Metabolism 1 and 2 : Metabolism overview, carbohydrate metabolism

Question 1

What are the fates of acetyl CoA

Answer 1

Fatty acid synthesis and sterols
Citric acid cycle
Ketone bodies

Question 1

Preferred fuels of liver

Answer 1

glucose, fatty acid oxidation, amino acids

Question 2

Preferred fuels of adipose tissue

Answer 2

Fatty acids

Question 3

Preferred fuels of skeletal muscle

Answer 3

At rest - beta oxidation (FA)

During exercise - glucose

Question 4

Preferred fuels of heart muscle

Answer 4

Beta oxidation

Question 5

Preferred fuels of brain

Answer 5

Glucose always, but in starvation it’ll use ketone bodies

Question 6

Major carbohydrates and fuels in which they are found

Answer 6

Amylose (starch) 
Sucrose (table sugar, desert)
Lactose (milk products) 
Fructose (fruit and honey)
gluocse (fruit, honey)
Maltose (barley)
trehalose (mushroom)
cellulose (plant walls)

Question 7

What will happen if a person who is lactose intolerant eats milk?

Answer 7

This person is deficient in lactase - this is going to make lactase go through tract an led to osmotic diarrhea and co2 production from bacteria metabolising the lactose.

Question 8

Carbohydrate metabolism pathways active in red blood cells

Answer 8

Glycolysis only - no mitochondria

Question 9

Carbohydrate metabolism processes in brain

Answer 9

Glycolysis, TCA, ETC

Question 10

Carbohydrate processes available to heart and skeletal muscle

Answer 10

Glycolysis, TCA, ETC, Glycogenolysis

Question 11

Adipocytes

Answer 11

Conversion of glucose to fats

Question 12

Hepatocytes

Answer 12

glycolysis, TCA, ETC, glycogenolysis, gluconeogenesis, pentose phosphate pathway

Question 13

Glut2

Answer 13

Insulin independent transporter (liver)
High capacity, low affinity (almost never saturated)
Bidirectional

Question 14

glut 4

Answer 14

insulin dependent transporter (low capacity, high affinity) - heart, skeletal muscle, adipocytes - not active in fasting states

Question 15

SGLT1

Answer 15

will transport glucose or galactose with using sodium as a secondary active transport assistant

Question 16

3 irreversible enzymes of glycolysis

Answer 16

hexokinase/glucokinase
phosphofructokinase 1
pyruvate kinase

Question 17

Tissue localization: Hexokinase vs glucokinase

Answer 17

Hexokinase - everywhere

glucokinase - liver and pancreas technically

Question 18

kinetic characteristics of hexokinase / glucokinase

Answer 18

Hexokinase - Low Km for glucose (constantly saturated)

Glucokinsae - High Km for glucose (rarely saturated)

Question 19

Regulation of hexokinase / glucokinase

Answer 19

Hexokinase - constitutively active, constant amount, but allosterically regulated by its product, G6P
Glucokinase- shuttled between nucleus and cytosol for activity, F6P will suttle to nucleus and glucose brings to cytosol - this one is also inducible and will be induced by insulin to be synthesized

Question 20

allosteric regulators of glucokinase and hexokinase

Answer 20

Hexokinase - allostericlally inhibited by glucose 6 phosphate

Glucokinase - allosterically activated by glucose, inactivated by fructose 6 phosphate

Question 21

Allosteric regulation of phosphofuctokinase 1

Answer 21

Activators: F-2,6-BP, AMP, ADP (low energy, high glucose/ active PFK2)
Inhibitors: Citrate, ATP (high energy, glycolysis and TCA are going on)

Question 22

Allosteric regulation of pyruvate kinase

Answer 22

Positive: F-1,6-BP (upstream)

Negative ATP, alanine

Question 23

Covalent regulation of pyruvate kinase

Answer 23

Insulin –> dephosphorylated –> more active

Glucagon/ epinephrine –> phosphorylated –> less active

Question 24

Hepatic PFK2 is phosphorylated in the ___ domain when glucagon and epinephrine are around, meaning __________.

Answer 24

Kinase

It going to have phosphatase activity going (you will not have F-2,6 BP and glycolysis is inhibited)

Question 25

Muscle PFK2 is going to be phosphorylated in -____ domain in presence of epinephrine? Meaning _____ about its activity

Answer 25

phosphatase

You get a lot of F-2,6-BP, glycolysis is going to be active

Question 26

What pancreatic hormone inhibits hepatic glycolysis

Answer 26

Glucagon

Question 27

How does glucagon affect hepatic glycolysis?

Answer 27

Inhibit enzymes (PFK1 via PFK2 being put in “phosphatase mode”, pyruvate kinase), and also decrease enzyme synthesis (glucokinase, PFK1, pyruvate kinase)

Question 28

How does epinephrine inhibit hepatic glycolysis but promote muscle glycolysis

Answer 28

differential pFK2 covalent modifications
Hepatic –> kinase phosphorylation (inactivates kinase)
muscle –> phosphatase phosphorylation (inactivates phosphatase)

Question 29

When will lactate –> pyruvate and acetyl coA

Answer 29

When there is extensive NAD - also in tissues with LDH that favors the lactate –> pyruvate conversion (like heart, instead of skeletal muscle which would prefer pyruvate –> lactate)

Question 30

heart LDH isozyme

Answer 30

LDH4 (favors making pyruvate)

Question 31

Skeletal muscle LDH isozyme

Answer 31

LDH5 M4 (favors lactate)

Question 32

negative regulators of PDH

Answer 32

NADH, Acetyl CoA

Question 33

Positive regulators of PDh

Answer 33

CoASH, NAD+, ADP, pyruvate, magnesium, calcium

Question 34

Is PDH active or inactive when phosphorylated

Answer 34

Inactive

Question 35

Vitamin cofactors that participate in reactions catalyzed by pdh

Answer 35

riboflavin, niacin, thiamine

Question 36

Arsenic poisoning does what to pdh activity

Answer 36

fucks it up

Question 37

Genetic deficiency in fructose aldolase

Answer 37

Intracellular trapping of F1P is result –> decline in inorganic phosphate and inability to make ATP –> absolutely must avoid fructose

Question 38

galactokinase or galactose 1 phosphate uridyl transferase deficiencies, what food should people avoid

Answer 38

avoid lactose at all costs
galactokinase deficiency – you get diarrhea, can’t utilize galactose
galactose 1 uridyl transferase deficiency is bad , you trap sugar phosphates and die