Questions 18 - 25

1
Questions 18 - 25

• Carbohydrate Disposal early stuff

2
18. Inadequate Digestion

• Which of the following scenarios would MOST
  likely lead to flatulence (ie production of
  volatile short chain fatty acids and gases in the
  lower bowel)?
• Consumption of sucrose by someone with lactase
  deficiency
• Consumption of amylopectin starch
• Consumption of amylose starch
• Consumption of dairy products pre-treated with
  lactase
• Consumption of glucose in association with an
  amylase inhibitor

lactase not involved with sucrose digestion
14 13 127 19 46
amylopectin easily digested by amylase
much passes into lower bowel
lactase will break down lactose and allow full
absorption
amylase not needed for glucose absorption
3
19. Blood Glucose Homeostasis

• Which statement is CORRECT?
• Two days of continual exposure to a blood glucose
  concentration of 10 mM will cause a coma
• The reaction between proteins and glucose is not
  an enzyme catalysed process
• Glycosylation does not affect the function of
  proteins
• When blood glucose concentration is 5 mM, the
  rate of reaction between proteins and glucose is
  zero
• Hyperglycemia causes problems faster than
  hypoglycemia

lots of people walk around with moderate
hyperglycemia
39 124 10 30 14
yes, no enzyme needed
glycosylation most certainly DOES cause
malfunction
glycosylation is proportional to glucose
concentration
hypoglycemia is immediate, hyperglycemia several
months or years
4
20. Glycemic Index

• Which statement is INCORRECT?
• It is not practical to measure the glycemic index
  of meat
• The reference food used in glycemic index
  determinations is normally glucose
• The glycemic index is a relative measure of the
  peak blood glucose concentration caused by a food
  
• Legumes have a lower glycemic index than white
  bread
• Sucrose has a lower glycemic index than
  amylopectin starch

true statement not enough carbs to give a 50 g
dose
32 12 133 7 34
true statement white bread sometimes used too
not the peak, the area under the curve
intuitively true (legumes contain amylose)
strange but true sucrose is half fructose which
is not glycemic
5
21. GLUT-4
51 29 55 33 53
E
A
B
GLUT-4 moves from Golgi to cell membrane after
meal
Glucose transporter number in response to a
glucose load (that is completely cleared from the
bloodstream in about 2 hours)
C
D
The number of GLUT-4 transporters in the vesicles
of the Golgi apparatus in muscle cells
6
22. GLUT-2
47 46 47 53 22
E
A
B
GLUT-2 present all the time
Glucose transporter number in response to a
glucose load (that is completely cleared from the
bloodstream in about 2 hours)
C
D
The number of GLUT-2 transporters on the cell
membrane of liver cells
7
23. GLUT-1
46 46 55 56 17
E
A
B
GLUT-1 present all the time
Glucose transporter number in response to a
glucose load (that is completely cleared from the
bloodstream in about 2 hours)
C
D
The number of GLUT-1 transporters on the cell
membrane of brain cells
8
24. Chemistry of Carbohydrates

• Which statement is INCORRECT?
• Anomeric forms of monosaccharides result from
  ring formation
• Glyceraldehyde and dihydroxyacteone are both
  trioses
• Interconversion of glucose and galactose occurs
  spontaneously in solution
• Glucose, fructose and galactose are all hexoses
• Conversion of glucose 6-phosphate to fructose
  6-phosphate involves changing an aldose into a
  ketose

true statement
12 14 94 73 23
they are
oh no! need epimerases
all six carbons
glucose is aldose, fructose is ketose
9
25. Rate Limiting Steps

• Which of the following enzymes is most likely to
  catalyse a rate limiting step in a pathway
• High Vmax enzyme that catalyses irreversible
  conversion of S?P with the prevailing S being
  about the same as the Km of the enzyme.
• High Vmax enzyme that catalyses reversible
  conversion of S?P with the prevailing S being
  about the same as the Km of the enzyme
• High Vmax enzyme that catalyses reversible
  conversion of S?P with the prevailing S being
  about 2-fold the Km of the enzyme
• Moderate Vmax enzyme that catalyses reversible
  conversion of S?P with the prevailing S being
  about 2-fold the Km of the enzyme
• Low Vmax enzyme that catalyses irreversible
  conversion of S?P with the prevailing S being
  about 20-fold the Km of the enzyme

Looking for slow, irreversible and saturated
fast, irreversible, not saturated
55 4 22 2 130
fast, reversible, not saturated
fast, reversible, not saturated
?fast, reversible, not saturated
slow, irreversible, saturated