cloning and biotechnology qp1

Question 1

as sugar concentration decreases, ethanol concentration increases
Explain this relationship

Answer 1

sugar/maltose/glucose is being converted to ethanol
-this is occurring in anaerobic respiration
-sugar undergoes glycolysis/ converted to pyruvate
-pyruvate loses carbon dioxide/ becomes decarboxylated/ forms ethanal
-NAD is regenerated
-correct ref to pyruvate decarboxylase/ ethanol dehydrogenase

Question 2

explain why ethanol is considered to be a primary metabolite of yeast

Answer 2

• ethanol is produced in all yeast growth phases/ all of the time
  -production of ethanol increases as yeast population increases
  -ethanol is a normal (metabolic waste) product of yeast

Question 3

what two factors may limit the maximum size of the yeast population

Answer 3

-if sugar concentration falls too low
-if pH falls too low
-high ethanol concentration damages/ poisons/ inhibits yeast

Question 4

a mixture of sugars are added to the batch fermenter, monoschaccarides are used forst, then disaccharides then trisaccharides. Explain why the yeast uses them in this order

Answer 4

-monosachariide can be used/ enters glycolysis directly without being broken down.
-maltose must be hydrolysed/ have glycosisic bonds brokwn
-enzyme/ maltase only made when glucose is running out.
- enzymes induced/ gene(s) switched on.
-transcription and translation takes time/protein synthesis takes time
-maltotriose requires two hydrolysis reactions/ breaking of glyosidic bonds or enzymes to break down trosemaltose last