Lecture--Chapter 21/22 Flashcards
a chart that describes the relative locations of genes of other DNA segments on a chromosome
genetic map
cloning techniques are used to determine location of genes (number of base pairs between genes)
physical mapping
use labeled cDNA or RNA to localise a specific DNA or RNA sequence in tissue
In situ hybridisation
uses fluorescently labeled DNA DNA probes
fluorescence in situ hybridisation (FISH)
a segment of DNA found at a specific site that can be uniquely identified by PCR and gel electrophoresis
genetic markers
What are the common types of molecular markers?
- restriction fragment length polymorphism (RFLP)
- microsatellite
- sequence-tagged site (STS)
A site in a genome where the distance between two restriction sites varies among different individuals. These sites are identified by restriction enzyme digestion of chromosomal DNA and the use of Southern blotting.
restriction fragment length polymorphism (RFLP)
A site in the genome that contains many short sequences that are repeated many times in a row.
microsatellite
This is a general term to describe any molecular marker that is found at a unique site in the genome and is amplified by PCR.
sequence-tagged site (STS)
generated by restriction enzyme digests (EcoRI, once every 4096 bp)
RFLPs
have variation from small deletions, duplications, and mutations
RFLPs
also called short tandem repeats or short sequence repeats
microsatellites
ancestral individual in which a disease first appeared
founder
What are the aspects of physical mapping?
- higher resolution than RFLP and microsatellites
- used to actually isolate DNA that contains genes of interest
- very labour and time intensive
- clones that are generated can be used for sequencing genome
Physical mapping involves what?
- cloning a piece of DNA from a chromosome
- characterising the clone for its size, genes that it contains and their relative locations
- matching a piece of the cloned DNA to another cloned DNA and repeating the process until all the DNA of a given chromosome is identified and organised
What are the steps of mapping?
- a sample of chromosomal DNA is cut into smaller pieces with restriction enzymes
- the fragments are cloned into vectors to create a DNA library
- the pieces are organised according to their exact location on a chromosome
a collection of overlapping clones (vectors)
contig
What are the cloning vectors that can accept large pieces of DNA?
- yeast artificial chromosomes (YACs)
- bacterial artificial chromosomes (BACs)
- P1 artificial chromosomes (PACs)
- cosmids
inserts from several hundred thousand to 2 million bp
yeast artificial chromosomes (YACs)
inserts up to 300,000 bp long
bacterial artificial chromosomes (BACs) and P1 artificial chromosomes (PACs)
hybrid between a plasmid vector and a bacteriophage. These can accept DNA fragments in the range of tens of thousands of bp
cosmids
What was the first prokaryotic genome sequenced, and when was it?
H. influenzae, 1995