DNA DeoxyriboNucleic Acid

The Structure of DNA (DEOXYRIBOSE NUCLEIC ACID)• A. DNA is a macromolecules

called NUCLEIC ACIDS. The other type of molecule in this category is RNA.

Remember…

• Since DNA is a macromolecule (POLYMER), it is really made of many (in this case billions) smaller molecules (MONOMERS!) put together. The DNA monomer is the individual NUCLEOTIDE.

Nucleotide•A single piece of the DNA strand

•Made of 3 parts▫Deoxyribose (sugar)

▫Phosphate▫Base (A,G,C or T)

Purines Pyrimidines

Adenine

Guanine Cytosine

Thymine

Phosphate group

Deoxyribose

 DNA Nucleotides

The backbone of 1 strand

•Alternates between the sugar (deoxyribose) and the phosphate group

•The base sticks out into the middle

Double-Stranded•The bases hydrogen bond

with each other to hold the strands together

•The base from one strand bonds with the base from the other forming a complementary base pair

a. ADENINE bonds with THYMINE

b. GUANINE bonds with CYTOSINE

•They coil into a double-helix

Hydrogen bonds

Nucleotide

Sugar-phosphate backbone Key

Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

Figure 12–7 Structure of DNA

Section 12-1

DNA Structure•Theorized to be a double helix consisting of 2 strands wrapped around each other

•Discovered by Watson and Crick AND Rosalind Franklin

Rosalind Franklin

•Provided the scientific evidence that allowed Watson and Crick to suggest the double helix

•But often does not receive credit and since she had died – couldn’t share in the Nobel prize

• What about the structure of DNA makes us unique???

ORDER OF BASE PAIRS

The Structure of RNA

A. RNA is made of a SINGLE strand of NUCLEOTIDES. Each of these is composed of:

1. NITROGENOUS BASE2. SUGAR (RIBOSE)3. PHOSPHATE

i. RNA also has 4 possible nitrogen bases BUT instead of thymine, RNA has a nitrogen base called URACIL.

What You Should Know about DNA structure

•The basic structure of a nucleotide

•The basic structure of DNA•How DNA and RNA differ•Base-pair rules•How the structure suggests a replication method

Genetic disorder projects•Find 4 people to work with then find a computer

and log on.•Once you have your disease start researching it.•Before you leave: Divvy up the work AND

SHARE EMAIL & phone numbers so you can contact each other.

•Next class you have time to work on the project. Your HW is prepare for this time together as it is the ONLY class time you will be given. Have your portion COMPLETE!!!

•The final project MUST BE EMAILED TO ME by:•A day- 2/24 9:30 pm•B day- 2/25 9:30 pm

2/21-2/24

•DNA Jewelry (~45 minutes)•Genetic presentation project (~40 minutes)

•HW: final presentation due to my email ▫A day- 2/24 9:30 pm▫B day- 2/25 9:30 pm