Biological Molecules Flashcards
What are carbohydrates made of?
Monosaccharides
How do monosaccharides join together?
By a condensation reaction.
Sucrose is made from:
Glucose and fructose
Lactose is made from;
Glucose and galactose
Maltose is made from:
Glucose and glucose
What type of reaction breaks polymers?
Hydrolysis reaction.
State the Benedict’s Test for Sugars:
1) Reducing sugars include all monosaccharides and some disaccharides.
2) Add Benedict’s reagent (blue coloured) to a sample and heat it in a water bath.
3) If the test is positive a coloured solution will form.
The more Reducing it is the more red the precipitate is.
A more accurate way to do this would be to filter the solution and weigh the precipitate.
State the Benedict’s test for non-Reducing sugars:
1) Add dilute HCl to the solution
2) Heat in water bath then add equal volume of Na2CO3
2) Add Benedict’s reagent (blue coloured) to a sample and heat it in a water bath.
3) If the test is positive a coloured solution will form.
The more Reducing it is the more red the precipitate is.
A more accurate way to do this would be to filter the solution and weigh the precipitate
Definition of a polysaccharide:
A carbohydrate (e.g. starch, cellulose, or glycogen) whose molecules consist of a number of sugar molecules bonded together.
What is starch made from?
Alpha glucose.
What are the 2 types of polysaccharides present in starch?
Amylose
Amylopectin
Describe the structure of amylose:
A long, unbranched chain of alpha-glucose. The angles of the glycosidic bonds give it a coiled structure. This makes it compact, and is so good for storage as you can fit more in a small space.
Describe the structure of amylopectin:
A long, branched chain of alpha-glucose. It’s side branches allow the enzymes to easily break down the molecule to get at the glycosidic bonds easily. This means glucose is quickly released.
Suggest a benefit of starch:
Starch is insoluble in water and doesn’t affect water potential so it doesn’t cause water to enter cells by osmosis, which would make them swell. This makes starch a good for storage.
What is glycogen made from?
Alpha-Glucose
Describe the structure of glycogen:
A long, highly branched chain of alpha-glucose. Side branches allow the enzymes that break down the molecule to break the glycosidic bonds quickly.
Lots of branches means energy can be quickly released.
Compact molecule.
What is glycogen the main energy store of?
Animals
What is starch the main energy source of?
Plants
What is cellulose used as?
It is used in plants cell walls.
Describe the iodine test for starch:
Add iodine dissolved in potassium iodide solution to the test sample.
If there is any starch present, the sample changes from a browny-orange colour to a blue-black colour.
What is cellulose made from?
Beta-Glucose
Describe the structure of cellulose and describe why this is:
Cellulose is made of long, unbranded chains of beta-glucose.
When the glucose molecules bind, they form straight cellulose chains.
These chains are linked by H bonds to form strong divers called microfibres. The strong fibres mean cellulose provides structural support for cells.
Maltose is a sugar. Describe how a molecule of maltose is formed:
Two molecules of alpha-glucose are joined by a glycosidic bond. A molecule of water is released/a condensation reaction takes place.
Describe the structure of a triglyceride:
Triglycerides have one molecule of glycerol with 3 fatty acid attached to it.
