Unit 2

Question 1

Functions of lipids

Answer 1

Cell membranes
Long-term energy storage
Insulation
Cushion for internal organs
Hormones

Question 2

Functions of proteins

Answer 2

Structural (collagen)
Enzymes
Messengers (hormones, insulin)
Transport (hemoglobin)
Defense (immunoglobin)

Question 3

Exceptions to 1 gene 1 polypeptide rule

Answer 3

1. Genes may be alternatively spliced
2. Not all genes code for proteins (e.g. tRNA)
3. Genes may be mutated and produce an alternate polypeptide

Question 4

Lipoproteins

Answer 4

Lipids don’t dissolve in water, so they form complexes with proteins to move through the bloodstream. Hydrophilic portions face outwards and shield internal hydrophobic components

HDL: high density lipoprotein. Good because it carries cholesterol from body to liver, which removes cholesterol
LDL: low density. Bad, high levels lead to plaque buildup. Carries cholesterol
VLDL: very low density. Bad. Carries triglycerides

Question 5

Significance of urea

Answer 5

Artificial synthesis of urea contradited the theory of vitalism, which postulated that organic compounds can only be synthesized by living things because of a special element

Question 6

Properties of water and benefits to living things

Answer 6

Cohesion: allows water to be transported from roots to leaves, allows insects to walk on water to catch prey

Adhesion: helps move blood through veins and water through plants

Thermal: evaporation of sweat cools body. Evaporation of water from leaves cools plants

Solvent: dissolves mineral ions in soil, dissolves substances to be carried by blood

Question 7

2 forms of proteins

Answer 7

Globular: spherical, active roles in cell’s metabolism, soluble in water

Fibrous: long and thread-like, structural roles, insoluble

Question 8

Examples of globular proteins

Answer 8

Rubisco: enzyme in chloroplasts, carbon fixation
Insulin
Immunoglobulin
Rhodopsin: pigment in retina

Question 9

Examples of fibrous proteins

Answer 9

Collagen: found in muscles, tendons, ligaments, provides tensile strength
Spider silk

Question 10

Examples of polysaccharides

Answer 10

Cellulose: found in plants, made of beta glucose, 1-4 linkages
Amylose: found in plants, made of alpha glucose, 1-4 linkages
Amylopectin: found in plants, made of alpha glucose, 1-4 and 1-6 linkages
Glycogen: found in animals, alpha glucose, 1-4 and 1-6 linkages

Question 11

Dehydration synthesis

Answer 11

Aka condensation, removal of water to create a bond

Question 12

Hydrolysis

Answer 12

Addition of water to break a bond

Question 13

Bond between two carbohydrates

Answer 13

Glycocidic bond

Question 14

Bond between a glycerol and fatty acid

Answer 14

Ester bond

Question 15

Bond between two amino acids

Answer 15

Peptide bond

Question 16

Pros and cons of using enzymes in industry

Answer 16

Pros:

• speed up reactions
• great specificity
• enzymes aren’t used up, cost efficient

Cons:
- removal of enzymes can be difficult, hence immobilized enzymes are often used

Question 17

Advantages of immobilized enzymes

Answer 17

• Can use a single batch many times
• Can stop the reaction by removing enzymes easily
• Product is not contaminated
• Enzymes are stabilized by bonding

Question 18

Production of lactose-free milk

Answer 18

Milk filtered through alginate beads with immobilized lactase, lactose converted to glucose and galactose