DNA

Deoxyribonucleic Acid

What are we going to learn?

What do you want to know?

Make observations and inferences about this picture.

A. Function

Information Storage Blueprint for the production of the entire

body Structural and functional components Information is carried in a coded message

B. Chemical composition

1. Organic molecule What does this mean? It contains carbon (and hydrogen) 2. Components - Three

A) 5 carbon sugar (deoxyribose) B) phosphate group C) Nitrogenous (nitrogen) base

Either a single or a double ring Four different types: Adenine, Guanine, Thymine,

Cytosine

OBSERVATION

INFERENCE

Purine

Pyrimadine

Purine

3. All three of these components are bonded together to form a nucleotide.

How many different nucleotides are possible?

4

Where do the bonds form?

What are the bonds called?

C. Genetic Code

The order of the nitrogen bases on the DNA strand acts as a code specifying the order of amino acids in a protein.

Analogy We have 26 letters….

Analogy

Using the letters C, A, T, B, R, E

You can make many words

What are some words?

At RatBrat RateBat RaceBet TabBear TareBeat TearBrace TarCare TeaCatCabCareCaterEar

DNA is a code

A,T,G & C all code for amino acids that will eventually make up ____?

Proteins The order that these

nitrogen bases are in will dictate which amino acids are used to make the protein

What might happen if a nitrogen base is added?

Mutation EX) BEAR REAR OR) CAR CARE

D. Watson and Crick

What did these scientists do? 1. DNA is composed of long, twisted

strands of nucleotides bonded together to form a ladder.

Uprights = sugars + phosphates Rungs = nitrogen bases (ATGC)

2. Because of molecular shape adenine must always bond to thymine.

Guanine must always bond to _____. Cytosine This is referred to as complimentary base

pairing.

3. The entire structure is twisted to form a double helix.

4. Since bases are complimentary, the order of the bases on one strand of DNA dictates the order of bases on the opposite strand of DNA.

Ex. 1: A-T-T-C-A-G-C-G-A-T-G-G-A 2: T-A-A-G-T-C-G-C-T-A-C-C-T

How long is DNA?

If you unraveled all your chromosomes from all of your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times.

Neat DNA facts! You probably know that no two people have exactly the

same DNA, but did you know that everyone's DNA is 99.9% identical?

Did you know that most of your DNA apparently does not code for any protein that we know of?

• Did you know that humans don't have that many more genes than an earthworm?

• Did you know that we are so similar to yeast, in some of our DNA, that human DNA can be substituted for the equivalent yeast gene--and it works just as well?

Calculating DNA length for each person, it would stretch across the diameter of the solar system. 6 000 000 000 000 base pairs 0.6 nm x 1013 cell = 3.6x1016 meters

If the information contained in the DNA could be written down, it would fill a 1000 volume encyclopedia