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BIOSCI106 2017 SEM 2 > Plants > Flashcards

Plants Flashcards

1
Q

Where does aspirin (salcylic acid) come from?

A

Willow

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2
Q

Where does taxol (anti cancer) come from?

A

Pacific yew

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3
Q

Where does digoxin (heart conditions) come from?

A

Fox glove

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4
Q

Where does artemesinin (maleria) come from ?

A

Artemisia

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5
Q

Vitamin C is an antioxidant, what does this mean?

A

It protects from reactive oxygen species and free radicles.

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6
Q

Can vitamin C be stored in the body?

A

Nope

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7
Q

What is vit C used to regenerate?

A

A-tocopherol which is vitamin E

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8
Q

What is the range of reccommended doses for vit C per day?

A

90mg to 2g

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9
Q

What do high doses of Vit C result in?

A

Diarrhea

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10
Q

What are poor sources of Vit C?

A

Lettuce, cucumber, banana, apple

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11
Q

What is the Order of highest to lowest vit C content?

A

Camu camu - 2g
Black currant/bell pepper - 200mg
Kiwifruit/broccoli - 90mg
Orange - 50mg

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12
Q

What are the pathways of Vit C synthesis in plants?

A
  1. Smirnoff-wheeler pathway (glalactose)
  2. Myo-inositol pathway
  3. Galacturonate pathway
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13
Q

What is the best way to cook broccoli to maximise Vit C synthesis?

A

Raw or steamed, boiled is worst

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14
Q

What is the major pathway in plants?

A

Smirnoff-wheeler pathways

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15
Q

Where does the Smirnoff-wheeler pathway occur?

A

Mitochondria, so it requires specific transporters for ascorbic acid

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16
Q

Describe mutants that cannot synthesise ascorbic acid:

A

They have reduced growth and reduced chlorophyll content

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17
Q

What are the 2 main roles of ascorbate in plants?

A

Antioxidant

Role in plant development - cell division and cell expansion

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18
Q

In a healthy plant, what should the ratio of DHA t ascorbate be?

A

10% DHA

90% ascorbate

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19
Q

What does APX ascorbate perioxidase do?

A

Detoxify H2O2 in cholorplasts

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20
Q

What does DHA reductase do?

A

2GSH + DHA = ascorbate + 2GSSG

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21
Q

What is special about cooking vitamin A containing foods?

A

The vitamin is not destroyed during any part of the cooking

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22
Q

What is reccommedended daily intake for VitA?

A

800 microgram

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23
Q

What are the top 3 vegetable sources of Vit A?

A

Sweet potato - 961
Carrots - 840
Spinach - 500

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24
Q

What is the precursor of Vit A?

A

B carotene (provitamin A)

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25
Q

How is B carotene made to retinal and where?

A

B carotene dioxygenase in the small intestine. Forms 2 retinal molecules

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26
Q

Once retinal is made in the small intestine, then what happens?

A

It forms retinol and then retinoic acid which are all fat soluble and stored in the liver

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27
Q

Is vitamin A fat or water soluble?

A

Fat

28
Q

What are the roles of Vit A?

A

Visual pigment rhodopsin
Gene expression
Maintenance of epithelial tissues
Regulation of growth and differentiation of cells, some cells of immune system

29
Q

Where is Vit A found outside of vegetables?

A

In milk and liver, eggs, meat etc

30
Q

How does Vit A regulate gene expression?

A

Retinoic acid binds to DNA receptors (transcription factors) which leads to modification of gene expressions

31
Q

At what stage of life is retinoic acid involved the most?

A

Embryonic development

32
Q

What are the symptoms of vit A deficiency?

A
  1. Dry cornea and blindness
  2. Night blindness
  3. Impaired immune function
33
Q

Where is Vit A synthesised in plants?

A

In choloplasts

34
Q

What is the pathway as to how B carotene is synthesised in plants?

A

Geranylgeranyl-PP to phytoene to lycopene to B carotene

35
Q

What enzyme converts Geranylgeranyl-PP to phytoene?

A

Phytoene synthase (PSY)

36
Q

What enzyme converts phytoene to lycopene?

A

Phytoene desaturase (PDS) + 2 other enzymes

37
Q

What enzyme converts lycopene to B carotene?q

A

Lycopene cyclase (LCY)

38
Q

Out of the 3 enzymes, what genes for them were expressed in rice endosperm?

A

Only lycopene cyclase

39
Q

What is special about agrobacterium tumefaciens and how does it transfer its DNA?

A

It has T-DNA that is able to transfer from a prokaryote to a eukaryote. If a plant has a wound and there is agrobacterium tumefaciens in the soil, it is able to transfer all the DNA from its plasmid in bteween the left and right borders to the plant

40
Q

Which genes are put in the T DNA to transform rice?

A

PSY - from daffidol

Carotene desaturase from bacteria Erwina CRT1 (can replace all 3 enzymes)

41
Q

In plant food source is iron non heme or heme?

A

Non heme - not well absorbed.

42
Q

How do you get heme iron?

A

Through food derived from animals which is well absorbed

43
Q

What are the 2 ways iron is used in the body?

A
  1. Deoxyhemoglobin

2. Ferrtin - stores

44
Q

What are some ways that we can increase iron availability?

A
  1. Chelation - increase siderophores (iron carriers that bind ferric form)
  2. Reduce Fe3+ and make Fe2+ so acidify the soil
45
Q

What is a way to increase translocation (shoot to root)?

A

Overexpressing a transporter - i.e ferroprotin

46
Q

What is a way to increase storage of iron in the endosperm?

A

Increase the ferritin gene

47
Q

What is the way to increase availibility of iron in plants to humans?

A

Phytates to reduce - a digestive enzyme phytase

48
Q

What are plant medicinals called?

A

Secondary metabolites

49
Q

What are the 3 types of secondary metabolites?

A
  1. Terpenes - made from mevalonic acid with carbon and hydrogens
  2. Phenolics - made from simple sugars
  3. Nitrogen containing compounds - may also contain sugar
50
Q

What are 2 examples of nitrogen containing compounds?

A

Alkaloids - caffeine, theobromine, theophylline, nicotine, opiotes
Glucosinolates - broccoli (anti cancer properties)

51
Q

What are alkaloids?

A

They are heterogenous group of chemicals where most are basic. Many are toxic to humans and animals

52
Q

What are the 3 purine derivatives of alkaloids?

A

Caffeine, theobromine, theophylline

53
Q

What are the 3 amino acid derivatives of alkaloids?

A
  1. From typtophane - nicotine
  2. From histadine - pilocarpine, histamine
  3. From tyrosine - opiates (morphine and codeine)
54
Q

Where does opium come from?

A

Dried latex of poppy

55
Q

How does coffee and chocolate work to affect your body?

A

They competitively inhibit phosphodiesterase, resulting in an increase in cyclic AMP and release of adrenaline. This leads to increased CNS stimulation, relaxation of smooth muscle and induces diuresis

56
Q

What is used for eye drops, the treatment of glaucoma and stimulation of sweat and lachrymal glands?

A

Pilocarpine

57
Q

How do you get addicted to heroin?

A

Because morphine binds to the u-opiod receptors which leads to addiction

58
Q

What are the therapeutic drug uses for opiates?

A
  1. Analgesia - pain reliever
  2. Antitussive - cough surpressent
  3. Antidiarrhea
59
Q

What is the solution for stopping people from getting addicted to opiates?

A

Make a mutant poppy that will not accumulate morphine/codeine. Mutagenesis using ethyl methyl sulfate (EMS) - alkylating agent on the guanine it switches a guanine for a A so transcribes a T. These poppies can be used as precursors for synthetic opiod production but carry little risk for addiction

60
Q

Where is glucoraphanin found and what does it do?

A

It is a glucosinolate found in broccoli and cauliflower. It can be made into raphanin (an antibiotic) by the enzyme myrosinase and into sulforaphane for anticancer

61
Q

Name and describe the 4 ways herbicides can affect plant growth:

A
  1. Growth regulation - division and expansion - plant hormones (auxins and 2,4D), crops can catabolise high concs, weeds killed
  2. Cell division - oryzalin blocks plant microtubules (not animals)
  3. Photosynthesis - atrazin interferes with e- transport chain
  4. Amino acid biosynthesis - glyphosate (roundup), affects aromatic amino acid synthesis
62
Q

Describe how roundup works:

A

It gets absorbed by the plant and prevents it from making food. It is transported through the weed to kill the entire weed . Dead weeds cant regrow. It is non selective so it kills everything

63
Q

How does roundup work enzymatically?

A

Shikimate 3 phosphate + PEP = 5-enolpyruvylshikimate-3-phosphate then to aromatic amino acids
This is done by the enzyme EPSPS which is inhibited by glyphosate

64
Q

How can you make plants that are resistant to herbacides?

A

By using T-DNA

65
Q

How are bt crops (insect resistant) made?

A

They are engineered from bacillus thuringiensis a soil dwelling bacterium. It forms crystals of cry toxins which are encoded by cry genes and the cry toxins affect pests such as insects

66
Q

What happens if a pest eats a plant with bt and cry toxins?

A
  1. Ingestion and solubilisation at alkaline pH (12) in forgut of larvae. It is the protoxin.
  2. Proteolytic cleavage of protoxin into active toxin
  3. Binding to membrane receptor in the midgut epithelial membrane
  4. Leads to pore formation and larvae death
67
Q

How many countries are producing genetically engineered crops?

A

26

BIOSCI106 2017 SEM 2 (7 decks)

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