lecture 23, metabolites part 2

Question 1

recap: functions of metabolites are …

Answer 1

• survival and propagation
• chemical signals
• plant defense against herbivores or pathogens
• allelopathy/competition
• provide protection from UV
• pollen and seed dispersal

Question 2

how are specialized metabolites restricted?

Answer 2

restricted in their distribution

Question 3

Laticifer is an example of ..

Answer 3

a specialized metabolite that is responsible in storage

Question 4

where does localization of secondary metabolites occur?

Answer 4

at organ, tissue, cell, and subcellular levels

Question 5

restriction distribution is …

Answer 5

lineage specific

Question 6

what are phytoalexins?

Answer 6

antimicrobial defence compounds that are biosynthesized upon demand during stress periods.

Question 7

what is the circadian rhythm in restricted distribution of specialized metabolites?

Answer 7

24 hour cycle in which there is gene expression that creates an enzyme activity of bottleneck steps/activation. this causes catabolism, breakdown and turnover of metabolites

Question 8

what are the types of specialized metabolites?

Answer 8

1. Alkaloids
2. Terpenoids
3. Phenolics

Question 9

significance of alkaloids:

Answer 9

class of basic, natural-occurring organic compounds that contain at least one nitrogen atom. they can also be neutral/weakly acidic.
- contain carbon, nitrogen, and hydrogen; sometimes oxygen, sulfur, and others
-produced by all kingdoms of life

Question 10

what drugs come from alkaloids?

Answer 10

• morphine: opium poppy; analgesic, cough suppressant - highly addictive
• cocaine: stimulant; anti-herbivory compound in Erythroxylum coca
• caffeine
• nicotine

Question 11

what is the significance of Terpenoids?

Answer 11

• largest class (60% of known plant natural products)
• derived from 5-carbon isoprene C5H8
• contain many oxygen atoms
• multi cyclic
• contain a lot of volatile organic compounds

Question 12

significance of Phenolics:

Answer 12

• water soluble
• accumulate in vacuoles
• human health
• aromatic ring with a hydroxyl group

Question 13

what kind of pigmentation do phenolics have?

Answer 13

co-pigmentation, complexing of:
- anthocyanin
- colourless flavone
- metal ion
- together: commelinin with intensely blue color in commelina communis

Question 14

what are the 5 major groups of plant hormones?

Answer 14

1. auxin
2. cytokinin
3. gibberellic acid
4. abscisic acid
5. ethylene

Question 15

what is auxin?

Answer 15

• a compound released by the terminal bud of a plant, inhibiting growth of lateral buds
• at the nexus of all plant functions; guides growth, cellular differentation, main site of biosynthesis (apical bud –> apical dominance)

Question 16

gibberellic acid vs. abscisic acid

Answer 16

• gibberellic acid is involved in growth processes and abscisic acid is involved in plant signaling
• gibberellic acid is produced at the site of growth, involved in cell elongation, breaking dormancy, and flowering.
  Abscisic acid is found throughout the plant, responsible for the initiation of seed dormancy, signaling for stomatal closure, and slowing growth

Question 17

what is ethylene?

Answer 17

• a VOC and a phytohormone
• roles in fruit ripening and senescence

Question 18

hormones are mechanisms of …

Answer 18

metabolic shift

Question 19

what is pathogen defence in plants driven by?

Answer 19

hormone signaling

Question 20

what happens with specialized metabolites in pathogen defense in plants?

Answer 20

they are modulated

Question 21

what are the two kinds of defences in plant pathogen defence?

Answer 21

induced and constitutive defences

Question 22

what are the two types of induced defences?

Answer 22

1. systemic acquired resistance
   - stress perceived and whole plant immunity raised
2. hypersensitivity response
   - programmed cell death
   - pathogen trapped in dead cells
   - stop progression