Lecture 9– DNA & RNA

What is pharmacogenomics?

A branch of pharmacology using DNA and amino acid sequences to inform drug development and testing, correlating individual genetic variation with drug responses. It aims to improve drug efficacy and reduce side effects. Genes influence disease susceptibility, predispose individuals to toxicities, and affect drug metabolism rates.

What are nucleic acids?

One of the four macromolecules in living things.

They contain hydrogen, oxygen, nitrogen, carbon, and phosphorus.

Two types: DNA and RNA.

Involved in storing/transmitting genetic information and coding for proteins.

Formed through dehydration synthesis and broken apart by hydrolysis.

What is DNA?

• Found in the cell nucleus, forming chromosomes.

• Contains genes that code for proteins, providing instructions for building proteins.

• Condensed by winding around histones, forming chromatin.

• Has a double helix shape.

• Sides made of deoxyribose sugars and phosphates.

• Rungs made of nitrogen bases.

What are the components of a nucleotide?

A phosphate, a sugar (deoxyribose), and a nitrogen base.

Nucleotides are linked with strong covalent bonds.

What are the nitrogen bases in DNA and how do they pair?

Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).

A always bonds with T, and C always bonds with G.

Purines (Adenine and Guanine) bind to pyrimidines (Cytosine and Thymine).

What forms the backbone of DNA?

Phosphate groups form the backbone with deoxyribose sugars. They are negatively charged, causing DNA to twist.

What are the ends of a DNA chain?

A nucleic acid chain has a 5' phosphate end and a 3' hydroxyl (-OH) end. DNA base sequences are written in the 5' to 3' direction.

What is RNA?

Has a ribose sugar.

Uracil (U) replaces Thymine (T) in RNA.

Typically single-stranded and relatively small.

What are the main types of RNA involved in protein synthesis?

mRNA and tRNA.

mRNA carries information from DNA in the form of codons.

tRNA transfers amino acids to the ribosome.

snRNA is involved in splicing mRNA, and

microRNA regulates gene expression.

What is DNA replication?

The process of making a copy of DNA.

Occurs during cell division.

The DNA molecule unzips, and nucleotides pair up with bases on both sides, forming two identical DNA strands.

Replication is semi-conservative.

What does it mean that DNA replication is semi-conservative?

Each new DNA molecule consists of one new and one old strand.

One strand of duplex passed on unchanged to each of the daughter cells.

What enzymes are involved in DNA replication?

Helicase, Primase, DNA polymerase, RNAase H, and DNA ligase.

Topoisomerases, Single strand binding proteins and Tethering protein.

What are the leading and lagging strands in DNA replication?

The leading strand is synthesized continuously in the 5’ to 3’ direction, while the lagging strand is synthesized in fragments (Okazaki fragments).

DNA ligase links Okazaki fragments.

Give examples of therapeutic uses of nucleotide analogues.

5-Fluorouracil is used in chemotherapy and affects RNA and DNA synthesis.

Acyclovir is used to treat cold sores and blocks viral replication.

AZT is a pyrimidine analog that inactivates HIV DNA polymerase.