Genetics is a very young branch of biology' It started with Mendel's experiments'

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?????????????????? History of Genetics Timeline

• Genetics is a very young branch of biology. It
  started with Mendel's experiments.

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• In genetics special attention is focused on the
  cell nucleus.  The cell nucleus is the control
  center of the cell.  It contains the cell's
  genetic information and controls the cell's
  actions. Many experiments have been done
  affecting the cell nucleus.

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• Importance of Cell Nucleus
• More complex cells called eukaryotes made
  their earthly debut.  Everything alive on Earth,
  except prokaryotes, is made up of one or more
  eukaryotic cells - plants, animals and even you.

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1858 Charles Darwin Alfred Russel Wallace
???????????????????????? (theory of natural
selection)
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• 1859 Charles Darwin ??????? The Origin of
  Species.
• 1866 Gregor Mendel ??????????????????????????????
  ????????? pea plants "factors"
• 1900 Carl Correns Hugo de Vries Erich von
  Tschermak ????????????????????????? modern
  genetics

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• Traits are carried by discrete units, or
  genes the results are not appreciated until 1900 

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• 1902 Walter Sutton ????????????
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• 1905 Nettie Stevens Edmund Wilson Independently
  described the behavior of sex chromosomes-XX
  determines female XY determines male.

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• 1908 Archibald Garrod Proposed that some human
  diseases are due to "inborn errors of metabolism"
  that result from the lack of a specific enzyme.
• 1909 - William Louis Johannsen.
• The introduction of basic genetic theories
  gene, genotype, phenotype.

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• 1910 Thomas Hunt Morgan Proposed a theory of
  sex-linked inheritance for the first mutation
  discovered in the fruit fly, Drosophila, white
  eye. This was followed by the gene theory,
  including the principle of linkage.

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• 1927 Hermann J. Muller Used x-rays to cause
  artificial gene mutations in Drosophila.
• 1928 Fred Griffith Proposed that some unknown
  "principle" had transformed the harmless R strain
  of Diplococcus to the virulent S strain.

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• 1931 Harriet B. Creighton Barbara McClintock
  Demonstrated the cytological proof for
  crossing-over in maize.
• late 1940 Barbara McClintock Developed the
  hypothesis of transposable elements to explain
  color variations in corn.

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• 1980 McClintock discovered transposable strands
  of genes in maize already in the 1940s, but her
  work was not fully recognized for a generation.
  ?The genome may be controlling aspects of its own
  mutation

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• In her 1983 Nobel lecture, McClintock said the
  genome is "a highly sensitive organ of the cell,
  that in times of stress could initiate its own
  restructuring and renovation."

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• 1941 George Beadle Edward Tatum Irradiated the
  red bread mold, Neurospora, and proved that the
  gene produces its effect by regulating particular
  enzymes.
• 1944 Oswald Avery Colin MacLeod Maclyn McCarty
  Reported that they had purified the transforming
  principle in Griffith's experiment and that it
  was DNA.

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• 1950 Erwin Chargaff Discovered a one-to-one
  ratio of adenine to thymine and guanine to
  cytosine in DNA samples from a variety of
  organisms.
• 1951 Rosalind Franklin Obtained sharp X-ray
  diffraction photographs of DNA.

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• 1953 Francis Crick James Watson Solved the
  three-dimensional structure of the DNA molecule.
• 1958 Arthur Kornberg Purified DNA polymerase I
  from E. coli, the first enzyme that made DNA in a
  test tube.

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• 1953 Watson and Crick deoxyribonucleic acid
  (DNA) is a double-strand helix of nucleotides.
  Each nucleotide consists of a deoxyribose sugar
  molecule to which is attached a phosphate group
  and one of four nitrogenous bases two purines
  (adenine and guanine) and two pyrimidines
  (cytosine and thymine). The nucleotides are
  joined together by covalent bonds between the
  phosphate of one nucleotide and the sugar of the
  next, forming a phosphate-sugar backbone from
  which the nitrogenous bases protrude. The two
  strands are linked by selective hydrogen bonds
  the purine adenine bonds only with the pyrimidine
  thymine, and the purine cytosine only with the
  pyrimidine guanine.

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• 1966 Marshall Nirenberg H. Gobind Khorana Led
  teams that cracked the genetic code- that triplet
  mRNA codons specify each of the twenty amino
  acids.

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• DNA replication is possible through the
  complementary nature of the two strands. The
  chemical complexity of the molecule is thought to
  be sufficient to store the requisite information.
  What is firmly demonstrated is that so-called
  structural genes manufacture the proteins for
  living tissues.

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• 1983 James Gusella Used blood samples collected
  by Nancy Wexler and her co-workers to demonstrate
  that the Huntington's disease gene is on
  chromosome 4.

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• 1985 Kary B. Mullis Published a paper describing
  the polymerase chain reaction (PCR), the most
  sensitive assay for DNA yet devised.
• 1988  The Human Genome Project began with the
  goal of determining the entire sequence of DNA
  composing human chromosomes.

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• 1989 Alec Jeffreys Coined the term DNA
  fingerprinting and was the first to use DNA
  polymorphisms in paternity, immigration, and
  murder cases.
• 1989 Francis Collins Lap-Chee Tsui Identified
  (CFTR) gene on chromosome 7 that, when mutant,
  causes cystic fibrosis.

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• 1990  First gene replacement therapy-T cells of
  a four-year old girl were exposed outside of her
  body to retroviruses containing an RNA copy of a
  normal ADA gene. gtimmune system functioning.
• 1993  Flavr Savr tomatoes, genetically
  engineered for longer shelf life, were marketed.

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• 2000 The Human Genome Project presents its
  preliminary results each of the body's 100
  trillion cells contains some 3.1 billion
  nucleotide units. Only 1 of these are thought to
  be transcriptional, clustered in possibly as few
  as 30,000 genes.
• An accurate chemical map of the genome tells us
  surprisingly little about how it functions.
  Targeted experimentation is now possible.

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• Gregor Johan Mendel is considered as the creator
  of genetics. He discovered the basic laws of
  heredity. He hypothesized the existence of
  factors that determinate the inheritance of
  traits.

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• Gregor Mendel (1822-84) was an Austrian monk. His
  experiments are the basis for inheritance.  In
  his experiments he used garden pea plants (Piscum
  Sativum).

1. Why Pea Plants?
2. Steps of Mendel's Experiment 3. Mendel's
Observations
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Why pea plant?

• Self-pollination?????????????????????
• Short-life harvest?????????????????????
• Dominant characteristics????????????????????
  ??????????

???????????????????? ?????????????????????
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Steps of Mendel's Experiment

• ????????????? 34 ???????????? 2 ?? ?22 ??????
• ??????????????????????????? (pure breeding)
• ?????????? (cross pollination) ???????????????????
  ????? (monohybrid cr.)
• ???????????????? (dihybrid cr.)
• 7 ?????? ????????????? ??? ???-?????, ?????
  ????-???, ??????????-???????, ??????????-???,
  ?????????????-?????, ??????-???,
  ??????????-??????

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7 pea characteristics
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Mendel's ObservationsMonohybrid cross
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Monohybrid explanation
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Mendels hypothesisprobability
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Dihybrid hypothesis
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• Mendel's Conclusions are Known as Mendel's Laws
• 1    Mendel's first law of genetics -  the law
  of segregation
• 2    Mendel's second law of genetics - the law
  of independent assortment

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Mendels first law

• ????????????????? (law of segregation)
• ???????????????????????????????????????????
  ????????????? (2 alleles) ????????????????????????
  ???????????????????

??????????????????????????? 1 ?????? (monohybrid
cross)
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Mendels second law

• ??????????????????????????? (law of independent
  assortment)

?????????????????????????????????????????????????
(2 alleles) ??????????? ??????????????????????????
??????????????????????????
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Test cross (?????????????????)
????????????????????????? (phenotype)
?????????????????????? ????????? (homozygous
genotype) ???? ?????? (heterozygote genotype)
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Test cross (?????????????????) ???????

• Pgt Known Homozygote Unknown genotype
• recessive
• ???????????????(F1) ?????????????????????????????
  

All dominant ?homozygote
F1gt
(?????????)
Dominant Recessive11 ?heterozygote (??????)
F1gt
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Test cross (?????????????????)
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• 1. ???????????????????????????????
  ???????????????????????? ?????????? dependent
  assortment ?????????????????????????????????
• 2. Flavr Savr tomatoes, genetically engineered
  for longer shelf life, were marketed.
  ??????????????????????????? ??????????????????????
  ?????????????
• ??????????????????