Midterm #2 Flashcards
1
Q
What are the stages of plants being infected with Claviceps fungus?
A
-
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
2
Q
What are the two possible contributing factors linking ergotism and the bubonic plague?
A
- Either type of ergotism can lower the immune system - makes person more susceptible to infection by plague
- 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
3
Q
Which NT receptors does ergoline effect?
What is the main receptor type it effects? What is this NT involved in?
A
- 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
4
Q
What are some modern uses for ergot alkaloids?
A
- Treat migraines
- Decrease prolactin levels resulting from pituitary tumours
- Decrease postpartum hemorrhage
- Treat senility and Alzheimer’s dementia
5
Q
Ergotamine biosynthetic pathway
A
6
Q
What are some of the ways that drugs can affect synapses?
A
- 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
7
Q
What are eicosanoids?
A
- Signaling molecules created from breakdown of arachidonic acid
- E.g., prostaglandins (inflamamtion, pain, fever, increase BP); epoxides; HPETEs
8
Q
What is the physiological role of PGE2?
A
- Vasodilator
- Maintains ductus arteriosus
- Helps maintain placental blood flow
- Clinical significance
- Alprostadil
- Targets PGE2
9
Q
Role of PGI2?
What are its analogues?
A
- 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)
10
Q
Role of PGF2?
A
- Contracts uterus
- Bronchoconstriction
- Contracts longitudinal muscles
- Induces ocular inflammation
- Decrease IOT by increasing US outflow
- Increases hepatorenal syndrome
11
Q
Role of PGD2?
A
- Anti-platelet aggregatory
- Bronchoconstrictor
- Evokes renin release
- Mainly secreted by mast cells
- Constituent of slow release substance of anaphylaxis
- Slowly metabolised
12
Q
Role of TXA2?
A
- Produced by platelets
- Potent inducer of platelet aggregation
- Constituent of release reaction
- Renal vasoconstriction
- Bronchoconstriction
13
Q
What is the process of the SAR response?
A
- 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
14
Q
What is the process of the induced systemic resistance response?
A
- 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
15
Q
What genes do plants need to be resistant to diseases?
A
- Need BOTH resistance gene in plant genotype and pathogen with ligand
- R_ = single dominant resistance gene in plant
- Avr_ = avirulence gene - ligand
16
Q
What are the 5 recognized classes of resistance genes?
A
- Nucleotide binding site (NBS)
- Leucine-zipper and leucine-rich repeat (LRR)
- Toll/IL-1R (TIR)
- Protein kinase (PK), receptor-like kinase (RLK)
17
Q
What are the five classes of plant hormones?
A
- 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
18
Q
What are some additional chemical signals seen in plants?
A
- 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
19
Q
Which mutants from arabidopsis affect SA synthesis either by elevating or reducing SA accumulation?
A
- 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
20
Q
What are some plant volatile chemical signals?
A
- SA: signal in defense responses to plant pathogens
- Jasmonates: Plant growth regulation and defense
- Nitric oxide: Signal in hormonal and defense responses
- Ethylene
21
Q
What is NPR1?
A
- DNA binding protein that plays critical role in how plant conducts itself
- Modulator of cross-talk between SA- and JA-dependent plant defense responses
22
Q
What is the *Plasmodium *life cycle within a human?
A
- 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
23
Q
Difference between quinine and artemisinin mode of action?
A
- Quinine prevents formation of hemozoin by blocking biocrystallization
- Artemisinin interacts with heme to form free radicals that kill parasites
24
Q
What are the active ingredients in may apple and how do they control cancer?
A
- Active ingredients are aliphatic alkaloids, podophyllins
- Podophyllotoxin and alpha-peltatin
- Control cancer by arresting cell division
- Inhibits DNA synthesis during S-phase
- Inhibits topoisomerase
25
Q
What are the anti-cancer properties of red clover?
A
- Salve made from flowers
- Isoflavone genistein as an antioxidant
- Prevents skin cancer
26
Q
How do autumn crocuses control cancer?
A
- Extracts inhibit cell division
- Contain alkaloid colchicine
- Disrupts spindle formation during mitosis (stops cell division)
- Stops MT formation/disassembly
27
Q
What is the mode of action of taxol?
A
- 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
28
Q
What are the anticancer agents and properties of the Madagascar periwinkle?
A
- 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
29
Q
What is bloodroot used to treat?
A
- Skin cancers
- Also used in oral rinses and toothpastes because it contains compounds effective against oral plaque-forming organisms
