quiz 5 mod 6

Question 1

Why is C. elegans used as a model organism for genetic studies in humans?

Answer 1

over 35% of worm genes have human homologs
these genes are important for human health and development.

Question 2

2. Compare forward and reverse genetic screens

Answer 2

forward–>gene unknown
Design SCREENS to identify genes involved in a particular developmental process, biochemical activity, or behavior, with no a priori model of which genes might be important(ie.. 1. Decide what process or pathway you want to study
2. Randomly disrupt the function of thousands of genes throughout the genome
3. Look for variant phenotypes relevant to the process of interest
4. Map and clone the altered gene
reverse–> gene known
1. Disrupt the function of your gene of interest
OR express gene of interest in different cell type or tissue)
2. Look for variant phenotypes to identify what role the gene plays

Question 3

3. Developmental stages of C. elegans. Generation time, difference between L4 and adult

Answer 3

small, fee-living nematode. Survives by feeding on microbes such as bacteria. Most are self-fertilizing hermaphrodite and a few are males.
● First multicellular organism to have its whole genome sequenced
L4 cannot reproduce, has clear cresent-shaped patch; adult can reproduce, you can see repro organs in adult, has longer lifespan asw

Question 4

4. Sexing in worms: differences between adult male and hermaphrodite C. elegans

Answer 4

hermaphrodite XX has vulva and uterus , oocytes and gonads tapered tail, males XO gonad blunt tail

Question 5

Mating in C. elegans: Cross fertilization vs self-fertilization
● Why do males only account for 0.1% of the wild type population of worms?

Answer 5

arise by spontaneous x CHROMOSOME NODISJUNCTION

Question 6

Mating in C. elegans: Cross fertilization vs self-fertilization
● How can you increase the male population in c. elegans culture?

Answer 6

increase temp to 30 degreescelcius for 4 hrs

Question 7

Mating in C. elegans: Cross fertilization vs self-fertilization
● What are Him-5 mutants and why are they used in experiments?>

Answer 7

high incidence males gives 30% males in the culture
To test the effect of heavy metals on both sexes