Biological Molecules

Question 1

Cellulose

Answer 1

Function:
Supports the structure of the cell wall, is insoluble and strong

• a Polymer of beta Glucose and alpha Glucose in an alternating straight chain structure with 1,4 Glycosidic bonds (the chains are attached by hydrogen bonds creating microfibrils)

Question 2

Glycogen

Answer 2

• Made with only alpha Glucose with 1,4 and 1,6 Glycosidic bonds- after 8 branches are formed which make it compact and allows more energy to be stored and removed quickly
• the molecule chains are insoluble so are broken up by hydrolysis during respiration

Question 3

Starch

Answer 3

AMYLOSE: (20-30%)
- Made is alpha Glucose joined by 1,4 Glycosidic bonds which makes a coiled helix structure which is compact and allows for storage in grains due to the angle of the bonds

AMYLOPECTIN: (70-80%)
- Made of alpha Glucose with 1,4 and 1,6 Glycosidic bonds which create a branched structure which is even more compact and allows multiple glucose molecules to be removed by hydrolysis at a time

Question 4

Testing for Carbohydrates

Answer 4

STARCH:
- add iodine, if present it’s will change from brown to blue//black and the iodine sticks to the amylopectin

REDUCING SUGARS (free aldehyde or ketone group):
- add Benedicts reagent and heat, if present it will change form blue to brick red - the colour can be seen as a semi quantitative result (a colorimeter can’t be used to show how reducing the sugar is - at low concentrations less precipitate is formed and therefore there’s a higher absorption of the red light, which makes the sample more blue)

NON-REDUCING SUGARS (No OH group attached):
- add HCl and heat in water bath, then neutralise and add Benedicts reagent before heating again. If non-reducing the more red the precipitate is, the more non-reducing the sugar being tested is - if blue it isn’t non-reducing

Question 5

Disaccharides

Answer 5

Glucose + Glucose —> Maltose

Glucose + Fructose —> Sucrose

Glucose + Galactose —> Lactose

^ condensations reaction forking C1,4 Glycosidic bonds between the two molecules al- the reaction also produces water

Question 6

ATP ( Adenosine Triphosphate )

Answer 6

• a Nucleic acid molecule with a single nucleotide (I like DNA or RNA)
• is a Triphosphate group attached to a ribose sugar so that chemical energy can be stored in the bonds between the phosphate group
• the chemical bonds// energy is released by hydrolysis as the bonds are broken down, converting ATP to ADP and he AMP
• the construction of a larger phosphate group (addition of a phosphate to an amino acid) is called phosphorylation

Question 7

Important molecules

Answer 7

Macromolecules (Carbohydrates for storage, Proteins for transport and structure, lipids for energy supplies and structures, also water and Nucleic acids of DNA and RNA)
^ crated by polymerisation of monomers

Question 8

Metabolism

Answer 8

ANABOLISM:
- larger, more complex molecules made up from smaller simpler ones using energy through a condensation reaction as Glycogenesis.

CATABOLISM:
- break down of larger complex molecules into smaller simpler ones releasing energy through hydrolysis as Glycolysis

Question 9

Water

Answer 9

• a polar molecule as there are a pair of bonded electrons and also 2 lone pairs which repel more
• this allows water molecules to be attached to each other by wear intermolecular forces of Hydrogen Bonds (between an H and a lone pair)
• This makes water a good solvent of hydrophilic substances and as a solid water is less dense than liquid as of the extent ion if the hydrogen bonds as they are in a fixed position dot the repel between the like poles creates a set lattice structure

(Water is a coolant, transport medium, habitat and solvent)