DNA Structure and Function

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DNA Structure and Function

• Homework 1 is posted
• Bonus 1 will be soon
• Discussions start M 9/10

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How is information transferred between cells?
Fig 7.2
Different strains of bacteria are injected into
mice.
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How is information transferred between cells?
Fig 7.2
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How is information transferred between cells?
Fig 7.2
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How is information transferred between cells?
Fig 7.2
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Fig 7.2
What has happened to the bacteria?
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• DNA is the transforming agent

Fig 7.3
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The Structure of DNA
If these two can win a Nobel prize
James Watson and Francis Crick
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Data showing uniformity of DNA structure.
Rosalind Franklin
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Fig 7.58.2
Nucleotides have a sugar backbone
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Fig 7.5 8.2
This subtle difference in structure has profound
effects.
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Fig 7.58.2
Plus four different bases
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Together with a phosphate nucleotide
Fig 7.5
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Fig 7.5
Together with a phosphate nucleotide
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Fig 7.8
Connect nucleotides by covalent bond
strand (notice 5-3 bond)
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Fig 7.8
DNA is typically double stranded and
anti-parallel The strands are connected by
hydrogen bonds
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Data showing uniformity of DNA structure.
Rosalind Franklin
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Figure 7-10
Fig 7.8

• Base pairing in DNA

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Figure 7-9
Fig 7.9

• Two representations of the DNA double helix

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Fig 8.11
DNA stores information, but does not do anything.
The information must be expressed to be useful.
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The relationship between DNA and genes
a gene
promoter
coding region
terminator
non-gene DNA
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DNA Composition

• In humans
• Each cell contains 6 billion base pairs of DNA.
• This DNA is 2 meters long and 2 nm wide.
• 97 does not directly code for amino acids
• In a single human cell only about 3-5 of genes
  are expressed at a time.

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Length of human DNA in each cell
Width of DNA
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DNA Composition

• In humans
• Each cell contains 6 billion base pairs of DNA.
• This DNA is 2 meters long and 2 nm wide.
• 3 directly codes for amino acids
• 10 is genes
• In a single human cell only about 5-10 of genes
  are expressed at a time.

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The relationship between DNA and genes
a gene - DNA used to produce RNA or protein
promoter
coding region
terminator
non-gene DNA
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Five Perspectives of a Gene
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Genes act as units of hereditystoring and
passing on information.
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Genes act as units of heredity storing and
passing on information.
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Genes are seen as a cause of disease
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Genes are seen as a cause of disease
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Sickle-cell anemia is caused by a single
nucleotide change in the hemoglobin gene
Fig 6.5
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Fig 8.11
Genes code for proteins
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• Five Perspectives of Genes
• Genes act as units of heredity
• Genes are seen as a cause of disease
• Genes code for proteins(we stopped here, and
  will continue with the 5 gene perspectives on F)
• Genes act as switches, controlling development
• Genes are replicators (selfish gene)