Midterm 2 - Notes 6 (Part 8)

Question 1

Where do plant pathways take place?

Answer 1

In the chloroplasts

- able to integrate with the plants

Question 2

What is an example of transgenic plants involved with insect resistance?

Answer 2

Bacillus thuringiensis

Question 3

Bacillus thuringiensis

Answer 3

Bacterial insect pathogen

- can infect many hosts but very specific

Question 4

What do Bacillus thuringiensis produce?

Answer 4

Cry toxins

- also host specific

Question 5

What are Cry toxins?

Answer 5

Crystal forming proteins (Bt)

Question 6

What do Cry toxins bind to?

Answer 6

Specific receptors in insects gut

Question 7

What breaks down gut walls?

Answer 7

Cry toxins

- only functions within the gut of a particular organism

Question 8

Where can bacteria proliferate?

Answer 8

Inside the body

- results in death

Question 9

Bt protein (3)

Answer 9

1. very unstable in environment
   - UV
2. Contact toxin
   - needs to be eaten by insect larva
3. No impact known on mammals
   - toxicity, allergenicity and carcinogenicity

Question 10

What are Bt protein or Bt spores used as?

Answer 10

Insecticides since 1920

Question 11

What are Bt protein or Bt spores main targets? (4)

Answer 11

1. European corn borer
2. Southwestern corn borer
3. Tobacco budworm
4. Cotton bollworm

Question 12

What are limitations for Bt protein or Bt spore? (3)

Answer 12

1. Short half life
2. Does not reach insects inside plants or at root system
3. Very host specific

Question 13

When are Bt proteins and Bt spores mainly used?

Answer 13

In organic farming

• major microbial pest control agent
• naturally occurring
• non pathogenic to humans

Question 14

What are 3 features of Bt over-expression? (3)

Answer 14

1. Marketed by different companies
2. Antibiotic or herbicide resistance marker used
3. Constitutive (35S) promoter or tissue specific (green tissue plus pollen) promoter used

Question 15

What is the efficiency of Bt corn vs. European corn borer?

Answer 15

1. 99% against first generation (spring)

2. 87-98% against second generation (depending on promoter used)

Question 16

What is golden rice?

Answer 16

Vitamin A deficiency is a serious problem in developing countries

Question 17

What is present in vitamin A?

Answer 17

Plant carotenoids

- produced in many green veggies but not produced in many of the main staple foods developing countries have access to

Question 18

What does rice produce?

Answer 18

Carotenoids

- but not in the endosperm of the kernel

Question 19

What does golden rice produce?

Answer 19

The recommended daily allowance of vitamin A precursors in ~140g of rice

Question 20

What are 4 features of golden rice constructs?

Answer 20

1. Non-antibiotic selectable markers
2. Corn PSY more efficient then daffodil PSY (although both monocots)
3. Bacterial CRTI replaces multiple plant genes
4. Endosperm specific promoter

Question 21

What are 6 GM-plant risks?

Answer 21

1. Transgene/expression stability
2. Outcrossing of transgenes to wild species
3. Resistance of pests/pathogens targeted
4. Selection marker
   - antibiotic resistance gene
5. Allergen potential of novel proteins
6. Unpredicted interaction of transgene product with plant metabolism