THE GENETIC MATERIAL

Notes: Pages 6 & 7

A DNA MOLECULE IS COMPOSED OF THE FOLLOWING CHEMICAL GROUPS:

1. 5-Carbon Sugar called DEOXYRIBOSE

2. Phosphate Group

3. Nitrogen Base (A, T, C, or G)

THE FOUR (4) NITROGENOUS BASES ARE:

A. Adeneine (A)

B. Cytosine (C)

C. Guanine (G)

D. Thymine (T)

PURINES PYRIMIDINES ADENINE CYTOSINE GUANINE THYMINE

In a DNA molecule:

Adenine always pairs with THYMINE Cytosine always pairs with GUANINE Thymine always pairs with ADENINE Guanine always pairs with CYTOSINE

NUCLEOTIDE (DEFINE & ILLUSTRATE)

A nucleotide is the BASIC UNIT of structure of a nucleic acid, such as DNA. It consists of a 5-carbon sugar, a phosphate group, and a nitrogen base.

A MOLECULE OF DNA CAN BE DESCRIBED AS A … Double Helix

It is often called the WATSON-CRICK Model of DNA, named after two of the scientists that first described its structure.

COMPLETE THE COMPLEMENTARY STRANDS OF DNA FOR THE FOLLOWING EXAMPLES:

ATTGCTAACC TAACGATTGG GGCCTTAAGC CCGGAATTCG

NOTE: In reality, the strands would be lined up NEXT to each other like this:

DNA REPLICATION (DEFINE)

The process by which a DNA molecule makes an EXACT copy of itself

- Base pairs are held together by HYDROGEN

BONDS- Before copying begins the DNA

molecule UNTWISTS & “UNZIPS”

- Bases of free nucleotides in the nucleus form the COMPLIMENTARY strands

DNA REPLICATION

DNA UNTWISTS

DNA “UNZIPS”

COMPLEMENTARY STRANDS FORM

EVENTUALLY, BOTH “NEW” DNA STRANDS RETWIST