DNA Structure and Function Homework #1 is posted and due 9/20 Bonus #1 is posted and due 10/25

How is information transferred between cells? Fig 7.2 Different strains of bacteria are injected into mice.

How is information transferred between cells? Fig 7.2

How is information transferred between cells? Fig 7.2

How is information transferred between cells? Fig 7.2

What has happened to the bacteria? Fig 7.2 What has happened to the bacteria?

DNA is the transforming agent Fig 7.3

If these two can win a Nobel prize… The Structure of DNA If these two can win a Nobel prize… James Watson and Francis Crick

Data showing uniformity of DNA structure. Rosalind Franklin

Nucleotides have a sugar backbone Fig 7.5+8.2 Nucleotides have a sugar backbone

This subtle difference in structure has profound effects. Fig 7.5 +8.2 This subtle difference in structure has profound effects.

Plus four different bases Fig 7.5+8.2 Plus four different bases

Together with a phosphate = nucleotide Fig 7.5

Together with a phosphate = nucleotide Fig 7.5 Together with a phosphate = nucleotide

Connect nucleotides by covalent bond = strand Fig 7.8 Connect nucleotides by covalent bond = strand

DNA is typically double stranded Fig 7.8 DNA is typically double stranded The strands are connected by hydrogen bonds

Data showing uniformity of DNA structure. Rosalind Franklin

Fig 7.8 Base pairing in DNA Figure 7-10

Fig 7.9 Two representations of the DNA double helix Figure 7-9

Fig 8.11 DNA stores information, but does not do anything. The information must be expressed to be useful.

The relationship between DNA and genes a gene promoter coding region terminator non-gene DNA

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.

Length of human DNA in each cell Width of DNA

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.

The relationship between DNA and genes a gene - DNA used to produce RNA or protein promoter coding region terminator non-gene DNA

Five Perspectives of a Gene

Genes act as units of heredity…storing and passing on information.

Genes act as units of heredity… storing and passing on information.

Genes are seen as a cause of disease

Genes are seen as a cause of disease

Sickle-cell anemia is caused by a single nucleotide change in the hemoglobin gene Fig 6.5

Genes code for proteins Fig 8.11 Genes code for proteins

Proteins are the “doers” of the cell. They act as: Enzymes Genes code for proteins… Proteins are the “doers” of the cell. They act as: Enzymes Structural Support Transporters Signals

Genes act as switches, controlling development

Genes act as switches, controlling development

Genes are replicators (selfish gene) From “Biology 7th ed.” by Campbell et al fig 19.14

Viruses infect living cells, take over, and produce more virus. Fig 5.25 Viruses infect living cells, take over, and produce more virus.

Bodies are vessels for the transmission of genes

Five Perspectives 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)

Transposons

Transposons: mobile DNA Genes are replicators (selfish gene) Transposons: mobile DNA

Barbara McClintock, discoverer of transposons

Transposons are self-moving DNA Fig 14.8

Transposons move within genomes via the action of transposase Fig 14.8 Transposons move within genomes via the action of transposase

Fig 14.4 transposase transposon

Fig 14.4

Fig 14.4

Fig 14.4

Fig 14.4

Genes are replicators (selfish gene) From “Biology 7th ed.” by Campbell et al fig 19.14

Transposons: mobile DNA Genes are replicators (selfish gene) Transposons: mobile DNA

Five Perceptions 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)

We did NOT cover this in class We did NOT cover this in class. I left it in if you are interested in learning more about it. This article in Nature has some good info: The RNA World pg 312

This subtle difference in structure has profound effects. Fig 7.5 +8.2 This subtle difference in structure has profound effects.

Connect nucleotides by covalent bond = strand (notice 5’-3’ bond) Fig 7.8 Connect nucleotides by covalent bond = strand (notice 5’-3’ bond)

Fig 8.11 DNA stores information, but does not do anything. The information must be expressed to be useful.

Where did this system come from? Fig 8.11 Where did this system come from?

Was RNA the first biological molecule? The RNA World pg 312

Living organisms must fit all of the following criteria: (modified from Campbell “Biology”) 1. They must have organization. 2. They must have metabolism. 3. They must respond to the environment. 4. They must be able to reproduce themselves.

Fig 8.2 U* RNA structure A G C

RNA can form base pairs within single stranded molecule Fig 8.10+9.12

RNA can form complex 3-D structures Ribosomes (rRNA) have enzymatic activity: Enzymatic RNA=ribozyme Fig 9.12

Some RNA molecules have catalytic activities pg 223

Living organisms must fit all of the following criteria: (modified from Campbell “Biology”) 1. They must have organization. 2. They must have metabolism. 3. They must respond to the environment. 4. They must be able to reproduce themselves.

RNA can (theoretically) be replicated using complementary bases

Experimental determination of RNA’s ability to self-ligate… A step towards self-replication from Freeman’s “Biological Science” (2002) chapter 3

Q: Can RNA self-ligate? Hypos: Yes. No. from Freeman’s “Biological Science” (2002) chapter 3

Column Chromatography RNA’s added in aqueous solution Some, with tag, bind to column Without tag, flow thru

Overall RNA self-ligation improves by selection

Theoretical evolution of self-replicating RNA

Hypothetical Origin of Life pg 214