Carbohydrates

3.1.1 + 3.1.2

What is the theory of evolution?

All organisms on Earth are descended from one ancestor and diversified

First evidence of evolution?

Share the same groups of carbon-based compounds that interact in similar ways

Second evidence of evolution

Use the same Nucleic acids as genetic material and the same amino acids to build proteins

Polymer

Large molecules composed of long chains of monomers joined together

Monomers

small units that can form a polymer

How is a polymer formed from two monomers?

From a condensation reaction, releasing a molecule of water and forming a glycosidic bond.

How to break a polymer to a monomer?

Using a molecule of water in a hydrolysis reaction.

Three monosaccharides?

Glucose, fructose and galactose

Glucose is a hexose sugar. What does this mean?

A monosaccharide with 6 carbon atoms in each molecule

What Monosaccharides for the disaccharide sucrose?

Glucose and fructose

What Monosaccharides for the disaccharide lactose?

Glucose and galactose

What Monosaccharides for the disaccharide Maltose?

Glucose and glucose

How to test for reducing sugars?

Add Benedict’s reagent to a sample and heat in a water bath.

How to test for non-reducing sugars?

Add dilute HCL and heat in a water bath and neutralise.

Positive result of the Benedict’s test?

Blue to brick red

Polysaccharides

Formed when more than two monosaccharides are joined by condensation reactions.

How do cells get energy from starch?

Excess glucose is stored as starch

What is starch a mixture of?

Amylose and amylopectin

What is amylose?

A long, unbranched chain of alpha glucose

Amylose is coiled. What does this mean?

It’s compact and good for storage

What is amylopectin?

Long, branched chain of alpha glucose

Amylopectin has side branches. What does this mean?

Allow enzymes that break down the molecule to get the glycosidic bonds easily.

Why is it important that enzymes get the glycosidic bonds easily?

Glucose can be released quickly

Why is starch being insoluble important?

Doesn’t affect water potential so it doesn’t cause water to enter cells by osmosis. Good storage.

How do animals get energy?

They store excess glucose as glycogen

Glycogen has lots of side branches. What does this mean?

Glucose can be released quickly

Glycogen is compact. Why is this important?

Good for storage

What is cellulose?

Long, unbranched chains of beta-glucose

How are microfibrils formed?

Cellulose chains linked together by hydrogen bonds

What are microfibrils?

Strong, structural support for cells in cell walls.

How to test if iodine is present?

Add iodine dissolved in potassium iodide solution

What happens if starch is present?

Colour change from orange to blue/black