Biological Molecules AS Biology Notes

Bonding 

Hydrogen Bonding: When an element reacts with hydrogen the electrons are moved slightly creating slight charges (shown as S- and S+)

Properties of Water 

Specific Heat Capacity- Molecules stick together. Acts as a buffer to sudden heat changes 

Latent Heat of Vaporisation- High due to lots of hydrogen bonds 

Cohesion- Large due to the hydrogen bonds causing molecules to stick together and get pulled up tubes 

Surface Tension- Can only support small organisms molecules meet in the air and get pulled back down.

Importance of Water 

Metabolism- hydrolyse and condensation reactions/ Photosynthesis/ aqueous medium reactions

Solvent- Gases/ Inorganic Ions/ waste (urea)/ small hydrophillic molecules 

Not Easily Supressed- Offers support

Transparent- Allows aquatic plants to photosynthesis and allows light rays into retinas.

Evaporates- Allows to cool down

Polymerisation

Polymer: Monomers that have been linked together 

Types of Reactions 

Condensation: Bonds are formed, water is formed 

Hydrolysis: Bonds are broken by water

Adenosine Tri-Phosphate

Structure: Adenosine, Ribose, Three Phosphate 

The weak bonds between the phosphates break really easily by ATP hydrolase. Lots of energy is released but only lasts a few seconds.

ATP+Water = ADP+Pi+energy

ADP+Pi = ATP+Water

Suitable Energy Source in Cells:

1. Little heat energy lost 

2. Readily available 

3. Rapidly resynthesis 

4. Does not leave cells 

Sources Of Energy For Biological Processes: 

Metabolic Processes- Needed to build up macromolecules 

Movement- Provides energy for muscular contractions 

Active Transport- Allows carrier proteins to change shape

Secretion- Needed to form lysosomes

Activation of Molecules- Lowers activation energies 

Properties of ATP that make it suitable:

• Energy released in smaller amounts 
• Soluble 
• Simple reaction 

Why humans need to synthesis lots of ATP:

• Only releases energy in small amounts 
• Can't be stored 

Carbohydrates 

Monosaccharides: Glucose, Galactose, Fructose 

Learn structures of alpha and beta glucose 

Disaccharides: 2 monosaccharides 

Maltose = glucose + glucose 

Lactose = glucose + galactose 

Fructose = glucose + fructose 

Disaccharides Enzymes 

Maltose = maltase 

Sucrose = sucrase 

Lactose = lactase 

Test for Reducing Sugars 

Reducing Sugars: all monosaccharides and some disaccharides

Uses the Benedict Reagent 

Positive Reaction= orange - brown 

1. Food sample dissolved in water 

2. Add an equal volume of benedicts reagent 

3. Heated in water bath and the orange - brown solution shows positive result.

Test for Non-Reducing Sugars

1. Add food sample and equal volume of reagent to test tube 

2. Place in a water bath for 5 minutes 

3. Add a volume of hydrochloric acid to hydrolyse to a monosaccharide 

4. Gently boil for a further 5 minutes 

5. Add sodium hydrogen carbonate to neutralise 

6. Test with a pH indicator to test to see if the solution alkalie 

7. Add a volume of benedict reagent and boil for 5 minutes 

8. Positive result shows a brick red solution 

Types of polysaccharides

Polysaccharide: Long chain of monomers that have undergone the condensation reaction to form glycosidic bonds. 

Properties of Starch: 

• Alpha glucose in helix 
• Coiled and compact meaning lots can fit ina small space 
• Insoluble, does not affect water potential 
• Large, can't diffuse out…