DNA (Deoxyribonucleic Acid)

Purpose of DNA: stores and transmits genetic information from parent to offspring DNA stands for DEOXYRIBONUCLEIC ACID Size of Chromosome and nitrogen bases: http://learn.genetics.utah.edu/content/begin/cells/scale/

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

(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)

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

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

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

CHARGAFF’S RULE: In DNA: “A” always pairs with “C” always pairs with http://learn.genetics.utah.edu/content/begin/dna/builddna/ “T” T A “G” G C

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

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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

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

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

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