Midterm #2

Question 1

What are the stages of plants being infected with Claviceps fungus?

Answer 1

• After infection in plant:
  
  • Fungal spores germinate in flower ovaries - destroy ovaries
  • Grain kernal (seed) replaced by sclerotia
    
    • Fungal fruiting body
    • Brownish violet horn-shaped structure
• At maturity:
  
  • Sclerotia fall off host plant, over-winter in soil
• Next growing season:
  
  • _​_Sclerotia sporulate
  • Spores can infect new crop
• Insects carry fungal spores from host plant to other susceptible plants

Question 2

What are the two possible contributing factors linking ergotism and the bubonic plague?

Answer 2

1. Either type of ergotism can lower the immune system - makes person more susceptible to infection by plague
2. If rats ate ergot infected rye, they would die and fleas would transfer to alternate human hosts

• Also have correlation between between weather and number of plague deaths
  
  • Fewer plague victims during dry weather
  • Fewer plague victims in areas where rye is not staple bread

Question 3

Which NT receptors does ergoline effect?

What is the main receptor type it effects? What is this NT involved in?

Answer 3

• Many alkaloid compounds identified from ergot and derived from ergoline - show antagonistic and agonist effects on serotonin, dopamine, and adrenergic receptors
• Serotonin is CNS and PNS NT involved in mood, sleep, appetite, temperature regulation, pain perception, vomiting, regulation of BP, depression, anxiety, migraines
  
  • Numerous 5HT receptor types
  • How alkaloid action affects these receptors is somewhat unclear

Question 4

What are some modern uses for ergot alkaloids?

Answer 4

• Treat migraines
• Decrease prolactin levels resulting from pituitary tumours
• Decrease postpartum hemorrhage
• Treat senility and Alzheimer’s dementia

Question 5

Ergotamine biosynthetic pathway

Answer 5

Question 6

What are some of the ways that drugs can affect synapses?

Answer 6

• Increase the number of impulses
• Release NTs from vesicles with or without impulses
• Block reuptake or block receptors
• Produce more or less NTs
• Prevent vesicles from releasing NTs

Question 7

What are eicosanoids?

Answer 7

• Signaling molecules created from breakdown of arachidonic acid
  
  • E.g., prostaglandins (inflamamtion, pain, fever, increase BP); epoxides; HPETEs

Question 8

What is the physiological role of PGE₂?

Answer 8

• Vasodilator
  
  • Maintains ductus arteriosus
  • Helps maintain placental blood flow
• Clinical significance
  
  • Alprostadil
  • Targets PGE₂

Question 9

Role of PGI₂?

What are its analogues?

Answer 9

• Inhibitor of platelet aggregator
• Mild bronchodilator
• Inhibits histamine release
• Evokes renin release
• Produced by vascular endothelium
• Hypotensive (more than PGE₂)
• Analogues:
  
  • _​_Treprostinil
  • Iloprost
  • PVD
  • Pulmonary hypertention (in combination with PGE₂)

Question 10

Role of PGF₂?

Answer 10

• Contracts uterus
• Bronchoconstriction
• Contracts longitudinal muscles
• Induces ocular inflammation
• Decrease IOT by increasing US outflow
• Increases hepatorenal syndrome

Question 11

Role of PGD₂?

Answer 11

• Anti-platelet aggregatory
• Bronchoconstrictor
• Evokes renin release
• Mainly secreted by mast cells
• Constituent of slow release substance of anaphylaxis
• Slowly metabolised

Question 12

Role of TXA₂?

Answer 12

• Produced by platelets
• Potent inducer of platelet aggregation
• Constituent of release reaction
• Renal vasoconstriction
• Bronchoconstriction

Question 13

What is the process of the SAR response?

Answer 13

• SAR = systemic acquired resistance
• Disease organisms stimulate plant to make SA
• Increase in SA causes plant to produce plant defense proteins
• These proteins provide resistance to a variety of pathogens

Question 14

What is the process of the induced systemic resistance response?

Answer 14

• Plant growth promoting rhizobacteria (PGPR) stimulate plant roots, cause production of plant defense hormones
• Hormones ethylene and jasmonate increase in plant and induce resistance to variety of pathogens

Question 15

What genes do plants need to be resistant to diseases?

Answer 15

• Need BOTH resistance gene in plant genotype and pathogen with ligand
• R_ = single dominant resistance gene in plant
• Avr_ = avirulence gene - ligand

Question 16

What are the 5 recognized classes of resistance genes?

Answer 16

• Nucleotide binding site (NBS)
• Leucine-zipper and leucine-rich repeat (LRR)
• Toll/IL-1R (TIR)
• Protein kinase (PK), receptor-like kinase (RLK)

Question 17

What are the five classes of plant hormones?

Answer 17

• Auxins
  
  • Leaf primordia, young leaves, developing seeds
  • Polarly (unidirectionality) and nonpolarly
• Cytokinins
  
  • Root tips (root development)
  • From roots to shoots via xylem
• Ethylene
  
  • Most tissues in response to stress
  • Diffusion from site of synthesis - positive feedback loop (speeds up fruit ripening)
  • Volatile
• Abscisic acid
  
  • Mature leaves and roots, seeds
  • From leaves in phloem and from roots in xylem
• Gibberllins (dwarfing abilities for plants)
  
  • Young tissues of shoot and developing seeds
  • Xylem and phloem

Question 18

What are some additional chemical signals seen in plants?

Answer 18

• Brassinosteroids - required for normal growth of most plant tissue
• Salicylic acid - signal in defense responses to plant pathogens
• Jasmonates - plant growth regulation and defense
• Polyamines - growth and development; mitosis and meiosis
• Systemin - long-distance signal that activates chemical defenses against herbivores

Question 19

Which mutants from arabidopsis affect SA synthesis either by elevating or reducing SA accumulation?

Answer 19

• Elevated SA accumulation:
  
  • dnd1 (defense, no death 1): Increase SA, but decrease HR; dnd1 gene encodes cyclic-nucleotide-gated ion channel
  • mpk4: Constitutive SA accumulation
  • edr1 (enhanced disease resistance 1): Defective MAPKKK
• Reduced SA accumulation:
  
  • eds1 (enhanced disease susceptibilit 1): Lipase homolog
  • pad4 (phytoalexin deficient 4): Another lipase homolog
  • sid1 and sid2 (salicylic acid induction-deficient): defects in chorismate pathway

Question 20

What are some plant volatile chemical signals?

Answer 20

• SA: signal in defense responses to plant pathogens
• Jasmonates: Plant growth regulation and defense
• Nitric oxide: Signal in hormonal and defense responses
• Ethylene

Question 21

What is NPR1?

Answer 21

• DNA binding protein that plays critical role in how plant conducts itself
• Modulator of cross-talk between SA- and JA-dependent plant defense responses

Question 22

What is the *Plasmodium *life cycle within a human?

Answer 22

• Infected with parasite (sporozoite form)
• Sporozoites replicate in the liver
• Merozoites are created
• Merozoites invade RBCs
• Multiply rapidly; decrease Hb; RBCs rupture
• New generation of merozoites released
• Rupture causes fever and chills

Question 23

Difference between quinine and artemisinin mode of action?

Answer 23

• Quinine prevents formation of hemozoin by blocking biocrystallization
• Artemisinin interacts with heme to form free radicals that kill parasites

Question 24

What are the active ingredients in may apple and how do they control cancer?

Answer 24

• Active ingredients are aliphatic alkaloids, podophyllins
• Podophyllotoxin and alpha-peltatin
  
  • Control cancer by arresting cell division
  • Inhibits DNA synthesis during S-phase
  • Inhibits topoisomerase

Question 25

What are the anti-cancer properties of red clover?

Answer 25

* Salve made from flowers * Isoflavone genistein as an antioxidant * Prevents skin cancer

Question 26

How do autumn crocuses control cancer?

Answer 26

* Extracts inhibit cell division * Contain alkaloid colchicine * Disrupts spindle formation during mitosis (stops cell division) * Stops MT formation/disassembly

Question 27

What is the mode of action of taxol?

Answer 27

* Blocks cell replication * M phase of cell cycle (mitosis and cytokinesis) * Prophase, MTs assemble to form spindle * Late anaphase/telophase the spindle structure is lost * MTs that make up spindle disassemble * Paclitaxel binds to MTs and prevents disassembly * Interrupts cell cycle * Cancer cells can't complete division - tumour growth is arrested

Question 28

What are the anticancer agents and properties of the Madagascar periwinkle?

Answer 28

* Anticancer agents: * Vinblastine * Vincristine (childhood acute lymphoblastomic leukemia; advanced stages of Hodgkin's disease) * Mode of action: * Inhibits mitosis * Prophase, start of mitosis, MTs assemble to form spindle * Vincristine and vinblastine block MT assembly - spindle does not form, mitosis is arrested; cell replication is inhibited

Question 29

What is bloodroot used to treat?

Answer 29

* Skin cancers * Also used in oral rinses and toothpastes because it contains compounds effective against oral plaque-forming organisms