WARM UP #4 2/5/13 • Where did the virus originate? • A vector is an intermediate carrier for the virus. What species was the vector in CONTAGION? • What species was the 1st host for the virus? • What are the symptoms?
Components and Structure of DNA—Chromosomes and DNA Replication Chapter 12 Section 1-2
Essential Question: What makes you different from others? Objectives: Understand that chromosomes are structures in the nucleus of a cell that carry genes Understand the structure of the DNA molecule What’s This All About?
Fact Is… • A humans DNA length is approximately 3m long per cell!
DNA Background Genes—Found in Chromosomes Chromosomes—Found in Nucleus • Genes do three critical things: • Carry information from one generation to the next • Determine heritable characteristics • Easily copied and replicated
Why Do We Need DNA • DNAis often called the blueprint of life. • DNA contains the instructions for making proteins within the cell.
What DNA is? • Made up of long molecules of units called Nucleotides • Made up of: • Phosphate • 5-Carbon sugar (deoxyribose) • Nitrogenous (nitrogen containing) base • Twisted Ladder—Double Helix
Structure of a Nucleotide • Deoxyribose • Phosphate Group • Nitrogen Base
One Strand of DNA • The backbone of the molecule is alternating phosphate and deoxyribose • The teeth are nitrogenousbases. • These three parts together make up a nucleotide
Purines Two Ring Structures Adenine Guanine Pyrimidines One Ring Structure Thymine Cytosine Uracil Nitrogen BasesRungs of the ladder
Complimentary Strand • Adenine always bonds with Thymine • Cytosine always bonds with Guanine
So How are We Different? • Nitrogen bases can be arranged in any order creating lots of possibilities! • Example: ATTTCGGGGCA or CGGGAAATTT • The complimentary strand must correspond though
DNA Replication • Every time a cell divides it MUST copy itself • Each cell has a complete set of DNA molecules
Steps to Replication • An DNA polymerase (enzyme) breaks the hydrogen bonds between the nitrogen bases, unzipping it • Each strand builds its opposite strand by base pairing • End up with 2 identical DNA molecules (1 original strand—1 new strand)
DNA 3-D Model • With a partner, you will each paint 4 popsicle sticks • Let the sticks dry • Label the sticks as A-T or C-G bases • We will place pipe cleaners on them to make a double helix
Warm-Up #2 2/1/12 • What is the structure of DNA called? • What are the individual components of DNA called? • What is a gene? • Where is DNA stored?
Quiz Tomorrow Warm-Up #3 2/2/12 • What are the three components of a nucleotide? • What bond holds the nitrogen bases together? • What enzyme “unzips” DNA before replication? • Why must DNA be replicated?
What does a purine look like? What does a pyrmidine look like? What is the scientific name for DNA? What is the picture demonstrating? Warm-Up #4 2/3/12 Quiz Today
DNA Model • By the end of today: • 4 sticks are red and white • 4 sticks are blue and yellow • Dry sticks have pipe cleaner attached