Carbohydrates Flashcards
When are polysaccharides formed?
A polysaccharide is formed when two or more monosaccharides are joined together.
What reaction forms polysaccharides?
Condensation Reactions.
What are polymers?
Polymers are large molecules that consist of many monomers joined together.
What are monomers?
Monomers are small basic molecular units.
What elements do all carbohydrates contain?
- Carbon
- Hydrogen
- Oxygen
What are the monomers of polysaccharides?
Monosaccharides
What is a condensation reaction?
A condensation reaction is when two molecules join together with the formation of a new chemical bond, a water molecule is released.
What bond forms between monosaccharides when a condensation reaction occurs?
A glycosidic bonds forms between two monosaccharides after a condensation reaction.
What is a disaccharide?
Two monosaccharides joined together.
What is polymerisation?
Process of reacting monomer molecules together in a chemical reaction to form polymer chains.
What is sucrose?
Sucrose is a disaccharide formed from a condensation reaction between:
• Glucose Molecule
• Fructose Molecule
What is lactose?
Lactose is a disaccharide, formed from:
• Glucose
• Galactose
What is maltose?
Maltose is a disaccharide, formed from:
• Two Glucose Molecules
What is covalent bonding?
Atoms share a pair of electrons in outer shell, and the outer shell of both atoms is filled and more stable.
What is ionic bonding?
- Ions with opposite charges attract one another.
* The electrostatic attraction is known as an ionic bond, and keeps ions together.
What reaction breaks down polymers?
Hydrolysis reaction.
What does a hydrolysis reaction do?
A hydrolysis reaction breaks the chemical bond between monomers using a water molecule.
What is the metabolism?
The chemical processes that take place in living organisms.
What is sugar?
Sugar is a term used for monosaccharides and disaccharides.
What are the two types of sugars?
- Non Reducing
* Reducing
What is the test for sugars?
Benedict’s Test
What is Benedict’s test for reducing sugars?
- Add Benedict’s reagent to a sample, heat it in a water bath that has been brought to the boil.
- If the sample contains reducing sugars, it will form a coloured precipitate.
What are the colours of the precipitate formed?
- Blue
- Green
- Yellow
- Orange
- Brick Red
What is the test for non reducing sugars?
- Break the sample down into its monosaccharides
- Get a sample of the test solution, add dilute hydrochloric acid.
- Heat it in a water bath that has been brought to the boil.
- Neutralise it with sodium hydrogen-carbonate.
- Carry out the Benedict’s test as normal.
- If the test is positive, it will form a coloured precipitate .
- If negative, it remains blue, indicating that there is no sugar present at all in the sample.
Where do plant cells get energy from?
- Glucose.
* Plants store excess glucose as starch.
What is the test for starch?
Iodine Test.
What is the iodine test?
- Place 2cm3 of the sample into a test tube.
- Add two drops of iodine solution and shake or stir.
- Presence of starch creates a blue-black coloration, if not the solution remains a brown/orange colour.
What is starch
Starch is a polysaccharide that is found in plants in the form of small grains.
Why is starch useful?
It is an important component of food, and is a major energy source.
What is the main purpose of starch?
Energy storage.
How does starch’s structure allow it to be useful as energy storage?
- Insoluble, and therefore doesn’t affect water potential, so water is not drawn into the cell via osmosis.
- Large and insoluble, so it will not diffuse out of the cell.
- Compact, so it can be stored in a small space.
- When Hydrolysed, forms alpha glucose, which is easily transported and readily used in respiration.
- Branched form has many ends, each which can be acted on by enzymes, meaning that glucose molecules are released very quickly.
What is starch made up of?
Starch is made up of two polysaccharides of alpha glucose:
• Amylose
• Amylopectin
What is amylose?
- A long un-branched chain of alpha glucose.
* Angles of glycosidic bonds provide a coiled structure/
How is amylose adapted to its function?
Angles of the glycosidic bonds give it a coiled structure, allowing it to be compact, meaning you can fit more in a small space.
What is amylopectin?
- A long branched chain of alpha glucose.
* Many side branches.
How is amylopectin adapted to its function.
- Side branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily.
- Glucose can therefore be released very quickly.
How do animal cells store excess glucose?
Excess glucose is stored as glycogen.
How is glycogen stored?
• Stored as small granules in the muscles and liver.
How is glycogen adapted to its function?
- It is insoluble, does not draw water into the cell via osmosis, nor will it diffuse out of cells.
- Compact, so a-lot can be stored in a small space.
- Highly branched, can be rapidly broken down to form glucose monomers, which are used for energy, provides quick energy release.
What is cellulose made of?
Cellulose is made of long un-branched chains or beta-glucose.
What is a difference in structure from cellulose to starch and glycogen?
• Forms straight un-branched chains, that run parallel to one another allowing for the formation of hydrogen bonds.
What bonds link together cellulose chains?
Hydrogen Bonds.
How does cellulose provide strong structural support for cells?
• Cellulose chains are linked together by hydrogen bonds to form strong fibres called micro-fibrils, strong fibres mean cellulose provides structural support for cells.
How is cellulose suited to its function of providing support?
- Cellulose molecules are made up of beta glucose, thus form long straight un-branched chains.
- Cellulose molecular chains run parallel to each other, and are cross linked by hydrogen bonds which add collective strength.
- Molecules are grouped to form microfibrils, which form fibres, which provide more strength.
How are microfibrils formed?
Cellulose chains being linked together by hydrogen bonds.
