Carbohydrate Metabolism - PP Exam 2

Question 1

Where in the cell is sucrose synthesized?

Answer 1

In the cytoplasm, synthesized from Triose-P that was produced from the Calvin cycle and transported to the cytoplasm.

Question 2

Where in the cell is starch synthesized? (Photosynthetic vs Non-photosynthetic)

Answer 2

In the plastids

In photosynthetic cells, starch is synthesized in the chloroplasts, from Triose-P produced from the Calvin cycle

In non-photosynthetic cells, starch is synthesized in the amyloplast, from Hexose-P produced from imported sucrose.

Question 3

What are amylose and amylopectin?

Answer 3

Amylose and amylopectin are polymers of glucose, used to form starch. Amylose is either linear or slightly branched, with 1-4 glycosidic linkages between glucose residues. Amylopectin is branched, with 1-6 glycosidic chains between chains.

Question 4

If the photosynthetic rate is high, how will it change the concentration of fructose-2, 6-bisphosphate

Question 5

When do plants synthesize starch, during the day or night?

Answer 5

It is synthesized during the day in plastids, and it is degraded during the night.

Question 6

If the ratio of sucrose synthesized to sucrose exported increases in a photosynthetic cell, how would this affect the concentration of fructose-6-phosphate?

Question 7

If the ratio of sucrose synthesized to sucrose exported increases in a photosynthetic cell, how would this affect the concentration of fructose-2,6-bisphosphate?

Question 8

If the ratio of sucrose synthesized to sucrose exported increases in a photosynthetic cell, how would this affect the synthesis of sucrose?

Question 9

If the ratio of sucrose synthesized to sucrose exported increases in a photosynthetic cell, how would this affect the synthesis of starch?

Question 10

How does starch travel through a plant?

Answer 10

it cannot travel in its natural form, so it must be broken down to sucrose and then transported

Question 11

How does Glucose 6-P increase the synthesis of sucrose?

Answer 11

• it increases the activity of sucrose phosphate
• it inactivates the kinase that converts sucrose-P synthase into an inactive form of the enzyme

Question 12

Where do the two amino acids from asparagine come from?

Answer 12

one comes from aspartate, after being synthesized from glutamine

second group comes from a molecule of glutamine