DNA & Replication Headings Vocabulary Important Words

CHROMOSOME CHROMATIN DNA NUCLEUS

Structure of DNA (DeoxyriboNucleic Acid) Using critical info from the work of others (Rosalind Franklin & Linus Pauling)…Rosalind Franklin James Watson & Francis Crick made 1 st 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!!!”

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

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 What Is the “Ladder”?

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

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

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

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 Why Do Organisms Look So Different?

Replication of DNA copyDuring cell division a copy of DNA must be made exact copyWhen new cells are formed each new cell gets an exact copy of the genetic information. Replication.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. 1.The 2 nucleotide strands separate at base pairs. DNA Helicase (enzyme)They unzip like a zipper using DNA Helicase (enzyme) 2.Each strand then builds its opposite strand by base pairing with nucleotides that float freely in the nucleus. 3.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 Growth Replication fork DNA polymerase New strand Original strand DNA polymerase Nitrogenous bases Replication fork Original strand New strand