Class 9

in a keto diet, why do we lose so much weight in the first week

all of our water from glycogen storage is depleted

what do carbohydrate rich foods form

glycogen

what degrades glycogen

glycogen phosphorylase

what does glycogen phosphorylase yield

glucose-1-phosphate

monomer used to extend glycerol chain

UDP-glucose

UDP-glucose means that what is activated

activated glucose

UDP-glucose is made from

Glucose-1-phosphate and UTP

what catalyzes the formation of UDP-glucose

UDP-glucose phosphorylase

what does making UDP-glucose free

the 2 outer phosphoryl residues

the breakdown of what drives the reaction of UDP-glucose synthesis

PPi

what catalyzes the transfer of glucose to a growing chain

glycogen synthase

where are new glucosyl units added

to nonreducing terminal residues of glycogen

UDP is displaced by

terminal hydroxyl of growing molecule

this transfer of glucose to a growing chain is catalyzed by 

glycogen synthase

what is the key regulatory enzyme in glycogen synthesis

glycogen synthase

what are the 2 forms of glycogen synthase that humans have

1. expressed in the liver 

2. expressed in the muscle and other tissue

glycogen synthase can add glucosyl residues only to a polysaccharide chain that already has more than ___ residues

4

what is the primer for glycogen synthesis

glycogenin

what does each subunit of the primer do

catalyzes the making of a-1,4-glucose polymers

how long are a-1,4-glucose polymers

10-20 glucosyl units

glycogen synthase only catalyzes ______ linkages

a-1,4

what are 3 reasons why branching is important

• increases solubility of glycogen

• creates a large number of terminal residues which is where glycogen phosphorylase and synthase are active

• increases the rate of glycogen synthesis/degradation

when does 1,6 branching happen

after a number of glucosyl residues are joined in a-1,4 linkages by glycogen synthase

how do you make branches

break an a-1,4 link, and make an a-1,6 link

how many residues are moved to the inside when making branches

about 7

the block of 7 residues must have a ______________ and come from a chain that was at least __ residues long

nonreducing terminus, 11

where does the new branch point have to be in regards to another branch

at least 4 away

what enzyme are branches made by

branching enzyme

what are the 2 forms of glycogen synthase

1. active (a) form: nonphosphorylated

2. inactive (b) form: phosphorylated

how is the interconversion of the 2 forms of glycogen synthesis regulated

covalent modification

a powerful activator of the enzyme, the amount is important for glycogen synthase

glucose-6-phosphate

how many molecules of ATP are required to incorporate dietary glucose into glycogen

2

complete oxidation of glucose from glycogen gives ____ molecules of ATP

31

glycogen synthesis is inhibited by the same __________ and __________ signaling pathways that stimulate glycogen breakdown

glucagon, epinephrine

insulin stimulates glycogen synthesis by

activating a signal transduction pathway

insulin facilitates glycogen synthesis by

increasing the number of GLUT4

what is an efficient storage form of glucose

glycogen

what regulated the blood-glucose concentration

glycogen metabolism in the liver

this leads to the inhibition of glycogen degradation (phosphorylase) in the liver…what does it increase

high blood glucose, this increases glycogen synthesis

diabetes mellitus results from

insulin insufficiency and glucagon excess

diabetes is characterized by

the presence of excess glucose and not using the fuel

where is excess glucose excreted

urine

insulin is not produced in which type of diabetes

type 1

insulin is produced but insulin-signaling pathway is unresponsive in this type of diabetes

type 2