DNA The Language of Life Ch

Cell Cycle Let’s review What occurs during the cell cycle? How does DNA fit into the cell cycle? What is the point of the cell cycle? To make exact copies. Copies the DNA!

Mitosis ProphaseMetaphase Anaphase Telophase

Objectives 1.Identify the building blocks of DNA 2.Describe DNA’s structure 3.Understand rules of base pairings

Griffith’s Experiment The mixture of strains killed mice! Some substance in the deadly strain remained active. Bacteria had been “transformed.” Using the scientific method to figure this out!

Hershey and Chase: Protein or DNA? Scientists still skeptical that genes were made of DNA rather than protein---to simple to account for so many traits It’s DNA, not proteins, that is the genetic material! Using the scientific method to figure this out.

Function of DNA Stores and controls: – production of proteins –inherited (genetic) information

The Structure of DNA Condensed DNA make up chromosomes. What does DNA stand for? DNA: Deoxyribonucleic acid

The Structure of DNA Human DNA has 46 chromosomes –23 from Mom and 23 from Dad Remember what a chromosome is? The coiling up of DNA around proteins.

Building Blocks of DNA DNA is a nucleic acid DNA is a polymer built from monomers (nucleotides). These monomers are called nucleotides There are only 4 types of nucleotides that make up DNA

Nucleotide Nucleotides have 3 parts: 1.Sugar called deoxyribose 2.Phosphate group 3.Nitrogen base REMEMBER: Nucleotides are the building blocks(monomers) of DNA (polymer)!

Four Types of Bases 1.Thymine (T)* 2.Adenine (A) 3.Cytosine (C) 4.Guanine (G) *We will use the “one letter”abbreviations from now on.

Sugar-Phosphate backbone Notice bond between sugar and phosphate to create this backbone. Why do we call this a backboone? Provides support and structure.

Complimentary Base Pairs C with G A with T ALWAYS!!

DNA Strands Nucleotides combine in MANY different sequences This is what makes you, you! Two strands form a double helix.

Double Helix Double Helix: –The winding of two strands of nucleotides. Bases pair up between the two phosphate-sugar backbones Sugar-phosphate make up the sides of ladder Bases make up the rungs of the ladder Which bases go with which? Who discovered the double helix? Watson and Crick, 1953 But….

Rosalind Franklin Discovered important facts about DNA’s structure –sugar-phosphate backbone is on outside –DNA has two strands, not three –Details about the shape and size of the double helix

Photo 51 X-ray diffraction image of DNA Presented to Watson and Crick by Rosalind’s peer, Wilkins at an informal seminar— WITHOUT Franklin’s permission This was the missing piece they needed regarding structure Published results in the journal Nature in 1953 Watson and Crick and Wilkins won the Nobel prize in 1962; Rosalind Franklin didn’t...

DNA Structure

Online Activity 11.2