Transcript Frontiers of Genetics - Ramsey Public School District

DNA
Technology
Chapter 12
Applications of Biotechnology
• Biotechnology: The use of organisms to
perform practical tasks for human use.
– DNA Technology: Application of biotechnology
in which genomes of organisms are analyzed and
manipulated at the molecular level
• Bacteria, such as E. coli, serve as useful
models for gene manipulations
– Do not undergo meiosis (reproduce asexually)
– Still have means of genetic recombination
• This natural recombination process is capitalized on in
current DNA technology procedures
Selective Breeding
• Cross-breed organisms with desired traits
– Enhance expression of trait
– Produce combination of desired traits
Lederberg & Tatum’s Experiment
Recombinant DNA Technology
• Combine genes from different sources, even different
species, into a single DNA molecule
• Bacteria have small circular pieces of DNA called plasmids
separate from their larger single chromosome
• Plasmids can replicate and pass between bacterial cells
allowing gene sharing – associated with antibacterial
resistance
Genetic Engineering
• Plasmids are used to
add genes for useful
products into bacteria
through a process called
gene cloning
– Remove plasmid
– Add useful gene
– Reinsert in bacteria
where genes are copied
many times
Genetically Engineering Insulin
Gene Cloning
How can we do this?
• Restriction enzymes are proteins that cut genes at specific DNA
sequences.
• Over 75 different kinds of restriction enzymes are known; each
one “recognizes” and cut DNA at a particular sequence
• Restriction enzymes allow DNA to be cut into fragments that can
be isolated, separated, and analyzed.
• The cut ends produce matching “sticky ends” on the DNA
fragment and the cut plasmids.
Restriction Enzyme Action & Cloning into a Plasmid
Inserting a DNA Sample into a Plasmid
Reverse Transcriptase & Gene Cloning
Cloning
Gel Electrophoresis
http://learn.genetics.utah.edu/content/labs/gel/
Restriction Sites
Layout of an Electrophoresis Gel
Loading the Wells of a Gel
Uses of Electrophoresis
• Isolation of DNA fragments so that they can
be incorporated into a plasmids or some other
vector.
• Creating a DNA map so that we know the
exact order of the nucleic acid base pairs (A, T,
C, or G) along a DNA strand.
• Perform DNA Fingerprinting, which can be
used to test organic items, such as hair or
blood, and match them with the person that
they came from. This is useful in criminal
investigations.
Polymerase Chain Reaction
Method of photocopying DNA in vitro to provide large
supply to avoid needing large sample size of cells to
extract it (DNA) from.
Prokaryotic Control of Gene Expression
Eukarotic Controls of Gene Expression
• Gene expression is the
transcription and
translation of genes into
proteins
• Eukaryotic controls are
elaborate than
prokaryotes
• Genes are not controlled
in clusters
• Proteins called
transcription factors
regulate transcription by
binding to promoters or
RNA polymerase
– Turned ON or OFF by
chemical signals in the cell
Cellular Differentiation
STEM CELLS are cells that
are undifferentiated and have
the potential to differentiate
into various types of cells
Homeotic Genes
• “Master switches”;
control formation
of body parts in
specific locations
• Small changes in
these genes can
result in major
morphological
changes