DNA and Genes

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DNA and Genes

• Chapter 11 pgs. 280-301

2
Take out 1 sheet of paper and write both lab
partners names on it. Discuss and answer the
questions from the powerpoint on the paper

• Textbook pg. 280
• 1. Pick one of the 3 bullet points under What
  Youll Learn and explain what you think it
  means.
• 2. Why is DNA important?
• 3. Explain how the characteristics of the
  Shetland pony relate to its DNA?

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? History of DNA

• 1800s Mendel determined that offspring inherited
  traits from parents
• 1944 Biomolecule that was involved with heredity
  was DNA (originally proteins were thought to pass
  on traits because DNA was too simple)
• SCIENCE IS TENTATIVE

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• Rosalind Franklin and Maurice Wilkins took
  diffracted photographs of DNA
• X-rays were passed through DNA crystals, the
  X-rays were bent by the atoms in the DNA molecule
  producing an image of the shape

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• 1953 Watson Crick developed a model of DNA
  using the diffraction photographs
• Double Helix DNA comes in 2 long strands that
  wrap around each other, spiral staircase

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Textbook pg. 283

• Look at figure 11.2 (dont forget to read the
  caption!)
• 4. What is another analogy used for the shape of
  DNA (besides a spiral staircase)?

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? Why is DNA so important?

• DNA is known as blueprint of life
• DNA contains instructions for making proteins
  within the cell
• Genes are on our chromosomes, chromosomes are
  made of DNA

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Turn to page 281

• Read the paragraph with the heading What is DNA?
• 5. List 3 places in your body that contain
  proteins
• 6. Enzymes are a type of protein. Why do we need
  them?

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Why is DNA so important?

• Important for all life on Earth, makes each
  individual plant or animal unique
• Helps us understand diseases better find
  potential cures
• Better food crops

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? DNA Nucleotides

• DNA is a nucleic acid made from subunits called
  nucleotides
• Nucleotide 3 parts five-carbon sugar,
  phosphate group, nitrogenous base
• Deoxyribose the sugar in a DNA nucleotide

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? How the Double Helix stays together
phosphates

• Double Helix has two strands that twist together
• One strand of DNA is like one half of a zipper
• The backbone of the molecule is alternating
  phosphates and deoxyribose sugar
• The teeth are nitrogenous bases

deoxyribose
bases
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• One strand of DNA (half of a zipper) is a polymer
  of nucleotides
• One strand of DNA has millions of nucleotides

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? Nitrogenous Bases

• DNA has four different bases
• Cytosine C
• Thymine T
• Adenine A
• Guanine G

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• 2 kinds of Nitrogenous Bases
• Purines double ring bases, A and G
• Pyrimidines single ring bases, T and C

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? Complementary Bases

• Nitrogenous bases on the 2 strands of DNA pair up
  with one another
• Cytosine pairs with Guanine with 3 (triple)
  Hydrogen Bonds
• Adenine pairs with Thymine with 2 (double)
  Hydrogen Bonds

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Textbook pg. 283

• Read the Problem-Solving Lab 11.1
• Answer the 3 Thinking Critically questions.
  These will be questions numbered 7-9 on your
  paper.

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? DNA Model