L19 - using genetics to understand biology

Question 1

what odour are C. elegans attracted to

Answer 1

diacetyl

Question 2

name the C . elegans olfactory neurons

Answer 2

AWA AWB AWC

Question 3

how can neurones in C.elegans be destroyed to test behaviour without them

Answer 3

laser

Question 4

what happened when the AWA neurone was removed from C. elegans
what does this tell us

Answer 4

no longer attracted to diacetyl but attracted to other compounds

AWA important in sensing diacetyl

Question 5

explain method of determining what genes responsible for C.elegans smell

Answer 5

1. use mutagens to generate random mutations in C. elegans and screen them to see which ones cant sense diacetyl
2. complementation analysis
3. focussed on 1 gene - odr10
4. carried out ‘rescue’ analysis
5. sequenced odr10 and found 2 mutations (deletion and substitution)

odr responsible for diacetyl sensing

Question 6

what happened in worms with mutated odr10

Answer 6

couldn’t sense diacetyl

Question 7

briefly describe rescue method

Answer 7

gene of interest added to mutants (transgenic) to see if the function of interest is restored

Question 8

what does odr10 encode

Answer 8

transmembrane receptor that transmits signals from outside C. elegans to inside cell (eg odour)

Question 9

explain method used to see where odr10 gene of interest was located in C. elegans

Answer 9

1. gfp attached to odr10 promoter
2. wherever promoter is active will fluoresce green

odr10 was expressed in AWA olfactory neurones

Question 10

how can the odr10 findings relate to humans?

Answer 10

mammals have ‘7 transmembrane proteins’ similar to odr10 throughout their olfactory receptors