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Developmental Lecture #4
Terms in this set (25)
The microscope allowed for careful and detailed study of whole and dissected embryos, later to be superseded by...
Describe how fate maps work.
Fate maps are used to demonstrate what a particular region of the embryo will give rise to. Single blastomeres can be labeled via injection of a non-toxic marker such as fluorescein-linked dextran-amine or by expression of a fluorescent protein like green fluorescent protein (GFP) from injected RNA.
Defined small populations of cells, or even single cells, can also be conveniently marked in chick embryos in the egg (in ovo) or in culture by introducing a ___ _________ encoding a fluroscent protein
DNA is injected into the embryo at a desired site with a fine pipette, and pulses of electric current applied using fine electrodes.
(Visualizing Gene Expression) Proteins expressed from gene transcripts can be detected by
specific antibodies labeled with fluorescent dyes (immunostaining)
What do DNA microarrays detect?
expression of large numbers of genes
at the same time
Total mRNA from tissue of interest is extracted, and is either ... or converted into ...
amplified as RNA, or converted into cDNA and amplified by polymerase chain reaction (PCR)
___ ___ is more accurate than microarrays.
Describe how to manipulate the embryo by
removing or adding cells to cleavage-stage embryos, or transplanting blocks of cells from one embryo to another
Which technique in the early embryo is easiest in Xenopus?
Microsurgical manipulation works for which two model organisms at all stages of development? Why?
Xenopus and chick. The embryos are tough and can withstand surgical manipulation.
Xenopus is unsuitable for which technique? Give 2 reasons for this.
Conventional genetic analysis, because of its long generation time, and also its tetraploid genome.
Study Fig. 3.34.
page 131 (make another quizlet set for this)
____ ___________ ________s were for a long time the only way that genetic disturbances of development could be studied.
rare spontaneous mutations
Describe forward genetics.
A mutant organism is recognized by its unusual phenotype and then genetic experiments are carried out to find the gene responsible.
Explain how large-scale mutagenesis screens can be used to identify recessive mutations in zebrafish.
Breeding for 3 generations.
Treat male fish with a chemical mutagen and cross them with WT females.
Take a male F1 and cross again with a WT female. Assume that this F1 male carries a mutation. Then cross male and female from F2 family: 50% of F2 family will be heterozygous. 25% in F3 will be between 2 heterozygotes, and 25% of these offspring will be homozygous for the mutation.
Animals into which an additional or altered gene has been introduced are known as
Transgenic techniques are most highly developed in...
ES cells injected into a __________ will become part of the _____ ____ ____ and can give rise to all the cell types in the mouse, including the ________.
inner cell mass
Describe homologous recombination.
Specially tailorered DNA constructs are introduced into the cell by
. By including some sequence that is homologus with the desired target gene, it is possible to make a transfected DNA insert at a predetermined site.
Homologus recombination between the transfected DNA and the target gene in the ES cell results in an insertion that renders the gene non-functional.
the stage of a mammlian embryo that corresponds in form to the blastula stage of other animal embryos, and is the stage at which the embryo implants in the uterine wall.
When one gene is replaced by another functional gene, it is called a ...
ES-cell transfer results in...
Describe the Cre/loxP System.
1. Insert loxP sequence (34 bp) on both sides of the gene (flank) and homologous recombination in ES cells in vitro is carried out.
2. Introduce genetically modified ES cells into blastocysts to make transgenic mice.
3. Select lines of homozygous transgenic mice all carrying the gene.
Study Fig. 3.38.
page 136 (make another quizlet set for this)
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