Glycogen Synthesis | Quizlet

What activates glycosyl units?

UDP-glucose pyrophosphorylase

What extends glycogen chains?

glycogen synthase

What transfers seven-residue glycogen segments?

glycogen branching enzyme

T/F: Glycogen synthesis from G1P is thermodynamically unfavorable

True

T/F: Glycogen synthesis and breakdown are on the same pathways

False

What are the 3 enzymes that participate in glycogen synthesis?

UDP-glucose pyrophosphorylase, glycogen synthase, glycogen debranching enzyme

UDP-glucose pyrophosphorylase activates glucosyl units which then creates what?

uridine diphosphate glucose (UDPG)

UDPG is an activated compound that can donate a ____ unit to the growing glycogen chain

glucosyl

T/F: The formation of UDPG itself has free energy of about zero

True

Subsequent exergonic hydrolysis of pyrophosphate by inorganic pyrophosphatase makes the overall reaction ____

exergonic

Glycogen synthase extends ____ chains

glycogen

Glycogen synthase transfers glucosyl units of UDPG to C4-Oh group on one of glycogen's _____ ends to form an α(1→4) glycosidic bond

non-reducing

The ′ΔG°′ for the glycogen synthase reaction is −13.4 kJ·mol−1 and the overall reaction is ____

spontaneous

T/F: Glycogen synthesis does not have an energetic price

false

How many UTPs are cleaved to UDP for each glucose residue incorporated into glycogen?

one

UTP is replenished using ____ as a substrate through a phosphoryl-transfer reaction mediated by nucleoside diphosphate kinase

ATP

T/F: UTP consumption is energetically equivalent to ATP consumption

True

T/F: Glycogen synthase can simply link together two glucose residues

false

Glycogen synthase can only extend an already existing _____-linked glucan chain

α(1→4)

In the first step of glycogen synthesis ____ acts as a glycosyltransferase and attaches glucose residue donated by UDPG to OH group of its Tyr 194

glycogenin; UDPG

Glycogenin extends the glucose chain by up to __ additional UDPG-donated glucose residues

seven

Each glycogen molecule is associate with 1 molecule of what?

glycogenin and glycogen synthase

Glycogen branching enzyme transfers how many residue segments?

seven

Glycogen synthase generates only α(1→4)linkages to yield ______

α-amylose

T/F: Branching by amylo-(1,4 → 1,6)-transglycosylase (branching enzyme) is distinct from glycogen debranching enzyme

True

T/F: In the glycogen branching enzyme, a branch is created by transferring a 7-residue segment from chain end to C6-OH group of a glucose residue on only the same glycogen chain

False

In glycogen branching enzyme, each transferred segment must come from a chain of at least ___ residues

eleven

Each branch point must be at least ____ residues away from other branch points

four

Branching pattern of glycogen has been optimized by evolution for the efficient _____ and _____ of glucose

storage and mobilization