biological molecules

monomers

Monomers are small units which are the components of larger molecules

examples of monomers

Glucose, amino acids, nucleotides

What reaction do monomers make polymers?

Condensation reaction

What is hydrolysis

When water is added to break a chemical bond between two molecules

What type of bond is formed in a condensation reaction?

Glycosidic bond

Isomers of glucose?

Alpha and beta glucose

Common monosaccharides

Glucose, galactose, fructose

What is the general formula of monosaccharides

(CH2O)n

Glucose + glucose

Maltose

Glucose+galactose

Lactose

Glucose + fructose

Sucrose

What are polysaccharides made from alpha glucose

Starch and glycogen

What are the polysaccharides formed from beta glucose

Cellulose

What are properties + structure of glycogen

• main energy storage molecule

• Joined by 1,4 and 1,6 glycosidic bonds

• Side branches(energy released quickly)

• Large but compact (store more energy)

• Insoluble (doesn’t affect water potential)

What polysaccharides are in starch

Amylose + amylopectin

Amylose properties

• unbranched

• 1,4 glycosidic bonds

• Coiled

• Very compact

Amylopectin properties

• branched

• 1,4 and 1,6 glycosidic bonds

• Many side branches

Cellulose properties

• long unbranched chains

• Beta glucose

• Has microfibrils

  (Strong chains of cellulose that run parallel rot one another joined by hydrogen bonds)

• Strengthens cell wall

Reducing sugar test

Benedict’s test

• add 2cm to liquid food sample

• Heat in water bath for 5mins

• Turns from blue to brick red

Examples of reducing sugars

All monosaccharides and maltose

Test for non reducing sugars

• 2cm of food sample

• Add Hcl (to hydrolyse)

• Heat in water bath for 5mins

• Add some sodium hydrogen carbonate to neutralise

• Retest (blue to brick red)

Test for starch

Iodine test

What are lipids

Biological molecules made of carbon, hydrogen and oxygen (only soluble in organic solvents e.g alcohols)

Two types of lipids

Triglycerides and phospholipids

Triglyceride structure

• one glycerol molecule

• 3 fatty acids

  • joined by ester bonds via condensation reaction

What are saturated lipids

Found in animal fats

• no c-c bonds

What are unsaturated lipids

Found in plants

• contain c-c double bonds

• Cannot pack together

• Liquid at room temp

Triglyceride properties

• excellent energy store (high ratio of energy storing c-h bonds to carbon atoms)

• Good storage in small volume

• Insoluble (doesn’t affect water potential)

Phospholipid structure

• two fatty acids

• One glycerol molecule

• Phosphate group

  Heads = hydrophilic

  Tails = hydrophobic

• POLAR molecule

Phospholipid properties

Bilayer formed - aqueous environment

Hydrophilic heads can hold at surface of cell membrane

Can form glycolipids with carbs (important for cell recognition)

Test for lipids

Emulsion test

• 2cm sample

• 5cm ethanol

• Shake

• Add 5cm water

• Cloudy white = lipid

What does NH2 mean in a protein

Amine group

What does COOH mean in a protein

Carboxyl group

What does R mean in a protein

Side chain

What bond is formed via condensation reactions in a protein

Peptide bond

What is two amino acids called

Dipeptide

What are many amino acids called

Polypeptides

What is the primary structure

Order and number of amino acids

What is the secondary structure

The shape of the chain of amino acids - either alpha helix or beta pleated sheet

What is the tertiary structure

The 3D shape of the protein

Bonds that maintain the structure -

• disulphide bridges (between sulfur in R group)

• ionic bonds (between carboxyl and amino groups)

• Hydrogen bonds

What are globular proteins

are compact