162b Endo Metabolism

Question 1

3 possible fates of glucose?

Answer 1

enters cell and converted to Glucose-6-P (trapped in cell) then can enter 3 pathways

1) Pentose phosphate shunt - produces NADPH and ribose sugars
2) glycolysis - every cell uses this
3) glycogen synthesis G6P –> G1P) - if enough E is present, storage

Question 2

glucose keys steps

Answer 2

glucose–>G6P–>PEP–>Pyruvate

provides parts for amino acids, TG, glycogen

Question 3

glycolysis - kep steps

Answer 3

hexokinase: G–> G6P
PFK-1: rate determining step, requires ATP
phopho ???

Question 4

aerobic vs anaerobic glycolysis

Answer 4

pyruvate - end of glycolysis

if O2, then can go to mitochondria to generate a lot of ATP

if no O2, then anaerobic (sepsis, exercise):
pyruvate –> lactase (regenerates NAD+ from NADH)

Question 5

regulation of glycolysis

Answer 5

allosteric regulation - metabolities bind and affect enxymes - inhibitors from end products; activators induce activity

post-translational modification - phosphorylation- can activate or inhibit

Question 6

rate limiting step in glycolysis

Answer 6

PFK-1 (F6P –> F1,6 bisP)
+ AMP, F-2,6-bisP
-ATP, citrate

allosteric regulation

Question 7

pentose phosphate pathway

Answer 7

detour pathway from glycolysis

provides NADPH - needed for rxns

produces 5 carbon sugar for nucleotides - DNA/RNA synthesis

active in liver, adrenals, lacting mammory glands

Question 8

G6P dehydrogenase deficiency

Answer 8

red cell lysis if deficient – triggers will cause lysis (fava beans, antiobotics like sulfa drugs/TB drugs)

x-linked - meditrainian decent

pentose phosphate pathway is very important in RBC to form NADPH –> reduces glutathione to deal with ROS

Question 9

gluconeogensis basic overview

Answer 9

glucose made from lactate (anaerobic glycolysis), glycerol (TG hydrolysis), and amino acids (protein breakdown)

Question 10

gluconeogensis

Answer 10

provides glucose during fasting

occurs in liver, requires E

Question 11

glycogen

Answer 11

a-1,4-glycosidic bonds with a-1,6-glycosidic branching

glucose is added onto the end of these branching chains

Question 12

glycogen synthesis

Answer 12

G –> G6P –> G1P –> UDP-Glucose (via G1P uridyltransferase) –> added to glycogen chain

Question 13

branching enxymes

Answer 13

keeps glycogen branches to about 6 glucose

Question 14

debranching enxymes

Answer 14

remmove 4 closest glucose to branch

Question 15

glycogen phosphorylase

Answer 15

breaks down long chain glycogen after debranchers

+AMP, Pi
-G6P, ATP

Question 16

glycogen synthase

Answer 16

+G6P

Question 17

key organ for blood sugar maintaince

Answer 17

liver

Question 18

muscle

Answer 18

used glucose for E - doesn’t regulate glucose levels

Question 19

key distinct enxyme in liver vs msucle

Answer 19

G6phosphatases - trapped glucose in liver (G6P) turned back to glucose and released into circulation

muscle doesn’t have G6 phosphotase

Question 20

what regulates glycogen in liver vs muscle?

Answer 20

liver - blood glucose, stress (epi)

muscle - AMP, contraction/Ca

Question 21

fasting - glycogensis goes down where?

Answer 21

liver (muscle remains constant)

Question 22

liver glycogen regulation in stravation and stress

Answer 22

glycogen phosphorylase P to active formed –> glucose shipped out to blood

Question 23

3 ways to activate glyocgen phorphylase in muscle

Answer 23

1) Epi
2) Ca
3) AMP

Question 24

glcyogen storage disease

type 1 - von Gierke’s disease

Answer 24

deficient liver G6 Phosphatase –> fasting hypoglycemia, liver enlargment

Question 25

glcyogen storage disease

type IV - andersen’s

Answer 25

deficient branching enzyme (can fully branch glycogen –> not soluble) –> liver dysfunction, early death

Question 26

glcyogen storage disease

type V - McAdrdle

Answer 26

deficienct muscle glycogen phosphorylase –> muscle cramps with exercise

Question 27

glcyogen storage disease

Type VII

Answer 27

deficienct muscle phosphofructokinase –> inability to exercise