Model Organisms

Question 1

why do we use model organisms? (4)

Answer 1

1. well suited for genetic studies
2. special features valuable for particular types of genetic or developmental analyses
3. serve as a “model” for related species or all species
4. have a community of scientists studying them to share resources

Question 2

what are the common characteristics of model organisms used in genetic analysis of development? (6)

Answer 2

• short generation time
• large number of progeny
• small size
• easy, inexpensive culture
• small genome size
• carry out process of interest

Question 3

Arabidopsis description (3)

Answer 3

• mouse-ear cress, thale cress
• belongs to the mustard family
• closely related to canola

Question 4

what are the advantages of using Arabidopsis as a model organism? (5)

Answer 4

• small genome size
• small, easy to grow, easy storage
• rapid life cycle (~6 weeks)
• self-fertilize
• easy to transform

Question 5

plasmid (2)

Answer 5

• small DNA molecule within a cell that is physically separated from a chromosomal DNA
• can replicate independently

Question 6

Agrobacterium tumefaciens (2)

Answer 6

• natural tool for plant transplantation

- contains a circular chromosome and a circular Ti plasmid

Question 7

what does the Agrobacterium tumefaciens plasmid consist of? (3)

• important portion
• components of important portion (2)

Answer 7

• portion of DNA called T-DNA (transfer DNA)
• T-DNA has a left border and right border with a specific sequence
• DNA between LB and RB is not important

Question 8

what are the steps in natural plant transplantation (5)

Answer 8

1. remove T-DNA from plasmid
2. replace T-DNA region with gene of interest
3. transform plasmid into an Agrobacterium cell
4. infect plant cell with bacteria to transfer the plasmid into the plant cells
5. gene of interest is inserted into plant chromosome

Question 9

specify why Arabidopsis is easy to transform

Answer 9

• Arabidopsis can be dripped into bacteria to be infected; not a difficult/complex procedure

Question 10

how does studying Arabidopsis contribute to society (4)

• main contribution to society
• methods of making this contribution (3)

Answer 10

can contribute to the alleviation of hunger by developing crop plants that:

1. are tolerant to drought stress
2. require less fertilizer or water
3. are resistant to pathogens

Question 11

how can plant drought tolerance be increased?

Answer 11

• altering even a single gene can make this change

Question 12

what have researchers learned from Arabidopsis studies? (6)

• main idea
• some specific ideas (5)
• generally know

Answer 12

better understanding of plant biology in general:

• mechanisms of resistance to pathogens
• oil synthesis and modification
• biosynthesis and perception of hormones
• light signal transduction
• plant development

Question 13

what are the advantages of using Drosophilia melanogaster (fruit fly) as a model organism? (6)

Answer 13

• small
• easy to culture
• short generation time
• large numbers of progeny
• rich scientific history
• small genome size

Question 14

what is the disadvantage of using fruit flies as model organisms?

Answer 14

• difficult to store (cannot stick in freezer to store; they will die)

Question 15

what are the major contributions of using fruit flies as model organisms? (6)
- generally know

Answer 15

• transmission genetics
• cytogenetics
• development (IMPORTANT ONE)
• behavioural genetics
• population genetics
• evolutionary genetics

Question 16

what are the advantages of using C. elegans as a model organism? (6)

Answer 16

• small, fairly simple animal
• self-fertilization
• large numbers of progeny
• short generation time (2-3 days)
• transparent
• small genome size

Question 17

what are the major contributions of using fruit flies as model organisms? (3)
- generally know

Answer 17

• development (can see all cell divisions due to transparent body)
• programmed cell death
• RNAi

Question 18

what are the advantages of using house mice as a model organisms? (4)

Answer 18

• mammal (can be more directly connected to humans)
• relatively small size
• short life cycle
• targeted knockouts

Question 19

what is the disadvantage of using house mice as model organisms? (2)

Answer 19

• large genome size

- relatively expensive to culture

Question 20

what are the major contributions of using house mice as model organisms? (5)
- generally know

Answer 20

• models for human diseases
• cancer research
• tests for carcinogens
• development
• immunology

Question 21

what is required for an organism to be a great genetic model?
A. short generation time
B. tissue easily attainable
C. small size
D. large # of progeny

Answer 21

A, C and D