4. Carbohydrates and lipids

Question 1

What are the main molecules of life?

Answer 1

1. Carbohydrates
2. Proteins
3. Lipids
4. Nucleic acids

Question 2

Explain synthesis and breakdown of polymers

Answer 2

Synthesis: carried out by enzymes that mediate chemical reactions - monomers are connected in dehydration / condensation (loss of water) - POLYMERISATION

Breakdown: also by enzymes - polymers broken into monomers - hydrolysis (water used) - DIGESTION

Question 3

What is the molecular logic of life?

Answer 3

Question 4

What are the types of sugars based on functional groups?

Answer 4

Question 5

What are the dissacharides and their monomers?

Answer 5

Maltose = 2 glucose

Sucrose = fructose + glucose

Galactose = lactose + glucose

Linked by 1, 4 glycosidic bonds in dehydration

Question 6

What are the carbohydrate polymers?

Answer 6

Starch: amylose + amylopectin (alpha 1, 4 links)

Cellulose: ( beta 1, 4 links) straight not branched - microfibrils - not dissolved in water

Glycogen: (alpha 1, 4 and 1, 6 links)

Question 7

What are the biological lipids?

Answer 7

1. Fats: glycerol (alcohol OH group) + 3 fatty acid chains -> triglycerides - saturated (no double bonds - solid - can clog up - eat not too much) / unsaturated (double bonds - liquid) fatty acids (cis / trans)

Uses of fats:

• insulation + protection of organs
• storage of E (better than carbohydrate) - E stored in bonds
  2. Phospholipids: hydrophilic heads - hydrophobic tails (phosphate) - bilayer formed due to different interactions with water - compartmentalisation important for cell function
  3. Steroids: ring structure - animal membranes (good / bad cholesterol), sex hormones