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Chapter 9 Notes
9-1 Manipulating DNA
Biotechnology relies on cutting DNA at specific places.
Scientists use several techniques to manipulate DNA.
Chemicals, computers, and bacteria are used to work with
DNA.
Scientists use these tools in genetics research and
biotechnology.
Restriction enzymes cut DNA.
Restriction enzymes act as “molecular scissors.”
1)come from various types of bacteria
2)allow scientists to more easily study and manipulate genes
3)cut DNA at a specific nucleotide sequence called a restriction
site
Restriction maps show the lengths of DNA fragments.
Gel electrophoresis is used to separate DNA fragments by size.
1)A DNA sample is cut with restriction enzymes.
2)Electrical current pulls DNA fragments through a gel.
9-2 Copying DNA - PCR uses polymerases to copy DNA
segments.
(Polymerase Chain Reaction)
PCR makes many copies of a specific DNA sequence in a
few hours.
PCR is a three-step process.
1)Separating – container with all reactants is heated to
separate the DNA strands
2)Binding – container is cooled; nucleotides bind to the
original DNA by base pairing
3)Copying – container is heated again and polymerases build
new strands of DNA. Polymerases continue adding
nucleotides until entire DNA segment has been copied.
PCR uses four materials.
1)DNA to be copied
2)DNA polymerase
3)A, T, C, and G nucleotides
4)two primers
*Each PCR cycle doubles the number of DNA molecules.
9-3 DNA Fingerprinting identifies people at the molecular
level.
A DNA fingerprint is a type of restriction map. DNA
fingerprints are based on parts of an
individual’s DNA that can by used for identification.
–based on noncoding regions of DNA
–noncoding regions have repeating DNA sequences
–number of repeats differs between people
–banding pattern on a gel is a DNA fingerprint
DNA fingerprinting is used for identification.
DNA fingerprinting depends on the probability of a match.
–Many people have the same number of repeats in a
certain region of DNA.
–The probability that two people share identical
numbers of repeats in several locations is very small.
Gel Electrophoresis:
1)DNA Extraction – the cells are opened and the DNA is
separated from the other cell parts.
2)Cutting DNA – restriction enzymes are used to cut the
DNA into smaller fragments
3)Separating DNA – Negative DNA molecules are moved
towards the positive end of the gel. The smaller
fragments move faster.
Gel electrophoresis separates DNA fragments based
on their size (larger
ones are slower so they are closer to the negative end,
smaller ones are
faster and closer to the positive end.)
9-4 Genetic Engineering – The DNA sequences of organisms
can be changed.
•Entire organisms can be cloned. A clone is a genetically
identical copy of a gene or of an organism. Steps of
Cloning:
1)The egg cell is taken from an adult
2)The nucleus from the egg cell is removed
3)The nucleus from the adult cell of the animal to be
cloned is put into the egg cell.
4)Normal cell division begins.
5)Embryo is put into the uterus of the foster mother.
6)Cloned offspring is born.
New genes can be added to an organism’s DNA.
Genetic engineering involves changing an organism’s DNA
to give it new traits.
Genetic engineering is based on the use of recombinant
DNA.
Recombinant DNA contains genes from more than one
organism.
Genetic engineering produces organisms with new
traits.
A transgenic organism has one or more genes from another
organism inserted into its genome.
9-5 Genomics involves the study of genes, gene functions,
and entire genomes.
Genomics is the study of genomes.
–can include the sequencing of the genome
–comparisons of genomes within and across species.
Technology allows the study and comparison of both
genes and proteins.
9-6 Basis for new medical treatments
Genetic screening involves the testing of DNA.
–determines risk of having or passing on a genetic
disorder
–used to detect specific genes or proteins
–can detect some genes related to an increased risk of
cancer
–can detect some genes known to cause genetic
disorders
Gene therapy replaces defective or missing genes, or adds
new genes, to treat a disease.