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AS level Biology > Section 1 - Biological Molecules > Flashcards

Section 1 - Biological Molecules Flashcards

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1
Q

What are three main groups of biological molecules?

A
  1. Carbohydrates
  2. Lipids
  3. Proteins
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2
Q

What is a carbohydrate?

A
  • A respiratory substrate (glucose)
  • structure in plasma and the cell wall (made of cellulose).
  • They are often polymers.
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3
Q

What does a lipid form?

A
  • bilayer of plasma membranes
  • hormones
  • some respiratory substrates.
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4
Q

What do proteins create?

A
  • enzymes.
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5
Q

What is nucleic acid?

A

They carry genetic code for the production of proteins.

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6
Q

What is a monosaccharides?

A

These are the monomers that make up carbohydrates.

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7
Q

What are the two types of glucose?

A

Alpha glucose

Beta glucose

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8
Q

What are the differences between the two types of glucose?

A

Alpha - The Hydroxyl group is on the bottom

Beta - The hydroxyl group is on the top.

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9
Q

what are two examples of Monosaccharides?

A
  • galactose
  • fructose
  • glucose
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10
Q

How do you join monosaccharides molecules?

A

Condensation Reaction

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11
Q

what is a condensation reaction?

A
  • two monosaccharide molecules
  • glycosidic bond
  • water molecule is lost.
  • makes a covalent bond between oxygen atoms which makes a disaccharide molecule.
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12
Q

What is released in a condensation reaction?

A

a water molecule

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13
Q

What is the bond called between two monosaccharide molecules?

A

Glycosidic bond (covalent between oxygen molecules)

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14
Q

How do you make a maltose molecule?

A

2 alpha glucose molecules.

One OH is split and bonds with OH to release water. Its caused by a condensation reaction and is a disaccharide molecule.

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15
Q

How do you make a sucrose molecule?

A

A glucose and fructose molecule.

Made in a condensation reaction.

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16
Q

How do you make a lactose molecule?

A

A glucose and galactose.

Made in a condensation reaction.

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17
Q

Give three examples of a disaccharide molecule?

A
  • Maltose
  • Sucrose
  • Lactose
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18
Q

What is made when you bond more than two monosaccharide molecules?

A

A polysaccharide molecule. - This is a polymer of monosaccharides

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19
Q

Give three examples of polysaccharide molecules?

A
  • Cellulose
  • Glycogen
  • Starch
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20
Q

How can you make a cellulose molecule?

A

Chains of Beta Glucose molecules

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21
Q

How do you make glycogen molecules?

A

Many alpha molecules

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22
Q

How do you make starch molecules?

A

many alpha glucose molecules but differently arranged than glycogen.

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23
Q

What is an isomer?

A

Similar to isotopes for example alpha and beta glucose molecules are different isomers of each other.

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24
Q

How do you break carbohydrate polymers?

A

By adding a water molecule

the glycoside bond is broken.

hydrolysis.

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25
Q

What are three distinguishing features of monosaccharide molecules?

A
  • sweet tasting
  • Soluble
  • General rule/formula (CH2O)n where n is a number between 3-7
  • Eg. Hexose - Glucose - 6 - C6H12O6
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26
Q

What three molecules do carbohydrates contain?

A
  • Carbon
  • Oxygen
  • Hydrogen
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27
Q

What is the structure of Starch monosaccharides?

A

ONLY IN PLANTS

  • chains on alpha
  • Forms close spirals packed tightly into cells.
  • chains branched or unbranched (tight coil very compact)
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28
Q

Where is starch found?

A

PLANTS

in forms of small grains

  • Large amounts in seeds and storage organs eg. potato tubers
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29
Q

How does the structure of starch help its function?

A

suited for energy storage:

  • insoluble
  • large (doesn’t diffused out)
  • compact (lots in a small place)
  • when hydralysed a-glucose is easily transported and used in reparation
  • branched can be acted on by enzymes simultaneously. so monomers are released rapidly. Not as quick as glycogen
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30
Q

What is the function of starch?

A

For energy storage in plants.

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31
Q

What is the structure of glycogen?

A

IN ANIMALS AND BACTERIA NOT PLANTS

  • a-glucose monosaccharides
  • shorter chains than starch but more highly branched
  • sometimes called animal starch
  • stored as small granules
  • Mainly in liver and muscles
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32
Q

Where is glycogen found?

A

IN ANIMALS AND BACTERIA NOT IN PLANTS

  • Mainly in the liver and muscles
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33
Q

How does the structure of glycogen help its function?

A
  • insoluble (so doesn’t draw water into the cells by osmosis) (low osmotic potential)
  • Doesn’t diffuse
  • compact (lots stored in small place)
  • more highly branched
  • more rapidly breaks down glucose monomers
  • means animals have a quicker metabolism and respiratory rate
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34
Q

What is the structure of cellulose cells?

A
  • B-glucose
  • straight and unbranched
  • run parallel to each other so hydrogen bonds can go between (cross-linkages) increasing collective strength
  • molecules are groups to form microfibrils which in run make groups of fibres. Which in turn increases the over all strength
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35
Q

How does the structure of cellulose help its function?

A
  • turgid
  • cells are pushed against each other
  • non-woody parts semi-rigid
  • Provide max SA for photosynthesis
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36
Q

How does a cellulose cell being turgid help its function?

A

rigid walls

This prevents cells bursting.

By exerting an inward pressure to stop influx of water

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37
Q

What is the function of cellulose?

A

forms a rigid wall

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38
Q

What is the function of glycogen?

A

It is a storage molecule. Of sugar.

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39
Q

Define - Osmotic potential

A

The amount of water that can enter a cell by osmosis to try and balance out the solutes.

In the aim to create equilibrium

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40
Q

What is the difference between the two types of starch?

A

Amylose - Is branched

Amylopectin - Is unbranched

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41
Q

What is starch used for?

A

Energy storage molecule

  • help to produce plant seeds and do germination
  • long term energy storage
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42
Q

How can you increase the rate of starch break down?

A

By using a branched polysaccharide you can increase the amount of enzymes available and so the alpha-glucose molecules are broken down more quickly.

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43
Q

Define - sugar

A

Sugar as a term that means monosaccharide and disaccharide are bonded. These can be reducing or non-reducing

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44
Q

What can you use to test for reducing sugar?

A

Benedict Reagents - an alkaline solution of copper 11 sulfate

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45
Q

Explain how to test for reducing sugar?

A
  1. Add 2cm^3 of food sample to be tested in a test tube. If the sample is not already in liquid form, first grind up into water.
  2. Add an equal volume of Benedict reagent (blue)
  3. Heat the mixture in a gently boiling water bath for 5 minutes
  4. look out for a colour change to see if reducing sugars are present
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46
Q

Define - Biological molecules

A

Particular groups of chemicals that are found in living organisms

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47
Q

What is meant by a polar molecule?

A

A molecule with uneven distribution of change is polarised.

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48
Q

Give three examples of naturally occurring ring polymers?

A
  • polysaccharides
  • polypeptides
  • polynucleotide
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49
Q

How can you form polynucleotides?

A

mononucleotide sub-units

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50
Q

How can you form polypeptides?

A

Linking together peptides that have amino acids in their basic sub-units

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51
Q

What does polypeptides hydrolysis into?

A

amino acids

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52
Q

What does starch hydrolysis into?

A

glucose

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53
Q

Define - Metabolism

A

All the chemical processes that take place in living organism.

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54
Q

What does the mole measure?

A

This is a unit for measuring the amount of substance and is abbreviated to mol

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55
Q

How many particles does a mole contain?

A

The same number of particles as there are in 12g of carbon-12 atoms.

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56
Q

What is avogadro’s constant?

A

6.022 x 10^23

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57
Q

Define - molar solution

A

A solution that contains one mole off solute in each litre of solution.

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58
Q

What is a mole?

A

A mole is the molecular mass expressed as grams (= one gram molecular mass)

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59
Q

State and explain the three types of bonding of atoms.

A
  • Covalent - share a pair of electrons in outer shell a molecule is formed
  • Ionic - lose or gain electron - weaker than covalent
  • hydrogen - when there is an uneven distribution of negative electrons. Making it polarised.
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60
Q

Describe Hydrogen bonding

A
  • electrons not evenly distributed
  • region more negatively charged than the rest of the molecule.
  • Said to be polarised, in other words it has a polar molecule.
  • The negative region of one polarised molecule and the positively charges region of another attract each other.
  • A weak electrostatic bond is formed.
  • individually weak collectively form important forces that alter the physical properties of molecules.
  • This is equally true for water.
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61
Q

Why is carbon so good at bonding?

A

It very rapidly forms bonds with other carbon atoms allowing a sequence of carbon atoms of various lengths to be built up which forms a backbone along which other atoms can attach

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62
Q

What are most polymers made up of?

A
  • carbon - hydrogen - oxygen - nitogen
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63
Q

what is another word for sugar?

A

saccaride

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64
Q

Define - reduction

A

a chemical reaction involving the gain of electrons of hydrogen

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65
Q

What is a reducing sugar?

A

a sugar that can donate electrons to another chemical

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66
Q

What is Benedict reagent?

A

An alkaline solution of copper (11) sulphate

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67
Q

What precipitate is form when you heat Benedict’s reagent?

A

Insoluble red precipitate of copper (1) oxide

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68
Q

What type of test is the benedicts test?

A

a semi-quantitative test

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69
Q

What does semi-quantitative mean for an experiment?

A

It means it can be used to estimate the approximate amount of reducing sugar in a sample

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70
Q

What are the results for the Benedicts test?

A

no Reducing Sugar - Blue very low RS - green low RS - yellow Medium RS - orange high RS - bricky red

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71
Q

Explain the method for testing for non-reducing sugars.

A
  1. if not a liquid then ground in water
  2. add 2cm^3 of food sample to cm^3 of Benedict reagent in a test tube and filter
  3. into gently boiling water bath for 5 mins if it does not change colour then a reducing sugar is not present
  4. add another 2cm^3 of food sample to 2cm^3 dilute hydrochloric acid in a test tube and place test tube in gently boiling water for 5 mins.
  5. The dilute HCl will hydrolyse any disaccharide present into its monosaccharides
  6. slowly add sodium hydrocarbonate solution to neutralise the acid.
  7. Test solution is alkaline.
  8. re-test for reducing sugars
  9. If a non-reducing sugar was present in the original sample the Benedict solution will now turn orange-brown
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72
Q

What feature makes polysaccharides suitable for storage?

A

That they are insoluble

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73
Q

How do you form starch molecules in chloroplasts?

A

Joining between 200 - 100000 alpha glucose molecules by glycosidic bonds in a series of condensation molecules

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74
Q

Explain the method of testing for starch?

A
  1. place 2cm^3 of a sample in test tube
  2. or add two drops of the sample into a depression on a spotting tile
  3. add two drops of iodine solution and shake of stir - The presence of starch is indicated by a blue-black colouration
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75
Q

How can starch be easily detected?

A

iodine in a potassium iodide solution from

yellow to blue-black

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76
Q

What characteristics for lipid substances share?

A
  • contain carbon, hydrogen and oxygen atoms
  • the proportion of oxgyen to carbon and hydrogen is smaller than in carbohydrates
  • they are insoluble in water
  • they are soluable in organic solvents such as alcohols and acetone
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77
Q

What are the two main groups of lipids?

A
  • Triglycerides
  • Phosopholids
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78
Q

What type of lipid is fat and oils?

A

triglyceride

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79
Q

At what chemical state are fats at 10-20*c (room temp) ?

A

solid

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80
Q

At what chemical state are oils at 10-20*c (room temp) ?

A

liquid

81
Q

What do phospholipids do in membranes?

A
  • flexibility
  • transfer of lipid-soluable substances across them
82
Q

What are roles of lipids?

A
  • cell membranes
  • source of energy
  • waterproofing
  • insulation
  • protection
83
Q

How do lipids provide a source of energy?

A

When oxidised twice the energy as the same mass of carbohydrates and release valuable water

84
Q

How do lipids provide waterproofing?

A

Lipids are insoluble in water.

Both plants and insects are wavy, lipid cuticles that conserve water, while mammals produce an oily secretion from the sebaceous glands in the skin

85
Q

How do lipids provide insulation?

A

fats are slow conductors of heat and when stored beneath the body surface help to retain body heat.

They also act as electrical insulators in the myelin sheath around the nerve cells

86
Q

How do lipids provide protection?

A

fat is often stored around delicate organs, such as the kidney

87
Q

What is another word for lipid?

A

fat

88
Q

Explain the structure of triglycerides?

A
    • a lipid
    • three fatty acids combined with glycerol
    • each fatty acid forms an ester bond with glycerol in a condensation reaction
    • hydrolysis of a triglyceride therefore produces glycerol and three fatty acids
89
Q

What causes differences in the properties of different fats and oils?

A
  • the glycerol molecule in triglycerides is the same
  • differences in the fatty acids
90
Q

How many types of fatty acids are there?

A

70

91
Q

what is the functional group of carboxyl?

A

-COOH

92
Q

When is a triglyceride explained as saturated?

A

chain between the carboxyl and hydrocarbon has no carbon-carbon double bonds.

As the carbon atoms are linked to the maximum possible number of hydrogen atoms

93
Q

Define - saturated bonds in triglycerides

A

When the carbon atoms are linked to the maximum possible number of hydrogen atoms

94
Q

What is the name given to a triglycerides with a single double bond?

A

mono-unsaturated

95
Q

What is the name given to a triglycerides with more than one double bond?

A

Polyunsaturated

96
Q

Explain how the structure of triglycerides relates to their properties

A
  • High ratio of energy - storing carbon - hydrogen bonds to carbon atoms
  • low mass to energy ratio - storage of molecules energy in a small volume
  • Reduces the mass - large, non-polar molecules and insoluble in water
  • not affect osmosis or the water potential of them - high ratio hydrogen to oxygen atoms
  • release water when oxidised - important source of water especially for organisms living in dry deserts
97
Q

Why does high ratio hydrogen to oxygen atoms in triglycerides relate to their properties?

A

This means they release water when oxidised and provide important source of water especially for organisms living in dry deserts

98
Q

Why does high ratio of energy in triglycerides relate to their properties?

A

This helps storing carbon - hydrogen bonds to carbon atoms and therefore an excellent source of energy

99
Q

Why does low mass to energy ratio in triglycerides relate to their properties?

A

This makes it good at storage of molecules because much energy can be stored in a small volume - especially benefits animals as reduces the mass they have to carry as they move around

100
Q

Why does being large, non-polar molecules and insoluble in water in triglycerides relate to their properties?

A

This means there storage does not affect osmosis in cells or the water potential of them

101
Q

What is the difference between triglycerides and phospholipids?

A

Phospholipids only have two fatty acid tails and the has a phosphate molecule instead

102
Q

What part of the phospholipids is hydrophobic ?

A

the fatty acid tails - repel water

103
Q

What part of the phospholipids is hydrophilic?

A

The phosphate molecules - attract water

104
Q

Define - hydrophilic

A

This means it interacts with water (or is attracted to it) but does not interact with fat eg. the head of the phospholipids

105
Q

Define - hydrophobic

A

This means it orients itself away from water but mixes readily with fat eg. the tail of the phospholipids

106
Q

Why is the phospholipids called polar?

A

As it has a molecule with two ends (poles) that behave differently

107
Q

What happens if phospholipids are placed in water?

A

position so hydrophilic heads are close to water and the hydrophobic tails are as far away from the water as possible.

Eg. in a circle with the tails inwards or creating a phospholipid bilayer

108
Q

How do you create a phospholipid bilayer?

A

When in water and a ball is created.

As this gets larger it squashes out to make a bilayer which is in a fluid mosaic model

109
Q

What is a fluid mosaic model?

A

molecules of phospholipid easily move and float around so things can float in and out for example proteins

110
Q

Explain how the structure of phospholipids relates to their properties.

A
  • polar molecules - in an aqueous environment form a bilayer within cell-surface membranes. - help to hold at the surface of the cell surface membrane
  • form glycolipids - combine with carbohydrates within the cell-surface membrane. These glycolipids are important in cell recognition
111
Q

Explain how to test for lipids

A

emulsion test

  1. take a completely dry and grease-free test tube
  2. to 2cm^3 of the sample being tested, add 5cm^3 of ethanol
  3. shake the tube thoroughly to dissolve any liquid in the sample
  4. add 5cm^3 of water and shake gently
  5. a cloudy-white colour indicates the presence of a lipid
  6. as a control repeat the procedures using water instead of the sample; the final solution should remain clear
112
Q

Why does the emulsion test make water cloudy?

A

Due to any lipid finely dispersed in the water to form an emulsion.

Light passing through this emulsion is refracted as it passes from oil droplets to water droplets, making it appear cloudy

113
Q

What are enzymes?

A
  • Catalysts lowering activation energy
  • Globular proteins that act as catalysts. speed up reactions
114
Q

What do catalysts do?

A

Alter the rate of a chemical reaction without undergoing permanent changes to themselves.

They can be used repeatedly and are therefore effective in small amounts.

115
Q

What are the conditions for a good reaction?

A
  • collide with sufficient energy to alter the arrangement of their atoms.
  • the free energy of the products must be less than that of the substrates.
  • initial amount of energy to start. Minimum called activation energy
116
Q

What is the activation energy of a reaction?

A

The minimum amount of energy needed to activate the reaction in this way

117
Q

Why would enzymes be useful?

A
  • The activation energy must be initially overcome before the reaction can proceed.
  • allows the reaction to take place at a lower temperature than normal.
  • This enables some metabolic processes to occur rapidly at the human body temperature of 37*C which is relatively low in terms of chemical reactions.
  • This speeds up a very slow and inefficient reaction
118
Q

State the structure of enzymes.

A
  • 3D sequence of amino acids (primary protein structure)
  • functional group/ active site specific.
  • n enzyme-substrate complex.
119
Q

Explain the induced fit model of enzyme action.

A
  • The proximity of the substrate leads to a change in the enzyme that forms the functional active site.
  • As the enzyme is flexible mould around substrate
  • The enzyme has a certain general shape but this alters in the presence of the substrate.
  • strain on the substrate molecule distorts a particular bond lowers the activation energy needed to break the bond.
120
Q

What is an amino acid?

A

A basic monomer unit which combine to make up a polymer called a polypeptide

121
Q

What is a polypeptide?

A

When amino acid units combine to make up a polymer called a polypeptide. These can be combined to form proteins.

122
Q

How many naturally occurring proteins are there?

A

20 - Out of 100 amino acids identified

123
Q

What does the number of amino acids prove?

A

20 Amino acids occur in all living organisms providing indirect evidence for evolution.

124
Q

Explain the structure of an amino acid.

A
    • The central carbon atoms are attached to four different chemical groups. -
  • Amino group (-NH2)
    • Carboxyl group (-COOH)
    • acidic group
    • Hydrogen atom (-H)
    • R (side) group
125
Q

What is the R group?

A

AKA a variable group

different chemical groups.

Each amino acid has a different R group.

126
Q

What do two amino acids make?

A

A dipeptide

127
Q

How is a dipeptide formed?

A

Condensation reaction

The water is made by combining an -OH from the carboxyl group of the amino acid and a -H from the amino group of another amino acid.

128
Q

What is the bond between two amino acids?

A

Peptide bond - between the carbon atom of one amino acid and the nitrogen atom of the other.

129
Q

How do you break a peptide bond?

A

Hydrolysis reaction

peptide bond of a dipeptide can also be broken by hydrolysis to give its constituent amino acids.

130
Q

Explain the primary structure of proteins

A
  • polypeptides
  • Amino acid monomers join in polymerisation.
  • This results in a polypeptide.
  • determined by DNA.
  • any sequence of the 20 naturally occurring amino acids
  • determines ultimate shape and function - A change can lead to a change in the function
131
Q

Explain the secondary structure of protein.

A
  • The linked amino acids that mark a polypeptide possess both
  • -NH (H is positive) and -C=0 (O is negative).
  • These readily form weak hydrogen bonds.
  • This caused the long polypeptide chains to be twisted into a 3D shape such as a coil of alpha-helix
132
Q

Explain the tertiary structure of proteins

A
  • twisted and folded to give the complex, and specific, 3D structure.
  • maintained by a number of bonds that occur depending on the primary structure of the protein
    • Disulfide bonds - fairly strong and not easily broken
    • ionic bonds - carboxyl and amino groups not involved in peptide bonds. Weaker than DB and easily broken by changes in pH
    • hydrogen bonds - numerous but easily broken Its this shape that is important to its function making proteins distinctive and recognisable to other molecules.
  • It can then interact with them in a very specific way.
133
Q

Explain the quaternary structure of proteins.

A
    • Only in large proteins
  • number of individual polypeptide chains that are links in various ways
    • This may include non-protein groups associated with the molecules, such as the iron-containing haem group in haemoglobin
134
Q

What is another word for non-proteins?

A

prosthetic

135
Q

Explain the test for proteins

A
  1. Place a sample in a test tube
  2. add an equal volume of sodium hydroxide solution at room temperature
  3. Add a few drops of very dilute (0.05%) copper(11) sulfate solution and mix gently
  4. A purple coloration indicates the presence of peptide bonds and hence a protein. If no protein is present, the solution remains blue
136
Q

What is another name for the protein test?

A

The biuret test - detecting peptide bonds

137
Q

What does the biuret test do?

A

This detects peptide bonds

138
Q

What is the positive result for the protein test?

A

A purple colouration

If no protein is present, the solution remains blue.

139
Q

What are the two types of protein?

A
  • Fibrous proteins - such as collagen which have structural functions.
  • Globular proteins - such as enzymes and haemoglobin which carries out metabolic function
140
Q

Explain the structure of fibrous proteins

A
  • Form long chains which run parallel to one another.
  • The chains are linked by cross-bridges and so form very stable molecules eg. Collagen
141
Q

Give an example of a fibrous protein

A

Collagen

142
Q

Explain the molecular structure of collagen

A
  • Primary sturcure is an unbranched polypeptide chain
  • Secondary structure - polypeptide chain is very tightly wound - Lots of amino acid, glycine helps close packing
  • Tertiary structure is twisted into a double helix
  • Quaternary structure is made of three polypeptide chains wound together in the same way as individual fibres are wound together in a rope.
143
Q

Where is collagen found?

A

tendons - joining muscle to bone.

When a muscle contracts the bone is pulled in the direction of the contraction

144
Q

How are individual collagen polypeptide chains in fibres held together?

A

Held by bonds between amino acids of adjacent chains

145
Q

What are two structural facts of enzyme reactions?

A
    • They must come into physical contact with its substrate
    • It must have an active site which fits the substrate
146
Q

Define - Time-course

A

How long it takes for a particular event to run its course.

147
Q

What changes are most frequently measured for enzyme-catalysed reactions?

A
  • The formation of the products of the reaction
  • The disappearance of the substrate,
148
Q

How do we measure the change in the rate of a reaction?

A
  • We can measure at any point on the curve of a graph.
  • gradient of at the chosen point
  • We have to accurately draw the tangent to a curve
149
Q

What does an increase in temperature do to molecules?

A

It increases the kinetic energy of molecules. As a result the molecules move around more rapidly and collide with each other more often.

150
Q

What does an increased temperature mean for an enzyme-catalysed reaction?

A

The enzyme and substrate molecules come together more often in a given time. There are more effective collisions resulting in more enzyme-substrate complexes being formed and so the rate of reaction increases.

151
Q

What negative thing can happen if the temperature is increased in an enzyme reaction?

A

It begins to cause the hydrogen and other bonds in the enzyme to break. This results in the enzyme, including its active site, changing shape. At first the substrate will fit less easily and the rate of reaction will be reduced. Then the enzyme will be so disrupted that it stops working altogether.

152
Q

At what temperature does enzymes and their active sites start to change shape?

A

45*C

153
Q

What temperature does an enzyme denature?

A

Around 60*C

154
Q

Define - Denaturation

A

A permanent change and, once it has occurred, the enzyme does not function again.

155
Q

Why has our body temperature evolved?

A
  • increase the metabolic rate slightly, the advantaged are offset by the additional energy (food) needed to maintain the higher temperature
  • Other proteins, apart from enzymes, may be denatured at higher temperatures
  • At higher temperatures, any further ruse in temperature, for example, during illness, might denature the enzymes
156
Q

What is the normal body temperature of a bird?

A

around 40oC

As they have a high metabolic rate for the high energy requirement of flight

157
Q

What is the human bodies optimum temperature?

A

37oC

158
Q

What is the pH?

A

The pH of a solution is a measure of its hydrogen ion concentration.

159
Q

What does a change in pH cause?

A

Away from the optimum affects the rate of enzyme action.

An increase or decrease in pH reduces the rate of enzyme action.

If it is more extreme then, beyond a certain pH, the enzyme becomes denatured

160
Q

In what ways does an pH affect how an enzyme works?

A
  • A change in pH alters the charges on the amino acids that make up the active site of the enzyme.
  • substrate can no longer become attached to the active site
  • enzyme-substrate complex cannot be formed -
  • The active site therefore changes shape
161
Q

On an active site on an enzyme has acted on its substate what happens next?

A
  • repeat the procedure on another substrate molecule
  • enzymes are not used up in the reaction and therefore work efficiently at very low concentrations.
162
Q

What happens if there is an excess of substrate and an increased enzyme concentration?

A
  • This leads to a proportionate increase in the rate of reaction.
  • Because there is more substrate than the enzyme’s sit can cope with
163
Q

What happens if the substrate is limited compared to the enzyme?

A
  • Not sufficient to supply all the enxymes active sites at one time a further increase would not effect the rate of reaction
  • The ROR is therefore stabilised at a constant level meaning the graph would level off.
  • As the available substrate is already being used as rapidly as it can be by the existing enzyme molecules.
164
Q

Explain what low enzyme concentration will do to the rate of reaction

A
  • Too few enzyme molecules to allow all substrate molecules to find an active site at one time
  • ROR is only half the maximum possible for the number of substrate molecules availiable
165
Q

Explain what intermediate enzyme concentration will do to the rate of reaction

A
  • With enough enzyme molecules for substrate, all active sites can be used at the same time
  • ROR is at max as all active sites are filled
166
Q

Explain what high enzyme concentration will do to the rate of reaction

A
  • The addition of more enzyme molecules than substrates has no more effects as some can not be used
  • No further increase in the rate of reaction
167
Q

Explain what low substrate concentration will do to the rate of reaction

A
  • Too few substrate molecules to occupy all available active sites.
  • ROR is less than max possible for the number of enzymes molecules available
168
Q

Explain what intermediate substrate concentration will do to the rate of reaction

A
  • More substrate molecules means all active sites are being used at one time
  • The ROR is at its maximum as all active sites are filled
169
Q

Explain what high substrate concentration will do to the rate of reaction

A
  • The addition of further substrate molecules has no effect as all active sites are already occupied
  • No increase in ROR
170
Q

What is the optimum temp for bacteria?

A

95*C and continue past 100*C

171
Q

What is a thermophilic?

A

Bacteria that loves hot temperatures

172
Q

What are enzyme inhibitors?

A

Substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduce its activity

173
Q

State the two types of enzyme inhibitors

A
  • Competitive - Bind to active site of enzyme
  • Non-competitive - Bind to enzyme at a position other than the active site
174
Q

Explain the structure of a competitive inhibitor

A
  • shape similar to substrate.
  • occupy the active site of an enzyme
  • compete with the substrate
175
Q

What effects the enzyme activity for competitive inhibitors?

A

The difference between the concentration of the inhibitor and the concentration of the substrate.

176
Q

What do non-competitive inhibitors do?

A
  • Attach at allosteric site
  • inhibitor alters the shape of the enzyme
  • so the enzyme cannot function

As the substrate and inhibitor are not competing for the same site, an increase in substrate concentration does not decrease the effect of the inhibitor

177
Q

What effect does a non-competitive inhibitor have on an increased amount of substrate?

A

As the substrate and inhibitor are not competing for the same site, an increase in substrate concentration doe not decrease the effect of the inhibitor

178
Q

What is a metabolic pathway?

A

A series of reactions in which each step is catalysed by an enzyme.

179
Q

Explain the properties of the metabolic pathways

A
  • many hundreds of different pathways
  • The enzymes that control a pathway are often attached to the membrane of a cell organelle in a very precise sequence.
  • Inside each organelle optimum conditions for the functioning of particular enzymes may be provided
  • To keep a steady concentration of a particular chemical in a cell, the same chemical often acts as an inhibitor of an enzyme at the start of a reaction.
180
Q

Give an example of end-product inhibition

A

In the metabolic pathways

  • If too much or little is produced there is a greater/less inhibition of the enzyme so the concentration returns to normal.
181
Q

Explain what end-product inhibition is?

A

If too much or little is produced there is a greater/less inhibition of the enzyme so the concentration returns to normal.

182
Q

Define - Saturated

A

No double bond

183
Q

Define - Monosaturated

A

One double bond

184
Q

Define - Polysaturated

A

Multiple double bonds

185
Q

What is the main cause of fatty acid variation?

A

Saturation

186
Q

If fat saturated or unsaturated

A

Usually saturated

187
Q

If oil saturated or unsaturated

A

Usually unsaturated

188
Q

What caused variation in triglycerides?

A
  • Glycerol are always the same
  • The fatty acid tails cause variation
189
Q

What chemical is stored in the tubers of potatoes?

A

Starch

190
Q

How can you test for starch?

A

Iodine test

  • Collect sample and place on tile.
  • Add a drop of iodine to the sample and if colour change then starch is present.
  • Orange to blue black
191
Q

Why may animals secrete acid?

A

To produce the optimum pH for the microbe being broken down.

192
Q

What type of substance is cellulase?

A

enzyme

193
Q

What is the function of cellulase?

A

breaks up cellulose

194
Q

Where in the cells and why what process is energy made available?

A

Mitochondria

  • Aerobic respiration
  • ATP In cytoplasm
  • Anaerobic respiration
195
Q

Which molecule is used to transport energy around cells?

A

ATP

196
Q

Required Practical 1

What is the IV for an investigation into the effect of a named variable on the rate of an enzyme-controlled reaction?

A

The different temperatures used

197
Q

Required Practical 1

What is the DV for an investigation into the effect of a named variable on the rate of an enzyme-controlled reaction?

A

The time taken to first see the X

198
Q

Required Practical 1

What should be controlled in an investigation into the effect of a named variable on the rate of an enzyme-controlled reaction?

A
  • Same marker pen
  • same milk powder
  • The same concentration of trypsin
  • Same person checking the visibility of X
199
Q

Required Practical 1

Explain the method for an investigation into the effect of a named variable on the rate of an enzyme-controlled reaction

A
  1. Marker an ‘X’ halfway down the side of three test tubes.
  2. Add 10cm3 of the solution of milk powder to each
  3. In three clean - Add 2cm3 of trypsin solution to 2cm3 of pH 7 buffer
  4. Stand all tubes in a water bath at 20°C.
  5. Leave 10 minutes.
  6. Combine one of each tubes content
  7. Bung each test tube - invert 5 times to mix thoroughly.
  8. Put the test tube back into the water bath.
  9. Time how long it takes for the milk to go clear. Stop when seeing X. (Can use colourimeter - trypsin = calibration)
  10. Record the time in a suitable table
  11. Repeat method at 30°C, 40°C, 50°C, 60°C.
  12. Process your data and draw a graph of your processed data.

AS level Biology (11 decks)

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