Biological molecules including proteins and enzymes

Glucose main function

energy source

fractose main function

energy source

galactose main function

energy source

Monosaccharides

Glucose, Fractose, Galactose

Disaccharides

Maltose, Sucrose, Lactose

Maltose main function

transport form

Sucrose main function

Transport form

Lactose main function

Transport form

Polysaccharides

Cellulose, Glycogen, starch

Starch main function

Storage form

Glycogen main function

storage form

Cellulose main function

storage form

a Glucose + a glucose =

maltose

glucose + fructose =

sucrose

glucose + galactose =

lactose

What bond joins monosaccharides

glycosidic bond

Reagent for reducing sugars test

Benedict’s reagent

Conditions for reducing sugars test

Put in a water bath

Positive reducing sugars test

Coloured precipitate

Test for non-reducing sugars conditions

Add dilute HCl and heat in water bath

Neutralise non-reducing sugars test by adding

Sodium hydrogencarbonate

In reducing sugars test, the further the colour change,

the higher the concentration of reducing sugars

Polysaccharide

More than two monosaccharides

amylose monomers

a-glucose

Amylose

Unbranched

Amylopectin monomers

a- glucose

Amylopectin

Branched

Amylopectin branched benefits

Allows enzymes to get at glycosidic bonds easily- releases glucose.

Starch

Insoluble in water

Animals store excess glucose as

Glycogen

Plants store excess glucose as

Starch

Glycogen monomers

a- glucose

Glycogen

Branched

Benefit of glycogen being branched

Glucose can be released quickly

Cellulose monomers

b- glucose

Cellulose chains linked by

Hydrogen bonds

Cellulose chains form

microfibrils

Cellulose provides

structural support for cells

What chemical do you use to test for starch?

Iodine

Positive test for starch

Solution goes from brown to blue-black

All lipids contain

Hydrocarbons

Triglyceride structure

One molecule of glycerol and three fatty acid tails

Lipids

Insoluble in water

Saturated fatty acids

No double bonds

Unsaturated fatty acids

Double bonds

What bond is formed in a triglyceride

Ester bond

Phospholipid structure

Phospholipid head, glycerol, two fatty acid tails

The phospholipid’s phosphate head is

hydrophilic

The phospholipid’s fatty acid tails are

Hydrophobic

Triglycerides are used for

Energy and storage

When the triglyceride’s tail is broken down, what is released?

Lots of energy

Why is it good that triglycerides are insoluble?

They don’t effect water potential

Phospholipids in membranes

Phospholipid bilayer

Phospholipid bilayer centre

Hydrophobic

Test for lipids

Emulsion test

Emulsion test

Shake with ethanol then pour into water

Emulsion test positive result

Milky emulsion

Protein monomers

Amino Acids

Dipeptide

Two amino acids

Polypeptide

More than two amino acids

Amino acid structure

-COOH -NH2 -R group attached to a C

How many amino acids are there?

20

Amino acids are linked together by what reactions?

Condensation

Bonds between amino acids

Peptide bonds

Four protein structure levels

Primary, secondary, tertiary, quaternary

Primary structure of a protein

Sequence of amino acids in the polypeptide chain

Secondary structure of a protein

H bonds form between amino acids in chain

What shapes can a protein be in secondary structure?

Alpha helix or beta pleated sheet

Tertiary structure of a protein

H bonds, ionic bonds and disulfide bridges form

Quaternary structure of a protein

The way the polypeptide chains are assembled together

Test for proteins

Add Sodium hydroxide then copper(II) sulfate

Positive test for protein

Turns from blue to purple

Structural proteins structure

Long polypeptide chains in parallel with cross- links

Transport proteins structure

Hydrophobic and hydrophilic amino acids

Antibodies structure

Two light polypeptide chains and two heavy polypeptide chains bonded

Active site

Where the substrate binds to the enzyme

Enzymes do what to the activation energy?

Lower it

When two substrates need to bind why is it good they’re attached to an enzyme?

Because the enzyme holds them closer together, reducing repulsion

When substrates need to breakdown why is it good they’re attached to an enzyme?

Because fitting into the active site puts a strain on the bonds in the substrate

Induced fit model

Substrate has to be the right shape and the active site has to change shape the correct way

What determines an enzyme’s properties and shape?

The tertiary structure

Tertiary structure of an enzyme is altered

Active site shape will change

Tertiary structure of an enzyme can be altered by

pH or temperature

Primary structure of a protein is determined by

Gene

If a mutation occurs in the primary structure of an enzyme,

The tertiary structure could change

Intracellular enzyme

Works within cells

Extracellular enzyme

Works outside of cells

An enzyme and a substrate can form

An enzyme-substrate complex

Lock and key model

Enzyme and substrate are completely complimentary to each other

Increased temp means the enzyme’s rate

Increases

Temperature is too high for the enzyme

Reaction stops and enzyme is denatured

What happens when an enzyme is denatured?

Bonds in enzyme break and active site changes shape

Enzyme optimum temperature in humans

37 degrees celcius

Above and below an enzymes optimum pH,

the H+ and OH- ions can disrupt the ionic and hydrogen bonds that hold an enzyme’s tertiary structure in place. Enzyme becomes denatured.

Most enzymes work best at what pH (excluding exemptions)?

pH 7

The higher the substrate concentration,

the faster the rate of reaction (more collisions)

‘Saturation’ point of substrate concentration

So many substrates that all enzymes active sites are full (graph plateaus)

Effect of increasing enzyme concentration on rate of reaction

Increases

Inhibition can be…

competitive and non-competitive

Competitive Inhibitors

Bind to the active site and block it