the key differences between DNA and RNA?

A

RNA has uracil, DNA has thymine
RNA has ribose, DNA has deoxyribose
RNA is single stranded, DNA is double stranded

59
Q

What enzyme breaks the hydrogen bonds between the complementary bases?

A

DNA helicase

60
Q

What is the role of DNA polymerase in DNA replication?

A

Joins the nucleotides on one strand together

61
Q

Describe the process of DNA replication

A

Helicase breaks bond between complementary base pairs, allowing helix to be unwound
Free nucleotides form hydrogen bonds with their complementary exposed bases
DNA polymerase joins the nucleotides on one strand together

62
Q

Name the chemical elements in a non-reducing sugar

A

Carbon, hydrogen and oxygen

63
Q

The condensation of alpha glucose leads to the formation of what polysaccharide?

A

Glycogen

Starch

64
Q

The condensation of beta glucose leads to the formation of what polysaccharide?

A

Cellulose

65
Q

Which type of saccharides form insoluble or colloidal structures?

A

Polysaccharides

66
Q

Which two polymers of glucose make up starch?

A

Amylose and amylopectin

67
Q

Which glucose isomer forms branched chains?

A

Alpha glucose

68
Q

Which glucose isomer forms unbranched chains?

A

Beta glucose

69
Q

What is the main role of starch?

A

Energy storage

70
Q

What is the animal equivalent of starch?

A

Glycogen

71
Q

What is the plant equivalent of glycogen?

A

Starch

72
Q

How is the structure of starch related to its function?

A

Insoluble - doesn’t affect water potential so water not drawn in by osmosis
Large and insoluble - doesn’t diffuse out of cells
Helical/spiral/coiled - compact, lots stored in small space (from MS)

(When hydrolysed forms ⍺ glucose - easily transported and readily used for respiration
Branched form has many ends - glucose monomers released rapidly)

73
Q

What is the key difference between the structure of starch and the structure of glycogen, and why is it necessary?

A

Glycogen has more branching - animals use more energy generally, so can be more rapidly broken down to release glucose

74
Q

Where is glycogen primarily found in animals?

A

In the muscles and in the liver

75
Q

How is the structure of glycogen related to its function?

A

Insoluble - doesn’t affect water potential so water not drawn in by osmosis
Large and insoluble - doesn’t diffuse out of cells
Compact - lots stored in small space
When hydrolysed forms ⍺ glucose - easily transported and readily used for respiration
Branched form has many ends - glucose monomers released rapidly (more so than starch)

76
Q

What is the key difference in the structure of cellulose when compared to starch and glycogen?

A

Cellulose is made from ϐ glucose, starch and glycogen made from ⍺

77
Q

Describe the structure of cellulose

A

ϐ glucose form straight, unbranched chains that are parallel to each other
H bonds form between chains forming cross-linkages
Cellulose molecules grouped to form microfibrils

78
Q

Which of these are found in plants: cellulose, starch, glycogen

A

Cellulose and starch

79
Q

How is the structure of cellulose related to its function?

A

ϐ glucose –> long, straight, unbranched molecules
Chains run parallel to each other to form H bonds - collectively add strength
Molecules grouped to form microfibrils, which in turn form - collectively add strength

80
Q

What are the two main groups of lipids?

A

Triglycerides and phospholipids

81
Q

What are some of the key roles of lipids?

A

Source of energy
Waterproofing - insoluble in water
Insulation - slow conductors of heat
Protection

82
Q

Hydrolysis of a triglyceride produces what?

A

Glycerol and three fatty acids

83
Q

What chemical group do all fatty acids contain?

A

-COOH attached to a hydrocarbon chain

84
Q

What is the main difference between fats and oils?

A

Fats = solids at room temp, oils = liquids

85
Q

What bond is formed between the fatty acid and glycerol in a triglyceride?

A

Ester bond

86
Q

Esterification is what type of reaction?

A

Condensation

87
Q

Describe how the structure of a triglyceride is related to its properties

A

High ratio of energy storing C-H bonds : C atoms - good energy source
Low mass to energy ratio - good storage molecules
Insoluble in water (large and non-polar) - don’t affect water potential of cells or osmosis
High ratio of O to H - release H2O when oxidised - important source

88
Q

Describe how the structure of a phospholipid is related to its properties

A

Polar (hydrophobic tail, -philic head) - form a bilayer
Phosphate ‘heads’ - help to hold at surface of cell surface membrane
Structure allows them to form glycolipids - combine w/ carbs within the cell surface membrane

89
Q

What term describes a fatty acid with more than one C double bond?

A

Polyunsaturated

90
Q

What term describes a fatty acid with one C double bond?

A

Monounsaturated

91
Q

What term describes a fatty acid with no C double bonds?

A

Saturated

92
Q

Describe and explain what having C double bonds does to the melting point of a fatty acid

A

Lowers it - creates a kink which means chains can’t pack as closely together

93
Q

‘A single polypeptide chain’ describes what structure of a protein?

A

Primary

94
Q

Describe the primary structure of a protein

A

Many amino acid monomers which have reacted to form a single polypeptide chain

95
Q

Describe the secondary structure of a protein

A

Can either form an alpha helix (twist into helix) or beta pleated sheet (‘fold’)

96
Q

Describe the tertiary structure of a protein

A

Different parts of the polypeptide chain are attracted to each other, causing the secondary structure to fold and twist into more complex and specific 3D shapes.

97
Q

What are the three main types of bond found in the tertiary structure of a polypeptide?

A

Disulfide bridges
Ionic bonds
Hydrogen bonds

98
Q

What is the strongest type of bond found in the tertiary structure of a protein?

A

Disulfide bridges

99
Q

Describe the quaternary structure of a protein

A

Multiple polypeptide chains combine to form one larger, more complex 3D molecule
Not all proteins have this

100
Q

Which type of inhibitor binds to the allosteric site of an enzyme?

A

Non-competitive

101
Q

Which type of inhibitor binds to the active site of an enzyme?

A

Competitive

102
Q

Describe the induced fit model of enzyme action

A

The active site has a certain general shape, which alters in the presence of a substrate to fit around the substrate
The active site is complementary to an extent

103
Q

Describe the lock and key model of enzyme action

A

The active site is a specific shape. It is also rigid, and so the substrate must be the exact complementary shape.

104
Q

Describe the structure of proteins (5) PPQ

A
  1. Polymer of amino acids;
  2. Joined by peptide bonds;
  3. Formed by condensation;
  4. Primary structure is order of amino acids;
  5. Secondary structure is folding of polypeptide chain due to hydrogen bonding;
  6. Tertiary structure is 3-D folding due to hydrogen bonding and ionic/disulfide bonds;
  7. Quaternary structure is two or more polypeptide chains;

AQA A Level Biology (11 decks)

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