DNA

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DNA RNA

• Chapter 12

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Griffith Transformation

• Discovered transformation using bacteria that
  causes pneumonia
• Transformation
• Process in which part of the nucleotide sequence
  of DNA is copied into a complementary sequence in
  RNA

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Avery DNA

• Retested Griffiths experiment to determine what
  caused transformation
• Discovered that the nucleic acid in DNA stores
  and transmits the genetic information from one
  generation of an organism to the next

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Hershey-Chase Experiment

• Studied viruses
• Concluded that DNA was the genetic material of
  bacteriophages, not protein

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Components Structure of DNA

• DNA is made up of Nucleotides
• Each nucleotide is made up of 3 basic components
• 5 carbon sugar (deoxyribose)
• A phosphate group
• Nitrogenous base
• 4 nitrogen bases
• Adenine
• Guanine
• Cytosine
• thymine

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Chargaffs Rule

• The observation that A T G C
• Found that in 4 different types of organisms the
  amount of A T were nearly the same as well as
  the amount of G C were nearly the same.

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Double Helix

• Watson Crick built a 3-D model of DNA based on
  the evidence found by Franklin using X-ray.
• Found that DNA was a double helix, in which two
  strands were wound around each other resembling a
  spiral staircase
• Hydrogen bonds hold the two strands together but
  only formed between AT and GC
• This is called base pairing

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12-2 Chromosomes DNA Replication
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DNA Replication

• Each strand of the DNA double helix has all the
  information needed to reconstruct the other half
  by the mechanism of base pairing.
• Replications proceeds in both directions until
  each chromosome is completely copied

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Duplicating DNA

• Before a cell divides it duplicates DNA
• During duplication, the DNA molecule separates
  into 2 strands, produces 2 new complementary
  strands based on base pairing.

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How Replication Works

• Replication is carried about by many enzymes, the
  principle enzyme is DNA polymerase
• It joins individual nucleotides to produce a DNA
  molecule
• Proofreads each new DNA strand

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12-3 RNA Protein Synthesis
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The Structure of RNA

• Consists of a long chain of nucleotides
• 3 main differences between RNA DNA
• The 5 carbon sugar is ribose, not deoxyribose
• RNA is generally single stranded
• RNA contains uracil instead of thymine

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Types of RNA

• RNA has many functions, but in the majority of
  cells most RNA molecules are involved in only one
  thing PROTIEN SYNTHESIS
• 3 main types of RNA
• Messenger RNA (mRNA)
• Ribosomal RNA (rRNA)
• Transfer RNA (tRNA)

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Types of RNA

• Genes contain instructions for assembling amino
  acids into proteins
• RNA molecules that carry copies of these
  instructions are known as mRNA
• Proteins are assembled on the ribosomes.
  Ribosomes are made up of several dozen proteins
  as well as a form of RNA called rRNA
• During protein construction, a third type of RNA
  molecule transfers each amino acid to the
  ribosome as it is specified by coded messages in
  mRNA. This is known as tRNA.

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Transcription

• RNA molecules are produced by copying part of the
  nucleotide sequence of DNA into a complementary
  sequence in RNA. This is called transcription.
• Requires RNA polymerase
• RNA polymerase binds to DNA and separates the DNA
  strands. RNA polymerase then uses one strand of
  DNA as a template from which nucleotides are
  assembled into a strand of RNA.

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RNA Editing

• DNA of eukaryotic genes contains sequences of
  nucleotides called introns that are not involved
  in coding for proteins.
• The DNA sequence that code for proteins are
  called exons because the are expressed in the
  synthesis of proteins.
• When RNA molecules are formed they copy both the
  introns and exons.

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The Genetic Code

• The language of mRNA instructions is called the
  genetic code.
• A codon consists of 3 consecutive nucleotides
  that specify a single amino acid that is to be
  added to the polypeptide
• There are 64 possible the base codons
• During translation, the cell uses information
  from mRNA to produce proteins

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Mutations Gene Regulation
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Kinds of Mutations

• Mutations are changes in the genetic material
• Point Mutations gene mutations involving
  changes in one or few nucleotides
• Include
• Substitutions
• Insertions
• Deletions
• Frameshift Mutations shift the reading frame
  of the genetic message

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Examples

• Point
• The fat cat ate the wee rat.
• The fat hat ate the wee rat.
• Frameshift
• The fat cat ate the wee rat.
• The fat caa tet hew eer at.

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Chromosomal Mutations

• Involve changes in the number or structure of
  chromosomes
• May change locations of genes on chromosomes
• 4 types
• Deletions
• Duplications
• Inversions
• Translocations

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Examples

• Original
• ABCDEF
• Deletions
• ACDEF
• Duplications
• ABBCDEF
• Inversion
• AEDBBF
• Translocations
• ABCJKL
• GHIDEF