806099
Description
Flashcards by Hannah Tribe, updated more than 1 year ago
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Created by Hannah Tribe
over 10 years ago
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| Question | Answer |
| What is the process that converts glucose to pyruvate? | Glycolysis |
| What is average blood glucose? | 2.5mM |
| Name 5 symptoms of hypoglycaemia | 1. Muscle weakness 2. Loss of coordination 3. Mental confusion 4. Sweating 5. Coma/death? |
| In hyperglycaemia, ________ can be modified without _______ because glucose is very ________. This can lead to conditions such as _________, and modify lipoproteins important in ____________. | proteins, enzymes, reactive, cataracts, atherosclerosis |
| What is another risk in hyperglycaemia? | Hyperosmolar coma - imbalance in water retention |
| What mechanisms are used to lower blood glucose? (3) | 1. Glycogen synthesis 2. Pentose phosphate pathway 3. Fatty acid synthesis |
| What mechanisms are used to raise blood glucose? (2) | 1. Glycogenolysis 2. Gluconeogenesis |
| Where is most glycogen synthesised? | Liver |
| At which stage of glycolysis is glycogen synthesised? | After conversion of glucose to G-6-P by glucokinase (in liver) |
| What protein is associated with glycogen? | Glycogenin |
| What is glycogen? | A storage molecule, capable of storing high concentrations of glucose. |
| Where is glycogen found? | Liver hepatocytes and muscle |
| Why can glucose not be stored in its natural state? | It is osmotically active |
| Glycogen is a much more efficient way of storing glucose. 400mM of glucose can be stored as _______ glycogen. | 0.01 microM |
| Why can fat not be used as the energy store? (3 reasons) | 1. Fat takes much longer to be mobilised 2. Fat cannot be used for energy if there is no oxygen 3. Fat cannot be directly converted to glucose |
| 1. G-6-P is converted to _______ | Glucose 1 phosphate (G-1-P) |
| 2. The G-1-P molecule is converted to ____-______ by the enzyme ____-________ __________________, using a molecule of ____. This activates the _________ molecules so they will readily _______. | UDP-glucose, UDP-glucose pyrophosphorylase, UTP, glucose, react |
| 3. ___-______ combines with _________ and a chain forms with multiple molecules of ____-_______, under the action of the enzyme __________ _________. | UDP-glucose, glycogenin, UDP-glucose, Glycogen synthase |
| 4. When the chain is approx ___ residues in length, a ________ _________ removes the last ___/___ residues and moves them down the chain to form a _______. | 11, branching enzyme, 6/7, branch |
| What is the advantage of having many branches? | There are lots of 'ends' which can be broken off in times of need and be converted to glucose. |
| What kind of links exist between the chain and branches? | Alpha 1,6 |
| What kind of links exist between each UDP-Glucose molecule in the chain? | Alpha 1,4 |
| Which enzyme removes the alpha 1-4 links between glucose molecules? | phosphorylase |
| Which enzyme converts the resultant G1P back to G6P in a reversible reaction? | phosphoglucomutase |
| What are the 2 possible fates of this G6P? | 1. In muscle, this will directly enter glycolysis to produce ATP 2. In the liver, it will be exported back into the bloodstream in order to raise blood glucose levels |
| Once the chain of glucose is too short on a branch, ____________ moves all but the last residue onto the end of the original chain. | Translocase |
| When there is a single glucose residue left on a branch, ___________ _________ removes the _________ __ __ bond and leaves a single _________ molecule. | debranching enzyme, alpha 1-6, glucose |
| If this occurs in the liver, it will be exported to the ______ ______ to raise _______ ________ levels. In muscle, it will be converted to ___ ___ ___ and enter __________ to produce ______. | blood stream, blood glucose, G6P, glycolysis, ATP |
| Which enzyme converts G6P to glucose? Where is it found? | Glucose 6 phosphatase, in the liver and kidneys |
| Mobilisation of glycogen is so efficient because multiple ____________ molecules bind to each glycogen particle at the same time. | phosphorylase |
| Glycogen phosphorylase is a _______-_______ complex, and can be activated by _____________. | multi-enzyme, phosphorylation |
| Which enzyme phosphorylates the inactive phosphorylase b to the active form? | phosphorylase b kinase |
| Breakdown of glycogen can be stimulated by hormones binding to the cell membrane. Examples are ________ and __________. They stimulate the ____ pathway to cause increased ______ and _____ inside the cell. It is the _____ which phosphorylates and therefore activates ____________ ___ ________ enzyme, so that ________ __________ can be activated. | glucagon and adrenaline, Gs, cAMP and PKA, PKA, phosphorylase b kinase, glycogen phosphorylase |
| PKA also phosphorylates ___________ _________ to its inactive form so that ____________ of __________ is inhibited. | glycogen synthase, synthesis of glycogen |
| Which ion can also activate phosphorylase b kinase? | Ca++ |
| How is a raise in calcium achieved in muscle and liver cells? | In muscle: Ca++ is released for contraction, which is when energy is also needed. In liver: stimulation of alpha-1 adrenergic receptors activates Gq pathway and causes increased Ca++ |
| Which molecule indicates the muscle cell is low on energy? | AMP |
| When levels of this are high in muscle cells, __________ __________ __ can be activated without ______________ by the enzyme. | glycogen phosphorylase b, phosphorylation |
| Similarly, when levels of _____ are high, the muscle cell does not need more energy so _____ binds to the same active site and ________ activation of ___________ _____________. | ATP, ATP, inhibits, glycogen phosphorylase |
| This is also inhibited by ___________ __ _________. | Glucose 6 phosphate |
| In the liver, high levels of ________ will inhibit activation of ___________ _____________. | glucose, glycogen phosphorylase |
| What activates glycogen synthase? (3) | 1. ATP 2. G6P 3. Dephosphorylation of glycogen synthase by protein phosphatase 1 |
| What inactivates glycogen synthase? | phosphorylation by protein kinase A |
| What is another fate of glucose 6 phosphate apart from forming pyruvate in glycolysis and being stored as glycogen? | Entering the pentose phosphate pathway |
| What is the resultant product of this? | Ribose 5 phosphate which can be used to form nucleotides and coenzymes to form DNA and RNA |
| This pathway produces 2 molecules of ______ which can be used to synthesise ______ _________. | NADPH, fatty acids |
| This process also releases one molecule of _____. | CO2 |
| What is the name of the pathway which converts pyruvate back to glucose? | Gluconeogenesis |
| Where does the majority of this take place? | Liver |
| What are the 3 main substrates for gluconeogenesis? | 1. Alanine 2. Lactate 3. Glycerol |
| In the __________ of the cell, _______ gets converted to pyruvate and combined with ________ to give ____________ ______, using the enzyme ___________ ____________. | mitochondria, lactate, alanine, oxaloacetic acid, pyruvate carboxylase |
| Oxaloacetic acid is combined with more ______ ______ to give _________ ________, using the enzyme ____________ __________ _____________. | amino acids, phosphoenol pyruvate, phosphoenol pyruvate carboxykinase |
| Phosphoenol pyruvate is combined with __________ (another 3C molecule) to produce ____________ __ __ ____________. This reaction does not require an enzyme, it is reversible. | glycerol, fructose 1,6-bisphosphate |
| The enzyme ________ ___________ breaks this down to __ __ __, which is broken down further by _______ __ _________ to give glucose. | fructose bisphosphatase, G6P, glucose 6 phosphatase |
| Where is the pyruvate formed? | Matrix of the mitochondria |
| In the reactions to produce oxaloacetic acid from pyruvate, the oxaloacetate must be transported out of the matrix in the form of ________, before the rest of the reaction can take place in the ________. | malate, cytoplasm |
| What stimulates gluconeogenesis? | Glucagon |
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