Genetics: Final Review, Part 6

Front 1

vulva

Back 1

the mating & egg-laying structure in hermaphrodites

Front 2

vulvaless (vul) and multivulval (muv)

Back 2

Two phenotypes associated with defects in vulval
development

Front 3

vulvaless

Back 3

worms can’t lay eggs
so eggs hatch inside
mom & eat their way out

Front 4

multivulval

Back 4

multiple cells adopt
vulval cell fate

Front 5

muv1(lf) --> vulval cell fate

Back 5

recessively

Front 6

muv1(gf --> vulval cell fate

Back 6

these mutants
act dominantly

Front 7

how to perform an epistasis test?

Back 7

Using 2 mutants that give different phenotypes, generate double homozygous mutants and compare them to each single mutant

Front 8

What is a complementation test?

Back 8

Cross 2 homozygous mutants that give a similar phenotype and analyze the phenotype of the progeny

Front 9

Loss of function mutations = ________
Gain of function mutations = __________

vulvaless or multivulva

Back 9

Loss of function mutations = vulvaless
Gain of function mutations = multivulva

Front 10

What would be a good general approach to identify genes that function downstream of let-23 in the VPCs?

Mutagenize let-23-/- and screen for Vul mutants
Mutagenize let-23-/- and screen for Muv mutants
Mutagenize let-23(gf)/+ and screen for Vul mutants
Mutagenize let-23(gf)/+ and screen for Muv mutants

Back 10

Mutagenize let-23-/- and screen for Muv mutants
Mutagenize let-23(gf)/+ and screen for Vul mutants

Front 11

A fifth gene in the pathway is identified, mek-2. Loss of function mutations
produce a vulvaless phenotype and gain of function mutations produce a
multivulval phenotype. You think mek-2 encodes a protein that acts between
LET-60 and MPK-1. Which double mutant combinations would allow you to
determine that it acts downstream of LET-60 and upstream of MPK-1?

mek-2(gf)/+; let-60(lf)/let-60(lf) and mpk-1(gf)/+; let-60(lf)/let-60(lf)

mek-2(gf)/+; let-60(gf)/+ and mek-2(gf)/+; mpk-1(gf)/+

let-60(gf)/+; mek-2(lf)/mek-2(lf) and mek-2(gf)/+; mpk-1(lf)/mpk-1(lf)

let-60(gf)/ let-60(gf); mpk-1(lf)/+ and let-60(gf)/ let-60(gf); mek-2(lf)/+

Back 11

let-60(gf)/+; mek-2(lf)/mek-2(lf) and mek-2(gf)/+; mpk-1(lf)/mpk-1(lf)

Front 12

PCR

Back 12

use primers that will report on the presence of neo DNA
or on the absence of part of the wild-type gene

Front 13

Southern

Back 13

use a probe that will report on the presence of neo DNA
or on the absence of part of the wild-type gene

Front 14

Sequencing

Back 14

sequence the middle of the gene

Front 15

You generate a mouse knock-out construct so that a portion of the gene is
removed when it homologously recombines. You know that EcoRI sites flank
the gene you knocked out. If you perform a Southern blot on EcoRI digested
DNA from F3 mice, which probe will allow you to identify your homozygous
mutant mice with out additional molecular analysis (i.e. PCR or sequencing)?

a) probe against the portion of the wildtype gene that is removed
b) probe against the neomycin resistance marker
c) neither of these probes will avoid additional molecular analysis
d) either of these probes will avoid additional molecular analysis

Back 15

probe against the portion of the wildtype gene that is removed

Front 16

maternal effect

Back 16

genotype of mom important

Front 17

zygotic genes

Back 17

genotype of embryo important