DNA%20(Deoxyribonucleic%20Acid)

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WARM-UP 7
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DNA(Deoxyribonucleic Acid)
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Genetic material of cells

• GENES units of genetic material that CODES FOR
  A SPECIFIC TRAIT
• Called NUCLEIC ACIDS
• DNA is made up of repeating molecules called
  NUCLEOTIDES

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DNA Nucleotide

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A HISTORY OF DNA
SEE p. 292-293

• Discovery of the DNA double helix
• A. Frederick Griffith Discovers that a factor
  in diseased bacteria can transform harmless
  bacteria into deadly bacteria (1928)
• B. Rosalind Franklin - X-ray photo of DNA.
• (1952)
• C. Watson and Crick - described the DNA
  molecule from Franklins X-ray.
• (1953)

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Watson Crick proposed

• DNA had specific pairing between the nitrogen
  bases
• ADENINE THYMINE
• CYTOSINE - GUANINE
• DNA was made of 2 long stands of nucleotides
  arranged in a specific way called the
  Complementary Rule

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DNA Double Helix

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DNA Double Helix

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Nitrogenous Bases

• PURINES
• 1. Adenine (A)
• 2. Guanine (G)
• PYRIMIDINES
• 3. Thymine (T)
• 4. Cytosine (C)

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Chargaffs Rule

• Adenine must pair with Thymine
• Guanine must pair with Cytosine
• Their amounts in a given DNA molecule will be
  about the same.

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BASE-PAIRINGS

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Genetic Diversity

• Different arrangements of NUCLEOTIDES in a
  nucleic acid (DNA) provides the key to DIVERSITY
  among living organisms.

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The Code of Life

• The code of the chromosome is the SPECIFIC
  ORDER that bases occur.
• A T C G T A T G C G G

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DNA is wrapped tightly around histones and coiled
tightly to form chromosomes
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DNA Replication

• DNA must be copied
• The DNA molecule produces 2 IDENTICAL new
  complementary strands following the rules of base
  pairing
• A-T, G-C

• Each strand of the original DNA serves as a
  template for the new strand

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DNA Replication

• Semiconservative Model
• 1. Watson and Crick showed the two strands of
  the parental molecule separate, and each
  functions as a template for synthesis of a new
  complementary strand.
• .

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Replication Quiz

• 1. Why is replication necessary?
• 2. When does replication occur?
• 3. Describe how replication works.
• Use the complementary rule to
• create the complementary strand

A---? G---? C---? T---? A---? G---? A---? G---? C-
--? A---? G---? T---?
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Replication Quiz

• 1. Why is replication necessary?
• So both new cells will have the correct DNA
• 2. When does replication occur?
• During interphase (S phase).
• 3. Describe how replication works.
• Enzymes unzip DNA and complementary nucleotides
  join each original strand.
• 4. Use the complementary rule to
• create the complementary strand

A---T G---C C---G T---A A---T G---C A---T G---C C-
--G A---T G---C T---A
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(1961) Watson Crick proposed

• DNA controlled cell function by serving as a
  template for PROTEIN structure.
• 3 Nucleotides a triplet or CODON
• (which code for a specific AMINO ACID)
• AMINO ACIDS are the building blocks of proteins.

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DNA Transcription

• DNA can unzip itself and RNA nucleotides match
  up to the DNA strand.
• Both DNA RNA are formed from NUCLEOTIDES and
  are called NUCLEIC acids.

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DNA Translation

• The cell uses information from messenger RNA to
  produce proteins

We will discuss details of this on a later date
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AMAZING DNA FACTS

• DNA from a single human cell extends in a single
  thread for almost 2 meters long!!!
• It contains information equal to some 600,000
  printed pages of 500 words each!!!
• (a library of about 1,000 books)

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LETS REVIEW DNA

• Summarize the relationship between genes DNA.
• Describe the overall structure of the DNA
  molecule.
• What are the 4 kinds of bases?