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Unit 2: Molecular Genetics Bi 1d: Central Dogma Bi 5a: DNA, RNA, protein structure and function Bi 5b: Base pairing rules. Introduction to DNA & RNA. proteins. DNA. Nucleic Acids. Function: genetic material stores information genes blueprint for building proteins

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slide1
Unit 2: Molecular Genetics

Bi 1d: Central Dogma

Bi 5a: DNA, RNA, protein structure and function

Bi 5b: Base pairing rules

Introduction to DNA & RNA

nucleic acids

proteins

DNA

Nucleic Acids
  • Function:
    • genetic material
      • stores information
        • genes
        • blueprint for building proteins
          • DNA  RNA  PROTEINS
      • transfers information
        • blueprint for new cells
        • blueprint for next generation
nucleic acids1
Nucleic Acids
  • Examples:
    • RNA (ribonucleic acid)
      • single helix
    • DNA (deoxyribonucleic acid)
      • double helix
  • Structure:
    • monomers = nucleotides

DNA

RNA

nucleotides
Nucleotides
  • 3 parts
    • nitrogen base (C-N ring)
    • pentose sugar (5C)
      • ribose in RNA
      • deoxyribose in DNA
    • phosphate(PO4)group

Nitrogen baseI’m the A,T,C,G or Upart!

Are nucleic acidscharged molecules?

types of nucleotides
Types of nucleotides

Purine = AG

Pure silver!

  • 2 types of nucleotides
    • different nitrogen bases
    • purines
      • double ring N base
      • adenine (A)
      • guanine (G)
    • pyrimidines
      • single ring N base
      • cytosine (C)
      • thymine (T)
      • uracil (U)
nucleic polymer
Nucleic polymer
  • Backbone
    • sugar to PO4 bond
    • phosphodiester bond
      • new base added to sugar of previous base
      • polymer grows in one direction
    • N bases hang off the sugar-phosphate backbone
pairing of nucleotides
Pairing of nucleotides
  • Nucleotides bond between DNA strands
    • H bonds
    • purine :: pyrimidine
    • A :: T
      • 2 H bonds
    • G :: C
      • 3 H bonds

Matching bases?Why is this important?

dna molecule
DNA molecule
  • Double helix
    • H bonds between bases join the 2 strands
      • A :: T
      • C :: G

H bonds?Why is this important?

copying dna
Copying DNA
  • Replication
    • 2 strands of DNA helix are complementary
      • have one, can build other
      • have one, can rebuild the whole

Matching halves?Why is this a good system?

when does a cell copy dna
When does a cell copy DNA?
  • When in the life of a cell does DNA have to be copied?
    • cell reproduction
      • mitosis
    • gamete production
      • meiosis
dna replication
DNA replication

“It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.”

James Watson

Francis Crick

1953

chargaff
Chargaff

1947

  • DNA composition: “Chargaff’s rules”
    • varies from species to species
    • all 4 bases not in equal quantity
    • bases present in characteristic ratio
      • humans:

A = 30.9%

T = 29.4%

G = 19.9%

C = 19.8%

RulesA = T

C = G

That’s interesting!What do you notice?

interesting note
Interesting note…
  • Ratio of A-T::G-C affects stability of DNA molecule
    • 2 H bonds vs. 3 H bonds
    • biotech procedures
      • more G-C = need higher T° to separate strands
    • high T° organisms
      • many G-C
    • parasites
      • many A-T (don’t know why)
the central dogma put this on your composition notebook right after the homework
The “Central Dogma”( put this on your composition notebook right after the Homework)
  • Flow of genetic information in a cell

Where do these processes occur in the cell?

transcription

translation

DNA

RNA

protein

replication

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