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A Level Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

What is a monomer?

A

Small basic molecular units

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2
Q

What is an example of a monomer?

A

Monosaccharides, Amino acids and Nucleotides

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3
Q

What is a polymer?

A

Large complex molecules composed of long chains of monomers joined together

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4
Q

What is an example of a polymer?

A

Carbohydrates, Proteins and Nucleic acids

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5
Q

What type of sugar is glucose?

A

Hexose

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6
Q

How many types of glucose are there?

A

2

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7
Q

What are the names of the types of glucose?

A

Alpha-glucose and Beta-glucose

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8
Q

What is a condensation reaction?

A

When 2 molecules join together with the formation of a new chemical bond, releasing a water molecule

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9
Q

Condensation reactions join which molecules?

A

Monosaccharides

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10
Q

What type of chemical bond forms between 2 monosaccharides?

A

Glycosidic Bonds

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11
Q

What is formed when 2 monosaccharides join together?

A

Disaccharides

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12
Q

Which 2 molecules make maltose?

A

Alpha glucose and Alpha Glucose

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13
Q

What is sucrose made from?

A

Alpha glucose and Fructose

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14
Q

Which 2 molecules make lactose?

A

Alpha glucose and Galactose

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15
Q

What is a hydrolysis reaction?

A

When 2 molecules are broken apart using a water molecule

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16
Q

What is broken down by hydrolysis to form monosaccharides?

A

Carbohydrates

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17
Q

What is the test for reducing sugars?

A

Add Benedict’s reagent to a sample and heat.If the test is positive, it will turn brick red, if it’s negative, it’ll stay blue

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18
Q

What is test for non reducing sugars?

A

Add dilute HCL to the sample and heat. Neutralise solution using sodium hydrogencarbonate. Then add Benedict’s reagent. If present brick-red.

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19
Q

What is a polysaccharide?

A

Formed when more than 2 monosaccharides are joined together by condensation reactions

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20
Q

What is the function of starch?

A

Used as an energy store

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21
Q

What makes up starch?

A

Amylose and Amylopectin

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22
Q

What is the structure of amylose?

A

Long, unbranched chain of alpha-glucose; has a coiled structure, making it compact and good for storage

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23
Q

What is the structure of amylopectin?

A

Long, branched chain of alpha-glucose, side branches allow the enzymes that break the molecule down to access the bonds easily, meaning glucose can be released quickly

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24
Q

What are the features of starch?

A

Insoluble in water, doesn’t affect water potential so water doesn’t enter the cell, which would make them swell

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25
Q

How do you test for starch?

A

Add iodine
If present turns from brown/orange to dark blue/black

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26
Q

What do animals store glucose as?

A

Glycogen

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27
Q

What structure is glycogen similar to?

A

Amylopectin, except it has more side branches, meaning stored glucose can released quickly, very compact

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28
Q

What is a major component of cell walls in plants?

A

Cellulose

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29
Q

What is the structure of cellulose?

A

Long unbranched chains of beta glucose

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30
Q

What is formed when beta glucose molecules bond?

A

Straight cellulose chains

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31
Q

What are the advantages of cellulose chains?

A

They’re linked together by hydrogen bonds to form microfibrils, providing structural support for cells

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32
Q

What is the structure of a triglyceride?

A

3 Fatty Acid Chains and 1 Glycerol

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33
Q

What are triglyceride tails made of?

A

Hydrocarbons

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34
Q

Are the triglyceride tails hydrophobic or hydrophilic?

A

Hydrophobic

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35
Q

Are lipids soluble or insoluble in water?

A

Insoluble

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36
Q

Triglycerides are formed by what type of reaction?

A

Condensation

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37
Q

What is a saturated fatty acid?

A

A fatty acid with no double bonds between the carbon atoms

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38
Q

What is an unsaturated fatty acid?

A

A fatty acid with at least one double bond between the carbon atoms

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39
Q

What’s the difference between a triglyceride and a phospholipid?

A

A triglyceride has 3 fatty acid tails. A phospholipid has 2 fatty acid tails and a phosphate group attached to the glycerol

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40
Q

Is the phosphate group hydrophilic or hydrophobic?

A

Hydrophilic

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41
Q

What are triglycerides used as?

A

Energy Storage in molecules

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42
Q

What do the hydrocarbon tails of triglycerides contain which is useful for us?

A

Chemical energy

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43
Q

Lipids contain how much more energy than carbohydrates?

A

Double

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44
Q

Are triglycerides insoluble or soluble?

A

Insoluble, they don’t affect the water potential

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45
Q

How do triglycerides act in cells?

A

They clump together as insoluble droplets, the tails face inwards and the heads face out

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46
Q

What do phospholipids do?

A

Make up the bilayer of cell membranes, meaning they control what enters and leaves the cell

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47
Q

What do phospholipids form?

A

A double layer, heads outside and tails inside, forming a barrier against water soluble substances

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48
Q

How do you do the emulsion test?

A

Add ethanol then shake the test substance with ethanol for a minute so it dissolves and pour the solution in water. Any lipid will show as a milky emulsion

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49
Q

What are the monomers of protein?

A

Amino acids

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50
Q

How is a polypeptide formed?

A

Formed by more than 2 amino acids join together

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51
Q

How are proteins made up?

A

Made up of one or more polypeptides

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52
Q

How many amino acids do all living things have?

A

20

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53
Q

What is the name of the bonds formed between 2 amino acids?

A

Peptide Bonds

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54
Q

Protein Structure: Primary Structure

A

Sequence of amino acids in the polypeptide chain

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55
Q

Protein Structure: Secondary Structure

A

Hydrogen bonds form between the amino acids in the chain, making it coil into an alpha helix or a beta pleated sheet

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56
Q

Protein Structure: Tertiary Structure

A

The coiled or folded chain is coiled further, more hydrogen and ionic bonds form.

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57
Q

When do disulfide bridges form?

A

Whenever 2 molecules of cysteine come close together

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58
Q

Protein Structure: Quaternary Structure

A

Made of several different polypeptide chains, held together by different bonds

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59
Q

How do you do the biuret test? (Test for proteins)

A

Add biuret solution if present turns lilac/purple

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60
Q

What are enzymes?

A

Biological Catalysts

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61
Q

What do enzymes do?

A

They catalyse metabolic reactions at both a cellular level and across the whole organism

62
Q

What can enzymes affect?

A

Structures in an organism (such as collagen production) and functions (such as respiration)

63
Q

What makes each enzyme different?

A

Their active site, which has a specific shape

64
Q

How are enzymes specific?

A

Their tertiary structure

65
Q

Do enzymes slow down or speed up a reaction?

A

Speed up

66
Q

How do enzymes speed up a reaction?

A

By lowering the activation energy

67
Q

What is the lock and key model?

A

Where the substrate fits exactly into the enzyme

68
Q

What is the induced fit model?

A

Where the substrate fits into the enzyme, then the enzyme changes it’s shape slightly to lock the substrate even tighter to itself

69
Q

What is it called when an enzyme and a substrate are joined together?

A

Enzyme-Substrate Complex

70
Q

What happens if the tertiary structure of an enzyme is altered?

A

The shape of the active site will change, meaning the substrate won’t be able to fit, meaning the enzyme is unable to carry out its function of catalyzing the substrate. It becomes denatured.

71
Q

What determines the primary structure of a protein?

A

A gene

72
Q

Why does temperature have such a large impact on enzyme activity?

A

Because each enzyme has its own optimum temperature, anything before that will decrease the rate of reaction and anything above that will result in bonds breaking and the enzyme becoming denatured

73
Q

How does pH affect enzyme activity?

A

All enzymes have an optimum pH (usually 7), Above and below the optimum temperature messes up the ionic and hydrogen bonds that hold the tertiary structure in place, denaturing the enzymes

74
Q

How does enzyme concentration affect enzyme activity?

A

The more enzyme molecules there are, the more likely there are to be collisions between enzyme and substrate molecules, forming more enzyme-substrate complexes

75
Q

How does substrate concentration affect enzyme activity?

A

The more substrate molecules there are, the more likely there are to be collisions between enzyme and substrate molecules, forming more enzyme-substrate complexes

76
Q

How can enzyme activity be inhibited by competitive inhibitors?

A

Competitive inhibitor molecules have a similar shape to substrate molecules, so will compete with the substrate to bind with the enzyme and block the active site. The higher the competitive inhibitor concentration, the more active sites are filled and less enzyme-substrate complexes are formed

77
Q

How can enzyme activity be inhibited by non competitive inhibitors?

A

Non-competitive inhibitors bind to the enzyme away from its active site, causing the active site to change shape so substrate molecules can’t bind to the enzyme

78
Q

What is the structure of Alpha glucose?

A

OH group attached to the first carbon atom in alpha glucose is located on the same side as the –CH2OH group

79
Q

What is the structure of Beta glucose?

A

OH group attached to the first carbon atom of in beta glucose is located on the opposite side from the –CH2OH group

80
Q

What is the basic structure of a fatty acid?

A

Carboxyl group -COOH
Variable R group = hydrocarbon tail

81
Q

What is the structure of amino acids?

A

Carboxyl group (-COOH), amine group (-NH2), R group (variable region) and hydrogen.

82
Q

What are monosaccharides and disaccharides known as?

A

Sugars

83
Q

What elements do all carbohydrates contain?

A

Carbon, Hydrogen and Oxygen

84
Q

What is an isomer?

A

Two or more molecules that have the same molecular formula but a different arrangement of atoms.

85
Q

What is the difference in the structure of alpha and beta glucose?

A

Alpha glucose order of OH - down down up down
Beta glucose order of OH - up down up down

86
Q

What does the R group of the amino acid mean?

A

R group is the variable region that determines the amino acid.

87
Q

How does increasing the temperature increase the rate of an enzyme-controlled reaction?

A

More heat means more kinetic energy = molecule move faster = substrate molecules more likely to collide with enzyme’s active site .
Energy of collisions also increases = collisions more likely to result in a reaction.

88
Q

What happens if the temperature is too high in an enzyme-controlled reaction?

A

The reaction will stop.
Rise in temperature makes enzymes vibrate more = at a too high temperature, vibrations can break some of the bonds that hold the enzymes shape = active site of the enzyme changes shape = substrate no longer fits = enzyme is denatured.

89
Q

What does DNA stand for?

A

DeoxyriboNucleic Acid

90
Q

What’s the function of DNA?

A

Stores genetic information

91
Q

What does RNA stand for?

A

RiboNuceleic Acid

92
Q

What’s the function of RNA?

A

Transfer genetic information from the DNA to the ribosomes

93
Q

What’s a nucleotide made up of?

A

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

94
Q

What are nucleotides?

A

Monomers that make up DNA and RNA

95
Q

What’s the name of the pentose sugar in DNA?

A

Deoxyribose

96
Q

What are the 4 bases in DNA?

A

Adenine, Thymine, Cytosine and Guanine

97
Q

What’s the name of the pentose sugar in RNA?

A

Ribose

98
Q

What’s the difference between the bases in DNA and RNA?

A

In RNA, Thymine is replaced with Uracil

99
Q

What is a polynucleotide?

A

A polymer of nucleotides

100
Q

How do the nucleotides join together?

A

A condensation reaction between the phosphate group of one nucleotide and the pentose sugar of the other

101
Q

What type of bond forms when a condensation reaction between the phosphate group of one nucleotide and the pentose sugar of the other occur?

A

Phosohodiester Bonds

102
Q

What is the chain of pentose sugar and phosphates known as?

A

Sugar-Phosphate Backbone

103
Q

What structure does DNA have?

A

Double Helix

104
Q

How do the 2 strands in DNA join together?

A

Hydrogen bonding between the base pairs

105
Q

What is complimentary base pairing?

A

Where a base can only join with a particular base

106
Q

What base does adenine always pair with?

A

Thymine

107
Q

What base does guanine always pair with?

A

Cytosine

108
Q

How many hydrogen bonds form between adenine and thymine?

A

2

109
Q

How many hydrogen bonds form between cytosine and guanine?

A

3

110
Q

What is Semi-Conservative replication and what happens during it?

A

DNA helicase breaks the hydrogen bonds between the 2 complimentary bases on the polynucleotide strands, making the DNA unravel to form 2 single strands. Each original strand acts as a template for the new strand to be formed. Due to complimentary base pairing, free nucleotides are attracted to their complimentary exposed bases.Condensation reactions join the free nucleotides of the strands. This is catalysed by DNA polymerase. Hydrogen bonds form between the bases of the original and the new strands. Each new DNA molecule contains a new strand and an old strand.

111
Q

What is a metabolite?

A

A substance involved in a metabolic reaction

112
Q

What is a metabolic reaction?

A

A chemical reaction that happens in a living organism to keep it alive

113
Q

What is water?

A

A metabolite

114
Q

How does water help with temperature control?

A

It has a high latent heat of vaporization and a high specific heat capacity

115
Q

Are water molecules cohesive?

A

Yes, they stick together very easily

116
Q

Is water a polar molecule?

A

Yes, it has a slight delta negative charge on the side with oxygen, and a slight delta positive charge on the side with the hydrogen

117
Q

What attraction is present between water molecules?

A

Hydrogen Bonding

118
Q

Why does water have a high latent heat of vaporisation?

A

Because it takes a lot of heat/energy to break the hydrogen bonding between molecules

119
Q

What can hydrogen bonds do?

A

Absorb a lot of energy

120
Q

Why does water have a high specific heat capacity?

A

Because it takes a lot of energy to heat it up

121
Q

How is water’s high specific heat capacity useful?

A

The water inside organisms remains at a stable temperature, helping them to maintain constant body temperature

122
Q

How is water a good solvent?

A

The partial charges will be attracted to the molecule, surrounding it completely, dissolving it

123
Q

What is cohesion?

A

The attraction between molecules of the same type

124
Q

What does strong cohesion help water to do? Why is it useful?

A

Helps water flow, it’s useful because it can transport substances

125
Q

What is ATP?

A

The immediate source of energy in a cell

126
Q

What is the structure of ATP?

A

The nucleotide base adenine
A ribose sugar
Three phosphate groups.

127
Q

What base is ATP made from?

A

Adenine

128
Q

What base is ATP made from?

A

Adenine

129
Q

Where is the energy in ATP stored?

A

High energy bonds between the phosphate groups

130
Q

What is ATP broken down into?

A

ADP and Phosphate

131
Q

What reaction breaks down ATP?

A

Hydrolysis

132
Q

What enzyme catalyses the breakdown of ATP?

A

ATP hydrolase

133
Q

What enzyme catalyses the resynthesis of ATP?

A

ATP synthase

134
Q

When does the resynthesis of ATP happen?

A

During respiration and photosynthesis

135
Q

What is an inorganic ion?

A

An ion which doesn’t contain carbon

136
Q

How many polypeptide chains is haemoglobin made up of?

A

4

137
Q

What ion does haemoglobin have in the centre of the polypeptide chains?

A

Iron

138
Q

What binds to the oxygen in haemoglobin?

A

The iron ions

139
Q

What ion determines pH?

A

Hydrogen ions

140
Q

Does a higher or lower concentration of hydrogen ions lower pH?

A

Higher

141
Q

What type of reaction is affected by pH?

A

Enzyme Controlled

142
Q

What do sodium ions do?

A

Help transport glucose and amino acids across membranes

143
Q

What 3 molecules contain phosphate groups?

A

DNA, RNA and ATP

144
Q

What do the phosphate groups in DNA and RNA do?

A

Allow nucleotides to join together to form polynucleotides

145
Q

What does antiparallel mean?

A

Running in opposite directions

146
Q

Each end of a DNA strand is slightly different in its structure, what are the 2 ends called.

A

3’ (3 prime) and 5’ 5(prime)

147
Q

What did Meselson and Stahl show?

A

DNA is replicated using semi-conservative method

148
Q

Which two isotopes did Meselsons and Stahls experiment use?

A

Heavy nitrogen (15N)
Light nitrogen (14N)

149
Q

Outline Meselson and Stahl’s experiment.

A

1) Two samples of bacteria were grown - one in a nutrient broth containing light nitrogen and one in broth of heavy nitrogen. As bac. reproduce, they took up nitrogen from broth, N became part of bac. DNA.
2) Sample of DNA taken from each batch of bac. spun in centrifuge. DNA from heavy nitrogen bac. settled lower down centrifuge tube, because its heavier.
3) Bac. grown in heavy nitrogen broth taken out and put in broth containing only 14N. Bac. left for one round of DNA replication, another DNA sample taken out and spun in centrifuge.
4) If replication conservative, 15N would still be together, would settle at bottom and 14N would settle at the top.
5) If replication semi-conservative, new bac. DNA molecules would contain one strand of old DNA containing 15N, and one strand of new DNA containing 14N. So DNA would settle between where light nitrogen DNA settled out and where heavy nitrogen DNA settled out.
6) DNA settled out in middle, showing that DNA molecules contained a mixture of heavy and light nitrogen. Bac. DNA had replicated semi-conservatively in the light nitrogen.

150
Q

What does ATP stand for?

A

Adenosine triphosphate

A Level Biology (7 decks)

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