Biomolecules and Enzymes (2.7-2.14B)

what elements are carbohydrates made of

carbon, hydrogen, oxygen

lipids are made of the elements…

carbon, hydrogen, oxygen

proteins are made of the elements…

carbon, hydrogen, oxygen, nitrogen, sulfur

starch and glycogen are made up of…

simple sugars

proteins made up of…

amino acids

lipids made up of…

fatty acids and glycerol

testing for starch

• add iodine solution to food sample

• reddish brown = no starch

• bluish black = starch present

test for glucose

• add Benedict’s solution to food sample

• heat in hot water bath

• blue - green - orange - brick red

• no sugar - bit of sugar - some sugar - lots of sugar

test for lipids

emulsion test

• add ethanol to food sample

• shake/stir

• add water

• clear, no emulsion - no lipids

• cloudy, white emulsion - lipids present

test for protein

Biuret test

• add Biuret solution

• shake

• blue = no protein

• mauve = protein present

what are enzymes?

they are proteins that function as biological catalysts - molecules that speed up a chemical reaction without being affected by it

what are enzymes made up of?

amino acids linked together in one or more polypeptide chains

what does “denature” mean?

the unfolding or breaking up of a protein, modifying its three-dimensional structure and causing the polypeptide chains to become disordered, leaving the molecules non-functional. Proteins can be denatured by heat, chemical action or pH. When bonds in enzymes break, the active site changes shape, leaving it unable to bond with a substrate.

how does temperature affect enzymes?

optimum temp of enzymes - around 37C

As temperature increases towards optimum, the enzymes will gain more kinetic energy, vibrating and moving faster

This allows more frequent successful enzyme substrate collisions to occur, increasing the activity rate

As temperature exceeds optimum, the enzyme will denature

This is because high temperature causes bonds to vibrate more, making it likely that the bonds within the enzyme will break

how does pH affect enzymes?

optimum pH - neutral (7)

unless it’s specific enzymes that work in very acidic/alkaline environments e.g. the stomach

pH too high - denature

pH too low - denature