exam 3

Question 1

types of nucleic acids

Answer 1

RNA and DNA

Question 2

difference in types of nucleic acid

Answer 2

RNA: has OH on Carbon 2
DNA: has H on Carbon 2

Question 3

Nucleic acid structure

Answer 3

DNA/RNA + phosphate backbone + base (A, G, C, T)

Question 4

nucleic acid (DNA) characteristics

Answer 4

Structure stabilization
- stacking interactions
- H - bonding
- Hydrophobic effects
Charge-charge interactions: destabilize phosphate backbone

Question 5

enzymatic cleavage in nucleic acids

responsible enzymes and nucleophile??

Answer 5

RNase: hydrolyze RNA, Nucleophile is 2 prime Carbon
DNase: hydrolyze DNA, nucleophile is water

Question 6

protein expression in organisms

enzymeor not??
type??

Answer 6

restriction enzymes cleave DNA at specific sites.

Question 7

Anabolic reactions

Answer 7

build up molecules from simpler building blocks and energy

Question 8

catabolic reactions

Answer 8

break down molecules to form building blocks and energy

Question 9

Amphibolic reaction

Answer 9

takes part in both catabolic and anabolic reactions depending on conditions

Question 10

Metabolites

Answer 10

substrates or products in metabolic pathways

Question 11

types of metabolic pathways

Answer 11

linear, cyclic, and spiral

Question 12

Why are metabolic pathways regulated

Answer 12

-organisms can react to environmental conditions(such as energy or nutrients_
- organisms respond to genetically programmed instructions

Question 13

how are pathways regulated

Answer 13

-steady-state concentration
-change in actual Gibbs free energy (not standard)controls flux
-feedback inhibition
-feed-forward activation

Question 14

what is flux

Answer 14

rate of flow or movement through a metabolic pathway.

Question 15

What affects flux

Answer 15

-decreases if conc. of initial substrate falls below a certain threshold
-decreases if the concentration of the final product rises.
- can be controlled to an extent by a regulatory enzyme

Question 16

Feedback inhibition

Answer 16

• usually occurs at the first dedicated step of the pathway
• occurs when a product (usually the end product) controls its production rate by inhibiting an earlier step.
• product inhibits the first enzyme from working
  -slows down and reverses flux.

Question 17

feed-forward activation

Answer 17

• usually occurs when the production of a metabolite early on activates an enzyme that catalyzes a reaction further down the pathway.
• increases flux

Question 18

if Gibbs controls flux, how do cells perform dis-favored reactions

Answer 18

• breaking pathways into smaller steps
• pairing with a favorable reaction
• cleavage cos similar energetically to ATP to ADP

Question 19

How is energy from ATP made available

Answer 19

• phosphate group transfer
• ATP synthesis by phosphate group transfer: used in more catabolic reactions.
• nucleotide transfer: gives access to another ATP equivalent

Question 20

Biochemical techniques to study Metabolism

Answer 20

• radiolabeling
• mutations
• invitro studies: inside test tube.
  FYI: In vivo is inside the cell, In silico is calculation computer based.