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| Pregunta | Respuesta |
| Describe the two independent ways in which glucose is transported into the muscle. | 1) GLUT-4 is a transporter protein which transports glucose across the membrane into the muscle fibre. Insulin stimulates GLUT-4 2)PA involves muscle contraction which transports glucose into the muscle fibre |
| Name the three processes for carbohydrate metabolism. | Glycogenolysis - breaking down glycogen Glycolysis - breaking down glucose Glycogenesis - synthesis of glycogen |
| What does a postfix of lysis mean? What does a postfix of esis mean? | Splitting Formation |
| Which hormones regulate a) glycogenolysis b) glycogenesis | Adrenaline Insulin |
| What is a carbohydrate with 3-7 carbons called? Name the specific name and example for each number. | Monosaccharide 3 - trioses eg dihydroxyacetone 4 - tetroses eg erythrose 5 - pentoses eg ribose 6 - hexoses eg glucose/fructose |
| What are two monosacccharides joined together called? What is the bi-product when this occurs? Give examples | Disaccharides Water Glucose + glucose = maltose + water Galactose + glucose = lactose + water Glucose + fructose = sucrose and water |
| What is it called when there is > 10 monosaccharides? Give examples | 10-20 = glucose polymers > 1000 - starch in plants, glycogen in animals |
| Draw a glucose molecule LEARN HOW TO DRAW THIS FOR THE EXAM | |
| Draw a Maltose molecule What type of bond joins the two glucose molecules? | |
| What is regulation of CHO metabolism? | The biochemical processes that regulate how our body transports, stores and uses CHO for energy, in this case how it produces ATP from CHO |
| What are the main sites involved in CHO metabolism? (1-3) | 1) Transportation of glucose into the muscle fibre 2) Glucose is transformed into Glucose-6-Phosphate (G-6-P Either glycolysis occurs to produce ATP OR it's transformed into G-1-P and stored as glycogen |
| What are the main sites involved in CHO metabolism? (4) | 4. The electron transport chain, by this stage we have pyruvate. In the absence of O2 it is used to produce ATP with a bi-product of lactic acid OR with O2 the pyruvate is transported into the mitochondria and made into Acetyl-CoA |
| What are the main sites involved in CHO metabolism? (5,6) | 5) Acetyl CoA enters the krebs cycle 6) Glycogenolysis occurs - the formation of glycogen |
| What are the two key regulators of blood glucose? | 1) The pancreas - insulin stimulates GLUT-4. Glucagon splits glycogen (glycogenolysis) so that the liver can maintain blood glucose levels 2)Muscle contraction (exercise) does not require insulin to transport glucose into the muscle |
| What is GLUT-4 | A glucose transporter protein |
| What are the 6 steps for insulin to transport glucose? | 1) It is outside the muscle fibre 2) Binds to a receptor inside the plasma membrane 3) Is phosphorylated - adding a phosphate group turns the molecule on 4) P13 kinase is activated 5) This activates AKt 6) Activated AS160 allowing translocation of GLUT-4 into the sarcolemma |
| How does exercise (muscle contraction) transport glucose? | 1) During exercise ATP is expended = an increase in the ratio of AMP:ATP 2) When this ratio is high AMP kinase is activated 3. This activates AS160 allowing translocation of GLUT-4 into the sarcolemma |
| Where is glucose stored and in what amounts? | 5g floating in the bloodstream 100g stored in the liver 400g stored in the muscle (close to the mitochondria so available for quick use) |
| To utilise more muscle glycogen than fat what must we do to exercise intensity? | Increase exercise intensity |
| What is the equation for breaking glycogen down to glucose-1-phosphate What enzyme catalyses this reaction? LEARN FOR EXAM | Glycogen (n units) + Pi -> Glycogen (n-1 units) + Glucose-1-phosphate Glycogen Phosphorylase |
| What is the equation for breaking glucose-1-phosphate down to glucose-6-phosphate What enzyme catalyses this reaction? LEARN FOR EXAM | Glucose-1-phosphate -> Glucose-6-phosphate Phosphoglucomutase |
| What regulates glycogen phosphorylase and how? | It is regulated through covalent modification via hormonal activation See notes for diagram |
| What affect does adrenaline have during moderate exercise? | Increases glycogenolysis, PDH activation and CHO oxidation |
| What does an increase of ADP and AMP do to glycogen phosphorylase? | Causes it to be switched on even more so it can transform more glycogen into glycogen-1-phosphate |
| What is the formula for glycolysis? What is the net gain? | Glucose + 2ADP + 2Pi + 2NAD+ -> 2 pyruvate + 2ATP + 2NADH + 2H+ 2ATP |
| What regulates the glycolysis reaction? What does it specifically do? What inhibits this enzyme? | Hexokinase Transforms glucose to glucose-6-phosphate. This is an irreversible reaction Too much G-6-P from glycogenolysis |
| What is phosphofructokinase (PFK)? | PFK is the regulatory enzyme in glycolysis |
| What affects how much PFK is switched on? | Amount of ADP, AMP, Pi, cAMP |
| What slows down PFK? | Excess H+, ATP and citrate |
| What is the link reaction? What is it facilitated by? | Turning pyruvate into Acetyl-CoA PDH. The regulatory hormone for CHO oxidation |
| What does any phosphatase do? eg. PDH phosphatase | Remove a phosphate group |
| What does any kinase do? eg PDH kinase | Any kinase adds a phosphate |
| What does adding a phosphate do to PDH? | Makes in inactive |
| Which hormones regulate glycogenesis, and therefore inhibits glycogenolysis? | Insulin |
| Which hormones regulate glycogenolysis, and therefore inhibits glycogenesis? | Adrenaline |
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