1.2: Exchange of Nutrients and wastes

Unit 1 topic 2

Carbohydrates

• include starch and cellulose

• used as structural support

• Most abundant organic molecules in nature

• monosaccharides; glucose, fructose, and galactose. used for releasing energy in respiration

• Disaccharides; maltose (gluc+gluc), sucrose (gluc+fructose), lactose (gluc+galactose)

• Polysaccharrides; starch, glycogen, cellulose (used for strengthening plant cell walls)

Lipids

• Contain C, H and O, often have hydrocarbon chains and may have phosphorus and nitrogen

• each lipids is made of 3 fatty acids joined to a molecule of glycerol

Functions

• Energy production; have 2x the energy content of .carbs

• Energy storage; hydrophobic meaning it doesn’t add body weight in a significant amount

• Insulation; a layer of fat used against temperature changes

• Cell membranes

• Hormones

• Shock absorbet; layer of fat around eg kidneys which protects against shocks and knocks

Proteins

• contain C, H O and N, and sulphur, phosphorous or other elements

• more complex than carbs and lipids

• made up of 20 different possible amino acids

• functions vary widely depending on the different kinds of proteins

Enzymes in Digestion

Villi and Microvilli

• lines intestines, which are folded

• tiny finger-like projections from intestinal cells

• each villus is covered with tiny microvilli

• increases the surface area for the absorption of nutrients

• absorption initally take splace via diffusion, but active transport also occurs.

• 90% of absorption occurs in the small intestine

Enzymes

a globular protein produced by a cell which acts as a biological catalyst for certain reactions.

• are specific (can only do some reaction per type of enzyme)

• Enzyme-substrate specificy

• Shape held by different bonds (hydrogen, ionic, peptides and disulphide bridges)

Lock and Key theory

when a specific substrate reacts with an enzyme that can be connected to perfectly

Induced fit theory

when the enzyme changes/adjust its shape to fit the substrate

Catalyst cycle

1. substrates enter active site

2. substrates held in by weak interactions

3. active sites can lower E_A (activation energy) and speed up reaction

4. substrates are converted unto products

5. products are released

6. active site is able to be used again

Factors affecting Enzyme activity

• Temperature; gives it more energy which speeds up reaction

• Concerntration; more can increase enzyme activity to a certain level

• pH; if not neutral/7 the enzymes becomes denatured

• Inhabitors; competitive (competes with substrate) or non-competitive (changes shape of enzymes)

• Cofactors; non-protiens molecule that supports biochemical reactions, can be produced by the body or found from food

Active Site

• matches the shape and chemical properties of its enzymes

• Can lower E_A and speed up reaction of enzymes