FORM & FUNCTION (CHO:Glucose)

Question 1

ATP

Answer 1

-energy currency
-when it hydrolyzes, energy is released
-drives reactions that has a positive change of energy

Question 2

reactions that have a positive change of energy

Answer 2

-active transport/pumping of ions to maintain osmotic balance
-muscle contraction (myosin & actin)
-synthesis of macromolecules and other biomolecules

Question 3

ways to generate ATP

Answer 3

1. CHO
   -glycolysis
   -55-75%
2. Lipids
   -beta oxidation
   -15-30%
3. Proteins
   -deamination
   -10-15%
   *all form Acetyl Co-A which will go into the TCA cycle

Question 4

carbohydrate

Answer 4

-sugar
-carbon hydrate (6C with water)
-mono-, di-, and poly-saccharides
-stored as polysaccharides (glycogen)

Question 5

glucose regulation

Answer 5

major form of mammalian fuel
1. Energy (ATP)
2. Storage (glycogen)
3. Storage (fat)

Question 6

normal glucose in blood

Answer 6

-5mmol/L
-excess glucose must be transported and processed in tissues

Question 7

hyperglycemia

Answer 7

-high blood glucose
Ex. diabetic: can’t take up glucose into tissues

Question 8

hypoglycemia

Answer 8

-low blood glucose
Ex. starvation

Question 9

glucose transporters (GLUT)

Answer 9

-class of proteins that allow glucose to passively transport into tissues
-most are unidirectional

Question 10

GLUT2

Answer 10

-transports glucose in AND out of liver
-insulin insensitive

Question 11

GLUT4

Answer 11

-transports glucose into heart, skeletal muscles and fat
-insulin sensitive
>when insulin is high=increase GLUT4=increase transport of glucose into cells

Question 12

skeletal muscle and fat

Answer 12

-major glucose depository
>where the body stores excess glucose

Question 13

glucose trapping

Answer 13

-glucose phosphorylation traps the molecules as charged phosphate group prevents diffusion out of cell
-liver uses glucokinase
-muscles use hexokinase

Question 14

glucokinase and hexokinase

Answer 14

-same catalytic activity
-different regulatory properties
*forms glucose 6-phosphate

Question 15

glucose 6-phosphate

Answer 15

-used for glycolysis and glycogen

Question 16

insulin (brief)

Answer 16

-high glucose caues high insulin
*goal is to move excess glucose out of blood and into tissues to avoid hyperglycemia

Question 17

liver insulin

Answer 17

-stimulates glucokinase to increae glucose trapping inside the cell

Question 18

muscle insulin

Answer 18

-stimulate GLUT4 to increase glucose uptake inside the cell

Question 19

glycolysis phases

Answer 19

1. preparatory
2. pay off

Question 20

preparatory phase

Answer 20

-spend ATP to make ATP
-hexokinase: traps glucose
-phosphofructokinase (PFK)

Question 21

PFK

Answer 21

-controls rate of glycolysis
-allosterically regulated by ATP level
*rate limiting step
-committed step (irreversible) *fructose 1,6-biphosphate destined to complete glycolysis

Question 22

PFK allosterically regulated

Answer 22

-high ATP inhibits enzyme (negative feedback, inhibits glycolysis)
-high AMP: reverse ATP inhibition (favours glycolysis)

Question 23

pay off phase

Answer 23

-4ATP molecules: substrate level phosphorylation
-2 NADH: shuttled to the ETC
-2 pyruvate molecules: enters the TCA
*anaerobic so far

Question 24

clinical relevance

Answer 24

-deficiency in muscle PFK: rare mutation in dogs
Ex. glycogen storage disease type 7

Question 25

glycogen storage disease type 7

Answer 25

-glycolysis slows down at step 3 (PFK)
-impairs glucose conversion to ATP
-PFK activity in muscle: 1-4% (exercise intolerant)
-PFK activity in RBC: 6-22% (hemolytic crisis: death of RBC)
-reported in spaniel breeds

Question 26

2 pyruvate from pay off phase

Answer 26

1. Aerobic condition: Acetyl-CoA
2. Anaerobic condition: lactate

Question 27

Lactate

Answer 27

-caused when rate of glycolysis is greater than TCA cycle (ex. intense exercise)
*primary role is to regenerate NAD+ (required for payoff phase)
-pyruvate is converted to lactate by dehydrogenase
*net ATP is still 2

Question 28

lactic acid

Answer 28

-weak acid
-pKa=3.8
-favours reation to lactate + H+

Question 29

prolonged anaerobic glycolysis

Answer 29

-can cause metabolic acidosis
-anion gap increased from a decrease in HCO3-

Question 30

glycolysis in RBC

Answer 30

1. Can only use anaerobic glycolysis
2. Contains an alternate pathway
   -2,3-biphosphoglycerate (2,3-BPG), is formed (regulateds Hb-O2 interaction)
   -up to 15% of glucose in RBC can pass through this shunt

Question 31

2,3-BPG function

Answer 31

-binding to Hb allosterically to regulate O2 affinity
-binding promotes oxygen dissociation=release oxygen to needy tissues
*decrease Hb-O2 saturation=improves re-oxygenation
-pH dependent