Genetics

1
Genetics Taxonomics

• OR
• How I Learned To Stop Worrying And Love Genetic
  Engineering

2
History

• Genetics is the study of how hereditary
  information is organized, expressed, and
  inherited
• Procreation has been going on for two billion
  years

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Gregor mendel

• First explained the foundation principles of
  genetics in 1865, based on his experiments with
  pea plants
• Not grasping the importance of the conclusions,
  No-one proceeded until 1900 when Mendels
  principals were rediscovered by three independent
  botanists

4
William Bateson

• Coined the term genetics to describe the study of
  inherited characteristics

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Ancient History

• Humans recognized long ago that all forms of life
  have offspring after their own kind (resembling
  their parents)
• Plant and animal breeding are among the earliest
  applications of scientific principals
• It made agriculture possible, which made
  civilization possible.

6

• Let us never forget that the cultivation of the
  earth is the most important labor of man. When
  tillage begins, other arts follow. The farmers,
  therefore, are the founders of civilization.
• Daniel
  Webster

7
Modern history

• In the early 20th century, scientists began
  applying experimental genetics to improve
  domesticated plants and animals
• Although agricultural methods contributed
  greatly, the largest scale contributor to the
  Green Revolution was genetic improvement.
• Crop yield increased sometimes fourfold in a mere
  20 years

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DNA

• Deoxyribonucleic Acid (DNA) is the primary
  carrier of genetic information
• It is a polymer made up of dideoxy neucleotide
  subunits
• The structure is very similar in all living
  things
• DNA was described about the same time that Mendel
  was conducting his experiments, but was not
  positively identified for its purpose until the
  1950s

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DNA representations
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DNA molecule

• DNA (and RNA) are nucleic acids
• Nucleic because they make up most of a cells
  nucleus
• Acid because it is acidic when dissolved in water

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DNA molecule

• Compared to most other molecules, it is of
  enormous size
• With 46 separate DNA molecules in each cell, the
  length is 5 cm if stretched out straight. If all
  46 were lined up they would measure over 2 meters
  (Fairbanks,Anderson 26)

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DNA nucleotides

• A DNA molecule is made up of four kinds of
  subunits called Nucleotides
• Each nucleotide consists of a five carbon sugar
  (deoxyribose), with a nitrogenous base attached
  to one end and a phosphate group at the other.

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DNA
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DNA

• The four Nitrogenous bases are
• Thymine (t)
• Cytosine (c)
• Adenine (a)
• Guanine (g)
• Each nucleotide is refered to by its base name

15
DNA Bases

• Cytosine and Thymine are called pyrimidines.
• Similar to each other, they have one six member
  ring in the nitrogenous base

16
DNA Bases

• Adenine and guanine are called the purines
• Also similar in structure, each is composed of
  two rings, a six member ring attached to a five
  member ring

17
Pairing

• In DNA, the structure is a double helix.
• Each link of the helix has a base pair
  combination
• Each combination can either be A-T,C-G,T-A or G-C
• Cytosine only pairs with guanine and thymine only
  pairs with adenine

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Amount of Data

• A single human Diploid cell contains 6 billion
  base pairs
• If a base pair has 4 possibilities it is 2 bits
  in hard drive space, and a byte is 8 bits, the
  hard drive space necessary to define Dr. Tey is
• 3 Gigabytes
• 11k for Morgan

19
Strand Separation

• As the strands separate, they must be allowed to
  unwind, or excess tension will build up and
  possibly form super coils
• Enzymes called helicases unwind the DNA as the
  replication fork proceeds along the molecule
• Enzymes called topoisomerases relieve the
  positive tension of unwinding

20
separation

• The two separated strands must be chemically kept
  apart
• Single-strand binding proteins (SSBs) do this

21
Synthesizing DNA

• DNA polymerases make new DNA strands using a
  single strand of DNA as a template
• DNA polymerase adds nucleotides only from the 5
  side towards the 3 end
• DNA polymerase does not initiate synthesis,
  therefore an RNA primer is required for
  initiation initiated by primase

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Replication driving force

• The free nucleotides that are incorporated into
  DNA strands are in the tri-phosphate form.
• As each nucleotide is added to the growing
  strand, phosphate groups are cleaved, releasing
  energy
• This energy is what drives DNA synthesis

23
Gene

• The word Gene was coined in 1909 by Wilhelm
  johannsen to describe the fundamental unit of
  inheritance
• It is a section of DNA that encodes an RNA
  molecule

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Central Dogma

• The central dogma of molecular genetics is that
  the information in a gene is transcribed into
  RNA, and the information in RNA is then
  translated into Protein

25
Polyploidy

• Diploidy - Pertaining to homologous chromosomes,
  where each chromosome number has a pair of
  chromosomes, such as the 23 pairs in humans
  totalling our 46 chromosome compliment.
• Cells (and their owners) are polyploid if they
  contain more than two haploid (n) sets of
  chromosomes that is, their chromosome number is
  some multiple of n greater than the 2n content of
  diploid cells. For example, triploid (3n) and
  tetraploid cell (4n) cells are polyploid.

26
Polyploidy

• The chromosome content of most plants groups
  suggests that the basic angiosperm genome
  consists of the genes on 7-11 chromosomes.
  Domestic wheat, with its 42 chromosomes, is
  probably hexaploid (6n, where n (the ancestral
  haploid number) was 7.

27
Manipulating genes

• Genetic Engineering is the making of something
  out of genes
• Gene mapping lets engineers know which genes can
  be snipped out (spliced) into plant genes.
• These plants can express the properties of those
  genes

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Legal Issues

• Market forces get genetic engineering companies
  to go too fast for safety
• Superior plant qualities may cause another green
  revolution, overproduction, market
  destabilization.
• Competition forcing poor farmers out of the
  business
• GE food may cause health problems

29
Taxonomics

• The science of biological classification that
  embodies the study of organic diversity and
  provides the tools to study the historical
  aspects of evolution
• As currently practiced, Taxonomy has its
  beginning in the work of Sweedish botanist and
  naturalist Carolus Linaeus (Carl Von Linne) and
  his contemporaries in the mid-eighteenth century

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Essential activities of systematics has changed
little over the last 250 years

• The recognition of basic units in nature, which
  are usually called species
• Due to improvement in understanding of the
  mechanism of inheritance, taxonomy has improved
• But with more than 2 million species of plants
  and animals, they are often recognized on the
  basis of morphological and other observable
  characteristics.

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• The classification of these species in a
  hierarchic scheme
• Early taxonomists like Linaeus were less
  motivated to investigate the forces that produced
  organic diversity than they were to describe the
  product themselves
• With the Darwinists, evolutionary process, rather
  than divine creation explained observable
  relationships.

32

• It still took 100 years for the development of
  methods for deducing relationships.

33

• The placement of information about species and
  their classification into a wider context.