Tats

Question 1

Describe how the structures of starch and cellulose molecules are related to their functions.

short

Answer 1

Starch is helically coiled. This means it is compact. It also is branches, which means glucose is easily released for respiration. Starch is also insoluble. As a result, it is osmotically inactive and doesn’t affect water potential. It is also a large molecule, which means it can not leave the cell membrane.
Cellulose is a long, straight, unbranded chain of beta glucose it is joined by hydrogen bonds, which form microfibrills that provide strength and rigidity.

Question 2

Describe the structure of proteins

short

Answer 2

Polymer chain of amino acids joined by peptide bonds from a condensation reaction. The primary structure is the number type and sequence of amino acids. The secondary structures are alpha helices and beta pleated sheets formed by hydrogen bonds. The tertiary structure is 3d folded amino acids by hydrogen and ionic bonding and disulphide bridges to form globular proteins. The quaternary structure has 2 or more polypeptide chains.

Question 3

Describe competitive and non-competitive inhibition of an enzyme.

short

Answer 3

Competitive
Inhibitors reduce binding of enzyme to substrates to prevent the formation of e-s complexes forming. Inhibitor is a similar shape to substrate. Binds to active sites can be overcome by more substrate
Non-competitive
Inhibitor binds to site on enzyme other than active. Prevents formation of active site. Cannot be overcome by adding more substrate.

Question 4

Describe the appearance and behaviour of chromosomes during mitosis.

issott

Answer 4

During prophase chromosomes coil and appear as chromatids joined at the centromere. during metaphase chromomsomes line up on the equator, and attach to spindle fibres by their centromere. During anaphase, the centromere splits, the sister chromatids are pulled to opposite poles of the cell. during telophase, chromatids uncoil and become thinner.