DNA Notes

What is DNA

• DNA stands for Deoxyribonucleic Acid

• DNA – The material inside the nucleus of cells that carries genetic information.

Discovering the Structure of DNA

Structure was discovered in 1953 by James Watson and Francis Crick

Function of DNA

• Stores genetic information that instructs the cell on what proteins to make and where to make them

• Responsible for determining all organism’s traits such as eye color, body structure, and cellular enzyme production (exact words from a previous TAKS test).

The Components of DNA• DNA is a long molecule made up

of repeating individual units called nucleotides.

– Nucleotides are made up of three parts:

1. Sugar

2. Phosphate Group

3. Nitrogenous Base

Nitrogenous Bases

• DNA contains four nitrogenous bases:1. Adenine (A)

2. Guanine (G)

3. Cytosine (C)

4. Thymine (T)

Nucleotides Put Together = DNA

DRAW THIS PART ON YOUR NOTES!

Structure of DNA

• Phosphate Group & Deoxyribose Sugar – Form the backbone or

sides of the ladder.

• Nitrogenous Bases – Form the “rungs” of the

ladder or middle of the molecule.

The Shape of DNA

• DNA looks like a “twisted ladder” called a Double Helix.

Pictures Of The Double Helix

In DNA, Which Bases Pair?

• Adenine (A) always pairs with Thymine (T)– Spells “AT”

• Guanine (G) always pairs with Cytosine (C)– “G” and “C” look very

similar

• This is the principle of base pairing

Complimentary Bases

• A - T and G - C are complimentary base pairs.

• Bases are held together by hydrogen bonds.

You Try It!

• What is the complimentary DNA strand if the original DNA strand is AGTCTA?

You Try It!

• What is the complimentary DNA strand if the original DNA strand is AGTCTA?

TCAGAT