Genetic basis for evolution Part I

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Genetic basis for evolution Part I

• DNA model

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Describe the history of the early discoveries of
DNA.

• A) Friedrich Meischer in 1869 isolated DNA from
  fish sperm and the pus of open wounds.
• Since it came from nuclei, Meischer named this
  new chemical, nuclein. Subsequently the name was
  changed to nucleic acid.

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1. Early History cont

• Now called deoxyribonucleic acid.
• b) Robert Feulgen, in 1914, discovered that
  fuchsin dye stained DNA.
• DNA was then found in the nucleus of all
  eukaryotic cells.

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1. Early history cont

• c) P.A. Levene 1920 analyzed the components of
  the DNA molecule. He found it contained four
  nitrogenous bases cytosine, thymine, guanine and
  adenine and a phosphate group.
• Basic unit (Nucleotide) was composed of a base
  attached to a sugar and that the phosphate also
  attached to the sugar.

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2. Describe the discovery of the DNA model.

• Watson and Crick gathered all available data in
  an attempt to develop a model of DNA structure.

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2. Discovery of DNA 3 D shape

• Used Rosaline Franklins x-ray diffraction
  photomicrographs of crystalline DNA extract, the
  key to the puzzle.
• Watson and Crick got all the credit (male
  scientists vs female).

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3. What is a nucleotide? What components are in
nucleotides what function?

• nucleotides  The subunits of nucleic acids ( DNA
  RNA) composed of a phosphate, a sugar, and a
  nitrogen-containing base. DNA made of
  nucleotides
• DNA Bases Adenine, guanine, cytosine and
  thymine.
• RNA Bases Adenine, guanine, cytosine and urasil
• Paired bases A.T and C.G always
• Some nucleotides are involved in information
  storage (as nucleotides in DNA), protein
  synthesis (as nucleotides in RNA), and energy
  transfers (as single nucleotide ATP)

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4. Draw a Nucleotide

• Basic unit
• P.A
• S

Link to additional nucleotides
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5. Draw a DNA molecule

• PA --- TP
• S S
• PG--- CP
• S S
• PC --- G..P
• S S
• P.T --- A. P
• S S

Key P phosphate S sugar (deoxyribose A
adenine base T thymine base G guanine base C
cytosine base
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5. Draw a DNA molecule cont
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6. What is a codon and why is it important?
Important in protein synthesis and replication of
DNA

• 1. DNA nucleotide bases arranged in triplets of
  3 bases, code for amino acids which are the base
  for proteins.
• Ex GGC TCA CCC GGG TTA ACC

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7. How does DNA function in evolution?

• DNA codes for proteins used in all cell
  functions.
• Proteins can be structural muscle
• Enzymes controlling all biochemical reactions
• Hormones control body functions

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7. Proteins evolution cont

• All variation in traits based on differences in
  protein structures or biochemical pathways
  controlled by enzymes
• Gene based traits selected for by environment.
• White coat vs brown (biochemical, enzyme)
• run faster (muscles biochemical)
• larger body size (structural proteins)
• adapted to high temperature (enzymes)
• more aggressive increase testosterone
  (hormones)

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8. Describe process of protein synthesis.

• Step 1 DNA contains message in codons
• Step 2 Transcription DNA code given to RNA
  messenger.
• Step 3 RNA copies DNA message and carries out
  of nucleus to Endoplasmic Reticulum
• Step 4 Translation -RNA joins up with transfer
  RNA which carries protein subunits called Amino
  Acids. Translates code from DNA. Occurs in
  ribosomes attached to endoplasmic reticulum.
• Step 5 Amino Acid subunits combined into
  proteins in cytoplasm.

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8. Protein synthesis continued
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8. Describe process of protein synthesis.

• DNAmRNA..tRNA.protein
• Transcription translation

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Photos refs

• http//www.estrellamountain.edu/faculty/farabee/bi
  obk/BioBookDNAMOLGEN.html