Changing the Living World

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Section 13-1
Changing the Living World A. Selective
Breeding 1. Hybridization 2. Inbreeding B. Increas
ing Variation 1. Producing New Kinds of
Bacteria 2. Producing New Kinds of Plants
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• Humans use selective breeding to pass desired
  traits on to the next generation.
• While inbreeding assures a set of characteristics
  it also causes genetic defects as well.
  (blindness, hip displeasure in dogs and
  hemophilia in humans)
• Wide variation is found in natural populations.
  Breeders can artificially introduce variation by
  inducing mutations.
• Plants tolerate extra sets of chromosomes.
  Polyploidy has resulted in new species of plants.

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Section 13-2
Manipulating DNA A. The Tools of Molecular
Biology 1. DNA Extraction 2. Cutting
DNA 3. Separating DNA B. Using the DNA
Sequence 1. Reading the Sequence 2. Cutting and
Pasting 3. Making Copies
132
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• Genetic Engineering
• Making changes in the DNA code of a living
  organism
• Restriction Enzyme
• An enzyme that divides DNA at a specific sequence
  of nucleotides.
• Gel Electrophoresis
• Process to separate out gene fragments in a
  mixture using an electric current and polarity of
  the fragments.
• Recombinant DNA
• Combining DNA from different sources.
• Polymerase chain reaction
• Process that makes many copies of a particular
  gene

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Genetic Engineering process in which a gene
from the DNA of one organism is removed, and then
transferred into the DNA of another organism
Boyle Cohen (1973) - FIRST people to
genetically engineer a new organism Removed the
gene for rRNA from a frog and inserted that gene
into the DNA of a bacterium. RESULT A bacteria
that produced large amounts of frog rRNA Genetic
engineering involves the making of a new
combination of DNA made from two or more
different organisms
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• IF you can cut out a gene, WHAT do you use to
  carry that gene into the cell of another
  organism???
• Vector
• agent used to carry the gene of interest into
  another organism's cell
• EXAMPLES of vectors viruses, yeast or plasmids
• PLASMID
• circular DNA molecules in bacteria that
• can replicate (copy itself) independently from
  the single main chromosome in bacteria

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Bacterial plasmids are often used to make
recombinant DNA.

• plasmids are loops of DNA in bacteria
• restriction enzymes cut plasmid and foreign DNA
• foreign gene inserted into plasmid

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Restriction enzymes cut DNA.

• Restriction enzymes act as molecular scissors.
• come from various types of bacteria
• allow scientists to more easily study and
  manipulate genes
• cut DNA at a specific nucleotide sequence called
  a restriction site

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• Different restriction enzymes cut DNA in
  different ways.

• each enzyme has a different restriction site

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• some cut straight across and leave blunt ends

• some make staggered cuts and leave sticky ends

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• A restriction map shows the lengths of DNA
  fragments between restriction sites.

• only indicate size, not DNA sequence
• useful in genetic engineering
• used to study mutations

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Gel Electrophoresis

• Smaller fragments move faster and travel farther
  than larger fragments.

• Fragments of different sizes appear as bands on
  the gel.

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PCR uses polymerases to copy DNA segments.

• PCR makes many copies of a specific DNA sequence
  in a few hours.

• PCR amplifies DNA samples.
• PCR is similar to DNA replication.

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PCR is a three-step process.

• PCR uses four materials.
• DNA to be copied
• DNA polymerase
• A, T, C, and G nucleotides
• two primers

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• The three steps of PCR occur in a cycle.

• heat is used to separate double-stranded DNA
  molecules
• primers bind to each DNA strand on opposite ends
  of the segment to be copied
• DNA polymerase binds nucleotides together to form
  new strands of DNA

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Section 13-3
Cell Transformation A. Transforming
Bacteria B. Transforming Plant Cells C. Transformi
ng Animal Cells
153
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• Plasmid
• A small circular DNA molecule used in bacteria
  transformation
• Genetic Marker
• A gene that identifies the plasmid from the
  foreign DNA

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Section 13-3
Figure 13-9 Making Recombinant DNA
Gene for human growth hormone
Recombinant DNA
Gene for human growth hormone
DNA recombination
Human Cell
Sticky ends
DNA insertion
Bacterial Cell
Bacterial chromosome
Bacterial cell for containing gene for human
growth hormone
Plasmid
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Genetic Engineering or recombinant DNA

• Connecting or recombining fragments of DNA from
  different sources
• 1. Isolate foreign DNA fragment to be inserted
• -Restriction enzymes- cut DNA strands at specific
  areas

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• 2. Attach DNA fragment to a carrier
• Vector- means by which DNA from another species
  can be carried into a host cell
• Biological vectors viruses, plasmids
• Mechanical vectors micropipette, gene gun
• 3. Transfer into a host organism
• Transgenic organism- plants and animals that
  contain functional recombinant DNA

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Recombinant Examples

• E.Coli bacteria to produce indigo dye-jeans
• Growth hormone- dwarfism
• Insulin-diabetes
• Hemophilia- sheep milk has clotting factor
• Pest resistant plants

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Section 13-4
Applications of Genetic Engineering A. Transgenic
Organisms 1. Transgenic Microorganisms 2. Transge
nic Animals 3. Transgenic Plants B. Cloning
154
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• Biotechnology is a result of genetic engineering.
• Transgenic Microorganisms
• Used in disease research. They are easy to grow
  and reproduce rapidly.
• Transgenic Animals
• Used to improve the food supply by making animals
  stronger
• Transgenic Plants
• Genetically modified plants increase the food
  supply, and additionally are able to produce a
  naturally occurring herbicide.

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Cloning occurs in nature.

• bacteria (binary fission)
• some plants (from roots)
• some simple animals (budding, regeneration)

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Mammals can be cloned through a process called
nuclear transfer.

• nucleus is removed from an egg cell
• nucleus of a cell from the animal to be cloned is
  implanted in the egg

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Cloning has potential benefits.

• organs for transplant into humans
• save endangered species
• Cloning raises concerns.
• low success rate
• clones imperfect and less healthy than original
  animal
• decreased biodiversity

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Section 13-4
Figure 13-13 Cloning of the First Mammal
A donor cell is taken from a sheeps udder.
Donor Nucleus
These two cells are fused using an electric shock.
Fused Cell
Egg Cell
The nucleus of the egg cell is removed.
An egg cell is taken from an adult female sheep.
The fused cell begins dividing normally.
Embryo
Cloned Lamb
The embryo is placed in the uterus of a foster
mother.
The embryo develops normally into a lambDolly
Foster Mother
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Genetic engineering produces organisms with new
traits.

• A transgenic organism has one or more genes from
  another organism inserted into its genome.

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• Transgenic bacteria can be used to produce human
  proteins.

• gene inserted into plasmid
• plasmid inserted into bacteria
• bacteria express the gene
• Transgenic plants are common in agriculture.
• transgenic bacteriainfect a plant
• plant expressesforeign gene
• many crops are nowgenetically modified(GM)

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• Transgenic animals are used to study diseases and
  gene functions.

• transgenic mice used to study development and
  disease
• gene knockout mice used to study gene function

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Section 14-3

• Human Molecular Genetics
• A. Human DNA Analysis
• Testing for Alleles
• 2. DNA Fingerprinting
• B. The Human Genome Project
• 1. Rapid Sequencing
• 2. Searching for Genes
• 3. A Breakthrough for Everyone
• C. Gene Therapy
• D. Ethical Issues in Human Genetics

14-3
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• Testing for Alleles
• Alleles responsible for genetic disorders have a
  different DNA sequences than the normal
  counterpart.
• Genetic testing Genetic tests have been
  developed to spot the defective sequence. Other
  tests detect changes in restriction enzyme
  cutting sites or differences in lengths of normal
  and abnormal alleles.
• Prenatal Testing
• Amniocentesis sample of fluid
• surrounding the fetus is taken with a long, thin
  needle
• Cells from the fluid can be grown in culture and
• karyotype prepared

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• Human Genome Project
• Started in 1990.
• Objective To sequence all human DNA.
• Finished in June 2000.
• First markers were found that allowed the DNA to
  be broken down to smaller segments.
• Second Private companies used a shot gun
  approach to sequence random segments.
• Third computers were used to find overlapping
  regions between the fragments to place them in
  order.

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• Gene sequencing is determining the order of DNA
  nucleotides in genes or in genomes.

• The genomes of several different organisms have
  been sequenced.

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Technology allows the study and comparison of
both genes and proteins.

• Bioinformatics is the use of computer databases
  to organize and analyze biological data.
• DNA microarrays are used to study the expression
  of many genes at once.

• Proteomics is the study and comparison of
  proteins.

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• DNA Fingerprints
• Restriction Fragment Length Polymorphism (RFLP) -
  used to identify base sequences in our DNA
• Restriction enzymes are used to cut DNA into
  fragments that have SPECIFIC lengths.
• DNA of different people contain different
  nucleotides sequences restriction enzymes cut
  the DNA from different people into pieces of
  DIFFERENT lengths.
• Separate the pieces by gel electrophoresis -
  DNA has
• negative charge smaller pieces move faster than
  larger pieces
• This produces a series of bands DNA
  fingerprint!!
• May use blood, hair, semen, bone - any cell with
  DNA.

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A DNA fingerprint is a type of restriction map.

• DNA fingerprints are based on parts of an
  individuals 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

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• Individual probabilities are multiplied to find
  the overall probability of two DNA fingerprints
  randomly matching.

• Several regions of DNA are used to make DNA
  fingerprints.

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• DNA fingerprinting is used in several ways.

• evidence in criminal cases
• paternity tests
• immigration requests
• studying biodiversity

• tracking genetically modified crops

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• Gene Therapy
• An absent or faulty gene is replaced by a normal
  working gene.
• Vector Benign virus is modified with the working
  gene then introduced into the body to start
  replicating the gene.
• Mixed results to date, it is still a high risk,
  experimental procedure.
• Ethical Issues
• Disease cure is generally accepted.
• Bioengineering to produce ideal human is not
  and becomes a societal discussion and decision
  question.

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Genetic screening can detect genetic disorders.

• Genetic screening involves the testing of DNA.
• determines risk of havingor passing on a
  geneticdisorder
• used to detect specificgenes or proteins
• can detect some genesrelated to an
  increasedrisk of cancer
• can detect some genesknown to cause
  geneticdisorders

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• Several experimental techniques are used for gene
  therapy.

• genetically engineered viruses used to infect a
  patients cells
• insert gene to stimulate immune system to attack
  cancer cells
• insert suicide genes into cancer cells that
  activate a drug

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• Scientists have concerns about some uses of
  genetic engineering.

• possible long-term health effects of eating GM
  foods
• possible effects of GM plants on ecosystems and
  biodiversity