Term
| Glucose stored in muscle? |
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Definition
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|
Term
| Which organ also stores glucose as glycogen? |
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Definition
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Term
| When is liver glucose released into the blood |
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Definition
| Between meals and during early fasting |
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Term
| What is liver glucose not used as? |
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Definition
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Term
| When is glycogen mobilised in the liver for use by muscles? |
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Definition
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Term
| Glycogen differ from starch? |
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Definition
| Glycogen is branched. Starch is not (as heavily) |
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Term
| Name given to the ends of a polymer chain in glycogen? |
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Definition
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Term
| Bond links glucose monomers in a straight polymer chain? |
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Definition
| Alpha 1,4 glycosidic linkage |
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Term
| Bond links glucose monomers at a branching point in a glycogen molecule? |
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Definition
| Alpha 1,6 glycosidic linkage |
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Term
| Part of the glycogen molecule which is synthesised or hydrolysed? |
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Definition
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Term
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Definition
| Vastly increases the number of non-reducing ends allowing for a faster rate of glycogen breakdown |
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Term
| Glycogen function in liver |
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Definition
| Maintenance of blood glucose between meals and during early stages of fasting (first 24 hours) |
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Term
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Definition
| Fuel reserve for muscle contraction |
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Term
| Is liver glucose exportable? |
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Definition
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Term
| Is muscle glucose exportable? |
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Definition
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Term
| Glycogen liver wet weight? |
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Definition
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Term
| Muscle glycogen wet weight? |
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Definition
| 1-2% although more total body glycogen weight |
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Term
| Liver glycogen hormonal control |
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Definition
Glucagon and Adrenaline promote breakdown
Insulin promotes synthesis |
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Term
| Muscle glycogen hormonal breakdown |
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Definition
Adrenaline promotes breakdown
Insulin promotes sythesis |
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Term
| Glycogen synthesis location |
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Definition
| Cytosol of liver and muscle cells |
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Term
| General stages of glycogen synthesis (3) |
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Definition
1. Glucose activation
2. Label with UDP
3. Glycogen synthase adds glucose to glycogen |
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Term
| Why does glucose need activating? |
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Definition
| Glucose is unreactive so it need chemically altering to make it active |
|
|
Term
| Glucose activation process: part 1 |
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Definition
Glucose --> glucose 6 phosphate
Hexokinase (ATP-> ADP) |
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|
Term
| Glucose activation process: part 2 |
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Definition
Glucose 6-Phosphate--> Glucose 1-Phosphate
Using phosphoglucomutase |
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|
Term
| Glucose labelling process |
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Definition
Glucose 1-Phosphate + UTP --> UDP-Glucose
Using UDP-glucosepyrophosphorylase |
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|
Term
|
Definition
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|
Term
|
Definition
UDP-Glucose + Glycogen(n) --> Glycogen(n+1) + UDP
Using glycogen synthase |
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Term
| What increases glycogen synthase activity? |
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Definition
|
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Term
| First stage of branch formation |
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Definition
| Branching enzyme hydrolyses off a 6C chunk from non-reducing end - alpha1,4 linkage broken |
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|
Term
| Second stage of branch formation |
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Definition
| 6C chunk moved to more interior site |
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|
Term
| Third stage of branch formation |
|
Definition
| Alpha 1,6 linkage formed at branch site |
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|
Term
| When is glycogen broken down from non-reducing ends? (2) |
|
Definition
1. Blood glucose levels falls (liver)
2. Muscles need glucose for ATP production |
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|
Term
| Glycogen BREAKDOWN process |
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Definition
| Gylogen + Pi -> Glucose 1-Phosphate + Glycogen(n-1) |
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Term
| What enzyme catalyses the breakdown of glycogen? |
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Definition
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Term
| What increases the activity of glycogen phoshporylase? |
|
Definition
Glucagon (liver only)
Adrenaline (liver and muscles) |
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|
Term
| In what form is glucose released from glycogen? |
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Definition
|
|
Term
| What is deactivated when glycogen breakdown occurs? |
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Definition
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Term
| What happens when glycogen phosphorylase reaches a branch point? |
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Definition
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|
Term
| Within how many monomers does glycogen phosphorylase stop cleaving? |
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Definition
|
|
Term
| What occurs after glycogen phosphorylase stops cleaving? |
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Definition
| Enzyme transfers 3 glucose units (on branch) to the end of a glycogen molecule |
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|
Term
| What occurs to the remaining glucose molecule? |
|
Definition
| It is hydrolysed off by an enzyme |
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|
Term
| What is different about the branching glucose monomer which is hydrolysed off? |
|
Definition
| It has not been phosphorylated |
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|
Term
| After the single branching glucose has been hydrolysed off what happens? |
|
Definition
| Phosphorylation starts again |
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|
Term
| What is the ratio of activated glucose (glucose 1-phosphate) to glucose? |
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Definition
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|
Term
| What is the fate of glucose 1-phosphate in the LIVER? |
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Definition
|
|
Term
| Why is the phosphate removed from glucose 1-phosphate in the liver? |
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Definition
| Phosphates are charged so cannot cross membranes and need removing |
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Term
| How is glucose 1-phosphate converted into glucose? (2) |
|
Definition
1. G1P -> G6P using phosphoglucomutase
2. G6P -> Glucose using glucose 6-phosphatase |
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|
Term
| Fate of glucose in MUSCLE? |
|
Definition
Glucose -> Glucose 6-Phosphate
Using ATP and hexokinase |
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|
Term
| Fate of glucose 1-phosphate in MUSCLE? |
|
Definition
| G1P -> G6P using phosphoglucomutase |
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|
Term
| What enzyme does the muscle not have which liver does? |
|
Definition
|
|
Term
| Why does MUSCLE not have glucose 6-phosphatase? |
|
Definition
| So the glucose 6-phosphate formed is trapped within the muscle cells for glycolysis |
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Term
| First stage hormone control breakdown |
|
Definition
| Adrenaline/Glucagon bind to receptors on cell membrane |
|
|
Term
| Second stage hormone control breakdown |
|
Definition
| Adenylate cyclase activated which converts ATP to cAMP |
|
|
Term
| What does cAMP do in hormonal control of glycogen breakdown |
|
Definition
| cAMP activates protein kinase A |
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|
Term
| What does protein kinase A do in glycogen breakdown (2) |
|
Definition
1. Acitvates phosphorylase kinae
2. Deactivates glycogen synthase |
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|
Term
| What does activated phosphorylase kinase do? |
|
Definition
| Activates glycogen phosphorylase |
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|
Term
| What describes this activation mechanism |
|
Definition
|
|
Term
| What are the benefits of an amplification cascade? |
|
Definition
| Causes a strong and rapid response |
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|
Term
| First stage hormone control synthesis |
|
Definition
| Insulin binds to receptor on cell membrane |
|
|
Term
| What effect does insulin binding to a receptor have? |
|
Definition
| Protein kinase is activated |
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|
Term
| What does protein kinase activate in hormonal control of synthesis? |
|
Definition
| Activates phosphoprotein phosphatase 1 |
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|
Term
| What effect does phosphoprotein phosphatase 1 have? (2) |
|
Definition
1. Glycogen phosphorylase deactivated
2. Glycogen synthase activated |
|
|
Term
| What is a major difference between hormonal control of synthesis and breakdown? |
|
Definition
| No cAMP is needed for hormonal control of synthesis |
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|
Term
| What is used as an activator molecule in these amplification cascades? |
|
Definition
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