Download Chap 8-11, pt 2 Mendel through Biotechnology

Past, Present and Future of this
constantly changing field
 Definition:
The use of biology to make useful
things and solve problems.
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Biotechnology mixes biological information with
computer technology to advance research in
other areas.
Mainly used in medical, ecological and
agricultural fields.
 Organisms
acquire their form and function &
behavior through heredity from ancestors.
Heredity establishes continuation of life
forms.
 “Apple doesn’t fall far from the tree.”
Offspring show traits of both parents and
even some of the “grandparent” generation
are visible.
 Genes are what get actually passed on from
the parents. Half from each parent.
All living forms use DNA
and RNA as method of
transmission for traits.
Genes are located on
chromosomes, which are
tight coils of DNA.
The use of DNA/RNA is one
of the most important
unifying concepts in
biology.
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Aristotle proposed the theory of pangenesis which held
that particles (called pangenesis) from all parts of the
body come together to form the eggs and sperm.
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In the seventeenth century, Anton van Leeuwenhoek
"observed " the homunculus, a miniature human being, in
human sperm cells. He and his followers (spermists)
believed that:
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Changes that occurred in the various body parts during an
organism's life could be passed on to the next generation.
Pangenesis was accepted by many (Lamarck and Darwin) and
was the prevailing theory into the nineteenth century.
The mother serves only as an incubator for the homunculus.
All characteristics are inherited from the father.
Also during the seventeenth century, Regnier deGraaf and
his followers (ovists) proposed that:
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The egg contains an entire human in miniature and that semen
only stimulates its growth.
All characteristics are thus inherited from the mother. deGraaf
was the first person to describe the ovarian follicle in which
human egg cells are produced.
 1822-1884
, mathematician Augustinian Monk
from what is now the Czech republic
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Mendel worked with his plants until he obtained
true-breeding plants.
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Parental plants of such a cross are called the P
generation.
The hybrid offspring of the P generation are the F1
generation (first filial).
Mendel also allowed F1 generation plants to selfpollinate to produce the next generation, the F2
generation.
Observed seven easily identifiable traits that he
tracked and used to develop his theory of heredity.
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Based upon their observations with ornamental
plant breeding, scientists in the nineteenth century
realized that both parents contribute to the
characteristics of offspring. The "blending" theory
then became the favored explanation of
inheritance. According to this theory:
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Hereditary materials from male and female parents mix
to form the offspring, and once blended, the hereditary
material is inseparable.
This theory was inconsistent with the observations
that:
Populations do not reach a uniform appearance.
 Some traits are absent in one generation and present in
the next.
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Modern genetics began in the 1860's with the
experiments of an Augustinian monk named Gregor
Mendel who discovered the fundamental principles
of inheritance.
Father of Modern Genetics

The Law of Segregation:
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There are alternative forms of a gene called
alleles
For each inherited characteristic, an organism
has two alleles, one inherited from each parent.
A sperm or egg carries only one allele for each
inherited characteristic, because allele pairs
separate (segregate) from each other during the
production of gametes.
When the two alleles of a pair are different, one
is fully expressed and the other is completely
masked. These are called the dominant allele
and recessive allele, respectively
 The
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Law of Independent Assortment:
when forming gametes, paired factors that
specify alternative phenotypes segregate
independently of one another.
This means that during the formation of
offspring, you have a game of chance.
Structural and numerical deviations that affect
many genes at once are aberrations also called
mutations. (An actual mutation is a change in
the gene that results in alteration of bases
within the DNA sequence)
 Once mutated, a gene will faithfully reproduce
itself as is.
 Helpful or Not Helpful
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Good- bring new possibilities for natural selection to
work
 Bad- may produce a lethal combination
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Changes in number are also called euploidywhen there’s addition or deletion of whole sets
of chromosomes
 Aneuploidy
is when a single chromosome is
added or subtracted from a diploid set.
 Polyploidy is most common
 Nondisjunction occurs during meiosis when a
pair of chromosomes fail to separate and
result in a monosomic animal. Survival is rare
because of the uneven balance of directions.
After teaching for 13 years at Bryn Mawr
College, he moved on to Columbia University
where he established the famous "fly room."
 Morgan chose to work with the fruit fly,
Drosophila melanogaster. This fly requires little
space, breeds quickly, has many observable
characteristics, and has only four chromosomes,
making it an ideal model organism for genetics
studies
 By examining thousands and thousands of flies
with a microscope and a magnifying glass,
Morgan and his colleagues confirmed the
chromosomal theory of inheritance: that genes
are located on chromosomes like beads on a
string, and that some genes are linked
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By examining
thousands and
thousands of flies
with a microscope
and a magnifying
glass, Morgan and his
colleagues confirmed
the chromosomal
theory of inheritance:
that genes are
located on
chromosomes like
beads on a string, and
that some genes are
linked
White eyed male
 Morgan
then went
to California to
establish the Biology
program at Caltechthis is where we
found Linus Pauling
among other
prominent American
geneticists.
 Est. Marine Lab
1953 to present
 1953-
James Watson & Francis Crick, along
with Maurice Wilkins and Rosalind Franklin
discover the structure of DNA. Watson and
Crick publish their findings
 1957- Francis Crick and George Gamov
explained how DNA functions to make
proteins
 1966- Marshall Nirenburg and Severo Ochoa
figured out the 20 codons that code for out
amino acids
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Restriction enzymes- bacterial proteins that are
biological scissors. Look for specific sequences
and cut there-
 1969-
Harvard Medical School team isolated
the first gene
 1971- Smith and Wilcox discovered the HindII
restriction enzyme
 Gel electrophoresis is the process that sorts
DNA fragments by using electrical currents to
leave us with a DNA fingerprint.
 1972- Paul Berg cut sections of viral and
bacterial DNA with the same restriction
enzyme, spliced viral DNA to the bacterial
DNA
 1973- Cohen and Boyer produced first
recombinant DNA organism- this was the
beginning of GENETIC ENGINEERING
 Genetic
Engineering: Altering someone's DNA
by cutting a piece out and inserting another
piece.
 http://www.cshl.edu/about/index.html
 -also in 1973 a team at Cold Spring Harbor
Lab refined DNA electrophoresis by using a
stain and gel. Same as we use today
 Vector- DNA that can replicate within a cell
and can carry foreign DNA (usually bacteria
or yeast)
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i.e. E. coli bacteria
 1974-
Scientists called for a worldwide
moratorium on certain classes of
experiments, the next year the recombinant
DNA techniques were places on moratorium
 1977- First practical application of genetic
engineering- human growth hormone
produced by bacterial cells
 1978-
Genetech, Inc. produced human insulin
in E. coli
 1979- Genetech, Inc. produced human GH &
2 kinds of interferon DNA from malignant
cells transformed a strain of cultured mouse
cells- new tool for analyzing cancer genes
ALSO the Federal regulations are relaxed
 1983- Genetech, Inc. :Kary Mullis, Biochemist
conceives of the so called PCR that will
enable scientists to rapidly reproduce tiny
snipits of DNA
 PCR
(polymerase chain reaction) works like a
xerox machine
 We use this to produce many copies of a
fragment of DNA
 Very common now, uses test tubes not cells
 Gene cloning occurs in cells, we could make
billions of copies of DNA in just a few hours…
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What potential do you see for this?
 Start
with your template and add polymerase
(enzyme)
 Heat to break up the DNA strand (like a
zipper)
 Free floating nucleotides and primer must
also be there
 Primer-
artificial piece of DNA that acts as a
stop and start point (20 or so pieces long)
that binds to the DNA and “marks” where the
template polymerase will start and stop
copying.
 1984-
Alec Jeffreys developed “genetic
fingerprinting” which uses unique sequences
of DNA to identify individuals
 1985- Supreme Court rules that plants can be
patented- why was this important?
 1985- First use of fingerprinting in criminal
investigation
 1986- First field trials of DNA recombinant
plants that are resistant to bugs and
viruses/bacteria
 Also, FDA approves the first genetically
engineered vaccine for humans, for Hep B
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James Watson helped launch the Human Genome
Project (it was completed in 2003, 3 years ahead
of schedule) This was mainly due to the
technology explosion that occurred in the 90s.
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Our genome only has 30,000 to 40,000 protein coding
genes
We also discovered that there was a lot more junk
than originally thought.
50% of our DNA is JUNK and 98% doesn’t code for
proteins
There are very random patterns between the genes
Controversy: Originally was how much to map? Who
gets the information? Insurance, doctors, etc. Who
will pay for the information?
 1990-
First successful gene therapy
performed on two girls with severe
immunodeficiency (bubble boy syndrome)
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Mary-Claire King finds evidence that a gene on
chromosome 17 causes the inherited form of
breast cancer and increases the risk of ovarian
cancer
 1992-
U.S. Army begins collecting blood and
tissue samples from all new recruits as a part
of a “genetic dog tag” program aimed at
better identification of soldiers killed in
action
 1993- Flavr Savr tomatoes sold to public
George Washington University: Researchers clone
human embryos and nurture them for several
days. This provokes protests from ethicists,
politicians and critics of genetic engineering.
 1994- Bovine GH is introduced to dairy cattle
 1995- O.J. Simpson found not guilty in high
profile murder case in which PCR and DNA
fingerprinting play a prominent but unpersuasive
role. It did bring the technology into the
spotlight.
 1997- Ian Wilmut leads a team that successfully
clones a sheep, Dolly- who lived to reproduce.
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 1998-
University of Hawaii scientists use
variations of Wilmut’s technique to clone 3
generations of clones
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DNA analysis of semen stains of Monica’s dress
match Bill’s blood sample, oops.
DNA testing proves that Thomas Jefferson
fathered at least one child with his slaves (Sally
Hemings) The book, Wolf by the Ears, tells the
story from that childs perspective.
Two research teams succeed in growing
embryonic stem cells.
2000- the rough draft of the human genome is
complete, while the complete genome for a pig
is finished
 Also- “Golden Rice," modified to make vitamin A,
promises to help third-world countries alleviate
blindness
 2002- Biotech crops grown on 145 million acres
in 16 countries. 27% of the global acreage was
grown in nine developing countries.
 Also, Researchers announce successful results for
a vaccine against cervical cancer
 2003- Dolly is put down after developing a
progressive lung disease
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2004- California voters pass Prop 71, which
supported embryonic stem cell research with $3
billion in funding over 10 years.
 2005- The British research firm PG Economics
Ltd. finds that the global use of biotech crops
has added $27 billion to farm income, and
greatly reduced agriculture's negative impacts on
the environment.
 2006- The National Institutes of Health begins a
10-year, 10,000-patient study using a genetic
test that predicts breast-cancer recurrence and
patients whose cancer is deemed unlikely to
recur will be spared chemotherapy. The genetic
test, Oncotype DXTM was developed by the
biotech company Genomic Health and is already
commercially available.
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 What
does all this
mean to YOU?