Today: How do genes work?

Discussions begin/began this week.

Information flow in cells

Protein

Fig 15.3

Chains of DNA can store information: Fig 4.6, .7

Each chain of DNA is made of individual

units = nucleotides

Fig 3.8

Proteins are a string of amino acids

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

Tbl 3.3Amino acids connect together to make proteins.

a gene - DNA used to produce RNA or protein

The relationship between DNA and genes

promoter coding region terminator non-geneDNA

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.

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.

a gene - DNA used to produce RNA or protein

The relationship between DNA and genes

promoter coding region terminator non-geneDNA

Five 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)

Fig 14.2Visualizing the perspectives about genes

Different strains of bacteria are injected into mice.

Visualizing the perspectives about genes

Fig 14.2

Fig 14.2 Visualizing the perspectives about genes

Fig 14.2

What has happened to the bacteria?

Visualizing the perspectives about genes

• What part of the cell contains/transfers the information?

Fig 14.3

Fig 14.2

1. Genes act as units of heredity2. Genes are seen as a cause of disease3. Genes code for proteins4. Genes act as switches, controlling

development5. Genes are replicators (selfish gene)

Visualizing the perspectives about genes

Fig 14.7In cells, DNA is a double-stranded helix

Five Definitions of 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)

?

4 nucleotides in DNA

20 amino acids in proteins

How can 4 nucleotides code for 20 amino acids?

If

Ratio(nucleotide:amino acid) Possible combinations

1:1 41 4

Fig 15.6

How can 4 nucleotides code for 20 amino acids?

If

Ratio(nucleotide:amino acid) Possible combinations

1:1 41 42:1 42 16

Fig 15.6

How can 4 nucleotides code for 20 amino acids?

If

Ratio(nucleotide:amino acid) Possible combinations

1:1 41 42:1 42 163:1 43 64

Fig 15.6

How can 4 nucleotides code for 20 amino acids?

If

Ratio(nucleotide:amino acid) Possible combinations

1:1 41 42:1 42 163:1 43 64

•There are more possible combinations than amino acids.

Fig 15.6

Combinations of 3 nucleotides code for each 1 amino acid in a protein.

Fig 15.8

the Genetic Code

Changes in DNA can change the protein

Fig 16.21

Changes in DNA can change the protein

Fig 16.21

The fat cat ate the rat.

change one letter

The zat cat ate the rat.

The fat cat ate the rat.

change one letter

The zat cat ate the rat.

The atc ata tet her at.

delete one letter

Combinations of 3 nucleotides code for each 1 amino acid in a protein.

Protein

How is DNA used to make proteins and RNA?

Both proteins and RNA are involved in the processes.

Fig 16.10

Differences between DNA and RNA

Fig 4.1

Protein

How is DNA used to make proteins and RNA?

Both proteins and RNA are involved in the processes.

Fig 16.10

Fig 16.10

Genes act as switches.

The information in genes is what to make and when to make it.

Protein

a gene

Genes have three basic parts

promoter coding region terminator non-geneDNA

Fig 16.10Genes 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

1. Genes act as units of

heredity

5. Genes are replicators

(selfish gene)

For life to exist, the information (genes) must be passed on.

Fig 11.1