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Crypt A level Biology > Module 2: Biological Molecules > Flashcards

Module 2: Biological Molecules Flashcards

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1
Q

Name the 4 functions of carbohydrates

A

Energy source e.g. glucose in respiration
Energy store e.g. starch
Structural support e.g. cellulose
Forms part of larger molecules e.g. nucleic acids or glycoproteins

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2
Q

Elements in a carbohydrate

A

C, H and O

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3
Q

General formula of a carbohydrate

A

Cn(H20)n

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4
Q

What is the difference between mono-, di-, and polysaccharides?

A 
Mono- = single sugar unit (monomer)
Di- = 2 monomer units bonded 
Poly- = multiple units bonded in a long chain forming a molecule
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5
Q

Characteristics of monosaccharides

A 
Monomer carbohydrates 
3-6 carbon atoms
Soulble in water
Form crystals 
Sweet tasting and white
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6
Q

Triose

A

3 carbons
Glyceraldehyde
C3H6O3

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7
Q

Pentose

A

5 carbons
Ribose
C5H10O5

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8
Q

Hexose

A

6 carbons
Glucose
C6h1206

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9
Q

Difference between alpha and beta glucose

A

Alpha has the hydroxyl group on the bottom on carbon , whereas beta has the hydroxyl group on the top of carbon 1

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10
Q

Define condenstaion reaction

A

Forming a larger molecule from a smaller one, by removing a molecule of water in order to form a new bond

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11
Q

Define hydrolysis

A

Forming a smaller molecule from a larger molecule, through the addition of a water molceule, hence breaking a bond.

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12
Q

What bond is formed and broken in condenstion and hydrolysis of a carbohydrate?

A

Glycosidic bond

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13
Q

Rules when drawing the formation of a glycosidic bond for a carbohydrate

A

Cirlce the groups involved
Show water is released
Cirlce and label the bond formed (1,4-glycosidic bond)

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14
Q

Formation of maltose

A

2 alpha glucose

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15
Q

Formaton of lactose

A

Gluocse and beta galactose

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16
Q

Formation of sucrose

A

Alpha glucose and frutose

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17
Q

Describe starch

A

Plants only
Granules in chloroplasts, seeds and storage organs
Alpha glucose
Insoluble to prevent lowering of water potential which would cause lysis
Compact
Main energy store/source

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18
Q

Name the two types of starch

A

Amylose and amylopectin

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19
Q

Describe amylose

A

Unbranched helical structure
Compact as a result so takes up less space and more can be stored
Only 1,4-glycosidic bonds

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20
Q

Describe amylopectin

A

Branched
More free ends so faster glucose release is possible
Both 1,4- and 1,6- glyosidic bonds

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21
Q

Describe glycogen

A 
Animal cells and fungi 
Granules in muscle and liver cells 
Alpha glucose
Branched structure (more than amylpectin due to higher metabolic demands)
1,4- and 1,6- glycosidic bonds
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22
Q

Function of glycogen

A

Main energy source
Energy store
Compavt
Insoluble

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23
Q

Describe cellulose

A 
Plants only 
Microfibrels to macrofibrels to fibres
Beta glucose 
1,4-glycosidic bonds 
Every other monomer is inverted 180 degrees 
Unbranched 
H bonds cross link between chains
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24
Q

Function of cellulose

A 
Provides sructural support for the cell 
High tensile strength 
Fully permeable 
Rigidity in plants 
Lignin sometimes between fibres
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25
Q

Define the primary structure of a protein

A

The order and sequence of amino acids in the polypeptide chain.
Repsonsible fo the final 3D shape of the protein. Chainging one amino acid alters the final protein

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26
Q

Define the secondary structure of a protein

A

How the polypeptide chain starts to fold or the regular arrangement of the polypetide chains stabilised by hydrogen.

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27
Q

Neame two types of secondary protein structure

A

Alpha helix
Beta pleated sheets
Structure are held together by hydrogen bond

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28
Q

Define the tertiary structure of protein

A

How the secondary structures present in the polypeptide chain start to fold even further to produce a precise 3D shape

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29
Q

Which bonds are involved in the tertiary structure?

A

H bonds
Ionic bonds
Disulphide bridges
Hydrophobic interactions

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30
Q

Describe disulphde bridges

A

Forms between 2 cysteine amino acids

Can be broken by reducing agents

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31
Q

Describe ionic bonds

A

Form between R groups with opposite charges

Can be broken by pH changes

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32
Q

Describe hydrophobic interactions

A

Occurs between non-polar side chains (R groups)

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33
Q

Describe hydrogen bonds

A

Forms between strongly polar groups ( H with N, O and F)

Can be broken by high temperatures and pH

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34
Q

Define quaternary structure of a protein

A

Association of 2 or more polypeptide chains, held together by 4 types of bonding (same as tertiary)
Highly folded

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35
Q

What are globular proteins? Give and example

A

Quarternary structure, spherical shape made of 4 polypeptide chains (2 alpha and 2 beta held together by h bonds).
E.g. haemoglobin
Each polypeptide chain contains a haem group containing an iron ion.

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36
Q

What is a prostheitc group? Example

A

A group part of the protein structure but not composed of amino acids.
Hb iron ion

37
Q

What is heamoglobin also known as?

A

Conjugated protein

38
Q

Properties of heamoglobin

A

1 molecule of O2 can bind reversibly with the Fe in the haem group
Each molecule of haemoglobin carry 4 O2 molecules

39
Q

What are fibrous proteins? Give an example

A

Quarternary protein which has structural roles, forming regular and repetitive sequences
Ususally form fibres and are insoluble in water
E.g. collagen found in cartilage and keratin
Form long, parallel chains

40
Q

What elements make up lipids?

A

C, H and O

41
Q

What’s the difference between fat and oil?

A

Fats are solid at room temperature and include many staurated lipids.
Oils are liquid at room termperature and include many unsaturated lipids.

42
Q

Functions of lipids and examples

A

Energy store - in adipose tissue
Insulator - blubber in whales to reduce heat loss and electrical insulation of nerves
Biological memebranes - phospholipids and cholesterol
Protection - waxy lipid layer on leaves against dessication
Buoyancy - uropygial gland on tail of ducks provides water resistant oil to be lightweight
Steroid hormones - cholesterol
Meatbolic source of water - respired to release water

43
Q

Structure of a triglyceride

A

3 fatty acids

1 gylcerol

44
Q

How are the bonds in a triglyceride joined?

A

Ester bonds

45
Q

Process of esterification for triglycerides

A

3 H2O molecules released in a condensation reaction

46
Q

Why are triglycerides insoluble in water?

A

The glycerol molecule in hydrophobic

47
Q

What is a saturated fatty acid?

A

Single bonds between carbons so maximum umber of hydrogens attached

48
Q

What is an unsaturated fatty acid?

A

One or more double bonds between carbons. Fewer hydrogens can bond

49
Q

Structure of a fatty acid

A

Carboxyl group and hydrocarbon chain

50
Q

Difference between a mono-unsaturated and poly-unsatured fatty acid

A 
Mono- = single carbon carbon bonds
Poly- = 2 or more carbon carbon bonds
51
Q

Explan how C=C bonds change the shape of an unsaturated fatty acid

A

Cause the chain to kink/bend. Makes the lipid more fluid

52
Q

Structure and bonds in a phospholipid

A

Hydrophobic and hydrophilic regions
Elements C, H, O, P
2 fatty acids, glycerol and phosphate group
Phosphate forms an ester bond with glycerol

53
Q

Function of phospholipids

A

Structure of plasma membrane forming a partially permeable phospholipid bilayer

54
Q

What causes the membrane to become more fluid?

A

Higher proportion of unsaturated fatty acids

55
Q

Structure and bonds in cholesterol

A

Hydroxyl group at periphery
Hydrophobic and hydrophilic ends - hydroxyl is hydrophilic and hydrocarbon tail is hydrophobic
4 carbon based rings (hydrophobic)

56
Q

Function of cholesterol

A

In phospholipid bilayer to regulate fluidity of the membrane, providing a stable sturture and mechanical strength

57
Q

What is cholesterol also a type of?

A

Sterol
Formed in liver and intestine
Used to form steroid hormones :oestrogen and testosterone

58
Q

Name the 2 types of sugar

A

Reducing

Non-reducing

59
Q

How to test for reducing sugars?

A

Add benedicts reagent to the sample and heat in a water bath
Positive is brick red precipitate
Negative is same colour - blue
E.g. glucose

60
Q

How to test for non-reducing sugars?

A

Only if reducing sugar test is negative
Add HCl and heat in a water bath - breaks the glycosidic bonds.
Add NaHCO3 to neutralise
Add bendicts reagent and heat in a water bath
Positive is brick red precipitate
Negative remains blue

61
Q

How to test for starch?

A

Add iodine solution
Positive is blue-black
Negative is yellow/orange (remains the same)

62
Q

How to test for lipids?

A

Add ethanol to the sample and mix.
Pour liquid into water.
Positive is cloudy white emulsion
Negative is no emulsion

63
Q

How to test for proteins?

A

Add biuret reagent (contains sodium hydroxide and copper (II) sulfate)
Do not heat
Positive is lilac/purple
Negative is blue (remains the same)

64
Q

Function of calcium ions

A

Nerve impulse transmission

Muscle contraction

65
Q

Function of sodium ions

A

Nerve impulse transmission

Kidney function

66
Q

Function of potassium ions

A

Nerve impulse transmission

Stomatal opening

67
Q

Function of hydrogen ions

A

Catalysis of reactions

pH determination

68
Q

Function of ammonium ions

A

Production of nitrate ions by bacteria

69
Q

Function of nitrate ions

A

Nitrogen supply to plants for amino acid and protein production

70
Q

Function of hydrogen carbonate ions

A

Maintenance of blood pH

71
Q

Function of chloride ions

A

Balance positive charge of sodium and potassium ions in cells

72
Q

Function of phospahte ions

A

Plasma mambrane formation
Nucleic acid and ATP formation
Bone formation

73
Q

Function of hydroxide ions

A

Catalysis of reactions

pH determination

74
Q

Purpose of a colorimeter

A

Measures the absorbance or transmission of light by a coloured solution. The more concentrated the solution, the more light will be absorbed, and less light will br transmitted. This calculates the concentration of a reducing sugar. Must calibrate using distilled water first.

75
Q

Purpose of biosensors

A

Use biological components to determine the presence and concentration of molecules like glucose.
Molecular recognition - transduction - display

76
Q

Function of catalase as an enzyme and a protein

A

Quaternary protein with 4 haem groups. These groups allow catalase to interact with hydrogen peroxide and speed up the breakdown, preventing the build up and any damage to cells.
A type of conjugated protein.

77
Q

What type of bond is present between amino acids?

A

Peptide bonds

78
Q

Insulin as an example of a globular protein

A

Regulates blood glucose concentration. Hormones are transported in the blood so need to be soluble. Has a precise shape to carry out its specific function

79
Q

Role of water as a solvent?

A

Role as a transport medium e.g. glucose in blood, urea transport. For polar molecules and ions. Allows for capillary action

80
Q

Cohesive properties of water?

A

Allow movement of unbroken columns of water through the xylem vessel in plants

81
Q

Water causes non-polar molecules to group together

A

Allows the formation of a phospholipid bilayer in the plasma membrane

82
Q

High latent heat of vaporistaion in water?

A

Large amount of energy required to evaporate water. Sweating as a cooling mechanism in mammals

83
Q

High surface tension of water?

A

Provides a habitat for some insects e.g. pond skaters

84
Q

Ice is less dense that liquid water?

A

Insulates bottom of ponds which allows inhabitants to survive and provide a habitat for some organisms.

85
Q

Water is not easily compressed?

A

Creates turgor pressure to support plant cells. Amniotic fluid supports fetus

86
Q

Water is transparent?

A

Allows aquatic plants to photosynthesise

87
Q

High specific heat capacity of water ?

A

Large amount of energy required to heat a given mass of water. Acts as a temperature buffer and coolant to maintain a stable environment in lakes/oceans. Organisms are able to survive, due to only being active at a narrow temperature range

88
Q

Change in density with temperature changes?

A

Changes in density allow nutrients to circulate in bodies of water - widely available to all organisms

Crypt A level Biology (8 decks)

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