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Flashcards in Biological Molecules Deck (122):
1

What is evidence for evolution?

Information that supports the theory of evolution

2

What is the theory of evolution?

That all organisms on earth are descended from one or a few common ancestors and that they have changed and diversified over time

3

What are polymers?

Large, complex molecules composed of long chains of monomers joined together

4

What are monomers?

Small, simple molecular units that can form a polymer

5

Name some examples of monomers

Amino acids
Nucleotides
Monosaccharides

6

What reaction occurs when polymers are formed from their monomers?

Condensation reaction

7

What happens during a condensation reaction between two monomers to make a polymer?

A condensation reaction forms a chemical bond between monomers, releasing a water (H2O) molecule

8

What reaction can break down polymers into monomers?

Hydrolysis reaction

9

What happens during a hydrolysis reaction when a polymer is broken down into monomers?

The hydrolysis reaction breaks the chemical bond between the monomers, using a water molecule

10

What is sugar a general term for?

Monosaccharides and disaccharides

11

What elements do all carbohydrates contain?

Carbon, hydrogen and oxygen

12

What are the monomers that carbohydrates are made from called?

Monosaccharides

13

Give some examples of monosaccharides

Glucose
Fructose
Galactose

14

What is meant by glucose being a hexose sugar?

It is a monosaccharide with 6 carbon atoms in each molecule

15

Name the two types of glucose

Alpha and beta

16

What is a isomer?

Molecules that have the same molecular formula as each other but with the atoms connected a different way

17

When is a disaccharide formed?

When two monosaccharides join together

18

Monosaccharides are joined together by what kind of reaction?

A condensation reaction

19

What kind of bond is between two monosaccharides when it forms a disaccharide?

Glycosidic

20

Glucose + glucose = what disaccharide?

Maltose

21

Glucose + fructose = what disaccharide?

Sucrose

22

Glucose + galactose = what disaccharide?

Lactose

23

When testing for a reducing sugar, if the sample stays blue once the benedict reagent is added, is it a positive or negative result?

Negative

24

What colour will the sample change when the benedict's reagent is added if the test for reducing sugar is positive?

A coloured precipitate (green, yellow, orange, brick red)

25

Name three examples of biological molecules

Carbohydrates
Amino acids
Lipids

26

What type of biological molecule are polysaccharides

Carbohydrates

27

What are the monomers of polysaccharides

Monosaccharides

28

How many monosaccharides must join together to form a polysaccharide

More than two

29

What reaction joins monosaccharides together to form a polysaccharide

A condensation reaction

30

What type of glucose molecules are joined together to form amylose

Alpha

31

What bonds join alpha glucose molecules together to form amylose

Glycosidic

32

What type of reaction can break polysaccharides down into their constituent monosaccharides

A hydrolysis reaction

33

What is the name of the molecule that cells get energy from?

Glucose

34

What do plants store excess glucose as?

Starch

35

When a plant needs more glucose for energy, what does it do?

Break down starch to release the glucose

36

Starch is a mixture of what two polysaccharides of alpha glucose?

Amylose and amylopectin

37

Describe the structure of amylose

It's a long, unbranched chain of alpha glucose

38

What do the angles of the glycosidic bonds in amylose do to its structure

Make it coiled, so it's compact

39

Describe the structure of amylopectin

It is a long, branched chain of alpha glucose

40

What do its branches allow enzymes to do?

To break the glycosidic bonds easily, meaning the glucose is released quickly

41

Is starch soluble or insoluble in water

Insoluble

42

Why does starch being insoluble make it good for storage?

Because it means it doesn't effect water potent ion and water doesn't move into the cells by osmosis, meaning that the cells don't swell

43

What do animals store excess glucose as?

Glycogen

44

What is glycogen a polysaccharide of?

Alpha glucose

45

Why does glycogen's structure make it good for storage?

It has a lot of branches coming off it meaning stored glucose can be released easily.

46

What is cellulose a polysaccharide of?

Beta glucose

47

Describe the structure of cellulose

It is long and unbranched

48

What happens when beta glucose molecules bond?

They form straight cellulose chains

49

What are the cellulose chains linked together by?

Hydrogen bonds

50

Which polysaccharide is the major component of plant cell walls?

Cellulose

51

What is the main energy storage material in plants

Starch

52

What is the main energy storage material in animals

Glycogen

53

If you want to test for the presence of starch in a sample, what test do you use?

The iodine test

54

What are lipids commonly known as?

Fats or oils

55

How are lipids different from proteins and carbohydrates?

Because they're not polymers formed from long chains of monomers.

56

What do all lipids contain

Hydrocarbons

57

What are hydrocarbons?

Molecules that contain only hydrogen and carbon atoms

58

What are the two types of lipids you must know?

Phospholipids and triglycerides

59

What are the components of triglycerides?

A molecule of glycerol and three fatty acids

60

What are the long tails made of on a fatty acid

Hydrocarbons

61

Are the fatty acid tails hydrophilic or hydrophobic?

Hydrophobic

62

What effect does the fatty acid tails being hydrophobic have with water?

It makes lipids insoluble

63

What varies in the structure of different fatty acids

Hydrocarbon tail

64

Name the two kinds of fatty acid

Saturated and unsaturated

65

Explain the difference between a saturated fatty acid and an unsaturated fatty acid

A saturated fatty acid doesn't have any double bonds between their carbons, unsaturated fatty acids do

66

What type of reaction forms triglycerides

Condensation

67

What type of bond is found in a triglyceride

Ester bond

68

What are the lipids called in cell membranes

Phospholipids

69

What's the difference in the structure between triglycerides and phospholipids

One of the fatty acid molecules that would be in a triglyceride is replaced by a phosphate group in phospholipids

70

Is the phosphate group in phospholipids hydrophilic or hydrophobic

Hydrophilic

71

Are the two fatty acid tails in phospholipids hydrophobic or hydrophilic

Hydrophobic

72

What is the main use of triglycerides

For storing energy

73

Why are triglycerides good for energy storage?

Because their long hydrocarbon tails of fatty acids contain lots of chemical energy

74

Because of their tails, how much more energy per gram do triglycerides contain than carbohydrates

Twice as much

75

Why does triglycerides being insoluble make them good as a energy storing molecule?

Because they don't affect theatre potential of the cell, meaning water doesn't enter the cell by osmosis

76

Because the fatty acid tails on triglycerides are insoluble what does this cause them to do together?

Bundle in a circle with the hydrophilic heads facing outwards and the hydrophobic tails facing inwards

77

What do phospholipids make up?

The bilayer of the cell membrane

78

What do cell membranes do

Control what does in and out a cell

79

The centre of the bilayer in a cell membrane is insoluble, what does this mean for water soluble substances passing through the membrane

That they can't easily pass through it

80

What test would you have to carry out in order to see if lipids in a sample were present

The ethanol/emulsion test

81

What does a positive result look like for the emulsion/ethanol test?

A milky white emulsion is present

82

Give two reasons why triglycerides are used as energy storage molecules

- they contain lots of chemical energy
- they're insoluble in water

83

What are the monomers of proteins?

Amino acids

84

What is formed when two amino acids join together

A dipeptide

85

What is formed when more than two amino acids join together?

Polypeptide

86

One or more polypeptide joins together to make up what?

A protein

87

What are the components in an amino acid structure?

A carboxyl group, an amino group, an R group, and a central C and H

88

How many amino acids are there?

20

89

What kind of reaction are amino acids joined up by to form dipeptides and polypeptides

Condensation reaction

90

What reaction breaks down dipeptides and polypeptides to into amino acids?

Hydrolysis

91

Name the four levels of a proteins structure

Primary
Secondary
Tertiary
Quarternary

92

Describe the primary structure of proteins

The sequence of amino acids in a polypeptide chain

93

Describe the secondary structure of a protein

Hydrogen bonds form between the amino acids
This makes them coil into an alpha helix or fold into beta pleated sheets

94

Describe the tertiary structure of a protein

The coiled/folded chains of amino acids is often coiled/folded further
More bonds form: hydrogen bonds, ionic bonds and disulphide bridges

95

Describe the quaternary structure of a protein

The way polypeptide chains with several different polypeptides are assembled together

96

How does haemoglobin's shape determine its function?

It is a compact and soluble protein which makes it easy to transport
Makes it good for carrying oxygen around the body

97

Name the 3 bonds that may be for,ed between the amino acids in a polypeptide chain to form the tertiary structure of a protein

Hydrogen bonds
Ionic bonds
Disulphide bridges

98

What test would you carry out if you needed to find out if a substance contained protein?

The biuret test

99

What are the two stages of the biuret test?

1. The test solution needs to be alkaline so you add a few drops of sodium hydroxide solution
2. Then you add some copper sulfate solution

100

What colour will the solution turn if the biuret test comes up positive for protein

Purple

101

What colour will the solution turn if the biuret test comes up negative for protein

Blue

102

What do enzymes work as

Biological catalysts

103

What is an example of an enzyme catalysing a reaction at a cellular level

Respiration

104

What is an example of an enzyme catalysing a reaction for the organism as a whole

Digestion

105

What term is used to describe an enzyme that acts outside of cells?

Extracellular

106

What term is used to describe an enzyme that acts within cells?

Intracellular

107

What binds to the active site of a enzyme

A substrate

108

When a substrate fits into the enzyme's active site what does it form?

An enzyme-substrate complex

109

What does the enzyme-substrate complex do?

Lower the activation energy for the chemical reaction to start

110

What is activation energy?

The certain amount of energy that needs to be supplied to the chemical before the reactions will start

111

What do enzymes do to the activation energy

They lower the amount of activation energy that is needed, speeding up the reaction

112

What is the lock and key model?

The model which says a substrate fits into the active site of an enzyme like a key fits a lock
Or
That the substrate has a complementary shape to the active site of the enzyme

113

What's the induced fit model

That the enzymes active site has to slightly change shape for the substrate to completely fit, therefore the substrate has to make the active site change shape

114

Enzymes are very specific therefore the usually only catalyse how many reactions?

1

115

Maltase only breaks down what?

Maltose

116

Sucrase only breaks down what?

Sucrose

117

Why do most enzymes only catalyse one reaction?

Because only one complementary substrate will fit into the active site

118

What is the active site's shape determined by?

The enzymes tertiary structure

119

What is an enzymes tertiary structure determined by?

It's primary structure

120

If the tertiary structure of a protein is altered in any way, what will happen to the shape of the active site and what does this mean?

It will change meaning the substrate won't fit into the active site and the enzyme won't be able to carry out its function anymore

121

What may alter the tertiary structure of an enzyme?

Changes in pH or temperature

122

If a mutation occurs in the gene which determines the primary structure of a protein what would happen to the tertiary structure in the enzyme

It would change