2.1.2 Biological Molecules - Carbohydrates Flashcards
What elements are found in carbohydrates?
Carbon, Hydrogen, Oxygen
How much of cells organic matter is carbohydrates?
10%
What is the chemical formula for Carbohydrates?
Cx(H20)y
What are carbohydrates also known as?
Saccharides or sugars
What is a single sugar unit known as? - Examples?
A monosaccharide
- Glucose
- Fructose
- Galactose
When two monosaccharides link together they form a…?
Examples?
Disaccharide
- Maltose - Glucose + Glucose
- Sucrose - Glucose + Fructose
- Lactose - Glucose + Galactose
When three monosaccharides or more are joined together. It is called a…? Examples?
Polysaccharide
- Starch
- Cellulose
- Glycogen
What monosaccharide is Glucose?
Hexose sugar ( as it has 6 carbons )
Why are glucose molecules soluble in water and why is this important?
They are polar molecules, due to the hydrogen bonds between the hydroxyl groups and water molecules
- Important as it means glucose can dissolve in the cytosol of the cell
What reaction joins glucose molecules together and what product is formed?
Condensation and water is produced
What bond is it when two glucose molecules are joined
Glycosidic bond
What are the two types of glucose, what is the difference between them and what are they to each other?
Alpha glucose - OH at Carbon 1 is below the plane
Beta Glucose - OH at Carbon 1 is above the plane
- They are isomers of each other
Properties of Fructose
- Hexose sugar
- Naturally occurs in fruit
- Sweeter than glucose
Properties of Galactose
- Hexose sugar
- Found in milk
- Less sweet than glucose
What are pentose monosaccharides and what are two examples?
5 Carbon atoms
- Ribose - DNA and RNA
- Deoxyribose - Ribose that has lost one oxygen - DNA
How many polysaccharides in Starch and what are they?
Two
- Amylose
- Amylopectin
Properties of Amylose
- Alpha glucose joined together by only glycosidic 1-4 bonds
- Forms a helix due to the angle of the bond, stabilised by hydrogen bonding
- Polysaccharide is much more compact and much less soluble than the glucose that made it
Properties of Amylopectin
- Made by Alpha 1 - 4 glycosidic bonds
- Also has Alpha 1 - 6 glycosidic bonds every 25 subunits
- Branched and coiled structure
- Because of its branches it is a good storage molecule
Storage molecule in Plants
Starch
Storage molecule in animals
Glycogen
Glycogen properties
- More branched than amylopectin and therefore more compact and needs less space to be stored which is important as animals are more mobile than plants
Properties of amylopectin and starch
- compact due to the coiled and branched chains, ideal for storage
- branching means many molecules of glucose can be broken off or added
- insoluble so don’t affect water potential of the cell
Reaction that breaks down the polysaccharides
Hydrolysis reaction, need to add water
What glucose is used to form cellulose?
Beta glucose
