gene manipulations in organisms Flashcards
(37 cards)
define transgenesis and how its delivered
controlled transfer of genetic information into the genome, with no reliance on selective breeding
often done by microinjection
what is meant by forward genetics
phenotype driven
random mutation, phenotype change observed, gene identification, and then interpret gene function
what is meant by reverse genetics
gene driven
gene identification, targeted mutation, phenotype change observed and then interpret gene function
what is meant by intermediate genetics
gene trapping
random TAG insertion, gene identified and phenotype change observed, then gene function is interpreted
why is a balancer chromosome often added in drosophila genetics?
it prevents crossover
contains identity markers
lethal recessive allele– thus no interference of natural selection
what is the hedgehog mutation?
Hh mutation
in flies, mutation causes failure of separation of the cerebral hemispheres
what is the one-eyed pinhead (Oep) mutation?
severe cyclopia in zebrafish, (one eye in the middle of the face)
what is the Weissherbst (weh) mutation
hypochromic blood (less hemoglobin/red in RBC) and decreased blood cells – often in zebrafish
what is the Hagoramo (hag) mutation
disrupted stripe pattern in zebrafish
what is meant by synteny
same genes but in different order in the chromosomes accross species
what are advantages of the mouse model (7)
- small
- reproductive efficiency (also non seasonal)
- tolerant to inbreeding
- small oestrus cycle ~ 4days
- 19 pairs of autosomes and X and Y
- all telocentric chromosomes
- same gnome size as humans – synteny
what is ENU (N-ethyl N-nitrosourea)?
a supermutagen– high efficiency
transfer of ethyl group in DNA resulting in mispairing
induces single base pair substitutions
what is a congenic strain, and explain what happens in gene linkage and non-linkage
when an inbred strain contains a small genetic region from another strain
linked– cause retention of small part of the other gene
no linkage– rapid elimination of heterozygosity
what are two markers used to detect mutations in mice?
- microsatellite markers
- single nucleotide polymorphisms (SNPs)
(often used to distinguish inbred mouse strains)
how is gene mapping or linkage analysis done?
1) homozygous mutant(marker added) X homozygous wildtype
2) back-crossing x10
–> the location of the mutation from the residual chromosome segment left will be the CANDIDATE REGION
4) the mutation can then be identified by PCR
Microinjection DNA is derived from what?
- plasmid
- bacterial artificial chromosome
- yeast artificial chromosome
in transgenesis where is the egg from?
superovulating female mated to a stud male
in transgenesis where is the male pronucleus from?
male pronucleus from a fertilized egg
when does implantation occur into pseudopregnant foster female in transgenesis?
after blastocyst formation
what influences does transgenesis have? (4)
- position effect– integrates at random location in ch
- mutagenic– may disrupt endogenous genes
- multicopy arrays– recombines to form concatemers before integration
- integrity– sometimes partially degraded before integration
what is meant by transfection of ES cells
select for genetic change and reintroduce cells into embryo
what is meant by chimera
combining 2 pre-implantation embryos and producing a single animal (eg 2 colours in coat)
what are the three layers of the blastocyst and what to they develop into?
epiblast– foetus (internal cells)
hypoblast– yolk sac (layer covering epiblast)
trophoblast– placenta (layer surrounding all)
what is the biggest origin of Embryonic Stem cells and what kind of potency do they have?
Epiblast (develops into foetus) and is pluripotent– often derived 3 days after fertilization
