Genetics

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Genetics
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BACKGROUND

• Genetics is the branch of biology that deals with
  heredity and the expression of inherited traits.
• Charles Darwin did not know anything about how
  traits (like flower color) where passed-on from
  parent to offspring.
• But that did not stop Darwin from studying change
  through time of species. (evolution)

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Background cont.

• Ironically, Mendel was working on the very
  mechanism that would have greatly supported
  Darwin's theories.
• But what neither one knew about - nor anyone
  until the early 20th century (1900's) was the
  mechanism of inheritance.
• While we don't know when people first recognized
  the existence of heredity, there is evidence that
  suggests the successful domestication of animals
  and cultivation of plants thousands of years ago.
• 8000-1000 B.C. horses, camels, oxen, dogs.
• 5000 B.C. maize (corn) wheat, rice, date palm.

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Background cont.

• Preformation a theory first put forward in the
  17th century (1600's). Stating that sex cells
  contain a complete miniature adult called a
  homunculus
• This theory was popular well into the 18th
  century (1700's).Later scientific discoveries by
  Casper Wolff (1733-1794) and others clearly
  disproved this ideal.
• During same time atomic theory and cell theory
  were being developed.

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Homunculus
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Take notes
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CONCEPTS

• What's the center of heredity in a cell?
• In eukaryotic organisms it is the nucleus, in
  prokaryotes it is the nucleoid region.
• What is the genetic material?
• In eukaryotes prokaryotes it is DNA, in viruses
  it can be either DNA or RNA.
• What do DNA RNA stand for?
• DNA deoxyribonucleic acid / RNA ribonucleic
  acid.
• How is DNA organized to serve as the genetic
  material?
• DNA, although single-stranded in a few viruses,
  is usually a double-stranded molecule organized
  as a double helix.

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General Animal Cell
Location of genetic material DNA
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General Bacteria Cell (prokaryote)
In bacteria, since they dont have a nucleus, the
DNA is found in an area called the nucleoid region
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Concepts cont.

• Contained within each DNA molecule are hereditary
  units called genes, which are part of larger
  elements, the chromosomes.
• What is a gene? The functional unit of heredity.
• A segment of the DNA molecule that codes for a
  characteristic/trait.
• There are many genes in a chromosome.

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CENTRAL DOGMA OF GENETICS

• Expression of the stored genetic information is a
  complex process.
• DNA ? transcription ? mRNA ? ribosomes ?
  translation ? PROTEIN
• Proteins were 1st thought to be the genetic
  material for hereditary traits.
• Later research pointed to nucleic acids (DNA)
  Frederick Griffith Medical officer in the
  British Ministry of Health.

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MOLECULAR STRUCTURE

• DNA is a chemical strand made-up of repeating
  nucleotides.
• Nucleotides are the building blocks of nucleic
  acids - DNA/RNA.
• These units are made-up of 3 parts a nitrogenous
  base, a pentose sugar (5-carbon sugar), and a
  phosphate group.
• There are 2 kinds of nitrogenous bases purines
  pyrimidines
• In nucleic acids, the purines are ADENINE
  GUANINE, the pyrimidines are CYTOSINE, THYMINE,
  URACIL

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Only visible during cell division
Chromosome (coiled chromatin) Chromatin
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MOLECULAR STRUCTURE cont.

• These chemicals are arranged into double-stranded
  helixes.
• This helix is referred to as chromatin during
  interphase of the cell cyce as chromosomes
  during mitosis and meiosis.
• In the double helix, complemetary strands
  match-up in a specific way.
• Think of it as a latter that got sawed down the
  middle.
• When you put it together again, each step
  connects to a step on the other side.
• In DNA, it is as follows A - T and G - C / in
  RNA T is replaced by U.

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Genetic material for all life on planet Earth
(Nucleic acid DNA double helix)
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Questions?