lecture 2- mutations & transgenics Flashcards
a mutation is a change in ___
genetic composition
(alteration in DNA that causes a change from that of standard, wild-type sequence)
what are mutations good for?
determining the function of a gene
- if you remove one part of the machine…what happens?how essential is it? is there redundancy?
types of mutations: physical is the ____
name 4 subsets
direct change of the DNA sequence
deletions
substitutions
transpositions
insertions
describe the physical mutation of deletions
single bp deletions & multiple bp deletions
describe the physical mutation of substitutions
missense- codes for diff amino acid
nonsense- codes for stop codon
silent
describe the physical mutation of transpositions
switch things from one place to another
- small & large scale
describe the physical mutation of insertions
single bp (point mutation)
duplication
types of mutations: non-physical and others
name the 6
silent
frameshift
reversion
neutral
adaptive
conditional
describe the non-physical mutation of silent mutations
change in DNA that does not affect the amino acid it codes for
describe the non-physical mutation of frameshifts
change in the AA reading frame
- the insertion of deletion of nucleotide bases that are not in multiples of 3’s
The red cat
T her edc at
describe the non-physical mutation of reversions
change of a mutation back to the original state
ATCG –> AACG –> ATCG
describe the non-physical mutation of neutral
no affect on fitness
describe the non-physical mutation of adaptive
positive affect on fitness
describe the non-physical mutation of lethals
causes death of the organism
name 7 mutation functional classes
1- loss of function
2- gain of function
3- leaky
4- conditional
5- dominant negative
6- homeotic
7- suppressor
describe loss of function
often recessive- gene has reduced or complete lack of function (null allele)
describe gain of function
often dominant- gene has gained a new or enhanced function
describe a leaky function
only a partial loss of function
describe a conditional function
the effect is dependent on certain conditions (such as temp sensitive)
describe a dominant negative function
a mutant gene product, which adversely affects the wild-type gene product in the same cell (possible by binding to it)
- usually works in an antagonistic manner, often more detrimental than a null allele
is a dominant negative function or a loss of function (null allele) more detrimental?
dominant negative
describe a homeotic function
one developmental pattern is replaced by another (Drosphilia antenapodia mutant has legs where its antennae should be)
describe a suppressor function
causes a reversion in a mutant phenotype due to a mutation at a site other than the original mutation (second site)
name 5 causes of mutations
1- chemical- alkylating agents, intercalating agents, base analogs: EMS
2- physical- chromosomal breaks
3- replication/transcriptional reading errors
4- energy/radiation (UV: thymine dimers) (gamma ray, x-ray, fast neuron- deletions, breaks)
5- biological (transposons, transgenics)
