DNA: The Molecule of Heredity Chemical nature of DNA Eukaryotic chromosomes are composed of Gene –

3.3.1 – Outline DNA nucleotide structure in terms of sugar (deoxyribose), base and phosphate. DNA is made up of a long chain of nucleotides. Each nucleotide has three parts. a Label:

3.3.2 – State the names of the four bases in DNA. The nitrogen containing bases are the only difference in the four nucleotides.

determined the by building models. They realized that DNA is a double helix that is made up of a with

Watson and Crick’s discovery built on the work of Rosalind Franklin and Erwin Chargaff. Franklin’s x-ray images suggested that . Chargaff’s rules stated that .

Nucleotides always pair in the same way 3.3.4 – Explain how a DNA double helix is formed using complimentary base pairing and hydrogen bonds. Nucleotides always pair in the same way A pairs with C pairs with Because a pyrimidine ( ) pairs with a purine ( ), the helix has a . C G T A

The backbone is connected by 3.3.3 – Outline how DNA nucleotides are linked together by covalent bonds into a single stand. 3.3.4 – Explain how a DNA double helix is formed using complimentary base pairing and hydrogen bonds. 3.3.5 – Draw and label a simple diagram of the molecular structure of DNA. The backbone is connected by The bases are connected by

When would a cell need to replicate it’s DNA? 3.4.1 – Explain DNA replication in terms of unwinding the double helix and separation of the strands by helicase, followed by formation of the new complementary strands by DNA polymerase. DNA Replication carry out the process of replication DNA serves as the When would a cell need to replicate it’s DNA?

The DNA molecule unzips in both directions. 3.4.1 – Explain DNA replication in terms of unwinding the double helix and separation of the strands by helicase, followed by formation of the new complementary strands by DNA polymerase. do the actual work of replication Helicase Free-floating nucleotides form with the template strand nucleotide The DNA molecule unzips in both directions.

DNA polymerase enzymes 3.4.1 – Explain DNA replication in terms of unwinding the double helix and separation of the strands by helicase, followed by formation of the new complementary strands by DNA polymerase. DNA polymerase enzymes DNA polymerase new strand nucleotide

3.4.2 – Explain the significance of complementary base pairing in the conservation of the base sequence of DNA. Original DNA Double Helix: 1. CGTATCCGGAATTT 2. GCATAGGCCTTAAA Template Strand (original) 1. CGTATCCGGAATTT Complimentary strand 1. Complimentary strand 2. Template Strand (original) 2. GCATAGGCCTTAAA

3.4.3 – State that DNA replication is semiconservative. Two new molecules of DNA are formed, each with an original strand and a newly formed strand DNA replication is original strand new strand Two molecules of DNA