1. DNA (Deoxyribonucleic Acid)

2. Purpose of DNA:
stores and transmits genetic information from parent to offspring
DNA stands for
DEOXYRIBONUCLEIC ACID
Size of Chromosome and nitrogen bases:

3. DNA is wrapped tightly around histones (proteins) and coiled tightly to form chromosomes3

4. (a library of about 1,000 books)
AMAZING DNA FACTS…
DNA from a single human cell extends in a single thread for almost 2 metres long!!!
It contains information equal to some 600,000 printed pages of 500 words each!!!
(a library of about 1,000 books)

5. Discovery of the DNA double helix
Friedrich Miescher – started investigating a compound he found in the nucleus of cells, called it “nuclein” (1869)
Rosalind Franklin - X-ray photo of DNA. (1952)
Watson and Crick - described the DNA molecule from Franklin’s X-ray. (1953) 5

6. DNA consists of: a 5-carbon/pentose sugar called deoxyribose
a PO4 group or phosphate
a nitrogen containing base

7. There are 4 different bases in DNA:
Purines
Adenine (A) Guanine (G)
Pyrimidines
Thymine (T) Cytosine (C)

8. CHARGAFF’S RULE: In DNA: “A” always pairs with “C” always pairs with
“T” T A
“G” G C

9. DNA Base Pairs
Adenine (A) always bonds with Thymine (T)
Guanine (G) always bonds with Cytosine (C) 9

10. 10

11. Overall Structure of DNA
Nitrogenous
Base (A,T,G or C)
“Rungs of ladder”
“Sides of ladder”
Phosphate &
Sugar Backbone
Double helix looks like a twisted ladder 11

12. DNA Double Helix P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A 12

13. Video Clip: Genetics 101 Part 1: What are Genes?
Watch the video and answer the following questions.
Where is almost all of the DNA found in the cell?
A gene is made up of a section of DNA that has the instructions to make a protein. How many genes are thought to be found in human DNA?
If you lined up the all of your DNA in a straight line, how many feet long would it measure?
How does DNA structure determine what you look like?
How many chromosomes do the following species have?
Species
Total # of Chromosomes
# of Pairs of Chromosomes
humans 46 23
Chickens 78
chimpanzees 24
Fruit Flies 4
Rhesus monkeys 42
Bananas 22
Cows 30

14. Create a list of terminology to help you.
Use this website or your notes to answer the following questions:
Where are the instructions for life located?
What does DNA stand for?
What kind of bonds hold the bases together?
Why is DNA called a blueprint?
The "twisted ladder" shape of the DNA molecule is called a ___________ ____________
Name the four bases found in a DNA molecule.
What do genes tell the cell to do?
What is a gene? (Hint - Look at the navigation bar at the top, you'll need to click on "What is a Gene)
How many genes do we have?
What happens if the hemoglobin gene is mutated?
What is a chromosome?
How long is the DNA in the nucleus of one cell? 14