Topic 1A- Biological Molecules Flashcards
What are polymers?
Large, complex molecules composed of long chains of monomers joined together
3 examples of monomers
Monosaccharides, nucleotides, amino acids
3 examples of monosaccharides
Glucose, fructose, galactose
What is a condensation reaction?
When two molecules join together by a glycosidic bond and a water molecule is released
What’s a disaccharide?
Two monosaccharides joined together
What’s sucrose
A disaccharide formed from a condensation reaction between a glucose and fructose molecule
What’s lactose made up of?
A glucose molecule and a galactose molecule
Hydrolysis reaction
Breaks the chemical bond between monomers using a water molecule
Benedict’s test
•Add Benedict’s reagent
•Heat in water bath
•Positive- precipitate is formed and will turn from blue to an orangey-red
Test for non-reducing sugars
•Add dilute hydrochloric acid and heat in water bath
•Neutralise with sodium hydrogen carbonate
•Do the Benedict’s test
•Positive- turns from blue to an orangey-red
What is a polysaccharide?
Formed when two or more monosaccharides are joined together by a condensation reaction
Starch information
Plants store excess glucose as starch, when plants need more glucose for energy, it breaks down starch to release glucose.
What is starch a mixture of?
Two polysaccharides of alpha-glucose: amylose and amylopectin
Structure of amylose
Long unbranched chain of alpha glucose, coiled structure to make it compact therefore good for storage
Structure of amylopectin
Long, branched chain of alpha glucose, side branches allow the enzymes that break down the molecule to get at the glycosidic bonds quickly
Why is it good starch is insoluble in water?
Doesn’t affect water potential so water can’t enter the cell through osmosis which makes starch good for storage
Iodine test
Add iodine dissolved in potassium iodide solution. If positive- it changes from browny-Orange to blue-black
How do animals store excess glucose?
As glycogen- another polysaccharide of alpha glucose
Glycogen structure
Loads of side branches coming off it so the stored glucose can be released quickly
Cellulose structure
Long unbranched chains of beta glucose, linked together by hydrogen bonds
Microfibrils definition
Strong fibres formed by hydrogen bonds in cellulose chains
Triglycerides?
Type of lipid
What are triglycerides made up of?
One molecule of glycerol and three fatty acids attached to it
Fatty acid tails
Long tails made up of hydrocarbons, hydrophobic so they repel water. These tails make lipids insoluble in water.
