Chapter 1 Aqa Biology

Front 1

What are biological molecules

Back 1

molecules made and used by living organisms e.g. Carbohydrates, Proteins, Lipids, DNA, ATP, Water, Inorganic Ions

Front 2

What are the functions of carbohydrates

Back 2

energy source (glucose in respiration)
energy store (starch in plants, glycogen in animals)
structure (cellulose in cell wall of plants)

Front 3

What are the building blocks for carbohydrates called

Back 3

monosaccharides

Front 4

Example of monosaccharides

Back 4

- glucose (alpha and beta),

- galactose,

- fructose

Front 5

Formula for monosaccharides

Back 5

C6H12O6 (isomers = same formula but different arrangement)

Front 6

Difference between alpha and beta glucose

Back 6

on Carbon 1, alpha glucose has a OH group on the bottom and beta glucose has a OH group on the top.

Front 7

Bond in carbohydrate

Back 7

glycosidic bond

Front 8

How are monosaccharides joined together

Back 8

condensation reaction (removing water) – between 2 OH groups.

Front 9

Example of disaccharides

Back 9

glucose + glucose = maltose

glucose + galactose = lactose

glucose + fructose = sucrose

Front 10

Formula for disaccharides

Back 10

C12H22O11

Front 11

How are polymers separated

Back 11

hydrolysis (add water)

Front 12

What is a polysaccharide

Back 12

Many monosacharrides joined by condensation reaction/glycosidic bonds.

Front 13

Example of polysaccharides

Back 13

1. Amylose (long chain of alpha glucose) which makes starch/glycogen.
2. Cellulose (long chain of beta glucose) which makes cell wall in plants.

Front 14

What are Polysaccharides

Back 14

carbohydrates
made of a long chain of monosaccharides joined by condensation reaction/glycosidic bonds.
3 examples: Starch, Glycogen, Cellulose.

Front 15

Properties of Starch and Glycogen as energy stores

Back 15

Insoluble = do not affect water potential of the cell, do not diffuse out of the cell
Coiled/Branched = compact, more can fit into a cell
Branched/Chained = glucose removed from the end

Front 16

Structure of Cellulose

Back 16

1. β-glucose arranged in a straight chain (each alternative β-glucose is rotated 180 degrees).
2. Many cellulose chains are cross linked by hydrogen bonds to form microfibrils.
3. Many microfibrils are cross linked to form marcrofibrils.
Creates a strong material.

Front 17

Test for starch

Back 17

add iodine, turns blue/black

Front 18

Test for reducing sugar

Back 18

heat equal ammounts of sample and Benadict's regent, turns brick red.

Front 19

Test for non-reducing sugar

Back 19

1. Test for reducing sugars
2. Take a new sample and add dilute hydrochloric acid (hydrolyses glycosidic bond) and heat gently.

3. Slowly Add sodium hydrogencarbonate (neutralises solution) until solution is alkaline.
4. heat with Benedict's - turns brick red

Front 20

What are 2 types of proteins

Back 20

Globular and Fibrous

Front 21

What are globular proteins

Back 21

Soluble proteins with a specific 3D shape e.g. enzymes, hormones, antibodies, haemoglobin.

Front 22

What are fibrous proteins

Back 22

strong/insoluble/inflexible material e.g. collagen and keratin

Front 23

What are the building blocks for proteins

Back 23

Amino acids

Front 24

Structure of amino acid

Back 24

central carbon, carboxyl group to the right (COOH), amine group to the left (NH2), hydrogen above and R group below.

Front 25

How do amino acids differ

Back 25

have different R groups e.g. glycine has a hydrogen in its R group – simplest amino acid

Front 26

How are amino acids joined together

Back 26

By condensation reaction between the carboxyl group of one and amine group of another, leaves a bond between carbon & nitrogen (called a peptide bond) forming a dipeptide.

Front 27

Define primary, secondary, tertiary, quaternary structure

Back 27

Primary = sequence of AA, polypeptide chain (held by peptide bonds)
Secondary = the primary structure (polypeptide chain) coils to form a helix, held by hydrogen bonds
Tertiary = secondary structure folds again to form final 3d shape, held together by hydrogen/ionic/disulfide bonds
Quaternary = made of more then one polypeptide chain

Front 28

Examples of quaternary structure proteins

Back 28

collagen (3 chains), antibodies (3 chains), haemoglobin (4 chains)

Front 29

Structure of collagen

Back 29

strong material, used to build tendons/ligaments/connective tissues.
1. Primary structure mainly made up of glycine.
2. Secondary structure forms a tight coil (not much branching due to glycine)
3. Tertiary structure coils again
4. Quaternary structure made from 3 tertiary structures wrapped around each other like rope.

Front 30

Test for protein

Back 30

1. Mix equal volumes of sodium hydroxide solution and the sample.

2. Add a few drops of dilute Copper(II) Sulphate solution.

3. Will turn purple in the presncence of proteins.

Front 31

What is an enzyme

Back 31

A biological catalyst that lowers activation energy required for a reaction top take place.

Front 32

What makes an enzyme specific

Back 32

It has a specific active site shape, only complementary substrates can bind to the active site to form enzyme-substrate complexes.

Front 33

Lock and Key Model vs Induced Fit Model

Back 33

LK = active site shape is rigid, only exactly complementary substrates can bind to form ES complexes.
IF = active site changes shape, the substrate binds to the active site – the active site changes shape so the substrate fits exactly forming an ES complex.

Front 34

Affect of substrate concentration on enzyme activity

Back 34

1. Increase substrate concentration.

2. Increases chance of successful collisions.

3. Increase chance of forming an ES complex.

4. Increase rate of reaction.
5. This continues until all the enzyme's active sites are full/saturated and the maximum rate of reaction is reached.

Front 35

Affect of enzyme concentration on enzyme activity

Back 35

1. Increase enzyme concentration,

2. Increases chance of successful collisions,

3. Increase chance of forming an ES complex,

4. Increase rate of reaction
5. This continues until all the substrates are used up the maximum rate of reaction is reached.

Front 36

Affect of temperature on enzyme activity

Back 36

1. As temperature increases the kinetic energy increases which causes the molecules to move faster.
2. There are more collisions occer which increases the chance of forming an ES complex.
4. So the rate of reaction increases until the optimum is reached.
5. Hydrogen and ionic bonds in tertiary structure break causing the structure of the molecule to change. So the substrate is no longer complimentary to the active site.

6. Less ES complexes form, reducing the rate of reaction.

Front 37

Affect of pH on enzyme activity

Back 37

If change pH away from optimum, bonds in tertiary structure break, lose active site shape, no longer form ES complex, the enzyme becomes denatured.

Front 38

Competitive vs Non-Competitive Inhibitors

Back 38

Competitive = a substance with a similar shape to the substrate and a complementary shape to the enzyme's active site, binds to the active site, blocking it, preventing ES complexes from forming.
Non-Competitive = a substance that binds to another site on the enzyme other then the active site, causes the active site to change shape, so less ES complexes can form.

Front 39

What are the 3 types of Lipids

Back 39

Triglycerides (fat for energy store, insulation, protection of organs).
Phospholipids (to make membranes).
Cholesterol (for membrane stability and make hormones).

Front 40

Structure of triglyceride

Back 40

Made of 1 glycerol and 3 fatty acids which are joined by condensation reaction.
there are 2 types of triglycerides: saturated fat and unsaturated fat

Front 41

Saturated vs Unsaturated Fat

Back 41

Saturated = has no carbon double bonds in the R group of the fatty acid
Unsaturated = has carbon double bonds in the R group of the fatty acid

Front 42

Structure of phospholipid

Back 42

made of 1 glycerol, 2 fatty acids and 1 phosphate
phosphate forms a hydrophillic head, fatty acids form hydrophobic tails
forms a phospholipid bilayer, basic structure of membranes