genes

Pages which contain `genes':

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the origin of new genes
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how to clone genes
Cloning Genes
Cloning Genes
Cloning Genes
LINKAGE MAPPING
If you analyze a cross involving two genes (A and B), the analysis
can become more complex. If the two genes are on different chromosomes
Recombination frequency between genes increases with increasing distance
between genes and can be used to create genetic maps of chromosomes.
Note: when two genes are unlinked (on different chromosomes or very far apart
Where near 0% recombination frequency means the genes are very tightly linked,
and 50% recombination frequency means the genes are entirely unlinked.
In a plant, leaf color and leaf shape are controlled by two linked genes.
factors: three genes, one of which is dominant; the genes are sex-linked;
First, we need to find out whether the three genes (bar, singed, forked)
point cross (a cross with three genes), the rarest class of progeny are
The future of genetic research
of the genes has already explained some of the once-mysterious basic
research. Recessive disorders tend to result from failures in genes that
but biological psychiatrists believe the genes are whispering an
biologists can find genes that are expressed only in the cochlea and
therefore are probably important in hearing. Once such genes have been
genes which are developmentally active in both Drosophila, the fruit
mammals, although the functions of these genes in humans are not yet
When genes of species that separated from each other many millions of
50,000 to 100,000 human genes remain totally unknown, and there is still
genes. But science is also stalking the genes that contribute to heart
Prokaryotic Gene Regulation
of genetics by treating genes as the minimal functional units of
region in E. coli is made up of several smaller genes which, in
We have also simplified our discussion of genes by leaving
aside the issue of when genes are or are not expressed. Most genes are
the lac genes of E. coli, they are only expressed when cells
expressing the genes of the lac operon only in the presence of lactose
By examining genes at a finer level, it is possible to examine
these are regions of DNA that code for proteins. These genes produce
proteins. (Note: some structural genes produce RNAs that are themselves
DNA to affect expression of adjacent structural genes. Generally,
The underlined symbols are names of genes.
which stimulates the expression of a gene or set of genes when it is added to
the culture medium. For example, expression of the genes of the lac operon
200-fold increase in expression of the genes of the lac operon. Adding a
operon. For example, lactose induces the genes of the lac operon but not
the genes of the trp operon.
Expressed at high levels under all conditions. The genes of the lac
Not expressed at high levels under any conditions. The genes of the
transcription. A mutant of this type cannot express the lac genes on the
type will show constitutive expression of the lac genes on the same
Note: Genes which are not explicitly listed as mutant are assumed to
Z indicates a strain where all genes but
(2) Mutations in different genes can result in the same b-gal
It is important to distinguish between genes that produce a protein (coding
regions) and genes that control the production of proteins (regulatory
At one time, it was not known how genes were regulated, thus the
distinction between structural genes and regulatory sites did not exist.
structural genes which produce proteins and can therefore act in
genes on the same piece of
how structural genes and regulatory sites
in a cell which carries a small number of genes and is
it is expressed. Be careful about which genes act in cis and which
induced to high levels. You have mapped 4 genes
genes in expression of yuckase in response to yuckose.
You construct an F'-plasmid carrying these genes and
- In each of the pairs of genes (repressor/operator and promoter/yuckase)
between the above possibilities by finding out which genes act in
trans (protein producing genes)
This is only possible if both genes produce protein products: B is the
7.012 Genetics Supplementary Handout Page 1
two different genes.
a - recessive mutant allele +a or +/a wild-type (+) linked genes
If you analyze a cross involving two genes (A and B), the analysis can become more
complex. If the two genes are on different chromosomes, analysis is straightforward:
Recombination frequency between genes increases with increasing distance between genes
Note: when two genes are unlinked (on different chromosomes or very far apart on the same
In a plant, leaf color and leaf shape are controlled by two linked genes. Leaves of the wild-type
three genes, one of which is dominant; the genes are sex-linked; and the cross is to wild-type,
- first, we need to find out whether the three genes (bar, singed, forked) are
cross with three genes), the rarest class of progeny are those that result from a double
b) Three genes in Drosophila with the recessive alleles l, m, and n are known to be linked.
genes on the chromosome)
Control of the Cell Cycle
12-24 hours. During early embryogenesis, most of the cells in an embryo
embryogenesis, an ever-decreasing proportion of cells are involved in
Use of DNA in Identification
of the different DNA patterns of different genes vary across the
Genetics: Introduction and Analyzing Crosses
think that it is two different genes.
Prokaryotic Genetics and Gene Expression Chapter
Regulation of Prokaryotic Genes
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relationship between recombination frequencies and the distance between two linked genes
Immunology Encyclopedia
major histocompatibility complex (MHC) A complex of linked genes,
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structure and function of eukaryotic genes
eukaryotic vs. prokaryotic genes
Examples of Viral Replication Pathways
as a factory for replicating the viral genes. The viral infection
enzyme cuts the host chromosome and integrates viral genes into it. When
its descendents. If the viral genes later undergo lysis and leave the
7.01Recombinant DNA Practice Problem
doesn't make repressor). In this strain, the lac genes will always be
Characteristics of Prokaryotes and Eukaryotes
Streptococcus pyogenes, the bacterium that causes
Southerns, Northerns, Westerns, & Cloning: Molecular Searching Techniques
thousands of genes, thousands of different mRNA species, and thousands
be used to study genes from different organisms or genes that are
7.012 Cloning Project: Agricultural Biotechnology
Sclerotina sclerotium pathogenesis"
c) How would you clone the OA degrading enzyme genes
b) You want to clone the genes from the bacterium that are responsible
OA as a carbon source and expression of the OA genes are not toxic to
encoding genes that produce proteins capable of helping the bacteria to
e) At this point, it isn't clear which genes must be expressed in order
promoters won't work in plants and plant genes are mono-cistronic. It
Lwoff's Pathways - Viral Replication
as a factory for replicating the viral genes. The viral infection
enzyme cuts the host chromosome and integrates viral genes into it. When
its descendents. If the viral genes later undergo lysis and leave the
discovery: that the genes injected into a bacterium by a phage can
Meiosis and Genetic Recombination
exactly alike? While genes determine most of our physical
characteristics, the exact combination of genes we inherit, and thus
Tracking the movement of genes during crossing-over helps geneticists
determine roughly how far apart two genes are on a chromosome. Since
there are more chances for a break to occur between two genes that lie
chromosome, while the other crosses over. So, genes that lie far
hand, genes that lie very close together are less likely to be
Genes that tend to stay together during recombination are said to be
resulting zygote contains a combination of genes arranged in an order