IN 89 & 91 Headings Vocabulary Important Words DNA & Replication

CHROMOSOME CHROMATIN DNA NUCLEUS

(DeoxyriboNucleic Acid) Structure of DNA (DeoxyriboNucleic Acid) Using critical info from the work of others (Rosalind Franklin & Linus Pauling)… James Watson & Francis Crick made 1st model of DNA in 1953 DNA is a Nucleic Acid (AKA: Organic Compound) DNA is made up of small subunits called: Nucleotides

DRAW THIS IN YOUR NOTES! “YES, THE ENTIRE PICTURE!!!”

What Makes Up DNA? Each nucleotide is made up of: Deoxyribose (sugar) Phosphate group (“P”) Nitrogen Base (4 types) Adenine- A Thymine-T Cytosine- C Guanine-G Purines Pyrimidines Pyrimidines Purines

What Is the “Ladder”? 2 long chains of nucleotides Joined together in the form of a ladder Ladder is twisted in the form of a double helix or spiral

Structure of DNA Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

Sides of the Ladder = Alternating Deoxyribose (Sugar) & Phosphate s-P-s-P-s-P-etc. Rungs or Steps of ladder = Pairs of Nitrogen Bases A-T or C-G T-A or G-C

Side Questions What does DNA stand for? Who made the first model of DNA in 1953? What makes up DNA? What is the DNA “ladder”?

How Do Nitrogen Bases Pair Up? Adenine(A) pairs up w/ Thymine(T) Guanine(G) pairs up w/ Cytosine(C) Example: A G C T A C G C A 5’ T C G A T G C G T 3’ 5’

Why Do Organisms Look So Different? All organisms have the same type of nucleotides Nucleotide arrangement provides for all the different types of organisms Ex: A mouse and a rosebush have the same nucleotides…but… Different Nucleotide Order = Different Organism!!! *This sequence of nucleotides = GENETIC CODE

Replication of DNA During cell division a copy of DNA must be made When new cells are formed each new cell gets an exact copy of the genetic information. This copy of DNA is made through a process known as Replication.

Let’s see DNA Replication at Work!

Steps of Replication During replication, each strand serves as a pattern to make new DNA molecule. The 2 nucleotide strands separate at base pairs. They unzip like a zipper using DNA Helicase (enzyme) Each strand then builds its opposite strand by base pairing with nucleotides that float freely in the nucleus. Each new DNA molecule has 1 nucleotide strand from the original DNA molecule and 1 nucleotide strand made from free nucleotides in the nucleus.

DNA Replication Original strand DNA polymerase New strand Growth Replication fork Replication fork Nitrogenous bases New strand Original strand

Write 3-4 Sentences for your summary! Side Questions How do nitrogen bases pair up? Why do organisms look so different? What is DNA replication? What are the main steps of DNA replication? Write 3-4 Sentences for your summary!