11. Nucleic Acids

1. Nucleotides2. DNA – nucleotide polymers3. RNA (transcription)4. Protein Synthesis (the Genetic Code)5. Mutations6. GMOs

11. Nucleic Acids

DNA is a polymer of 4 molecules referred to as dexoyribonucleotides …..

Each dexoyribonucleotide contains ….. 1. 1 of 4/5 bases referred to by letters A, G, C, T (U) 2. The sugar 2-deoxy ribose 3. 1-3 phosphate groups attached to C #5 by phosphate ester bonds

11. Nucleic Acids

DNA is a polymer of dexoyribonucleotides …..

Each dexoyribonucleotide contains …..

The sugar 2-deoxy ribose

3. 1-3 phosphate groups attached to C #5′ by phosphate ester bonds

DNA

RNA

11. Nucleic Acids

DNA is a polymer of dexoyribonucleotides …..

Each dexoyribonucleotide contains ….. 1. 1 of 4 bases referred to by letters A, G, C, T U is found in RNA only

The bases contain the information content of DNA/RNA determined by their ability to form H-bonds with each other.

Base Pairs are formed by H-bonds between bases of DNA/RNA

Base pairs must have ….purine + pyrimidine

GC or AT/AU

A Gdonor acceptoracceptor donornone donor

C T Udonor acceptor acceptoracceptor donor donoracceptor acceptor acceptor

Naming Nucleotides

Naming Nucleotides

Letter Base Name Nucleoside Name Found inA adenine adenosine DNA/RNAG guanine guanosine DNA/RNAC cytosine cytosine DNA/RNAT thymine thymidine DNAU uracil uridine RNA

Adenosine triphosphate - ATP deoxyadenosine triphosphate - dATP

Base Pairs are formed by H-bonds between bases of DNA/RNA

Base pairs must have ….purine + pyrimidine

GC or AT/AU

A Gdonor acceptoracceptor donornone donor

C T Udonor acceptor acceptoracceptor donor donoracceptor acceptor acceptor

ReplicationCopying DNA molecules (entire chromosomes)

occurs every time a cell divides (mitosis)

DNA (chromosome) – 1 chromosome contains many genes

DNA mitosis – Makes two identical cells containing ‘nearly’ exact replica of DNA. These cells have the same set of instructions for making proteins. Following these instructions dependent on environment.

DNA is not destiny (100%)

mitosis

ReplicationdATPdGTPdCTPdTTP

} → DNA + nPPi DNA template strand

ReplicationCopying DNA molecules (entire chromosomes)

occurs every time a cell divides (mitosis)

P-P-P C S P G

SP A

SP T

SP T

SP

P-P-P A S P A

SP T

SP C

SP G

SP

5

35

3

DNA forms a double helix using H-bonds Base pairs must have ….

purine + pyrimidineGC or AT/AU

Gene ExpressionMaking proteins from DNA genes transcription + translation

Protein sequenceYMGCFTSSGLIVVEHY...

Structure

Function

DNA (gene) – 1 chromosome contains many genes

mRNA Translation

makes proteins using information

In mRNA

Transcription makes RNA

using informationin DNA

The Genetic Code Table

The Genetic Code Table indicates how 3 consecutive bases in mRNA can instruct the cell which amino acid to insert into a growing polypeptide chain.

Sources of Mutations• Sometimes when DNA replicates, errors occur. This is a spontaneous

mutation. • Environmental agents that produce mutations in DNA are mutagens:

many mutagens are carcinogens. • Viruses can also cause mutations.• One common chemical mutagen is sodium nitrite (NaNO2), a preservative

in processed meats. In the presence of amines, sodium nitrite forms nitrosamines, which assist in the conversion of cytosine into uracil.

• If a mutation occurs in a somatic cell (any cell type other than egg or sperm), it affects only the individual organism and can cause conditions like cancer.

• Mutations that occur in germ cells (sperm or egg cells) can be passed on to future generations. Germ cell mutations cause genetic diseases. More than 4,000 genetic diseases have been identified.

GMOGenetically Modified Organism

Move gene from one organism into another essentially a cut/past job

Examples human insulin is now made in bacteria

previously isolated from cows/pigs

bT corn – resistant to insectsBacterial pesticide gene inserted into corn DNA

Cystic FibrosisMissing Cl- transporter gene inserted into lung cells

Uses disabled virus to insert DNA

Polymers of Amino AcidsPROTEINS

Protein sequenceYMGCFTSSGLIVVEHY...

Structure

Function

DNA (gene)

mRNA

Replication makes DNA copies when cells divide

Translation makes proteins

using informationIn mRNA

Transcription makes RNA

using informationin DNA

ReplicationdATPdGTPdCTPdTTP

} DNA + nPPi

DNA forms a double helix using H-bonds Base pairs must have ….

purine + pyrimidineGC or AT/AU

The Genetic Code Table

The Genetic Code Table indicates how 3 consecutive bases in mRNA can instruct the cell which amino acid to insert into a growing polypeptide chain.

Sources of Mutations• Sometimes when DNA replicates, errors occur. This is a spontaneous

mutation. • Environmental agents that produce mutations in DNA are mutagens:

many mutagens are carcinogens. • Viruses can also cause mutations.• One common chemical mutagen is sodium nitrite (NaNO2), a preservative

in processed meats. In the presence of amines, sodium nitrite forms nitrosamines, which assist in the conversion of cytosine into uracil.

• If a mutation occurs in a somatic cell (any cell type other than egg or sperm), it affects only the individual organism and can cause conditions like cancer.

• Mutations that occur in germ cells (sperm or egg cells) can be passed on to future generations. Germ cell mutations cause genetic diseases. More than 4,000 genetic diseases have been identified.

GMOGenetically Modified Organism

Move gene from one organism into another essentially a cut/past job

Examples human insulin is now made in bacteria

previously isolated from cows/pigs

bT corn – resistant to insectsBacterial pesticide gene inserted into corn DNA

Cystic FibrosisMissing Cl- transporter gene inserted into lung cells

Uses disabled virus to insert DNA