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DNA & BIOTECHNOLOGY
DNA & BIOTECHNOLOGY
Keywords
Keywords
Biotechnology
 Recombinant DNA
 Gene splicing
 Restriction enzymes
 Sticky ends
 Ligase & DNA-ase
 DNA sequencing
 Gene probes


DNA profiling
 Short tandem
repeats
 Gel electrophoresis
 Capillary
electrophoresis
WHAT IS BIOTECHNOLOGY?
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Biotechnology is using
living things to create
products or to do tasks
for human beings.
It is the practice of using
plants, animals and
micro-organisms and
their biological processes
to some benefit eg. in
medicine, agriculture and
industry
Researchers use DNA,
genes, yeast, bacteria
and cells
WHY USE BIOTECHNOLOGY?
For ourselves
For the environment
Biotechnological
research has been used
to assist human health in
many areas:
Biotechnology is a tool
used:
antibiotics
 vaccines
 genetic disorders
 DNA profiling &
forensics

to help control pests
 for conservation of
plant & animal species
 leach metals from the
soil for cleaner mining
 clean up heavy metal
contamination

RECOMBINANT DNA & GENE SPLICING
RECOMBINANT DNA & GENE SPLICING
 Recombinant
DNA is a method
of cutting and pasting a foreign
piece of DNA into the DNA of a
cell.
 It brings together genetic
material from multiple sources,
creating new sequences of
DNA.
 Enables the genome to be
manipulated very precisely
RECOMBINANT DNA
Recombinant DNA is used
for the production of
specific proteins
 The first chemical
produced by this mehtod
was human insulin
 The human gene is
placed into a bacterium
which can then use the
genetic information to
produce the human
hormone.
 The hormone is refined
from the culture of
bacteria.

RECOMBINANT DNA & GENE SPLICING
Steps to gene splicing:
1. Restriction enzymes
 Cut the DNA at a specific location
 Leaves the DNA strand with ‘sticky
ends’
2. Sticky ends
 Unattached (unpaired) nucleotides
 Match up with the DNA to be
inserted
3. Ligation
 Ligase enzymes help form the
hydrogen bonds between
nucleotides
 DNA-ase helps form the bonds
between the side strands
(backbone)
Fluorescent green protein
transgenic mouse
RECOMBINANT DNA
& GENE SPLICING
Young man with cystic fibrosis taking medication using a nebuliser.
Wellcome Library
The gene responsible for cystic fibrosis has been
identified and it is hoped that, using recombinant
DNA technology, it will be possible to transfer a
normal copy of the gene into affected cells.
DNA SEQUENCING & GENE PROBES
DNA SEQUENCING AND DNA PROFILING
 DNA
sequencing is
used to work out the
exact order of the base
pairs in a section of
DNA. Knowing the
base sequence can be
helpful in locating and
identifying specific
genes.
 Gene probes can then
be made and used to
locate these genes
GENE PROBES
The search for a particular gene
uses a single-stranded piece of
DNA called a gene probe.
 Probes are constructed with a
radioactive or fluorescent tag so
that they can be detected after
attaching to the DNA.
 We know the base sequences
in a number of disease-causing
genes.
 Gene probes can detect if these
genes are present in individuals
being tested.

DNA PROFILING & GEL
ELECTROPHORESIS
DNA SEQUENCING & DNA PROFILING
 DNA
profiling is
used to identify
individuals
 Gel electrophoresis
is used in DNA
profiling.
SHORT TANDEM REPEATS
Short tandem repeats (STRs) are sequences of non-coding
DNA.
 They are sections of DNA that make each individual unique
 Closely related individuals will share many of the same
STRs
 STRs are used in DNA profiling to identify individuals
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Gel electrophoresis
separates fragments of
DNA using an electric
current.
DNA has a slight negative
charge. It will migrate
towards the positive end
of the gel.
Smaller fragments move
faster through the gel
than larger fragments.
At the end of the ‘run’ a
pattern of bands will be
produced. Each band
represents a fragment
size of DNA from the
sample. Different
samples will have
different patterns.
GEL ELECTROPHORESIS
FRAGMENT LENGTHS AND GEL ELECTROPHORESIS
Blotting is a method of ‘photographing’ the resulting sequence of DNA
fragments once they have gone through the process of gel
electrophoresis.
DNA BLOT ANALYSIS
In the example below, what is the genotype of the father? Rule out all the
mother’s alleles. The ones left are from the father.
DNA PROFILING - SUMMARY
Steps in DNA profiling
1. Collect samples of
material containing cells
2. Extract DNA from
samples
3. Place solution of DNA into
gel electrophoresis
4. Run gel
5. Process gel to see
location of DNA bands
6. Photograph the gel (DNA
or Southern blot)
CAPILLARY ELECTROPHORESIS
• STR profiles are more easily stored and compared
in the form of numbers and letters rather than
pictures of lines.
• Capillary electrophoresis is a way of collecting
numerical data that is plotted on a line graph.
• The peaks on the graph represent the different
STRs
Sample
Amelogenin D3S1358
vWA
FGA
D8S1179
D21S11
D18S51
Victim
XY
14, 15
18, 20
24
13, 16
28, 30.2
14, 15
Suspect
XY
14, 15
15, 18
21, 22
13, 14
30
14, 15
Blood Stain
from Crime
Scene
XY
14, 15
15, 18
21, 22
13,14
30
14, 15
Capillary electrophoresis graph
USES OF DNA PROFILING
Identification
 Criminals
 Victims – crimes, disasters
 Family members
 Species – quarantine, smuggling
 Genetic differences between populations
Information is kept in data banks