This document discusses the key discoveries and components of DNA. It explains that DNA contains the genetic instructions that make each individual unique and determines traits like appearance. It also notes that while DNA is found primarily in the nucleus of cells, small amounts are also present in mitochondria and prokaryotes. The document outlines Chargaff's rules on nucleotide base pairing and how Rosalind Franklin's and Watson and Crick's work led to the discovery of DNA's double helix structure. Finally, it defines nucleotides as the building blocks of DNA and their components.

1. Charles Rosenthal

2.  Follow me onTwitter @_SwagScience_

3.  Deoxyribonucleic acid
 DNA is the hereditary material found in
humans and almost all other organisms
 DNA contains the biological instructions that
make each individual unique
 DNA is what gives people their traits such as
hair and eye color, height, health.
 “It’s in your genes!”

4.  True or false……….DNA is only found in the
nucleus of the cell…….
 False

5.  In eukaryotes (organisms with a nucleus)
DNA is found in the nucleus
 Complex organisms like humans have a small
amount of DNA in structures known as
mitochondria
 In prokaryotes, DNA is found in the nucleoid.

6.  Erwin Chargaff
 Discovered molecular structure for DNA
 Chargaff’s rules
▪ The number of Adenine nucleotides equals the number ofThymine
nucleotides
▪ The number of Guanine nucleotides equals the the number of Cytosine
nucleotides
▪ The number of Purines (Adenine and Guanine) always equal the number of
Pyrimidines (Thymine and Cytosine)
▪ Adenine always pairs withThymine, and Cytosine always pairs with
Guanine

7.  True or false……..In a DNA molecular
structure Adenine always pairs withThymine
and Cytosine always pairs with Guanine
 True

8.  Rosalind Franklin
 Studied DNA fibers using X-ray crystallography
 Discovered that DNA must be in a helix structure
 Original hypothesis was that shape was double helix
 Later revised hypothesis to state that the shape of DNA was a triple
helix

9.  Watson and Crick
 Discovered structure of DNA in 1953
 Used Chargaff’s and Franklin’s discoveries to come to their
conclusion
 Used toy models to discover true shape of DNA
 Discovered shape was a double helix

11.  Nucleotides
 Nucleotides are the building blocks of DNA
 Twitter Question:The nucleotides that make
up DNA are classified into groups called
Purines and Pyrimidines
 True
 Adenine and Guanine are Purines
 Thymine and Cytosine are Pyrimidines

12.  Nucleotide has 3 parts
 Deoxyribose sugar
 Nitrogenous base
▪ Adenine, Guanine,Cytsoine,Thymine
 Phosphate group
▪ Phosphate in the middle, oxygen on the outside

13.  How many nucleotides “make up” DNA?
 4

14.  Purines
 Have 2 Carbon chains
 Adenine
 Guanine

15.  Pyrimidines
 Have 1 Carbon chain
 Cytosine
 Thymine

16.  The DNA double helix is formed when
nucleotides are bonded together through…..
 A- Covalent Bonding
 B- Hydrogen Bonding
 B- Adenine bonds withThymine and Guanine
bonds with Cytosine through hydrogen bonds

17.  How many carbon chain(s) do Purine
nucleotides have?
 2

18.  How many carbon chains do Pyrimidine
nucleotides have?
 1

19.  DNA is short for Deoxyribonucleic acid
 DNA is what makes you, you
 DNA is found in the nucleus, the nucleoid,
and in mitochondria
 Nucleotides are the building blocks of DNA
 Nucleotides are made up of a deoxyribose
sugar, a nitrogenous base, and a phosphate
group