Section 8-1 & 8-2 “DNA” overview Genetics 101

This mouse’s green glow is from Green Fluorescent Protein (GFP) which glows under ultraviolet light. The gene came from a glowing jelly fish. Researchers hope to track cancer genes using GFP.

Chapter 8 – From DNA to Proteins Objectives Describe the three-dimensional structure of DNA Explain the process of DNA Replication and describe the roles of enzymes in DNA replication Explain the process of Transcription – the conversion of a gene (DNA) into RNA Explain the process of Translation – the conversion of an mRNA message into a polypeptide or protein Summarize how Mutations change DNA and may or may not affect phenotype.

What is DNA? Deoxyribonucleic acid is a molecule that carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses.

DNA Deoxyribonucleic Acid It’s the instructions for how to make YOU!

8-2 KEY CONCEPT DNA structure is the same in all organisms

DNA is composed of four types of nucleotides DNA is made up of a long chain of nucleotides

DNA is composed of four types of nucleotides DNA is made up of a long chain of nucleotides Each nucleotide has three parts: a phosphate group a deoxyribose sugar a nitrogen-containing base

Nitrogen Containing Base Each nucleotide has three parts: Nitrogen Containing Base Phosphate Group Deoxyribose (sugar) G

Each circle represents a nucleotide

The nitrogen containing bases are the only difference in the four nucleotides

Each circle represents the sugar phosphate backbone.

Each circle represents the base pairs.

Each circle represents the hydrogen bonds.

Watson and Crick determined the three-dimensional structure of DNA by building models They realized that DNA is a double helix that is made up of a sugar-phosphate backbone on the outside with bases on the inside

The three-dimensional structure of DNA is a double helix – like a twisted ladder.

Base Pairing Rules Adenine and Thymine pair up A - T Guanine and Cytosine pair up G - C ALWAYS!!! A pyrimidine (single ring) pairs with a purine (double ring) The double helix has a uniform width

Adenine and Thymine These two nitrogen containing bases always bond together. 2 hydrogen bonds to hold them together

Guanine and Cytosine These two nitrogen containing bases always bond together. 3 hydrogen bonds to hold them together

Questions – page 233