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Biological Molecules Flashcards

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AP® Biology flashcards
1
Q

What are biological molecules?

A

Groups of chemicals found in living organisms

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2
Q

What are the 3 most common bonds in biology?

A

Covalent bonding
Ionic bonding
Hydrogen bonding

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3
Q

What is a covalent bond?

A

Atoms share a pair of electrons in their outer shell forming molecules

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4
Q

What is ionic bonding?

A

Electrostatic attraction between two ions

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5
Q

What is hydrogen bonding?

A

Weak electrostatic bonds between a negative region of a polarised molecule and positively charged region

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6
Q

What is a monomer?

A

A small molecule that combines with other small molecules to form a larger molecule called a polymer

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7
Q

What is a polymer?

A

A large molecule made up of repeating smaller molecules called monomers

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8
Q

What is the process of joining monomers to make a polymer called?

A

Polymerisation

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9
Q

What element are monomers usually based on?

A

Carbon

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10
Q

What is condensation?

A

A chemical process where two molecules combine to form a more complex molecule often creating water

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11
Q

What is hydrolysis?

A

The breaking down of large molecules into smaller molecules by the addition of water

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12
Q

What is metabolism?

A

The chemical process that take place in living organisms

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13
Q

What is a monosaccharide?

A

A sweet tasting carbohydrate

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14
Q

What is the formula for monosaccharides?

A

(CH20)n where n iOS any number from 3 to 7

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15
Q

List the 3 monosaccharides

A

Glucose (a and b)
Fructose
Galactose

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16
Q

What is the difference between alpha glucose and beta glucose?

A

Aloha has a hydrogen atom next to oxygen

Beta has OH next to the oxygen atom

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17
Q

What is a reducing sugar?

A

A monosaccharide (and some disaccharides such as maltose) that can reduce another chemical

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18
Q

What is the test for a reducing sugar?

A

Benedicts Test

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19
Q

What is Benedicts reagent?

A

An alkaline solution of copper (II)sulphate

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20
Q

How do you carry out the Benedicts test?

A

Add Benedicts reagent to a substance and heat

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21
Q

What are the results for the Benedicts test?

A

Brick red signals high amounts of reducing sugars

remains blue: no reducing sugars are present

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22
Q

What is a disaccharide?

A

A pair of monosaccharides chemically bonded by a glycosidic bond

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23
Q

What is a glycosidic bond?

A

The carbon-oxygen-carbon bond between two monosaccharide molecules

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24
Q

Alpha glucose + Alpha glucose =

A

Maltose

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25
Q

Maltose is broken down by

A

Maltase

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26
Q

Alpha glucose + fructose =

A

Sucrose

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27
Q

Sucrose is broken down by

A

Sucrase

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28
Q

Alpha glucose + galactose =

A

Lactose

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29
Q

Lactose is broken down by

A

Lactase

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30
Q

List three disaccharides

A

Maltose
Sucrose
Lactose

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31
Q

What is the test for non-reducing sugars?

A

Hydrolyse the reducing sugar into its monosaccharides

Add Benedicts reagent and heat

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32
Q

What is a polysaccharide?

A

A polymer chain of many monosaccharide molecules joined by glycosidic bonds

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33
Q

What are the common features of a polysaccharide?

A

Large molecules
Insoluble
Good for storage
Can be hydrolysed into disaccharides and monosaccharides

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34
Q

What is the test for starch?

A

Add potassium iodide solution (iodine solution)

Shake or stir

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35
Q

What are the results for the test for starch?

A

Blue-Black starch is present

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36
Q

What is starch?

A

A polysaccharide found in plants in the form of small fm grains

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37
Q

What is starch made up from?

A

200-100,000 alpha glucose monosaccharides

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38
Q

What is amylose?

A

An unbranched coiled chain of starch

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39
Q

What is amylopectin?

A

A long branched chain of starch

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40
Q

What is the main role of starch?

A

Energy storage

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41
Q

How is starch suited for its function?

A

It’s insoluble and doesn’t affect water potential

Large so it doesn’t diffuse out of cells

Compact so it can be stored in small space

Produces a glucose when hydrolysis E for easy transportation and respiration

Branched can be catalysed rapidly

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42
Q

What is glycogen?

A

A polysaccharide found in animal cells stored as small granules

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43
Q

What is the function of glycogen?

A

Major carbohydrate storage for animals (particularly in the liver)

44
Q

How does the structure of glycogen make it suitable for its job?

A

Insoluble doesn’t affect water potential

Insoluble so doesn’t diffuse out of cells

Compact can be stored in small space

More branches broken down rapidly into glucose for respiration

45
Q

Why is rapid glucose production more important to animals than plants?

A

It is used in respiration

Animals have a higher metabolic rate

Therefore a higher respiratory rate as they are more active

46
Q

What is cellulose made from?

A

Alpha glucose monosaccharides

47
Q

What is cellulose?

A

A polysaccharide found in fibre like strands

48
Q

What is cellulose made from?

A

Beta glucose monosaccharides

49
Q

Describe the structure of cellulose

A

Straight unbranched chains running parallel to one another allowing hydrogen bonds between chains

Grouped together to form microfibres which group together to form fibres

50
Q

What is the function of cellulose?

A

Provides rigidity to plant cell walls

Prevents cells bursting from oso modus by exerting inward pressure

Keep non-woody parts of plants turgid

51
Q

How is cellulose adapted to its function?

A

Hydrogen bonds forming cross links between chains gives collective strength

Microfibres turn into fibres providing more strength

52
Q

What is a lipid?

A

Insoluble fats that provide energy, insulation and protections for organisms

53
Q

What properties do lipids have?

A

Carbon hydrogen oxygen based (in smaller amounts than carbohydrates)

Insoluble in water

Soluble in organic solvents (eg alcohol and acetone)

54
Q

What are the main lipid groups?

A

Triglycerides and phospholipid

55
Q

What is the role of lipids in cell membranes (cell-surface and around organelles?)

A

Phospholipids contribute to flexibility and transfer of lipid so liable substances

56
Q

What are the roles of lipids?

A

Energy source

Waterproofing

Insulation

Protection

57
Q

How do lipids work as a source of energy?

A

Provide water and more than twice as much energy than carbohydrates when oxidised

58
Q

How do lipids work as waterproofing?

A

Insoluble in water

Plants and insects have waxy lipid cuticles that conserve water

Mammals produce an oily secretion from sebaceous glands in the skin

59
Q

How do lipids provide insulation?

A

Fats are slow conductors of heat and help retain body heat when stored beneath the surface of the body

Act as electrical insulators as the myelin sheath in nerve cells

60
Q

How do lipids act as protection?

A

Fat is stored around delicate organs such as the kidney and heart

61
Q

What are the differences between fats and oils?

A

Fats : saturated fatty acids, solid at room temperature (10-20C)

Oils: unsaturated fatty acids, liquid at room temperature (10-20C)

62
Q

What is a triglyceride?

A

Glycerol and three fatty acids

63
Q

What is an ester bond?

A

The bond that forms between H and HO in glycerol and fatty acids

64
Q

What causes different properties in fats and oils?

A

The combinations and variations of fatty acids

65
Q

How many fatty acids are there?

A

Over 70

66
Q

What structure do all fatty acids have?

A

A carboxyl group with a hydrocarbon chain

67
Q

What is a saturated fatty acid?

A

A hydrocarbon chain with no carbon-carbon double bonds

68
Q

What is a monounsaturated fatty acid?

A

A hydrocarbon chain with one carbon-carbon double bond

69
Q

What is a polyunsaturated fatty acid?

A

A hydrocarbon chain with more than one carbon-carbon double bond

70
Q

Why are triglycerides a good energy source?

A

High ratio of energy storing carbon-hydrogen bonds to carbon atoms

Low mass to energy ratio- more energy stored in small volume

Insoluble so no affect on water potential and osmosis in cells

Provide water when oxidised

71
Q

What are phospholipids?

A

Similar to a lipid it has fatty acid tails however has a phosphate molecule

72
Q

What is an important feature of phospholipids?

A

Polar molecule / solvable

Fatty acids are hyrophobic

Phosphate molecule is hydrophilic

73
Q

What does hydrophilic mean?

A

Interacts with water but not fat

74
Q

What does hydrophobic mean?

A

Interacts with fat but not water

75
Q

Which parts of the phospholipids are hydrophobic and which are hydrophilic?

A

Head - hydrophilic

Tail - hydrophobic

76
Q

How does phospholipids being bipolar relate to its function?

A

Forms a bilateral within cell surface membranes Forming a hydrophobic barrier between the inside and outside of a cell

Help hold the surface of the cell membrane

Allows formation of glycolipids important for cell recognition

77
Q

What is the test for lipids?

A

The emulsion test

78
Q

How do you carry out an emulsion test?

A

Add ethanol

Shake thoroughly to dissolve any lipids in the sample

79
Q

What are the results of an emulsion test?

A

Cloudy - lipid present

Clear - no lipid present

80
Q

What is a protein?

A

A very large molecule important in living organisms that differs greatly from organism to organism

81
Q

What is an amino acid?

A

A monomer unit that combines with other amino acids to form dipeptides and polypeptides

82
Q

How many amino acids are there?

A

About 100

20 of which naturally occur in proteins

83
Q

What is the structure of an amino acid?

A

An amine group
A carboxyl group
A hydrogen atom
A functional group

84
Q

What is a dipeptide?

A

Two amino acid monomers joined by a condensation reaction and a peptide bond

85
Q

What is a peptide bond?

A

A bond between a carbon and nitrogen atom involving the formation of water

86
Q

What is the primary structure of a protein?

A

A polypeptide chain formed by polymerisation

87
Q

What is polymerisation?

A

When many amino acids condense to form a polypeptide chain

88
Q

How is the primary structure of a protein formed?

A

The sequence of amino acids determined by DNA

89
Q

What is the importance of the primary structure of a protein?

A

It determines the final shape of a protein and hence its function

90
Q

A proteins function depends on its…

A

Shape

91
Q

What is the secondary structure of a protein?

A

Alpha helix

Beta pleated sheets

92
Q

How does the secondary structure of a protein form?

A

Hydrogen bonds form between H+ and O- in different amino acids

This causes the polypeptide to bend or coil

93
Q

What is the tertiary structure of a protein?

A

Further 3D structures develop due to more twisting and folding

94
Q

What bonds are found in the tertiary structure of proteins?

A

Disulphide bridges
Ionic bonds
Hydrogen bonds

95
Q

What causes the bonds to occur in specific places in a protein?

A

The primary structure / amino acid sequence

96
Q

Why is the 3D shape of a protein important?

A

It makes each protein distinctive

Allows it to interact with other molecules due to its shape

97
Q

What is the quaternary structure of proteins?

A

More than one polypeptide chain bonded together

98
Q

What may the quaternary structure of a protein have that no other structure has?

A

A prosthetic group (eg. Haem)

99
Q

What is the test for proteins?

A

Biuret test

100
Q

What is the biuret test?

A

Add biuret (copper sulphate solution) reagent to the sample

101
Q

What is the result of a biuret test?

A

Purple - Protein present

Blue - No protein present

102
Q

What are the two basic types of protein?

A

Globular

Fibrous

103
Q

What is a fibrous protein?

A

A protein with structural function

104
Q

What are the properties of fibrous proteins?

A

Long polypeptide chains that run parallel linked by cross-bridges

105
Q

Give an example of a fibrous protein

A

Collagen

Keratin

106
Q

What is a globular protein?

A

A protein carrying out metabolic functions

107
Q

Give an example of a globular protein?

A

Enzymes

Haemoglobin

as aqa biology (8 decks)

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