Today: How do genes work?

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Today How do genes work? Discussions
begin/began this week.
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Fig 15.3
Information flow in cells
Protein
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Fig 4.6, .7
Chains of DNA can store information
Each chain of DNA is made of individual units
nucleotides
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Fig 3.8

• Proteins are the doers of the cell.
• They act as
• Enzymes
• Structural Support
• Transporters
• Signals

Proteins are a string of amino acids
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Tbl 3.3
Amino acids connect together to make proteins.
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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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DNA Composition

• In humans
• Each cell contains 6 billion nucleotides of DNA.
• This DNA is 2 meters long and 2 nm wide.
• 98 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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DNA Composition

• In humans
• Each cell contains 6 billion base pairs of DNA.
• This DNA is 2 meters long and 2 nm wide.
• 1.5 directly codes for amino acids
• 25 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 about Genes
• Genes act as units of heredity
• Genes are seen as a cause of disease
• Genes code for proteins
• Genes act as switches, controlling development
• Genes are replicators (selfish gene)

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Fig 14.2
Visualizing the perspectives about genes
Different strains of bacteria are injected into
mice.
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Visualizing the perspectives about genes
Fig 14.2
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Fig 14.2
Visualizing the perspectives about genes
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Fig 14.2
Visualizing the perspectives about genes
What has happened to the bacteria?
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• What part of the cell contains/transfers the
  information?

Fig 14.3
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Fig 14.2
Visualizing the perspectives about genes

1. Genes act as units of heredity
2. Genes are seen as a cause of disease
3. Genes code for proteins
4. Genes act as switches, controlling development
5. Genes are replicators (selfish gene)

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Fig 14.7
In cells, DNA is a double-stranded helix
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• Five Definitions of Genes
• Genes act as units of heredity
• Genes are seen as a cause of disease
• Genes code for proteins
• Genes act as switches, controlling development
• Genes are replicators (selfish gene)

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20 amino acids in proteins
4 nucleotides in DNA
?
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Fig 15.6
How can 4 nucleotides code for 20 amino
acids? If Ratio (nucleotideamino
acid) Possible combinations 11 41 4
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Fig 15.6
How can 4 nucleotides code for 20 amino
acids? If Ratio (nucleotideamino
acid) Possible combinations 11 41 4 21
42 16
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Fig 15.6
How can 4 nucleotides code for 20 amino
acids? If Ratio (nucleotideamino
acid) Possible combinations 11 41 4 21
42 16 31 43 64
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Fig 15.6

• How can 4 nucleotides code for 20 amino acids?
• If
• Ratio
• (nucleotideamino acid) Possible combinations
• 11 41 4
• 21 42 16
• 31 43 64
• There are more possible combinations than amino
  acids.

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Combinations of 3 nucleotides code for each 1
amino acid in a protein.
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Fig 15.8
the Genetic Code
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Fig 16.21
Changes in DNA can change the protein
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Fig 16.21
Changes in DNA can change the protein
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The fat cat ate the rat.
change one letter
The zat cat ate the rat.
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The fat cat ate the rat.
change one letter
The zat cat ate the rat.
delete one letter
The atc ata tet her at.
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Combinations of 3 nucleotides code for each 1
amino acid in a protein.
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Fig 16.10
How is DNA used to make proteins and RNA?
Both proteins and RNA are involved in the
processes.
Protein
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Differences between DNA and RNA
Fig 4.1
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Fig 16.10
How is DNA used to make proteins and RNA?
Both proteins and RNA are involved in the
processes.
Protein
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Fig 16.10
Genes act as switches. The information in genes
is what to make and when to make it.
Protein
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Genes have three basic parts
a gene
promoter
coding region
terminator
non-gene DNA
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Fig 16.10
Genes contain the information to make RNA and/or
proteins. Genes act as switches. The
information in genes is what to make and when to
make it.
Protein
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Fig 11.1
For life to exist, the information (genes) must
be passed on.
1. Genes act as units of heredity 5. Genes are
replicators (selfish gene)