Building DNA (October 7th)

Watson and Crick pairing

A binds to T (2 Hydrogen bonds)

C binds to G (3 Hydrogen bonds)

What is a nucleotide?

The fundamental building block of DNA

Components are a Phosphate (negative charge), a Sugar, and a Nitrogenous base

Nucleoside refers to….

The Sugar and Nitrogenous base in a nucleotide

What are the categories of Nitrogenous bases?

Purines (larger with 2 rings) and Pyrimidines (smaller with 1 ring)

Purines

(A) Adenine and (G) Guanine

Pyrimidines

(T) Thymine and (C) Cytosine

Genomic DNA

Double stranded

Sugar/Phosphate backbone

Nitrogenous base rung

Right-handed twist

Major and Minor Grooves

The Sugar/Phosphate backbone is….

negatively charged and run anti-parallel (direction differ between stems)

What is the purpose of the Major and Minor Grooves?

Serves as the DNA binding site

2 Hydrogen bonds

A-T

3 Hydrogen bond

G-C

The strands of the Double Helix are held together by….

Hydrogen bonds

Genome

Total genetic information (DNA) in a cell (and therefore an organism)

Within a genome is a collection of genes

DNA strands are…..

complementary and Anti-parallel

Basics of DNA Replication

Partially decompress DNA

Unwind double helix

Read old DNA and write new DNA

The double helix is unwound using….

helicase and breaking of Hydrogen bonds

The reading and writing of DNA requires….

DNA Polymerase and Primer

Primer

a short RNA sequence that is complementary to the template

5’-3’

goes up

3’-5’

goes down

All Polymerases

Read 3’-5’

Write 5’-3’

What is the purpose of a Helicase?

to break through the Hydrogen bonds and separate the two strands

5’ end

has PO₄

3’ end

has OH

Avery et al.

found that DNA from one organism can transform another

Chargaff

found that Gs and Cs are equal ratios in DNA

Hershey and Chase

found that DNA is inherited

Watson and Crick

found that DNA is a double helix of nucleic acid

Griffin

found that cellular material from one organism can be used to transform another