Carbohydrates 3.1.2 Flashcards
What is a single monomer of a carbohydrate
Monosaccharide
List four traits of monosaccharides
Sweet tasting
Soluble
Made of C, H and O atoms
Have the general formula (CH2O)n where n can be any number from 3-7
What is the name given to a three carbon carbohydrate
Triose
What is the name given to a six carbon carbohydrate
Hexose
What is the name given to a five carbon carbohydrate
Pentose
What two monomers make maltose
Glucose and glucose
What two monomers make sucrose
Glucose and fructose
What two monomers make lactose
Glucose and galactose
What happened to disaccharides are in the presence of water
They hydrolyse into their constituent monosaccharides monomers. Within cells, these reactions are catalysed by specific enzymes
What are two uses of polysaccharides
Storage molecules and structural support to plant cells
Amylopectin is…
Branched. It had 1:4 and 1:6 glycosidic bonds
Amylose is…
Unbranched. It has 1:4 glycosidic bonds
Where is starch found
Starch is found in many parts of plants in the form of small granules or grains
How do you test for starch
Apply iodine solution to the sample. If starch is present in the sample will stain deep blue
How is starch suited to its role
- It is insoluble - So it does not affect water potential and water is not drawn into the cell by osmosis.
- It is large and insoluble - So it does not diffuse out of cells
- It is compact - So a lot of it can be stored in a small place.
- amylopectin has many ends - Each of which can be acted upon by enzymes simultaneously - So glucose monomers are released rapidly
Where is glycogen found
Glycogen is found in animal and bacterial cells, but never plant cells. It is stored as small granules, mainly in muscles and the liver.
How is glycogen suited to its role
- It is insoluble - So it does not affect water potential and water is not drawn into the cell by osmosis.
- It is large and insoluble - So it does not diffuse out of cells
- It is compact - So a lot of it can be stored in a small place.
- It is more highly branched than starch - So it has more ends which can be acted upon by enzymes simultaneously - So glucose monomers are released rapidly, which are used in respiration. This is important in animals as they have a higher metabolic rate and respiratory rate than plants because they are more active.
How to Celulose differ from starch and glycogen
Celulose is formed from beta glucose molecules rather than alpha glucose molecules
Describe the structure of cellulose
Celulose has straight, unbranched chains, running parallel to one another, allowing hydrogen bonds to form cross linkages between adjacent chains. Whilst each individual hydrogen bond as very little to the strength of the molecule, the sheer number of them overall, makes a significant contribution to strengthening the molecule and makes it a valuable structural material
How are cellulose molecules arranged
Cellulose molecules are grouped together to form microfibrils, which are arranged in parallel groups called fibres
How is Celulose suited to its function
- Cellulose molecules are made up of beta glucose - So form long straight, unbranched chains.
- Celulose molecular chains run parallel to each other and are cross-linked by hydrogen bonds - which add collective strength.
- Molecules are grouped to form microfibrils and then fibres - Which provides more strength.
Test for reducing sugars
Add 2 cm³ of the sample to be tested to a test tube
Add an equal volume of Benedict’s reagent
Boil the mixture in a gently boiling water bath for 5 mins
Test for non reducing sugar
Add 2 cm³ of the food sample to 2 cm³ of dilutes hydrochloric acid in a test tube and then place the test tube in a gently boiling water bath for five minutes.
Slowly add some sodium hydrogen carbonate solution to the test tube in order to neutralise the acid
retest the resulting solution by heating it with 2 cm³ of Benedict’s reagent and heat the mixture in a gently boiling water bath in five minutes
