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Alevel Biology > 2.2 > Flashcards

2.2 Flashcards

1
Q

What are monomers?

A

A small molecule which binds to many other identical molecules to form a polymer

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2
Q

What are polymers?

A

a large molecule made from many smaller molecules called monomers

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3
Q

What is a condensation reaction?

A

Reaction that occurs when two molecules are joined together with the removal of water

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4
Q

What is a hydrolysis reaction?

A

Reaction that occurs when a molecule is split into two smaller molecules with addition of water

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5
Q

What is a monosaccharide?

A

Monomers from which larger carbohydrates are made

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6
Q

How is a glycosidic bond formed?

A

A condensation reaction between two monosaccharides

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7
Q

Name three main examples of polysaccharides.

A

Glycogen, starch, cellulose

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8
Q

Describe Benedict’s test for reducing sugars.

A

Gently heat a solution of a food sample with an equal volume of Benedict’s solution for five minutes, the solution turns orange/brown if reducing sugars are present

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9
Q

Name two main groups of lipids.

A

Phospholipids, triglycerides

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10
Q

Give four roles of lipids.

A

Source of energy, waterproofing, insulation, protection

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11
Q

What is an Ester bond?

A

A bond formed by a condensation reaction between glycerol and a fatty acid

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12
Q

Describe the emulsion test for lipids.

A

Mix the sample with ethanol in a clean tube, shake the sample, add water, shake sample again, a cloudy white colour indicates that a lipid is present

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13
Q

What are the monomers that make up protein?

A

Amino acids

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14
Q

Draw the structure of an amino acid.

A 
R
              |
N2N—-C—-COOH
              |
              H
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15
Q

How is a peptide bond formed?

A

A condensation reaction between two amino acids

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16
Q

What is a polypeptide?

A

Many amino acids joined together

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17
Q

Describe the biuret test for protein.

A

Mix the sample with sodium hydroxide solution at room temperature, add very dilute copper(II) sulphate solution, mix gently, a purple colour indicates that peptide bonds are present

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18
Q

How does an enzyme effect a reaction?

A

It lowers its activation energy

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19
Q

Give five factors which can effect an enzyme action.

A

Temperature, pH, enzyme concentration, substrate concentration, inhibitor concentration

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20
Q

What is a competitive inhibitor?

A

A molecule with a similar shape to the substrate, allowing it to occupy the active site of the enzyme

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21
Q

What is a non-competitive inhibitor?

A

A molecule that changes the shape of the enzyme by binding somewhere other than the active site.

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22
Q

What is a hydrogen bond?

A

A weak interaction that can occur wherever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen atom

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23
Q

Carbohydrates

A

A group of molecules containing C, H, O

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24
Q

Glycosidic bond

A

A bond formed between two monosaccharides by a hydrolysis reaction

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25
Q

Isomers

A

Same formula but different molecular structure

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26
Q

Lipids

A

A group of substances that are soluble in alcohol rather than water. Including triglycerides, phosolipids, glycolipids and cholesterol

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27
Q

Macromolecule

A

Very large organic molecule

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28
Q

Phospholipid

A

Molecule consisting of glycerol, two fatty acids and one phosphate group

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29
Q

Primary structure

A

The sequence of amino acids found in a molecule

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30
Q

Quaternary structure

A

Protein structure where a protein consists of more than one polypeptide chain. For example insulin has a quaternary structure

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31
Q

Secondary structure

A

The coiling or folding of an amino acid chain, which arises often as a result of hydrogen bond formation between different parts of the chain. The main forms of secondary structure are the helix and the pleated sheet

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32
Q

Tertiary structure

A

The overall three dimensional shape of a protein molecule, it’s shape arises due to interactions including hydrogen bonding, disulphide bridges, ionic bonds and hydrophobic interactions

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33
Q

fibrous protein

A

Has a relatively long, thing structure, is insoluble in water and metabolically inactive , often has structural role within organism

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34
Q

Globular protein

A

Has molecules of relatively spherical shape, which are soluble in water and often have metabolic roles within organisms

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35
Q

Prosthetic group

A

A non-protein component that forms a permanent part of functioning protein molecule

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36
Q

What gases does human body consist of

A

Nitrogen, hydrogen, oxygen, carbon, other(trace of potassium, zinc, iron)

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37
Q

3 different types of biological molecules

A

Carbohydrates, lipids and proteins

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38
Q

How are covalent bonds formed and why do they form

A

Atoms contain nucleus surrounded by full outer shell and atoms are stable when there outer shell is full. By sharing an electron with another atom they form a strong covalent bond.

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39
Q

What happens during condensation reaction

A

Two molecules join as water is removed

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40
Q

What happens in hydrolysis reaction and what can a hydrolysis reaction break

A

Two molecules split apart as water is added, can break a covalent bond

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41
Q

What is it called when two monomers join

A

Dimer

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42
Q

What is it called when many monomers are joined

A

Polymer

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43
Q

Give an example of monomers to polymers

A

In proteins: amino acid -> proteins

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44
Q

What is water made up of

A

Two hydrogen and one oxygen

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45
Q

Why is water polar

A

Oxygen has more protons in nucleus so has stronger attraction for shared electrons, this makes oxygen atoms slights negative and hydrogen comes slightly positive

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46
Q

What is a hydrogen bond and when does it occur

A

It is a weak interaction which happens every time molecules contains slightly negative charge bonded to a slightly positive charged hydrogen atom

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47
Q

Is covalent or hydrogen bond stronger

A

Covalent

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48
Q

What does carbon having a balance of 4 mean

A

For every carbon atom there is 4 covalent bonds from it

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49
Q

What are the main 3 elements in organic molecules

A

Carbon, oxygen, hydrogen

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50
Q

What is the name for when monomers form polymers

A

Polymerisation

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51
Q

What happens to hydrogen bonds as water moves

A

They constantly break and make new hydrogen bonds

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52
Q

Why is it hard for water to turn to gas

A

The hydrogen bonds between molecules make it hard for molecules to escape

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53
Q

Even with hydrogen bonds does what’re have low or high viscosity

A

Low viscosity

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54
Q

Why is it good that water has low viscosity

A

Provides habitats for living things in rivers, sea and lakes, form large part of tissue in living organisms, provides reaction medium for chemical reactions, provides effective transport medium (blood)

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55
Q

What would happen if water was less dense

A

Aquatic animals couldn’t float

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56
Q

Why does ice float on water and why is this different to other liquids

A

With most liquids they get more dense as they cool, but water only gets mor expense to 4degrees but from freezing water molecules align in a structure less dense than water (due to waters polarity)

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57
Q

Why is it good that ice is less dense than water

A

Aquatic organisms have stable environment to live in and ponds and other mass waters are insulated against extreme cold as layers of ice reduce heat loss from rest of the pond

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58
Q

Water is a good solvent for many substances in living things, what is an example of this?

A

Solutes like NaCl and covalent solutes like glucose

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59
Q

How does waters polarity effect is a a solvent

A

Waters negative and positive parts attract to the solutes negative and positive parts

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60
Q

Why do water molecules attach around charged part of the solute molecules

A

To help keep them apart so they dissolve and a solution is formed

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61
Q

What two things can molecules and ions do because water is a good solvent

A

They can move around and react together in water (cytoplasm) and they can dissolve in water and transport around living things

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62
Q

Why does a drop of water on a flat surface not spread out but looks spherical

A

As hydrogen bonding between molecules pulls them together and water molecules demonstrate cohesion

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63
Q

Why are water molecules more attracted to water molecules than air molecules

A

As at the surface the water molecules are all hydrogen bonded to molecule beneath them

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64
Q

What happens when water drop touches water

A

Surface of water contracts as molecules pulled inwards and it gives water surface ability to resist force applied to it (surface tension)

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65
Q

Examples of cohesion and surface tension of water in everyday life

A

Pond skaters can walk on water and columns of water in plant vascular tissue brought up through xylem tissue from roots

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66
Q

What is amount of high specific heat capacity

A

4.2kJ of energy to raise the temp of 1kg of water by 1degree

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67
Q

Why does water not heat or cool easily

A

There are lots of hydrogen bonds holding it together meaning it has high specific heat capacity

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68
Q

Why is it important for organisms that water has high specific heat capacity

A

Organisms need stable temp for enzyme controlled reactions to happen and aquatic organisms need stable environment to live in

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69
Q

What helps molecules turn into gas from water

A

Latent heat of vaporisation

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70
Q

Is latent heat of vaporisation high or low in water

A

High

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71
Q

Why is high latent heat of vaporisation necessary in water

A

So that water can cool living things and keep their temp stable for example animas cool when sweat evaporates

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72
Q

Examples of where water acts as a reactant

A

Photosynthesis, hydrolysis reactions

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73
Q

Why is waters properties as a reactant important

A

Digestion and synthesis or large biological molecules

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74
Q

What does waters properties as a solvent depend on

A

It’s polarity with H+ and O-

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75
Q

What does it mean if a molecule is polar

A

There is an unevenly distributed electrical charge, so there are positive and negative regions

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76
Q

What causes waters polarity

A

Water isn’t a straight chain, so hydrogen bonds form

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77
Q

In the body of its cold outside are body temp doesn’t change and enzymes don’t denature (why)

A

Water has high specific heat capacity so it’s good at maintaining steady temp

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78
Q

If cohesive forces of water were weaker what would happen to trees

A

They would be shorter

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79
Q

Why is it important that water is transparent

A

As few organisms could live without light and it would prevent plants from photosynthesising

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80
Q

What do carbohydrates contain

A

Hydrogen, carbon, oxygen

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81
Q

What does hydrated carbon mean

A

For every carbon there are 2 hydrogen and one oxygen atom

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82
Q

What are the 3 different functions of carbohydrates and give examples

A

Energy source (glucose), energy store (starch), structural units (cellulose)

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83
Q

What are 3 main carbohydrates groups

A

Monosaccharides, disaccharides and polysaccharides

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84
Q

What is the simplest carbohydrate and what is its purpose

A

Monosaccharide, important source of energy in longing things

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85
Q

Why are monosaccharides suited to their job

A

Have a large amount of carbon-hydrogen bonds

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86
Q

What are monosaccharides properties

A

They are sweet sugars which are soluble in water and insoluble in non-polar solvents

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87
Q

What is the shape of a monosaccharide

A

Can be straight line, rings or cyclic forms and have a backbone of single bonded carbon atoms with one double bonded to oxygen atom to form carboxyl group

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88
Q

What is the difference between a-glucose and B-glucose

A

In alpha the -OH group is below on carbon 1 and in B-glucose the -OH group is above

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89
Q

Difference between hexose and pentose in terms of make up

A

Hexose has 6 carbon atoms and pentose had 5

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90
Q

What does it mean when glucose can exist as a number of isomer when in a straight chain or cyclic form

A

Molecules with same formula but atoms arranged differently (ring shaped isomers can also form)

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91
Q

When is a ring structure formed in monosaccharides

A

When oxygen attaches to carbon 1 and carbon 5

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92
Q

Properties of disaccharides

A

They are sweet and soluble in water

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93
Q

What are the most common disaccharides

A

Maltose, sucrose and lactose

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94
Q

Which out of maltose, lactose and sucrose are reducing sugars

A

Maltose and lactose reducing sugars and sucrose non-reducing sugar

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95
Q

A-glucose+a-glucose ->

A

Maltose

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96
Q

a-glucose+fructose ->

A

Sucrose

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97
Q

B-galactose+a-glucose ->

A

Lactose

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98
Q

B-glucose-B-glucose->

A

Cellobiose

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99
Q

What happens when two monosaccharides bond

A

Condensation reaction takes place, forming a glycosidic bond

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100
Q

Where does the condensation reaction happen when disaccharides form

A

Between the 2 -OH groups so only a single oxygen left which binds the two molecules togeteher

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101
Q

How are disaccharides broken into monosaccharides

A

Hydrolysis reaction

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102
Q

What happens when glycosidic bond formed and hydrolysed by living things

A

Reaction catalysed by enzymes

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103
Q

What type of bond is a glycosidic bond

A

Covalent

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104
Q

What is glucose based on how many carbon atoms it contains

A

6 carbon atoms so is a hexose sugar

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105
Q

What is glucose general formula

A

C6H12O6

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106
Q

What is glucose purpose and properties

A

Energy source for most cells and is highly soluble and main form of transporting carbohydrates round the body

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107
Q

What is the term for glucose existing in 2 different forms

A

Structural isomers

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108
Q

Can pentose sugars form rings

A

Yes like hexose they are long enough to form rings

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109
Q

What are the most important pentose molecules which are structural isomers

A

Ribose and Deoxyribose

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110
Q

What is the structural difference of ribose and deoxyribose

A

Ribose has one H atoms and one OH group attached to carbon 2 and deoxyribose has 2 H atoms and no OH group on carbon 2

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111
Q

How is maltose formed

A

2 glucose joined by alpha 1-4 glycosidic bond

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112
Q

How is sucrose formed

A

From glucose and fructose joined by alpha 1-4 glycosidic bond

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113
Q

How is lactose formed

A

From galactose and glucose joined by beta 1-4 glycosidic bond

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114
Q

What is the general disaccharide formula

A

C12H22O11

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115
Q

Properties of polysaccharides

A

Don’t taste sweet and are insoluble in water

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116
Q

Why are polysaccharides good carbohydrate store

A

They have a compact structure

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117
Q

How is sugar got in polysaccharides

A

They are insoluble so can’t be diffused but if necessary a hydrolysis reaction can happen to break it off

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118
Q

Examples of polysaccharides

A

Starch, glycogen and cellulose

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119
Q

What are polysaccharides

A

Polymers containing many monosaccharides linked by glycosidic bonds

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120
Q

How are polysaccharides and disaccharides similar

A

Both formed by condensation reaction

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121
Q

Uses of polysaccharides

A

Mainly used as energy store and as structural components of cells

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122
Q

What are the major polysaccharides

A

Starch, cellulose and glycogen

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123
Q

What does a hydrolysis redaction do to polysaccharides

A

Used to break them into monosaccharides, which is the opposite of a condensation reaction

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124
Q

Where is carbohydrates used in plants

A

Cellulose for structure, glucose for respiration, starch as energy store

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125
Q

What are properties of starch

A

Major carbohydrate storage molecule in plants, stored as intracellular starch grains or in organelles called plastids, starch produced from glucose made in photosynthesis and broken down in respiration to provide energy

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126
Q

What are the two different types of starch

A

Amalyose and amylopectin

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127
Q

What is amalose and it’s properties

A

Long chain of a-glucose and has 1-4 glycosidic bonds, it has helix structure and OHgroup on carbon 2 is on the inside coil making it less soluble so hydrogen bonds form, holding the structure together

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128
Q

What is amylopectin and what is its structure

A

Long chain of a-glucose with 1-4&1-6 glycosidic bonds to create highly branches structure, this could in spiral shape held with hydrogen bonds with branches emerging from each spiral

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129
Q

What is glycogen and it’s structure

A

a-glucose molecule with 1-4&1-6 glycosidic bonds, the 1-4 chains are smaller than amylopectin so less likely to coil but it has more branches so is more compact and easier to remove monomer units as there are more ends

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130
Q

What is cellulose

A

A polysaccharide and main part of cell walls, most abundant organic polymer

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131
Q

What are cellulose properties

A

It is strong and stops cells bursting when there is excess water, it is also fibrous and tough and insoluble

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132
Q

Why is cellulose a homopolysaccharide

A

It is made from 15,000 B-glucose molecules bonded through condensation reaction forming 1-4 glycosidic bond

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133
Q

In cellulose why is every over molecule rotated 180degrees and why doesn’t it spiral

A

-H and -OH are inverted on carbon1 in B-glucose so every other one is rotated and the 1-4 glycosidic bonds prevent spiralling

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134
Q

Why is cellulose strong in terms of molecular structure and how do they form

A

Hydrogen bonding between rotated B-glucose molecules provide extra strength as -OH groups on carbon 2 struck out allowing them to form between chains

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135
Q

What is the structure of cellulose

A

Formation of macrofibrils which are embedded in pectin to form cell wall and cross cross in all directions for extra strength

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136
Q

Do animals store carbohydrates as glycogen or starch

A

Glycogen

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137
Q

Where and how is glycogen stored in animals

A

As small granules in muscle and liver

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138
Q

Is glycogen more or less dense and soluble than starch and what does this mean

A

It is less dense and more soluble than starch so can be broken down more rapidly

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139
Q

Why is it important that glycogen can be broken down rapidly

A

Higher metabolic requirements of animals means we need it more rapidly than plants

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140
Q

What is advantageous about glycogen

A

It is highly branches and compacted and has free bonds at the end so more glucose can be added easily

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141
Q

Why is cellulose good in plant walls

A

As the macrofibrils and microfibrils have high tensile strength due for eh strength of the glycosidic bonds and hydrogen bonds between chains

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142
Q

How strong are macrofibrils

A

Stronger than steel if the same diameter

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143
Q

How to macrofibrils get extra strength

A

Run is all directions, criss crossing wall

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144
Q

Why is cellulose hard to digest

A

The glycosidic bonds are hard to break and most animals don’t have the right enzymes to catalyse this reaction

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145
Q

Why is cellulose essential in plants

A

Plants don’t have ridged skeleton so each cell needs strength to support whole plant

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146
Q

Why is plant cell wall fully permeable

A

There is space between macrofibrils for water and miners ions to pass on way in and out of the cell

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147
Q

Why is it necessary that cell walls have high tensile strength

A

Prevents cells bursting when there turgid as turgid cells push against each other holding plants structure and the wall protects delicate membranes

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148
Q

Give an example of another substance that helps macrofibrils provide extra strength

A

Waxes that block spaces in cell walls to make it waterproof

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149
Q

Give some examples of items that contain cellulose

A

Cotton, cellophane, paper

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150
Q

What is the structure of a bacteria cells wall

A

Structure is called peptidoglycan and made from long polysaccharide chains that lie in parallel, cross linked by short peptide chains made from amino acids

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151
Q

How is insects exoskeleton made from chitin different from cellulose and it’s similarities

A

It has an acetylamino group rather than an OHgroup on carbon2, it forms cross links of long parallel chains of acetylglucosamine in similar way to cellulose

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152
Q

Do glycogen and starch take up lots of room

A

No they are compact

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153
Q

How are glucose molecules removed from polysaccharides by

A

Hydrolysis reaction

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154
Q

Is poly or monosaccharides more soluble in water

A

Monosaccharides

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155
Q

What type of sugar are polysaccharides formed from

A

Hexose sugar

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156
Q

Is amalyse branched

A

No it has a helix structure

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157
Q

Where is glycogen within a cell

A

In the cytoplasm

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158
Q

What is structure of microfibrils in cell wall

A

60-70 chains of them massed together to form microfibrils

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159
Q

What are microfibrils embedded in

A

Hemicellulose and pectin

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160
Q

What is hemicellulose

A

Short polysaccharides that bing tightly (not covalent) to surface of cellulose microfibrils and to each other

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161
Q

What are pectins

A

Polysaccharides in cell walls which have negative charge

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162
Q

How are lipids stored

A

As adipose tissue

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163
Q

What is the purpose of adipose tissue

A

It provides heat insulation in mammals underneath skin and around delicate organs like kidneys to act as a cushion in impacts

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164
Q

What is the properties of lipids

A

Diverse group of compounds which are insoluble in water but soluble in organic solvents like ethanol

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165
Q

What is the most commun type of lipid

A

Triglycerides

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166
Q

Give examples of lipids

A

Triglyceride, waxes, steroids and cholesterol

167
Q

Why are lipids insoluble in water

A

They are not polar

168
Q

Why aren’t triglycerides, phospholipids and steroids monomers

A

They are macromolecules as they have different molecules binding them together

169
Q

What do lipids contain in terms of atoms

A

Lots of hydrogen and carbon but little oxygen

170
Q

What are triglycerides made up of

A

Glycerol and 3 fatty acids

171
Q

What is a complete fatty acid

A

Fatty acids we eat not produce

172
Q

How does glycerol and fatty acid bond to make triglyceride

A

Condensation reaction forming 3 water molecules and 3 ester bonds

173
Q

What bond holds lipids together

A

Ester bond

174
Q

What is glycerols structure and properties

A

Has 3 carbon atoms and is alcoholic so has 3 OH groups which are important to triglycerides structure

175
Q

What is the structure of a fatty acid

A

Have a carboxyl group on one end attached to hydrocarbon tail (made of only one carbon and hydrogen atom), they can be from 2-20 carbon long

176
Q

In fatty acid when carboxyl group ionises what is produces and why does it make it an acid

A

A H+ and COO- group and this makes it an acid as it can produce free H+ ions

177
Q

What is the structural difference between saturated and unsaturated fatty acid

A

When it’s saturated there are no c=c bonds but if it’s unsaturated there are c=c so less hydrogen atoms bonded to molecule

178
Q

What does a single c=c bond make a fatty acid acid and what does more than one c=c bond make a fatty acid

A

Monosaturated and more make it polysaturated

179
Q

How does having one or more c=c chain change the shape of hydrocarbon and what does this do

A

It gives a link where the double bond is which push molecules slightly apart making them more fluid

180
Q

When forming a triglyceride where is the condensation reaction formed

A

Between -COOH group of fatty acid and -OH group of glycerol

181
Q

What is an ester bond

A

Covalent bond formed during condensation reaction holding lipids together

182
Q

How are triglycerides used as an energy source

A

Broken down in respiration to release energy and ATP

183
Q

How are triglycerides broken down

A

Hydrolyse ester bonds, then glycerol and fatty acids can be broken down to CO2 and H2O

184
Q

Does respiration of lipids produce more or less water than respiration of sugar

A

More

185
Q

Why are triglycerides good energy store

A

Insoluble in water as not polar so can be stored without affecting water potential of a cell

186
Q

Does fat or glucose release more energy and why

A

Fat, 1g of fat releases twice as much energy as 1g of glucose because lipids have higher proportion of hydrogen than carbohydrates and little oxygen

187
Q

In what ways is lipid a good insulator

A

In whales acts as heat insulation known as blubber, is an electrical insulator in nerve cells and allows hibinating animals to store extra fat

188
Q

Why is it good that fat is buoyancy

A

Fat less dense than water so aquatic animals have fat to stay afloat

189
Q

Do lipids or carbohydrates contain more oxygen

A

Carbohydrates have more oxygen than lipids

190
Q

What are the two groups of lipids

A

Fats and oils and steroids and terpenes

191
Q

At room temp is fat solid or liquid

A

Solid

192
Q

Do either glycerol or fatty acids have structural variations

A

Only one sort of glycerol but fatty acid has many variations

193
Q

What disease can high triglycerides levels cause and what happens

A

Coronary heart disease - causes mass build up of connective tissue and fat in artery walls which slows blood flow and could cause a clot

194
Q

Why is fat a good insulator

A

As it conducts heat slowly

195
Q

What is the difference is structure of a phospholipid

A

Phospholipid have one less fatty acid which is replaced with a phosphate group compared to triglycerides

196
Q

Where is an ester bond formed on phospholipid

A

Condensation reaction between OH group on phosphate acid molecule and one of 3 OH groups on glycerol form

197
Q

Do fatty acids in phospholipids have even or odd amount of carbons

A

Even (18/16)

198
Q

Is a phospholipid saturated or unsaturated

A

Usually one chain is saturated and one is unsaturated

199
Q

What happens to the phosphate group of phospholipid in water

A

Phosphate group has negative charge, making it polar (attracted to water)

200
Q

Why are fatty acid tails repelled by water

A

They are non polar

201
Q

What is the name given to head and tail of phospholipid

A

Hydrophilic and hydrophobic

202
Q

Why are phospholipid AMPHIPATIC

A

As the head is hydrophilic and tail is hydrophobic

203
Q

What type of lipids are amphiphatic and what aren’t

A

Membrane lipids are but lipids involved in storage aren’t

204
Q

In phospholipid lipid is tail hydrophobic or hydrophilic

A

Hydrophobic

205
Q

Is phospholipid is phosphate hydrophilic or hydrophobic

A

Hydrophilic

206
Q

What happens to to amphamatic phospholipids in water (layers)

A

May form layers on surface with heads in water and tails sticking out of water

207
Q

What does an amphamatic phospholipid do in water (sphere)

A

Form micelles,bring ball with tails pointing inwards and hydrophilic heads pointing outwards creating a spherical shape

208
Q

What are amphamatic phospholipids good for

A

Good at forming membranes around cells and organelles as inside and outside the cells is an aquatic solution

209
Q

What shape do phospholipids go into when they act as a membrane

A

Form a bilayer with heads on outside and tails on inside aquatic solution

210
Q

Can phospholipids move around when there in a bilayer

A

They can move around in there but won’t move anywhere where there hydrophobic tail is exposed to water which gives membrane stability

211
Q

How permeable is the phospholipid bilayer as a membrane and what does this mean

A

Semi-permeable as it only lets small and non polar molecules move through tail in bilayer which controls what goes in and out of the cells and keeps it functioning properly

212
Q

What do cholesterol

A

A steroid alcohol which is a type for lipid made from neither fatty acid or glycerol

213
Q

What is cholesterol structure

A

Has 4 carbon based rings or isoprene units

214
Q

Is cholesterol large or small and is it hydrophobic or philic

A

It’s a small and hydrophobic molecule

215
Q

Why is it good that cholesterol is hydrophobic

A

So it can sit in the hydrophobic part of bilayer

216
Q

What does cholesterol do

A

Regulated fluidity of membrane preventing it from coming to fluid or too stiff

217
Q

Where is cholesterol made and found

A

Made in liver of animal and cholesterol derives in plants membranes called stigmasterol which is slight different from cholesterol

218
Q

What are examples of things made from cholesterol

A

Testosterone, oestrogen and vitamin d

219
Q

Why can steroid hormones made of cholesterol pass through cell membranes

A

They are small and hydrophobic

220
Q

Is the phosphate group acidic or alkaline

A

Acidic

221
Q

How is phospholipid formed

A

Phosphoric acid reacts with one of 3 OH groups of glycerol and other 2 OH react with fatty acid

222
Q

What is the most known steroid

A

Cholesterol

223
Q

Is all cholesterol bad

A

No some is essential

224
Q

Where is essential cholesterol found

A

Membrane of animals cells to keep them fluid

225
Q

What happens when cholesterol interacts with hydrocarbon chains of phospholipid molecule

A

Chances stability and flexibility of membrane

226
Q

Why and what part of phospholipid is insoluble in water

A

Long hydrocarbon chain is insoluble but end of glycerol molecule is soluble as it has polar groups

227
Q

What is a mono layer

A

Formed when fat is half in contact with air and half with water, head in water and tail out of water

228
Q

What happens to fat when in water surface with isn’t in contact with air

A

Bilayer like plasma membrane

229
Q

What are proteins

A

Large monomers made of amino acids

230
Q

What is proteins function (structure)

A

Structural components in animals (muscles made from protein)

231
Q

What is function of protein (enzymes)

A

Tendency to adopt specific shapes make proteins important as enzymes

232
Q

Do both animals and plants need amino acids to make proteins

A

Yes

233
Q

Do animals make all there proteins

A

They make some but must I gets others

234
Q

What’s an essential amino acid

A

Amino acids which we must ingests and cannot produce

235
Q

When can plants make amino acids

A

If they have a fixed access to nitrogen

236
Q

What is an amino acids structure

A

They each contain oxygen, carbon, hydrogen, nitrogen and sometimes sulfur

237
Q

What does each protein chain of amino acids have

A

An amino group (NH2) and a carboxyl group (COOH) at the other end

238
Q

What does r mean on amino acid structure

A

Varys depending on which amino acid it is

239
Q

How can r groups vary

A

By size, charge, polarity, if there hydrophobic or hydrophilic

240
Q

How are amino acids bonded

A

Amino acid joined together by condensation reaction forming covalent peptide bond

241
Q

How do you break a peptide bond

A

Hydrolysis reaction (addition of water)

242
Q

Give an example of when peptide bonds are broken

A

Protease in intestines breakers down peptide bonds during digestion and can break down hormones so effect isn’t permanent

243
Q

What is the name of two amino acids bonded

A

Dipeptide

244
Q

What is a long chain of amino acids called

A

Polypeptides

245
Q

How many polypeptides does a protein have

A

Of at least one but sometimes more bonded together

246
Q

How does structure of protein differ from lipids and carbohydrates

A

Contains nitrogen and sometimes sulfur which others don’t

247
Q

What is glycines R on amino acid

A

H-hydrogen

248
Q

How many proteins used in biosynthesis of proteins

A

20

249
Q

Why can amino acids act as buffers

A

They have a positive and negative charged region

250
Q

Which part of amino acid is possible and negative

A

Amine group is positive and carboxyl group negative (NH3+ —RCH—COO-)

251
Q

What does buffer mean

A

Amino acids can combine with acid or alkali substances as they can resist change of pH on addition of acid or alkali

252
Q

Give an example of amino acids acting as a buffer

A

If acidic hydrogen taken up by -COOH group, decreasing acidity of surrounding (NH3+ — RCH —COOH) and if alkane hydrogen ions released from amino group, increases acidity round it (NH2 — RCH — COO-)

253
Q

Why is it important that proteins are buffers

A

Useful in blood, tissue fluid and within cell to help keep pH stable which important in homeostasis

254
Q

What is primary structure

A

Sequence of amino acids in a protein chain

255
Q

Why is order and number of amino acids important

A

Changing just one amino acid can alter function of the protein

256
Q

Why is there a large variety of proteins

A

20 different amino acids which can all be arranged differently and chains usually 100 amino acids long so 20*100 ways of rearranging amino acids

257
Q

What does function of protein depend on based on shape

A

Whether it’s a primary, secondary, tertiary or quarternary structure

258
Q

What is a secondary structure

A

Chain of amino acid which isn’t straight but twisted into shape, some are a-helixes and some are B-pleated sheets

259
Q

How many amino acids does a secondary a-helix structure have

A

36 amino acids per 10 turns of helix

260
Q

How is secondary helix structure held together

A

Hydrogen bonds between NHgroup of amino acid and COgroup of another (4 places ahead in chain)

261
Q

What is B-pleated structure and how is it held togeteher

A

Folds slightly in a zigzag and hydrogen bonds between NH group of one amino acid and CO group further down the chain to hold sheet together

262
Q

Why are a-helix and b-pleated strong

A

hydrogen bonds are weak but there are many of them so makes them stable at optimal pH and temp

263
Q

When is tertiary structure formed

A

when coils and pleats from secondary structure start to fold along with areas of straight chain of amino acids

264
Q

Why does tertiary structure have precise structure

A

Held firmly in place by bonds between amino acids which lie close to each other

265
Q

What shape do tertiary structure adopt in fibrous and globular proteins

A

Supercoiled in fibrous and spherical in globular

266
Q

What bonds found in tertiary structure

A

Ionic bond between a positive R and a negative R, disulphides bond between the sulfur, hydrogen bond between NH and OC

267
Q

What is a quarternary structure

A

Many proteins made up of more than one polypeptide chain

268
Q

What bonds do quaternary have

A

Same as tertiary, disuflide, hydrogen, ionic

269
Q

When do hydrogen bonds form in proteins

A

When hydrogen atom has slight + charge and other atom has slight - charge which e.g. hydrogen bond may form between amino group of one amino acid and carboxyl soup for another amino acid

270
Q

What do ionic bonds form between and what do these form into

A

Carboxyl and amino groups that are part of R group, which ionise into NH3+ and COO-

271
Q

Why does ionic bond form when something + and -

A

Positive and negative groups are strongly attracted to each other forming ionic bond

272
Q

What in an amino acid contains sulfur

A

In the R group but only certain amino acids like cysteine

273
Q

Where are disulphides links formed between and how strong are they

A

Formed between r group of two cysteines and are strong covalent bonds

274
Q

Where do hydrophobic parts of r group associate together and hydrophilic parts

A

In middle of polypeptide to avoid water contact so hydrophilic parts found near edge to be close to water

275
Q

What do hydrophobic and hydrophilic interactions cause and what does this mean

A

Can cause twisting of amino acid chain which changes protein shape and can influence its functions as most proteins surrounded by water in living organisms

276
Q

What bonds are there in primary structure

A

Only covalent peptide bonds between each amino acid

277
Q

What bonds do secondary structures have

A

Hydrogen bonds

278
Q

What are two different secondary structures

A

B-pleated sheet and a-helixes

279
Q

Where are a-helixes found

A

In hair (keratin) and enzymes and antibodies

280
Q

Why does b-helix have relatively flat structure

A

Hydrogen bonds between parallel chains which then becomes folded

281
Q

B-pleated or a-helix more common

A

A-helixes

282
Q

Where are b-pleated sheets found

A

Silk and strong and thick protein and structures

283
Q

What may the structure of polypeptide be in tertiary structure

A

Cross links formed between either hydrogen, ionic or disulphide bonds

284
Q

Examples of proteins joined with other molecules

A

Glycoproteins - protein and carbohydrates

285
Q

What is it called when protein and other molecule joined

A

Conjugated protein

286
Q

Where may you find glycoproteins

A

Mucus, connective tissue, eukaryotic plasma membrane

287
Q

Use of lipoproteins

A

Transport soluble lipids round the body

288
Q

When is quarternary structure present

A

Only present when 2 or more polypeptide chains

289
Q

Give an example of quaternary structure and its function

A

Haemoglobin in red blood cells contains tightly packed polypeptide chains which has spatial arrangement vital for efficient functioning of molecule

290
Q

What are inorganic ions essential for

A

Constituents of skeletal structures, maintains osmotic pressure and constituent of soft tissue, nerve impulse transmission and muscle contraction, activator for enzymes, hormone and vitamins

291
Q

What is a cation

A

Positive ions

292
Q

Is calcium cation or anion

A

Cation (ca*2+)

293
Q

What is calcium’s structural use

A

Increases fidgety in bones, teeth, cartilage and component of exoskeleton of crustances)

294
Q

How is calcium useful in human body

A

Clotting blood and activator for severe enzymes (lipase, ATPase, chlorinerase), stimulates muscle contraction and regulates transmission of nerve impulses, regulates permeability of cell

295
Q

Who is calcium important in plants

A

In their cell wall development and middle lamella between cell walls

296
Q

Is sodium cation or anion

A

Cation (Na+)

297
Q

How is sodium useful in human body

A

Involved in regulation of osmotic pressure, controls water levels and maintains pH, affects absorption of carbs in intestines and water in kidneys, contributes to nervous transmission and muscle contraction

298
Q

How is sodium useful in plants

A

Constituent in vacuole to maintain turgidity

299
Q

Is potassium cation or anion

A

Cation (K+)

300
Q

How is potassium useful in animals

A

Involved in water levels in body fluid and pH maintenance, assists active transport of cells across membranes, involved in synthesis of glycogen, protein and glucose breakdown, contributes to nerve transmission and muscle contraction

301
Q

How is potassium used in plants

A

In flowering plants it generates healthy leaves and flowers , component of vacuole in plant to maintain turgidity

302
Q

Is hydrogen cation or anion

A

cation (H+)

303
Q

Hydrogen use in plants

A

Involved in Photosynthesis and respiration

304
Q

Hydrogen use in animals

A

Involved in transport of oxygen, CO2 in the blood and involved in pH regulation of blood

305
Q

Is ammonium cation or anion

A

Cation (HH4+)

306
Q

Use of ammonium in human body

A

Essential component of nucleic acid, maintains pH in human body, component of nitrogen cells

307
Q

Use of ammonium in plant and human

A

Component or amino acid, proteins, chlorophyll and some hormones like insulin

308
Q

Is nitrate cation or anion

A

Anion (NO8-)

309
Q

Uses of nitrate

A

Component of amino acid, proteins, vitamins, chlorophyll, essential in nucleic acids and some hormones made of proteins, also component of nitrogen cycle

310
Q

Is hydrocarbonate cation or anion

A

Anion (HCO3-)

311
Q

Uses of hydrocarbonate in human body

A

Involved in blood pH regulation and involved in CO2 transport in and out of blood

312
Q

Is chloride cation or anion

A

Anion (cl-)

313
Q

Uses of chloride in human body

A

Helps urine production in kidney by maintaining water balance, involved in CO2 transport in and out of blood, regulates affinity of haemoglobin to oxygen, involved in blood pH regulation and used to produce HCL in stomach

314
Q

Is phosphate cation or anion

A

Anion (PO4*3-)

315
Q

Use of phosphate in human

A

Increases bone, teeth, cartilage ridgity, component of phospholipid, ATP, nucleic acids, several important enzymes, involved in regulation of blood pH

316
Q

Use of phosphate in plants

A

Helps root growth in plants

317
Q

Is hydroxide cation or anion

A

Anion (OH-)

318
Q

Hydroxide use in body

A

Regulation of blood pH

319
Q

What’s a macronutrient

A

Ions required in large amounts

320
Q

What’s a micronutrient

A

Ions required in small amounts

321
Q

If human or plant has deficiency what does this mean

A

Doesn’t consume enough of certain ions or particular ions

322
Q

What does cobalt defficency lead to

A

Anaemia

323
Q

What does copper defficency in plants lead to

A

Young shoots dying back

324
Q

What are some functions for minerals in large organic molecules

A

molecules, e.g. proteins contain sulfur and nitrogen, enzymes contain metal ions like copper, ion, zinc, phospholipid and nucleic acids contain phosphorus

325
Q

Function of minerals in small organic molecules

A

ATP contains phosphorus (phosphorus also required for activation of small organic molecules), e.g.glucose has phosphorus added before freak down in respiration, hormone thyroxine has iodine

326
Q

What is the functions of minerals in certain pigments

A

Haemoglobin and chlorophyll both contain iron and magnesium

327
Q

Function of minerals as structures

A

Calcium and phosphate found in bonds and calcium found in plant cell wall

328
Q

Function of minerals in determining anion-cation balance in cells

A

Sodium and potassium and chloride ions, important especially on nerves, muscles and sensory cells involved in impulse transmission

329
Q

Function of minerals in determining water potential

A

Mineral salts and other solutes determine water potential of cells and body fluids, most organisms water potential canning function outside of narrow limits

330
Q

What is a qualitative test

A

Test for a substance, not how much substance there is

331
Q

What three types of carbohydrates can you test for

A

Starch, reducing sugars, non-reducing sugars

332
Q

How do u test for starch

A

Add iodine to sample and if starch present goes from yellow-brown to blue-black

333
Q

What does potassium iodine change colour when starch is present

A

When starch dissolved in potassium iodine, iodine forms a triiodide ion (I3-) which slips into middle of amaloyse helix causing colour change

334
Q

What are reducing sugars

A

Monosaccharides and some disaccharides, they can give or reduce electron to other molecules

335
Q

Method for test for reducing sugars

A

Heat the sample with Benedict’s solution and the colour will change from blue -> green -> yellow -> orange-red

336
Q

Why does solution change colour in reducing sugars test

A

Benedict’s contains Cu2+ ions which are reduced to Cu+ ions forming orange-red copper oxide called precipitate as comes out of solution and forms solid

337
Q

How do you test for non-reducing sugars

A

Boil sample with hydrochloric acid to hydrolysis the sample, then cool sample and use hydrogen carbonate to neutralise it, test for reducing sugars, green, yellow, organs, red all indicate presence of non reducing sugar

338
Q

What test do you use to test for lipids

A

Emulsion test

339
Q

Method for emulsion test

A

Take sample and mix with ethanol, then remove some of it and add water to a new test tube with it in, a colour white emulsion indicates presence of lipids

340
Q

Why in emulsion test is lipids on top of the water

A

Made it tiny lipid droplets which come out of solution when mixed with water

341
Q

What test do you use to test for proteins

A

Biuret test

342
Q

Method of biuret test

A

Add biuret onto sample and if protein present will turn from blue to lilac

343
Q

Why does colour change in biuret test

A

Colour formed by complex between nitrogen atoms in peptide chain and Cu2+ ions, so test really tests for presence of peptide bonds

344
Q

What equipment would you use for a quantitive test for reducing sugars

A

Colorimeter

345
Q

What is colorimetry

A

Try to quantify sugar concentration in original sample by assessing how these two variables changed

346
Q

How does a colorimeter work

A

By shinning light through same, for reducing sugars you would use centrifuge to separate precipitate and excess Benedict’s solution (supernatant)
You would use a pipette to remove supernatant into cuvette which is placed into colorimeter and colorimeter need resetting to 100% transmission by using a blank after each reading

347
Q

Why must there be no finger prints on curvette

A

Made of glass or plastic so fingerprints would affect light transmission

348
Q

Why are colour filters used on colorimeter

A

For more accuracy, red filters detect how much light passes through filter in percentage transmission

349
Q

Is the solution was red what colour light filter would be the best and worst to use

A

Blue = best and red= worst as blue would be absorbed by red solution but red light would just be reflected

350
Q

What happens in colorimeter if there is lots of unreacted copper silva the and supernatant is still blue

A

Absorption of red light is high and percentage transmission would be low

351
Q

What happen when the supernatant has a little unreacted copper surface and supernatant less blue

A

Absorption of red light low and percentage transmission is high

352
Q

What blank is often used to reset colorimeter

A

Water

353
Q

How do u make a calibration curve

A

Take series of known concentrations for reducing sugars, using a sample of each do Benedict’s test and then use colorimeter to record percentage transmission of light through each supernatant to the concentration of reducing sugar, you can then use this curve to found out how much sugar a sample has with only knowing light transmission or concentration

354
Q

What is a biosensor

A

Uses biological or chemical variable which can’t easily by measured and transferred into electrical signal, they can detect water contamination and pathogens and toxins in food and can detect air born bacteria used in bioterorism programmes

355
Q

Fibrous proteins

A

Have regular and repetitive sequences of amino acids and usually insoluble in water so they can form fibres, usually have structural function

356
Q

Examples of fibrous proteins

A

Collagen, elastin (connective tissue), keratin (in hair)

357
Q

Globular proteins

A

Rolls up into almost spherical shape, hydrophobic R groups turn into centre and hydrophilic ones on outside making it soluble in water as water molecules cluster and bond round them

358
Q

Uses of globular proteins

A

Specific shape do function as enzymes, hormones(insulin), haemoglobin

359
Q

Collagen function

A

To provide mechanical strength

360
Q

Collagen use in artery walls

A

Layers of collagen prevent artery busting when in high pressure from blood pumping to heart

361
Q

Collagen use in tendon and connective muscle

A

Tendon and connective tissue made from collagen to allow them to pull on bones

362
Q

Collagen use in bones

A

Bones made from collagen and reinforced with calcium phosphate to make them hard

363
Q

What tissue and bone like structure can collagen make

A

Cartilage and connective tissue

364
Q

What is Keratin

A

Rich in cysteine so lots of disulphides bonds formed between peptide chains and hydrogen bonds making it very strong

365
Q

Where is keratin found

A

Wherever body part needs to be hard and strong

366
Q

Examples of where keratin is found

A

Fingernails, hair, claws, hooves, horns, scales, fur and feathers

367
Q

What does keratin provide

A

Mechanical protection and impermeable barrier to prevent infection and waterproof protecting entry of water-born pollutants

368
Q

Structure and properties of elastin

A

Cross-linked coiling makes elastin structure strong and extensive

369
Q

Where is elastin found

A

Living things where they must stretch or adapt their shape as part of life’s process

370
Q

Function of elastin in skin

A

Means skin can stretch round our bones and muscles, without it after being pinched skin wouldn’t recoil

371
Q

What is use of elastin in lungs

A

Allows them to inflate and deflate

372
Q

Use of elastin in bladder

A

Allows bladder to expand and hold urine

373
Q

Elastin use in blood vessels

A

Like collagen, it helps blood vessels stretch and recoil as blood pumped through them helping to maintain pressure wave of blood

374
Q

What structure is haemoglobin and how many polypeptides is it made of

A

Quaternary structure made of 4 polypeptides, has 2 a-globin chains and 2 B-globin chains and each of these has its own tertiary structure, but fitted together forms haemoglobin molecule

375
Q

How is haemoglobin held together

A

By bonds and interactions giving it very specific shape

376
Q

What does it mean that haemoglobin is a prosthetic group

A

At one position on outside of each chain, theres a space where haem group help and this group called prosthetic group

377
Q

Function of haemoglobin

A

Carry oxygen from lungs to tissues

378
Q

How does haemoglobin pick up oxygen from lungs

A

Oxygen molecules bond to iron in each 4 haem groups of haemoglobin molecule causing it to go from purple-red to bright red and oxygen released by haemoglobin when it reaches the tissue

379
Q

What is insulin made of

A

2 polypeptide chains, A chain starts with section of a-helix and B chain ends with B-pleated which both fold into tertiary structure and joined by disulphides links

380
Q

Why is insulin soluble

A

As amino acids with hydrophilic R group on outside of molecule

381
Q

What is insulin function

A

It binds to glycoprotein receptors on outside of muscle and fat cells to increase their glucose uptake from the blood, which increases glucose rate of consumption

382
Q

What is pepsin

A

Enzyme that digests protein I stomach, made of 327 amino acids in single polypeptide chain

383
Q

What structure is pepsin

A

Fold into symmetrical tertiary structure

384
Q

Why is pepsin very stable in stomach acidic environment

A

As has very few amino acids with basic R groups but 43 acidic amino acids, meaning there are few basic groups to except H+ions so little effect on enzyme structure

385
Q

What binds hold pepsin tertiary structure together

A

Hydrogen bonds and 2 disulphides bridges

386
Q

Example of when it is useful to be able to predict the shape of protein

A

Predicting occurrence of biologically active binding sites on a protein molecule can help identify medicines

387
Q

What are the two types of predicting a protein shape

A

Ab inito protein molecule, comparative protein modelling

388
Q

What is Ab initial protein modelling

A

Model built based on physical and electrical properties of an atom in an amino acid sequence, in this there are multiple solutions to same amino acid sequence and other methods need applying to reduce number of solutions

389
Q

What is comparative protein modelling

A

One approach is protein threading which scans amino acids sequence against a database of solved structures and produces set of possible models which would match the sequence

390
Q

Why is it important enzymes have a globular structure

A

As globular structures are tightly fixed and enzymes role depends on its shape

391
Q

Properties of globular properties

A

Used in buffering and usually water soluble

392
Q

What is a collid

A

Particle that remains dispersed in solution rather than dissolving, settling or floating

393
Q

Give examples of collids

A

Many larger molecules such as proteins and lipids

394
Q

Why are proteins and lipids collids

A

Too small to settle out under gravity but to large to dissolve as large SA making them readily available for chemical reactions

395
Q

What type of structure is antibodies

A

Globular protein

396
Q

What is most globular proteins function

A

Involved in transport out of cells and around body

397
Q

Is steel or collagen stronger

A

Collagen

398
Q

Structure of collagen

A

3 polypeptide chains coiled round each other in triple helix (rope like) structure

399
Q

What is Transamination

A

Process of synthesising non-essential amino acids

400
Q

What can an error in synthesis of proteins cause

A

Sickle cell animea of cystic fibrosis

401
Q

How can you separate proteins from solvent

A

Electrophoresis, progressive hydrolysis and chromatography

402
Q

Principal of chromatography

A

To separate mixture into constituents (eg. Biological molecules)

403
Q

What are the two stages of chromatography

A

Stationary and mobile phase

404
Q

What is the stationary phase

A

Chromatography paper or thin layer chromatography (TLC)plate (made form cellulose), in both cases there are free OH groups pointing out in contact with mobile phase

405
Q

Mobile phase

A

Solvent for biological molecules (use of water for polar molecules or ethanol for non-polar molecule) mobile phase flows through and across stationary phase carrying biological molecule with it

406
Q

What is the practical for separating amino acid from solution

A

1.wear eye protection. 2.draw pencil line on chromatography paper and put tiny dot to show where solution solution mixture will be placed 3.put solution mix on for 6times and allows to dry in between each using capillary tube 4.place into solvent below pencil line 5. Cover beaker with watch glass 6.let solvent run till just below top of paper, then remove from solvent and allow to dry

407
Q

What happen in chromatography practical

A

As solvent travels up the less soluble component of solution will travel slower, you can use Rf value to help identify components

408
Q

How does chromatography work in colourless molecules like protein

A

You can use UV so paper will flow except where pigment is, you can use Ninhydrin to see amino acid, when you spray paper amino acids become brown or purple, or iodine crystals in a closed container with paper and iodine binds to each molecule in each spot making them visible

409
Q

What does the soles of a complement in solution depend on

A

Solubility in given solvent and polarity

410
Q

How does chromatography work

A

Exposed OH groups make surface of paper very polar allowing hydrogen bonds to form with molecule and other interactions

411
Q

What happens to highly polar solute in chromatography and low polar

A

Stick to surface being absorbed, so move slower but non-polar solute will travel fast

412
Q

What should you do in chromatography if two molecules travel at same speed

A

Change the solvent or the pH

413
Q

What is chromatography commonly used for

A

Used to monitor progress of reactions as it works relatively quick and also urine testing for illegal drugs in athletes

Alevel Biology (25 decks)

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