Transcript Biology Chapter 9

Section One: Manipulating DNA
 Manipulating DNA
 Artificial nucleotides
can be made
 Chemical mutagens can
change a DNA sequence
 Enzymes can cut and
copy DNA
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Enzyme: protein that
catalyzes, or speeds up,
chemical reactions in
organisms
Section One: Manipulating DNA
 Restriction Enzymes
 Enzymes that cut DNA
molecules at specific
nucleotide sequences
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Created from bacteria
Nucleotides sequences
where cut occurs is called a
restriction site
Each restriction enzyme has
a different restriction site
 Scientist can cut out small
sections of DNA to study
Section One: Manipulating DNA
 Restriction Enzymes
 Some make staggered
cuts
 These leave tails of free
DNA
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Tails are called sticky ends
If two complementary
sticky ends come together,
the two segments can
bond toghether
Section One: Manipulating DNA
 Gel Electrophoresis
 Allows DNA fragments to be
separated by size
 Uses electricity
 The length of the DNA
fragment can be determined
by the distance it travels on
the gel
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Larger fragments will travel
slower and not make as far
down the gel
 Restriction Maps: show the
lengths of DNA fragments
between restriction sites in a
strand of DNA
Section Two: Copying DNA
 Polymerase Chain
Reaction
 A technique used to
produce copies of a
DNA sequence
 Can make millions to
billions of copies in a
few hours
 Can be used to study
DNA
Section Three: DNA Fingerprinting
 DNA Fingerprint
 the representation of parts of
an individual’s DNA that can
be used to identify a person at
the molecular level
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Every DNA fingerprint is unique
for every person unless they are
an identical twin
They are visualized using gel
electrophoresis
DNA fingerprints of individuals
can be compared to identify
people and compare related
individuals
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When determining paternity, a
child must receive a band from
either the mother or the father. If
the bands do not match, that male
cannot be the father
Section Three: DNA Fingerprinting
 DNA Fingerprinting
 Each person has a different number of copies of repeats
of nucleotides
Section Three: DNA Fingerprinting
 DNA Fingerprinting
 Can be used to identify someone based on probability
 Usually compares 13 regions of the genome
 Can be used for crime scenes
Section Four: Genetic Engineering
 Cloning
 Clone: genetically identical copy of a gene or of an
organism
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Human identical twins are clones of each other
Dolly the sheep was the first cloned mammal in 1997
Clones may not look exactly or act exactly like the original
since gene expression is also affected by other factors like
environment
Being studied to help endangered species and creating human
organs for transplants
Controversial because the success rate is low, it can reduce
biodiversity, and clone mammals develop can develop many
problems like short life spans
Section Four: Genetic Engineering
 Genetic Engineering
 Changing an organism’s DNA to give the organism new
traits
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Can be used because all organisms use the same genetic
code
Uses recombinant DNA
 Recombinant DNA: DNA that contains genes from more
than one organism
Bacteria is commonly used for genetic engineering
 Bacteria have plasmids
 Plasmids: tiny rings of DNA found in bacteria
 Plasmids can be cut open and foreign DNA can be
inserted to close the ring if the sticky ends match
Section Four: Genetic Engineering
 Genetic Engineering
 Produces organisms with new
traits
 Transgenic Organism:
organism has one or more
genes from another organism
inserted into its genome
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Plants: can gain resistant genes
to pests, diseases, and frost
Animals: transgenic mice are
used to study human
development and disease
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Can help us understand how
cancer works
Can also tell us the function of
some genes
Section Four: Genetic Engineering
 Genetic Engineering
 Concerns
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How will it effect human health?
Is it ethical?
GM foods could cause allergic reactions or other unknown
side effects
How will it effect biodiversity and the environment
Could decrease genetic diversity
Section Five: Genomics
 Genomics
 The study of genomes
 Includes sequencing all an organism’s DNA
 Gene sequencing: determining the order of DNA
nucleotides in genes or in the genome
 Human Genome Project Goals
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Map and sequence all of the DNA base pairs of the human
chromosomes
Identify all of the genes within the sequence
All genes were sequenced in 2003
Section Six: Genetic Screening and
Gene Therapy
 Genetic Screening
 The process of testing
DNA to determine a
person’s risk of having or
passing on a genetic
disorder
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Can only tests for certain
diseases as our knowledge
of the genome is limited
Can be done to a baby in
utero
Can be done to determine
the chances of breast cancer
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Do they have the BRCA1
gene?
Section Six: Genetic Screening and
Gene Therapy
 Gene Therapy
 The replacement of defective or missing genes, or the
addition of a new gene, into a person’s genome
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Can be used in stem cells for sick patients
Can insert “suicide” genes into cancer cells
Extremely difficult and still experimental