2.1 - 2.5 Molecules + enzyme

Question 1

Anabolism vs catabolism

Answer 1

Ana: synthesis of complex molecules from simpler molecules, use of energy
Energonic

Cat: breakdown of complex into simpler, release energy
Exergonic

Question 2

Draw: a/b glucose, ribose + formula

Answer 2

Glu” c6h12o6
ribose: c5h10o5

Question 3

Role of urea

Answer 3

Excretion of nitrogen: access amino acids > urea at liver > excreted in kidney

Urea is fertilizer

Question 4

Properties of water (6) and significance

Answer 4

• Polar and hydrogen bonding:
  O more electronegative than H
  Partial positive/negative, net dipole
  H bond: H is attracted to O on neighbouring atom
• High shc
  Insulator, thermally stable and constant environment for biochemical reactions to occur.
• High lhv
  Evaporative coolant - remove heat: sweating
• High lhf
  Cells unlikely to freeze
• Cohesion/adhesion/surface tension
  Cohesion: attraction between water molecules
  Adhesion: attraction between water molecules and other polar molecules of different substances
  Capillary action
  Surface tension: how difficult it is to break surface of a liquid - small insects move on surface of water
• Universal solvent
  Dissolve polar substances
  Ions and polar groups surrounded by water molecules, form hydration shells
  Ions separated from each other
  Transport medium

Question 5

Water v methane

Answer 5

Boiling point: due to imf of attraction
Polar/nonpolar
Can/cannot form hydrogen bonds

Question 6

Condensation v hydrolysis

Answer 6

condensation: 2 molecules combine to form larger molecule, production of water as byproduct
hydrolysis: large molecule reacts with molecule of water, split into 2 smaller molecules.

Question 7

Functions of carbohydrates (7)

Answer 7

• Energy
• Cellulose
• Nucleic acid
• Nectar
• Lubricant
• Glycoprotein
• Used to produce AA/fats

Question 8

Amylose v amylopectin v glycogen

Answer 8

All a-glucose

Amylose: 1-4, helical coiling into complex shape

Amylopectin: 1-4, 1-6, branching with long side chains (20-25 monomers)

Glycogen: 1-4. 1-6, branching with short side chains, more compact than amylopectin.

Question 9

Advantages of glycogen structure

Answer 9

Branching provides site for enzymes to cleave off glucose molecules, allows for rapid hydrolysis, produce high levels of glucose more quickly, higher resp

Question 10

Cellulose structure

Answer 10

b-glucose molecules
1-4, every alternate molecule inverted
long, straight, unbranched
chains run parallel to each other
hydroxyl groups project outwards enable hydrogen bonding between neighboring chains
rigid cross linking

Question 11

Cis vs trans, significance of boiling point

Answer 11

Cis - pronounced kink, H at same side of double bond chain extends in diff direction, prevents tight packing, lower mp, do not solidify as readily.

Trans - less pronounced kink, H at diff side of double bond, chain extends in same direction, can be packed closely with each other, higher mp.

Question 12

Example of simple, compound, derived lipids

Answer 12

Triglyceride, phospholipid, cholesterol

Question 13

Lipid functions (6)

Answer 13

Long term energy storage
Structure - phospholipid
Signaling - steroid hormones
Insulation - subcutaneous tissue
Protection - adipose tissue surround and cushion internal organs
Buoyancy - less dense than water, animals float

Question 14

Lipids v carbohydrates

Answer 14

Lipids higher energy per gram
Solubility in water
Long term energy storage
Aerobic vs ana/aerboic resp

Question 15

Types of protein structures (4) and explain

Answer 15

Primary - linear sequence of aa in specific order, held together by peptide bonds
Secondary - regular folding, twisting, coiling of primary structure to form a helix or b pleated sheet
Tertiary - folding of secondary structures to form 3D conformation
Quaternary - Comprised of more than one polypeptide chain to form functional protein.

Question 16

Proteome vs genome’

Why proteome is larger?

Answer 16

Proteome - set of proteins produced by cell/organism at given time and defined conditions

Genome - set of genes in cell/organism
Proteome is larger - alternative splicing and modification of proteins.

Question 17

Functions of proteins (9) but prob 7 is enough

Answer 17

• Hemoglobin
• Actin and myosin
• Tubulin
• Membrane proteins (adhesion)
• glycoproteins
• digestive enzymes
• fibrinogen
• collagen
• Histones

Question 18

Collagen - function and structure

Answer 18

insoluble, fibrous protein
Structural support, elasticity to connective tissue, along with elastin
Found in extracellular matrix

Question 19

Zwitter ions?

Answer 19

Ionized carboxyl and amino groups.

Question 20

Fibrous protein v globular protein

Answer 20

insoluble v soluble
long and narrow v rounded
Structural/support, functional/metabolic
Collagen v hemoglobin
More sensitive to changes in pH/temp, less sensitive

Question 21

Enzyme - definition

Answer 21

Globular protein
Biological catalyst
Speed up rate of organic rxn
lower activation energy
Not consumed by rxn

Question 22

Lock and key vs induced fit

Answer 22

L/K:
Enzyme active site is specific to shape of substrate
Active site is rigid, inflexible
Only substrates with exact, complementary shape can bind.
Could not explain why some active sites can bind to multiple substrates

I/F:
- Active site is flexible and not necessarily complementary
- Binding induces change in conformation, better fit substrate
- Change in shape reduces Ea, facilitates bond breaking

Question 23

Effect of temp on enzyme activity

Answer 23

Increase to optimum
- increase in ke
- increase in frequency of collisions, effective collisions
- increase rate of es complex formation
- increase rate of rxn

Optimum - highest rate of rxn

Past optimum
- Thermal agitation of enzymes
- H bond, ionic interaction, weak hydrophobic interactions which give 3d shape disrupted.
- 3D conformation enzyme and active site disrupted
- Enzyme denatured

Question 24

Effect of pH on enzyme activity

Answer 24

Low/high ph:

Ionic charges of acidic and basic groups on side chains of amino acid residue are altered, resulting in the disruption of ionic and hydrogen bonds which allow for 3d shape of enzyme. 3d conformation of active site is lost, enzyme denatured.

Question 25

Substrate concentration

Answer 25

Low concentration
- not all active sites occupied
- increase substrate conc - increase frequency of effective collisions
- increase e/s complex formation
- increase rate

High concentration
- all actives sites occupied
- enzymes become saturated
- substrate no longer limiting factor
- rate reaches a plateau

Question 26

Competitive vs non competitive inhibitors

Answer 26

Competitive
- binds to active site, prevents substrate from binding
- similar structure to substrate, competes with substrate for active site
- reverse inhibition by increasing substrate concentration, substrate molecule displaces inhibitor.
Eg: penicillin

Noncompetitive
- binds to allosteric site not active site, but causes enzyme, and active site to change shape, prevents es complex formation
- not similar shape with substrate
- effect cannot be reversed by addition of more substrate
- Eg: CO poisoning

Question 27

Inhibition in antimalarial drug

Answer 27

Plasmodium digests protein part of hemoglobin of invaded blood cell.
Converts residual heme to harmless insoluble precipitate with enzyme (heme is toxic)
Chloroquine inhibits enzyme, leading to build up of heme, kills parasite.

Question 28

Define feedback inhibition, describe process of feedback inhibition

Advantages of fb inhibition

Answer 28

Def: Method of metabolic control, end product of metabolic pathway acts as inhibitor of enzyme within the pathway

When end product is low - dissociates from allosteric site of enzyme
Metabolic pathway starts again when there is shortage of end product

When end product is high - metabolic pathway switched off.
End product act as non-competitive inhibitor, binds to to allosteric site results in change in active site conformation, prevents substrate from binding to form es complex.

Prevents build up of intermediates, conserves energy
No unnecessary accumulation of end product

Question 29

describe End product inhibition of isoleucine from threonine

Answer 29

bacteria synthesize isoleucine from threonine
isoleucine is noncompetitive inhibitor, binds to allosteric site of threonine deaminase, required for isoleucine synthesis
High concentration of isoleucine - switch off metabolic pathway, noncompetitive inhibition occurs.
As isoleucine is used up for protein synthesis, concentration falls, isoleucine dissociates from allosteric site, threonine deaminase is no longer inhibited.

Question 30

Applications of enzymes (3)

what is immobilized enzymes, what are its benefits.

Answer 30

Lactose free milk - convert lactose present into glucose + galactose, for people who do not produce lactase in pancreatic juice. In such ppl bacteria in the large intestine feed on the lactose to produce fatty acids and methane, cause diarrhea and flatulence.

Pectinase in fruit juice production - hydrolyze pectin in fruit cell walls, help in extraction of fruit juice

Proteases in biological washing powders - break down protein stains, e.g. from blood.

Immobilized enzymes - immobilized in alginate beads
- product in enzyme free
- enzymes can be reused