Chapter 2- Biological molecules

Question 1

Why is water important?

Answer 1

Helps transport other molecules through the body
Part of photosynthesis
Hydration- 70-80% of the body needs to be water for key chemical reactions to occur
Major habitat
Required for health and metabolism

Question 2

Why are hydrogen bonds important?

Answer 2

Join individual water molecules together and they will always form between negative oxygen and positive hydrogen
Are important to allow water to flow- they are weak alone but very strong together

Question 3

What are the main characteristics of water?

Answer 3

Ice is less dense than water- float on top of a liquid
Water has a high specific heat capacity- 4.2J of energy to heat 1g of water by 1 degrees leading to thermostability
Cohesive- attracted to itself and so forms bonds
Adhesive- attracted to other substances and allows to travel up the xylem of a plant
Amphoteric- can act as an acid or a base and allows water to be a pH buffer
Described as a universal solvent- substances that are polar dissolve in it

Question 4

What are the categories that carbohydrates are organised into?

Answer 4

Monosaccharides- 1 sugar unit
Disaccharides- 2 sugar units
Polysaccharides- 2+ sugar units

Question 5

What are the different categories further split into?

Answer 5

Triose- 3
Pentose- 5
Hexose- 6
Number of carbohydrates in their structure

Question 6

What are the main 3 disaccharides and what monosaccharides are they made of?

Answer 6

Glucose, fructose and galactose
Glucose + glucose = maltose
Glucose + galactose = lactose
Glucose + fructose = sucrose

Question 7

What are the main types of bonds between carbohydrates?

Answer 7

1-4 glycosidic bonds

1-6 glycosidic bonds

Question 8

What are the 3 main examples of polysaccharides?

Answer 8

Glycogen
Starch
Cellulose

Question 9

What are the characteristics in gylcogen?

Answer 9

Main energy storage unit in animals
Left-over glucose in the blood will be converted into glycogen
It is insoluble
Formed by repeating alpha glucose joined together
Both 1-4 and 106 glycosidic bonds
Most branched polysaccharide- rapid hydrolysis by enzymes

Question 10

What are the characteristics of starch?

Answer 10

Main storage for plants
Composed of 2 polysaccharide chains- amylose (1-4) and amylopectin (1-4+1-6)
Only contains alpha glucose

Question 11

What are the characteristics of cellulose?

Answer 11

Located in plant cell walls as it provides strength and support
Composed of only beta glucose- every other beta glucose is inverted so the hydroxyl group can interact so H2O can form creating a 1-1 glycosidic bond
Incredibly strong as hydrogen bonds form between each microfibril

Question 12

What is a microfibril?

Answer 12

At least a50 b-glucose connected through condensation reactions

Question 13

What are the benefits of lipids?

Answer 13

Used for insulation for the organism and individual cells
More energy per gram than any other biological molecule
Waterproofing- hydrophobic so they repel water

Question 14

What are triglycerides?

Answer 14

Group of lipids called macro-molecules
Composed of 3 fatty acids and a glycerol molecule
Ester bonds form between O of glycerol and C of FA
Formed through a specific condensation reaction called esterification

Question 15

What are the two types of fatty acids and their differences?

Answer 15

Saturated fatty acids- no double bonds, fully saturated with hydrogen, solid at room temp and the main example is animal fats
Unsaturated fatty acids- not fully saturated with hydrogen, double bonds between carbons do exist which causes the hydrocarbon chain to kink, C-H bonds are often far apart

Question 16

What are proteins required for and some examples of what they create?

Answer 16

Growth and repair

Examples- hair, skin, nails, muscles, DNA, enzymes

Question 17

What are proteins made up of?

Answer 17

Amino acids

Question 18

What is the bond between different amino acids?

Answer 18

Peptide bonds

Question 19

What is the test for reducing sugars?

Answer 19

1- Reducing sugars can donate electrons and when they do this they become oxidised
2- Sample turns red as it contains glucose as benedicts reagent contains Cu2+ and it donates an electron to the Cu2+

Question 20

What is the test for non reducing sugars?

Answer 20

1- When testing to see if sucrose is reducing, it remains blue
2- Add HCl as it breaks down the glycosidic bond between glucose and fructose which exposes glucose and turns red

Question 21

What is the primary structure of proteins?

Answer 21

sequence of amino acids

bond- peptide bond

Question 22

What is the secondary structure of a protein?

Answer 22

Dependant upon where hydrogen structures form
two different types- a-helix and b-pleated sheet
bonds- peptide bonds and hydrogen bonds

Question 23

What is the tertiary structure of proetins?

Answer 23

final structure of a single polypeptide chain
interaction between the R-variable groups of each AA involved in a protein
Bonds- peptide bonds, hydrogen bonds, ionic bonds and disulfide bonds

Question 24

What is the quaternary structure of a protein?

Answer 24

Only occurs if the protein is composed of more than one polypeptide chains
Examples- insulin is made of 2 chains and haemoglobin is made of 4 chains

Question 25

What are globular proteins?

Answer 25

Compact and water soluble
Take part in chemical reactions
Form when proteins fold into their tertiary structure and the hydrophobic R-variable groups are kept away from aqueous environment

Question 26

What are conjugated proteins?

Answer 26

Contain a non-protein group
examples- lipoproteins and glycoproteins
Haem groups- an iron ion, catalase and haemoglobin both contain these

Question 27

What are fibrous proteins?

Answer 27

Responsible for building the body
Eg- keratin, collagen and elastin
They are- unreactive, insoluble and strong