Question | Answer |
What are the three classes of carbohydrates? | Monosaccharides, disaccharides, polysacharides |
What is the general formula for carbohydrates? | (CH2O)n |
Describe triose sugars | Simplest monosaccharides. 3-carbon sugar |
What sugar is in DNA | deoxy-ribose sugar |
Is sucrose a monosaccharide or a disaccharide? | Disaccharide |
What is SUCROSE composed of? which monomers? How are they bonded? | The 1st carbon of a glucose molecule and the 2nd carbon of a fructose molecule are joined by a 1-2 glycosidic bond |
What is LACTOSE composed of? Which monomers? How are they bonded? | The 1st carbon of a galactose molecule and the 4th carbon of a glucose molecule forms a 1-4 glycosidic bond |
What is MALTOSE composed of? Which monomers? How are they bonded? | The 1st carbon of a glucose molecule and the 4th carbon of a glucose molecule joined by a 1-4 glycosidic bond |
Where are disaccharides digested? | Small Intestine |
Why must disaccharides be broken down in the small intestine? | The body cannot absorb disaccharides across a cell membrane, they are too large |
What is lactose intolerance caused by? | Reduced lactase production |
What monomers make up STARCH and how are they bonded? | Polymer of glucose, a1-4 glycosidic bonds |
What breaks down starch? | Amylase |
What monomers make up CELLULOSE and how are they bonded? | Polymer of glucose, β1-4 glycosidic bonds |
Can amylase break down cellulose | No |
What is the optimum blood glossed range in a normal human? | 4-6mM |
Why is glycogen necessary in the body? | The body needs an insoluble store of glucose to allow a steady supply of soluble glucose in the blood |
Describe glycogen | A glucose polymer joined by a1-4 glycosidic bonds. Branched molecule. Store of energy |
What bonds join branchs to the main glycogen strand? | a1-6 glycosidic bonds |
Where is glycogen stored? | In the liver and the muscles |
How is glycogen stored? | Stored as large insoluble granules in the cell |
Why must glycogen be stored as a INSOLUBLE molecule? | Glucose (like all sugars) has an osmotic affect, it draws water into the cell. Glucose must therefore be stored in an insoluble form when stored because it no longer has an osmotic effect |
What is the role of a branching enzyme | Adds branches to glycogen at random intervals |
What enzyme breaks up glycogen? | Glycogen phophorylase |
What enzyme snips the branches of glycogen? | De-branching enzyme |
How is glycogen used in a muscle cell? | Glucose-1-phosphate is converted into glucose-6-phosphate and is then used completely in the muscle cells. NEVER leaves the cell that stored the glucose in the first place, glucose-6-phosphate is trapped |
How is glycogen used in the liver? | Glucose-6-phosphate is converted back into glucose using glucose-6-phosphatase and can then leave the cell. |
Why is glycogen stored by the muscles? | Use in exercise |
Why is glycogen stored by the liver? | Supports circulating blood glucose |
What is Von Gierke's disease caused by? What are the symptoms? | Deficiency og glucose-6-phosphatase= liver cannot release glucose back into the blood. Hypoglycaemia and hepatomegaly (swollen liver) |
What is Cori's disease caused by? Symptoms? | Defects in the deb ranching enzymes. Mild hypoglycaemia and heptomegaly |
What is McArdle's disease caused by? Symptoms? | Absence of usable muscle phosphorylase but only in the muscles, liver is fine. Muscle cramps when exercising. |