How does genetic information become traits we can observe? Molecular Genetics Essential Question: How does genetic information become traits we can observe?

Big picture- Information follows this path: DNA RNA Proteins

Introduction to DNA

The Basics DNA = deoxyribonucleic acid Function is to store and transmit the genetic information. DNA tells cells which proteins to make and when to make them. The proteins form the structural units of cells and help control the chemical processes within them.

DNA- The Blueprint of Life Why might we call DNA the “blueprint of life”? Blueprints tell builders how to build a house; DNA tells cells how to build the organism.

Structure of DNA The basic parts of DNA are the same in all living organisms. Made up of many nucleotides 3 parts of a nucleotide A sugar molecule (deoxyribose) A phosphate group A nitrogen-containing base

Nitrogenous Bases 4 different bases: 1. Adenine (A) 2. Guanine (G) 3. Thymine (T) 4. Cytosine (C)

The shape of DNA is called a double helix. What does this look like to you? Twisted ladder The sides of the ladder are made of alternating sugar and phosphate molecules. The rungs of the ladder are made of pairs of nitrogenous bases.

There are very strong bonds between the sugar and phosphates of neighboring nucleotides. Bases have weak bonds, called hydrogen bonds, with the bases on the opposite chain. Base pairing rules: Cytosine always pairs with Guanine Adenine always pairs with Thymine

Complementary Base Pairing The sequence of bases on one chain is called complementary to the sequence of bases on the other chain. Example: Chain 1: A T C G C C T A A G G Chain 2: T A G C G G A T T C C

Review: 1. What does DNA stand for? 2. What is the function (job) of DNA? 3. What is DNA made of? 4. What are the 3 parts of a nucleotide? 5. What are the sides of the DNA ladder made of? 6. What are the 4 nitrogenous bases? 7. What are the base paring rules?