Aqa As Biology Biological Molecules

Front 1

What are living things made of?

Back 1

Thousands of different chemicals which are called organic because they contain the element carbon

Front 2

What kind of compounds do organic and inorganic compounds contain?

Back 2

• Organic compounds contain carbon-carbon bond

• Inorganic compound don't

Front 3

What are the 4 types of organic molecules found I living organism?

Back 3

• Carbohydrate

• Protein

• Lipids

• Nucleic acids (DNA)

Front 4

What elements do carbohydrate contain?

Back 4

• Carbon

• hydrogen

• oxygen

Front 5

What is the monomer of carbohydrate?

Back 5

• Monosaccharides

• Most important and common is Glucose

Front 6

What are the isomers of glucose?

Back 6

• Galactose

• Fructose

Front 7

How are disaccharides formed?

Back 7

• When two monosaccharides are joined together by GLYCOSIDIC BOND

Front 8

What is the reaction called where two molecules combine to form a bigger molecules?

Back 8

Condensation reaction

Front 9

What is the reaction where a big molecule is split into two smaller molecules?

Back 9

Hydrolysis

Front 10

What are the three common disaccharides and what are they made from?

Back 10

Glucose + Glucose = Maltose

Glucose + Fructose = Sucrose

Glucose + Galactose = Lactose

Front 11

What is starch broken by and into what?

Back 11

• Amylase

• Maltose

Front 12

Give 3 examples if polysaccharides?

Back 12

• Starch

• Cellulose

• Glycogen

Front 13

What are lipids?

Back 13

• Mixed group of hydrophobic compounds

• Carbon, hydrogen, oxygen, phosphorus

Front 14

What are the most common types of lipids?

Back 14

Triglycerides and phospholipids

Front 15

What is triglyceride made of and what are they used for?

Back 15

• 3 fatty acid + 1 glycerol

• Joined by ester bond

• known as fats or oil

• insoluble in water(don't dissolve)

> Used for storage

> Insulation

> Protection

Front 16

Why are triglycerides not a good source of energy?

Back 16

Because they cannot be mobilised quickly as they are insoluble so not good for quick energy requirement

Front 17

What does saturated mean?

Back 17

No C=C bond

• High melting point

• found in warm blooded animals

• Room temperature they are solid

Front 18

What does unsaturated mean?

Back 18

Has a C=C bond

• Low melting point

• Found cold blooded animals and plants

• Room temperature are liquids

Front 19

What is the structure of phospholipid?

Back 19

They have 2 fatty acid, a glycerol and a phosphate

• Hydrophilic head

• Hydrophobic tail

Front 20

What type of bond are amino acids joined together by?

Back 20

Peptide bonds through condensation reaction

Front 21

How are proteins made?

Back 21

Through polymerisation of amino acid in protein synthesis which takes place in ribosomes and requires a RNA template.

The sequence of amino acid in polypeptide chain is determined by the sequence of bases in the DNA

Front 22

What is the primary structure of a protein?

Back 22

Sequence of amino acid in a polypeptide chain

Front 23

What is the secondary structure of protein?

Back 23

• Held together by hydrogen bond to form backbone

• Alpha helix

• Beta sheet

Front 24

What is the tertiary structure of protein?

Back 24

• Compact globular shape

• polypeptide chain folded together

• Every protein has a unique tertiary structure which is responsible for its properties and function

Front 25

What is the quaternary structure of proteins?

Back 25

• Compose of more than one polypeptide chain

• Arrangement of different chain

Front 26

What are the 3 dimensional shape of protein?

Back 26

Globular and fibrous protein

Front 27

What is the test for starch?

Back 27

• Add few drops of iodine to sample

• Blue-black colour formed

Front 28

Describe the test for reducing sugar

Back 28

• Add few drops of benedict reagent to sample

• Shake and heat for a few minute in a water bath at 95 degrees

• A coloured ppts indicates reducing sugar (brown/red)

Front 29

Describe the test for non reducing sugar

Back 29

• First hydrolyse to monosaccharide

• By boiling tube with dilute hydrochloric acid

• To hydrolyse glycosidic bond

• Add sodium hydrogen carbonate

• Do the test for non reducing sugar

Front 30

Describe the test for lipids

Back 30

• Emulsion test

• Shake test sample with ethanol

• Put into a test tube of water

• A cloudy white emulsion is formed

Front 31

Describe the test for protein

Back 31

• Add biuret solution to the sample

• Shake

• Turns lilac-purple

Front 32

What are enzymes?

Back 32

Enzymes are biological catalyst that speed up the rate of reaction

Front 33

How do enzymes work?

Back 33

1) Manipulate substrate in active site

2) Provide an alternative pathway

3) Lower activation energy

Front 34

Describe the lock and key model of enzyme action

Back 34

• Active site is complementary to substrate

• Substrate fits 'perfectly'

• Binds with one substrate only

Front 35

Describe the induced fit model

Back 35

• Enzyme is flexible

• Active site can change shape

• Isn't excited complementary to substrate

• When substrate binds, active site changes shape to for the substrate

• Distorts substrate molecule

• Change into product

Front 36

What are the factors that affect rate of enzyme?

Back 36

• Temperature

• PH

• Enzyme concentration

• Substrate concentration

• Inhibitors

Front 37

How does temperature affect rate of enzyme reactions?

Back 37

• Organisms have an optimum temperature which they work best

• Higher temperature increases the rate of reaction until it reaches the optimum temp

• There's more kinetic energy

• More molecules have enough energy to overcome activation energy

• At too high a temperature

• Enzyme is denatured as

• Weak hydrogen bond holding tertiary structure is broken

• So enzymes lose specific shape becomes random coil

• Substrate can no longer bind

Front 38

How does PH affect the rate of enzyme reactions?

Back 38

There's an optimum PH at which enzymes work best

• Increase in PH will increase the rate of reaction

• Too high of an increase would denature the enzyme as the shape of enzyme would be changed

• As well as the charge of the active site

Front 39

How does enzyme concentration affect the rate of reaction?

Back 39

• As enzyme concentration increases the rate of reaction increases

• More enzyme to catalyse the reaction

• At very high enzyme concentration the substrate conc may be limiting

• So the rate of reaction slows down

Front 40

How does substrate concentration affect the rate of reaction?

Back 40

• Curve dependence

• As substrate conc increases rate of reaction increases

• More substrate molecule collides with enzyme so more reaction takes place

• At higher conc the active site becomes Saturated with substrate

• So there are few enzyme molecules

• Adding more substrate won't make any difference

Front 41

How does inhibitors affect rate of reaction?

Back 41

Inhibitors work by reducing the rate of reaction.

They are used artificially as drugs, pesticides and research tools.

2 types:

Those that bind weak- reversible inhibitor

Those that bind strongly-irreversible inhibitor

Front 42

What are the 2 types of inhibitor?

Back 42

1) Competitive inhibitor-

- similar structure to normal substrate molecule

- so compete with substrate for active site

2) Non-competitive inhibitor

- different structure to normal substrate

- do not fit the active site

- bind to other site other than the active site

- change the shape of the whole enzyme including active site

- substrate can no longer bind to enzyme

Front 43

Distinguish between enzyme and receptors

Back 43

- Enzyme had an active site, receptors have binding site

- In enzyme the substrate is changed and released as a different molecule

- In receptors the substrate remains the same