8.2 Structure of DNA

DNA structure is the same in all organisms.Question Set #1 Go to the link and answer the question

in your DNA Project Guide. Glowing Mice

8.2 Structure of DNA

• Question Set #2

Go to the link below and watch the first 11:00 minutes of “Cracking the Code of Life”. Answer the questions in DNA Project Guide.

Cracking the Code of Life

8.2 Structure of DNA

DNA—(Deoxyribonucleic Acid)-a nucleic acid that carries the genetic information of the cell.

It forms and controls the physical make-up and chemical processes of living organisms.

IN OTHER WORDS—IT IS THE

“CODE OF LIFE”

8.2 Structure of DNA

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

phosphate group

deoxyribose (sugar)

nitrogen-containingbase

8.2 Structure of DNA

• The nitrogen containing bases are the only difference in the four nucleotides. Be sure to put all 4 bases in your notes!!

8.2 Structure of DNA

• Question Set #3

• The History of DNA

• Go to the site “Interactives of DNA” using the link below. Use the timeline to answer the questions in your DNA Project Guide.

Interactives of DNA

8.2 Structure of DNA

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. In 1953, they won the Nobel Prize for the discovery of the double helix structure of DNA.

8.2 Structure of DNA

• Watson and Crick’s discovery built on the work of Rosalind Franklin and Erwin Chargaff.

– Franklin’s x-ray images suggested that DNA was a double helix of even width.

8.2 Structure of DNA

TAC

G

Nucleotides always pair in the same way.

• The base-pairing rules show how nucleotides always pair up in DNA.

• Because a pyrimidine (single ring) pairs with a purine (double ring), the helix has a uniform width.

– A pairs with T– C pairs with G

8.2 Structure of DNA

• The backbone is connected by covalent bonds.

hydrogen bond covalent bond

• The bases are connected by hydrogen bonds.

8.2 Structure of DNA

Nucleic Acids Store Information!

• Nitrogenous bases form a code with four “letters”.

• Inside the cell, this code is deciphered and used as a template to build proteins (you will get the details on this later on).

• All cells in an organism have the same molecules of DNA in every cell. In other words, each cell carries the same “library” of information in its nucleus.

8.2 Structure of DNA

DNA GAME

Question Set #4

Go to the link below. Play the DNA Double Helix Game.

Place the names of the three identified organisms on your DNA Project Guide.

DNA The Double Helix Game

8.2 Structure of DNA

Nucleotide Polymers

•A strand of DNA can have more than 100 million nucleotides

linked in a chain. A train with that many cars would easily stretch

across the US. And I’m talking about a toy train with cars only a

couple of inches long!

8.2 Structure of DNA

I:Anatomy of A Chromosome

• Click on the hyperlink and view the interactive.

Journey into Human DNA

8.2 Structure of DNA

Karyotypes—Human Chromosomes—Just for Fun!!