7307905
Description
Flashcards by Emma Lloyd, updated more than 1 year ago
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Created by Emma Lloyd
over 7 years ago
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| Question | Answer |
| What elements do carbohydrates contain? | Only carbon, hydrogen and oxygen. Carbohydrate literally means 'hydrated carbon' (carbon with H2O). |
| What is the general formula of carbohydrates? | C x (H20) y |
| What other names do carbohydrates go by? | They are known as sugars or saccharides. One single sugar unit is known as a monosaccharide and multiple units of sugar are known as polysaccharides. |
| Examples of Monosaccharides? | Glucose, fructose, ribose |
| Examples of Disaccharides? (Two saccharides joined together) | Lactose and sucrose |
| Example of polysaccharides? | Glycogen, cellulose, starch |
| Glucose monomers make up a variety of biologically essential carbohydrates. What is the formula of glucose? | C 6 H 12 O 6 |
| How many carbons are in glucose? | Six - therefore it is a six carbon monosaccharide (a hexose sugar) |
| What is the difference between alpha (α) glucose and beta (β) glucose? | Alpha has both OH groups (on 1st and 4th carbon) facing downwards. Beta has the OH group on the 1st carbon facing upwards and the carbon on the 4th facing downwards. |
| What is the structure of an alpha glucose molecule? | |
| What is the structure of beta glucose? | |
| What are the properties of glucose molecules? | They are polar and water soluble due to hydroxyl groups hydrogen bonding with water. This is important as glucose is dissolved in water in the cell cytosol. |
| What happens when two alpha glucose molecules are side by side? | A condensation reaction - the OH group on the 4th carbon of the one molecule reacts with the OH group of the 1st carbon on the other. This forms a glycosidic bond and H2O is released. The bond is known as a 1,4 glycosidic bond. |
| What is formed by the condensation reaction between two alpha glucose molecules? | Maltose - a disaccharide |
| Examples of pentose sugars? (Saccharised with 5 carbons) | Ribose (from RNA) and deoxyribose (from DNA) |
| What is the structure of amylose? | Alpha glucose molecules lined up side by side joined by 1,4 glycosidic bonds. The 1,4 bonds cause the amylose to curve, forming a helix shape. The shape is held together by further hydrogen bonds between molecules. It's much less soluble than glucose. |
| What is the structure of amylopectin? | Amylopectin also has 1,4 glycosidic bonds between two alpha glucose molecules, but it also has 1,6 bonds once every 25 glucose molecules, forming branches. |
| How is glycogen (glucose storage in animals and fungi as it is starch in plants) similar to amylopectin? | Glycogen also has 1,6 bonds forming branches. However, these branches are more frequent so that the structure is more compact and takes up less storage space. The branching also means that there are more exposed ends so glucose can be taken more easily for usage. |
| What are hydrolysis reactions? | Reactions where water is added to storage molecules (glycogen, starch) to reduce them back to glucose which can be used i cellular respiration. |
| Why can beta glucose molecules not react the same was as alpha glucose molecules? | The OH groups on carbon 1 and 4 are too far away from one another, as one is facig downwards and one is facing upwards. |
| How is the problem of beta glucose not being able to react resolved? | One molecule of beta glucose is flipped upside down so that the two OH groups are next to one another. Due to this, a straight chain of beta glucose is formed that does not coil or branch. |
| What is the polysaccharide formed by the joining of lots of beta glucose molecules? | Cellulose |
| Cellulose makes cell walls. How are these formed from beta glucose molecules? | The beta molecules join up into a straight chain polymer. Multiple polymers connect through hydrogen bonding, producing microfibrils. The microfibrils combine to produce fibres and these fibres are strong and insoluble enough to form cell walls. |
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