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DNA Fingerprinting and Karyotyping
DNA Technology
TEKS
6.H: Students will…
describe how techniques such as DNA
fingerprinting, genetic modifications, and
chromosomal analysis are used to study the
genomes of organisms
Karyotyping (Chromosomal Analysis) The arrangement of homologous chromosomes, from
largest to smallest
Humans normally have 23 pairs of chromosomes (46 total) For each pair, one copy comes from mom and one comes from dad
Pairs 1 – 22 are known as autosomes
The 23rd pair are the sex chromosomes – X and Y
XX = female
XY = male
A karyotype can tell you If the individual is male or female
If the individual has any chromosomal disorders (chromosome mutations)
Karyotyping (Chromosomal Analysis)
Chromosome Mutations
Nondisjunction
Occurs during meiosis, when sister chromatids fail to
separate properly
This causes abnormal gametes (sex cells – sperm or egg)
The gametes can have too many or too few chromosomes
Deletion– only one chromosome (monosomy)
Duplication– three copies of a chromosome (trisomy)
Mutations can also occur when chromosomes have
translocations or inversions
Karyotyping (Chromosomal Analysis)
Examples of Autosomal Chromosome Mutations
Down’s Syndrome – trisomy 21
Edward’s Syndrome – trisomy 18
Examples of Sex Chromosome Mutations
Klinefelter’s Syndrome – XXY
Turner’s Syndrome - XO
Karyotyping (Chromosomal Analysis)
Normal Karyotype
Karyotyping (Chromosomal Analysis)
Abnormal Karyotype
DNA Fingerprinting
A method of isolating and making images of
sequences of DNA
Used for criminal identification and
paternity testing
Step 1: Obtain sample of DNA
If the sample is not large enough for testing, it needs
to be amplified
PCR (polymerase chain reaction) can be used to
copy a single DNA molecule millions of times
Polymerase Chain Reaction (PCR)
DNA Fingerprinting
Step 2: Add restriction enzymes to the DNA
Restriction enzymes are proteins made by bacteria
Restriction enzymes recognizes specific sequences of
bases, and cut the DNA at those bases
Restriction enzymes make 2 cuts – one through each
sugar-phosphate backbone of the DNA strand
Restriction enzymes can make two different kinds of cuts
“Sticky ends” – an overhang in the DNA
“Blunt ends” – cut straight across both strands of DNA
DNA Fingerprinting
Blunt Ends
Sticky Ends
DNA Fingerprinting
Step 3 – Once the DNA is cut into various sizes,
they are placed on a gel. This gel is then subjected
to an electric current (gel electrophoresis)
The DNA fragments move from the negative pole
(cathode) towards the positive pole (anode)
Shorter fragments move through the gel faster –
why?
Step 4 – Once sorted by electrophoresis, the gel is
blotted to transfer the strands onto a nylon sheet,
which can be “read”
DNA Fingerprinting
DNA Fingerprinting
DNA Fingerprinting
DNA Fingerprinting
DNA Fingerprinting
Genetic Engineering
Inserting extra DNA or DNA from another organism
First, a particular section of DNA must be isolated using
gel electrophoresis
Then the fragment of DNA can be removed from the gel
and combined with a DNA fragment from another source
– it is then called “recombinant DNA”
Recombinant DNA is carried by a vector into a host cell –
like a bacterial cell – in order to be copied and/or studied
A commonly used vector is called a plasmid
A plasmid it made by cutting the vector and the DNA fragment
with the same restriction enzyme
Genetic Engineering