DNA

Deoxyribose Nucleic Acid

DNA…your book of life

• http://www.cbsnews.com/8301-3445_162-57556650/a-need-to-know-the-worst-news-you-will-ever-hear/

• Would you want to know?

2 Main Functions of DNA1.Carry the Code of Life-instruction manual for every living organism2. Blueprint for making proteins

The structure was discovered in 1953 by two scientists: James Watson & Francis

Crick

Double Helix=shape of DNA

Nucleotides are the basic structural units of DNA and consist of 3 things:1.Phosphate 2. Sugar (Deoxyribose)3.Nitrogen Base (Can be a Pyrimidine or Purine)

Watson’s Discovery Watson's Ideas

Nitrogen BasesPurine = Adenine (A), Guanine (G)

Pyrimidine =Thymine (T), Cytosine (C)*All 3 have a Y

Base PairingA-TC-G

Nitrogen Bases attached to Deoxyribose (sugar)http://www.dnalc.org/resources/3d/21-chargaff-ratios.html Chagraff’s Rule

Hydrogen bonds are the glue that hold

everything together

Sugar – DeoxyribosePhosphate Groups

(spacer)

Nitrogen Bases – Code of Life in ATCG

Thymine always pairs with Adenine

Guanine always pairs with Cytosine

A T

T A

C G

G C

G C

G C

What makes up the “Backbone” of the DNA Double Helix?

Which structure in the backbone is directly attached to the Nitrogen bases?

What are the “spacers” between each step?

Why were Mike&Ikes a good example for the purines?

Why were Skittles a good example for the pyrimidines?

DNA must replicate or make a copy of itself before a cell can divide.

•Play DNA Replication video from PBS in home folder

Remember Interphase?

DNA Replication – DNA makes a copy

of itselfImportant

during meiosis & mitosis because it makes sure

the daughter cells have the appropriate number of

chromosomes.DNAi animation

If the original strand of DNA is AATTGGCC

The complementary strand of DNA is TTAACCGG