Transcript 13-1 Changing the Living World

Biology
Biology
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13 Changing the Living World
EQ: How can genetics be used to
change organisms?
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13-1 Changing the Living World
Selective Breeding
Selective Breeding
Selective breeding allows only those organisms
with desired characteristics to produce the next
generation.
Nearly all domestic animals and most crop plants
have been produced by selective breeding.
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13-1 Changing the Living World
Selective Breeding
Humans use selective breeding to pass
desired traits on to the next generation
of organisms.
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Selective Breeding
Hybridization
Hybridization is the crossing of dissimilar
individuals to bring together the best of both
organisms.
Hybrids, the individuals produced by such
crosses, are often hardier than either of the
parents.
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Selective Breeding
Inbreeding
Inbreeding is the continued breeding of
individuals with similar characteristics.
Inbreeding helps to ensure that the characteristics
that make each breed unique will be preserved.
Serious genetic problems can result from
excessive inbreeding.
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13-1 Changing the Living World
Increasing Variation
Breeders increase the genetic variation
in a population by inducing mutations.
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Increasing Variation
Mutations occur spontaneously, but breeders can
increase the mutation rate by using radiation and
chemicals.
Breeders can often produce a few mutants with
desirable characteristics that are not found in the
original population.
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Increasing Variation
Producing New Kinds of Bacteria
Introducing mutations has allowed scientists to
develop hundreds of useful bacterial strains,
including bacteria that can clean up oil spills.
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Increasing Variation
Producing New Kinds of Plants
Mutations in some plant cells produce cells that
have double or triple the normal number of
chromosomes.
This condition, known as polyploidy, produces new
species of plants that are often larger and stronger
than their diploid relatives.
Polyploidy in animals is usually fatal.
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13-1 Changing the Living World
The Tools of Molecular Biology
The Tools of Molecular Biology
How do scientists make changes to DNA?
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13-1 Changing the Living World
The Tools of Molecular Biology
Scientists use different techniques to:
extract DNA from cells
cut DNA into smaller pieces
identify the sequence of bases in a DNA molecule
make unlimited copies of DNA
In genetic engineering, biologists make changes
in the DNA code of a living organism.
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The Tools of Molecular Biology
DNA Extraction
DNA can be extracted from most cells by a simple
chemical procedure. The cells are opened and the
DNA is separated from the other cell parts.
Cutting DNA
Most DNA molecules are too large to be analyzed,
so biologists cut them into smaller fragments using
restriction enzymes. Each restriction enzyme
cuts DNA at a specific sequence of nucleotides. Slide
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13-1 Changing the Living World
Separating DNA
In gel electrophoresis, DNA fragments are placed
at one end of a porous gel, and an electric voltage
is applied to the gel.
Making Copies
Polymerase chain reaction (PCR) is a technique
that allows biologists to make copies of genes.
Small amounts of DNA can be multiplied making it
easier to analyze
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13-1 Changing the Living World
Transgenic Organisms
Transgenic Organisms
An organism described as transgenic, contains
genes from other species.
Genetic engineering has spurred the growth of
biotechnology.
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Transgenic Organisms
Transgenic Microorganisms
Transgenic bacteria produce important substances
useful for health and industry. Transgenic bacteria
have been used to produce:
• insulin
• growth hormone
• clotting factor
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13-1 Changing the Living World
Cloning
Dolly and Bonnie
Cloning
A clone is a member of
a population of
genetically identical
cells produced from a
single cell.
In 1997, Ian Wilmut
cloned a sheep called
Dolly.
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13-1 Changing the Living World Cloning
Cloning Dolly
Donor Nucleus
Fused cell
Egg Cell
Embryo
Cloned
Lamb
Foster Mother
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Cloning
Cloning Dolly
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Cloning
Cloning Dolly
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13-1 Changing the Living World
Cloning
Cloning Dolly
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13-1 Changing the Living World
Cloning
Researchers hope cloning will enable them
to make copies of transgenic animals and
help save endangered species.
Studies suggest that cloned animals may
suffer from a number of genetic defects
and health problems.
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