Chapter 11 Glycogen Metabolism Flashcards
For skeletal muscles: define which mechanism goes for each of the ff:
a. ) when the muscle is at rest
b. ) during exercise
a. ) glycogenesis
b. ) glycogeneolysis
- only composed of linear alpha 1-4 linkages is found in ?
- which is called ?
- plants
- amylose
Structure and Function of Glycogen
- main storage for glycogen
- what is the main purpose of glycogen ?
- the liver’s role in storage of glycogen ?
- the presence of glucose 6- phosphatase in the liver allows the release of ?
- In a normal resting muscle how much grams of glycogen is maintained ?
- skeletal muscle and the liver
- fuel reserve for the synthesis of ATP during muscle contraction
- is to maintain glucose levels in the blood during early stages of fasting
- glucose
- 400 g 1% to 2% of the resting muscle
The enzyme responsible for making alpha 1-4 linkages in the glycogen chain
glycogen synthase
when cAMP is removed; how will it affect KINASE mechanism
cAMP triggers PKA
PKA triggers phosphorylation
Phosphorylating a molecule shifts the molecule to either activated state or inactivated state
what are the two levels for the synthesis and degradation
- Glycogen synthase
- Glycogen Phosphorylase
Stucture of Glycogen
- describe the chain of glycogen
- name the primary glycosidic bond of glycogen
- how many lnkages of alpha 1-4 appears in this molecule ?
- describe the structure
- branched-chain polysaccharide (alpha-D glucose)
- alpha 1-4 linkage
- 8 to 14 glucosyl residues
- large spherical polymers (cytoplasmic granules)
Protein Kinase A is stimulated when Glucagon and Epinephrine binds on receptors on the hepatocyte.
how does protein kinase affect adenylyl cycalse ?
AC becomes activated making more cAMP and activate cAMP-dependent kinase
(PKA)
Glucose-1 -Phosphate G1P is generated from G-6P (glucose 6 phosphate) by the enzyme called ?
Phosphoglucomutase (basically just moving the phosphate from carbon 1 to carbon 6.
An enzyme that stays associated with and forms the core of a glycogen granule (sugar blob)
Glycogenin
Synthesis of Glycogenesis
- Glycogen is synthesized from
- The process of glycogenesis occurs where ?
- ATP is needed in this process because of the phosphorylation of ?
- alpha D glucose
- in the cytosol
- the phosphorylation of glucose and UTP
Branching Synthesis
- branches are made by the action of the branching enzyme called ?
- 4:6 transferase (amylo-alpha (1-4)** to alpha (**1-6)transglycosylase
- amylo-alpha-1-4 to alpha 1-6 transglycosylase
- breaking a (a-1-4) attaching it (a-1-6)
makes alpha 1 - 4 linkages
glycogen synthase
Uridine diphosphate glucose synthesis:
- the source of all glucosyl residues that are added to growing glycogen molecule ?
- UDP-glucose is synthesized by
- UDP-glucose phosphorylase reaction proceeds in the production of what product ?
- UDP-glucose
- glucose-1-phosphate & UTP by UDP-glucose pyrophosphorylase
- UDP- glucose production
when the body is fasting; what mechanism is favored ?
glycogenolysis: breaks more sugar blobs into smaller units to give to the blood
what mechanism occurs on well fed states?
Glycogenesis
building sugar blobs from single unit sugars to store for energy
epinephrine and glucagon binding to GPCR calls a signal for what mechanism ?
signals the need for glycogen to be degraded. Break sugar blobs to single units so they can become glucose and rise concentrations of themselves in the blood
how is glycogen synthase and glycogen phosphorylase regulated ?
they are regulated by hormones (via covalent phosphorylation** and **dephosphorylation
Break or Make
Catabolize or Anabolize
Energy is needed to build
Energy is released to break
These are important keywords
cAMP-PKA cascade
tag team
elevated insulin level results in overall increased
a. ) glycogenesis
b. ) glycogenolysis
a.) glycogenesis
elevated glucagon and epinephrine causes
a. ) glycogenesis
b. ) glycogenolysis
b.) glycogenolysis
Breaking blobs of sugar into single units
Phosphorylase inactive B and active A
Glucose-6-Phosphate
effects on a well fed state ON
a. ) Glycogen Synthase
b. ) Glycogen Phosphorylase
glucose synthase is activated
glycogen phosphorylase is inhibited
