2. Lipids, water and inorganic ions

How to test for lipids in a sample?

1. Dissolve solid samples in ethanol

2. Add equal volume of water and shake

3. Positive result is a milky white emulsion forms

How do triglycerides form?

Codensation reactions between 1 molecule of glycerol and 3 fatty acids form ester bonds

What are the features of a saturated fatty acid?

• Contain only single bonds

• Straigh chain molecules

• High melting point

• found in animal fats

What are the features of a unsaturated fatty acid?

Countain C=C double bonds

Kinked molecules have fewer contact points

Lower melting point

Found in plant oils

What is the structure of phospholipids?

Glycerol backbone attached to 2 hydrophobic fatty acids tails an 1 hydrophillic polar phosphate head

What is the function of phospholipids?

Forms phospholipid bilayer in water

Why is water a polar molecule?

O is more electronegative than H, so attracts the electron density in the covalent bond stronger

What are the 4 bioloically important properties of water?

• Solvent

• High specific heat capasity

• High latent heat of vapourisation

• Cohesion between molecules

What is water important to living organisms?

• Can be dissolved to allow cheical reactions

• Enables organisms to avoid fluctuations in core temperature

• Coesion tension of water molecules in transpiration stream

What are inorganic ions?

• Ions that do not contains carbon atoms

• Found in cytoplasm and extracellular fluid

• May be in very high or very low concentrations

What is the role of hydrogen ions in the body?

High concentration of H+ = low PH (acidic)

H+ ions can cause proteins to denature

What is the role of iron ions in the body?

Fe2+ bonds to form haem group in haemoglobin

Haem group has binding site to transport 1 O2

4 haem groups per haemoglobin molecule

What is the role of soduim ions in the body?

Involved in co-transport for absorbtion of glucose and amino acids

Causes action potentials in neurones

What is the role of phosphate ions in the body?

DNA

ATP

NADP

cAMP