dev geneticsmutants

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  • Created by: Sarah
  • Created on: 30-04-17 08:50
what is forward genetics?
you have the mutant phenotype (see weid)then clone the gene
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what is reverse genetics? example?
you clone a gene and then look for weird mutant phenotype eg mouse KOs
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what is reverse and forward genetics a part of?
genetic analysis
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what does the white mutation cause?
white eyes
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what is the white gene required for?
red eyes
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is the white mutation recessive or dominant?
recessive
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what does it mean that white is recessive?
only see phenotype (white eyes) in homozygous state, one normal copy then normal
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what are different versions of genes known as?
alleles
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what doeshaplosufficient mean?
one wild type copyis sufficient for function (usually genes recessive)
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if heterzygous parents how many will be recessive mutant?
1 in 4
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what is the ratio ofphenotypes for recessive white?
red:white; 3:1
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what is the ratio of genotypes for recessive mutations?
+/+: +/- : -/- = 1:2:1
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what does brachyury affect?
tail length
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what happensif you are homozygous for brachyury mutation?
embryonic lethal
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what shows the phenotype for brachyury?
the heterzygous mutant has a short tail
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what is brachyury gene required for the development of?
mesoderm
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what does it mean that brachyury is semi dominant?
an intermediate phenotype is visible in heterozygote
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what is a dominant mutation?
one mutant copy gives a phenotypic effect
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what does haploinsufficient mean?
one wild type copy is not enough for normal function
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what is it called if the mutant copy produces a product that inteferes with wild type function?
dominant negative (antimorphic) form
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what is the ratio of genotypes in semid dominant mutations?
+/+;+/T;T/T= 1:2:1
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ratio of phenotypes in semidominant brachyury mutation?
WT: short tail: Embryonic lethal= 1:2:1
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what is a mutation?
any change in the sequence of genomic DNA
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why would a mutation affect gene activity?
be in a promoter region-> affects mRNA transcription, affects translation or stability, is in coding region
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what types of mutations are there?
insertions, deletions, single bp changes, chromosomal rearrangements
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what are mobile elements?
sections of DNA that can move around the genome but can disrupt genes by landing in them
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what is a missense mutation?
changes one amino acid to another aa
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what is a nonsense mutation?
codes for a stop codon
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what is a frameshift mutation?
changes the reading frame of DNA
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what is it called when you have a complete loss of function mutation?
null or amporphic mutation
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how do null or amorphic mutations happen?
ligand cant bind to rec, truncation, deletion of gene
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what is a hypomorphic mutations?
partial loss of WT function, is a weak allele
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whats an example of hypomorphic alleles?
receptor can't signal as well as before, may be temperature sensistive often with missense mutations
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what s a hypermorphic mutation?
overexpression of transcription unit, overactivity of gene product
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whats an example of a hypermorphic receptor?
receptor sends signals even when no ligand is present
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what mutation is it when a gene product prevents function of WT, eg competitive inhibitors eg ligand binds interaction but no activity?
dominant negative antimorphic
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how can be mutations be induced?
by using mutagens such as 1)DNA-modifing chemicals2)ionizing radiation
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the rate of sponatnaeous mutations is low or high?
low
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what are some dna-modifiying chemicals?
alkylating agents: ethyl methane sulphonate and ethyl nitrosourea
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how do alkylating agents work?
donate alkly groups to amino or keto groups in nucleotides to change bp affinities
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go through the process of what happens by alkylating agents?
changes bp, G-> modified G (has ethyl group) -> G with ethyl group looks like adenine to RNA polymerase, in rep the new strand has T to pair with thought adenine, 2nd rep puts adenine
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in mutagenesis what animal is used why?
males as they usually target sperm
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steps in method of mutagenesis?
expose adult male to mutagen (target sperm) -> breed the mutations until homozygosity -> screen for phenotypes-> complementatin testing
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mutagenesis in this way is an example of forward or revese genetic analysis why?
forward genetics as mutagenesising looking for phenotypes before know which genes hit
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what is complementation testing for?
seeing what gene loci the mutation is on
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whats the ideal characteristics for animals for genetic manipulation?
small organism, large batches of embryos, short generation time, sequenced genome
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why is it ideal to have a short generation time for mutagenesis?
usually have to breed through 3 generations at least would take long
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why would you want large batches of embryos for mutagenesis?
mutation rates might be very small so need lots of embryos to mutate to get phenotype
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what animals arent suitable for genetic analysis?
chick and frog as adults too big for large nums, generation times long
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what animals are ideal for genetic analysis?
bacteria, yeast, drosophila/fly,worm, fish and mouse
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what is reverse genetics? example?

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you clone a gene and then look for weird mutant phenotype eg mouse KOs

Card 3

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what is reverse and forward genetics a part of?

Back

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Card 4

Front

what does the white mutation cause?

Back

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Card 5

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what is the white gene required for?

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