DNA: “The Blueprint of Life” Spring 2014

DNA: Scientists in History

Frederick Griffith Trying to figure out how people got sick with pnuemonia—he focused on bacteria Tested two types of bacteria: rough and smooth 1939

He noticed:

Frederick Griffith Discovered TRANSFORMATION: bacteria (circular DNA) can change by absorbing genetic material SO…scientists can engineer bacteria to make things like human insulin by putting that gene in with bacteria for them to absorb.

Oswald Avery Question: Which macromolecule is responsible for transformation? Repeated Griffith’s experiment, but used enzymes to kill one of the 4 macromolecules for each experiment Discovered - nucleic acids store and transmit genetic information. 1937

Alfred Hershey and Martha Chase  Question: How is transformation connected to bacteriophages (viruses that attack bacteria)? Is it the protein coat or the DNA/RNA that carries genetic material?  Radioactively labeled protein and nucleic acids in bacteriophages  Radioactive DNA was found in the bacterial cell while radioactive protein was not  Concluded: DNA is the hereditary material

Looking for the Structure of DNA Chargoff’s Rules : #Adenine = #Thymine #Cytosine = #Guanine WRITE THIS DOWN!

Nitrogen Bases 2 types of Nitrogen Bases Purines Double ring G & A Pyrimidines Single ring C & U & T PGA CUT PY

Looking for Structure of DNA Rosalind Franklin: Pictures of DNA - x-ray diffraction

Looking for Structure of DNA James Watson and Francis Crick: Used Franklin’s pictures, discovered structure of DNA, double helix (Nobel Prize) DNA stores information (genetic blueprint) for making proteins, these proteins determine the phenotype (physical characteristics) of an organism 1953

What is DNA? Deoxyribonucleic acid contains all the genetic information for living organisms. It is a very long molecule of repeating units called nucleotides, which contain bases of either adenine (A), guanine (G), cytosine (C), and thymine (T)

DNA or RNA Structure 3 ways to find DNA or RNA Linear - forms in a line Chromatin inside nucleus of eukaryotes Circular in prokaryotes Eukaryotes - DNA wrapped around histones (a protein) DNA and RNA DNA = deoxyribonucleic acid RNA = ribonucleic acid Deoxyribose and ribose are sugars…remember –ose?

DNA Structure Remember DNA is a type of nucleic acid, one of the 4 macromolecules DNA (polymer) = two long strands of NUCLEOTIDES (monomers). Each strand is constructed in opposite directions (5’-3’ or 3’-5’)

DNA consists of two strands of nucleotides. The two strands are complimentary to each other. This means that nucleotides on one strand pair with nucleotides on the other strand in this way: Adenine (A) pairs with Thymine (T) Guanine (G) pairs with Cytosine (C) Therefore: # of adenine nucleotides = # of thymine nucleotides # of guanine nucleotides = # of cytosine nucleotides

A Nucleotide Made of 3 parts Deoxyribose Sugar (5 Carbons) Phosphate group Nitrogen Base (2 types) Purines: (2 rings) Adenine and Guanine Pyrimidines: (1 ring) Cytosine and Thymine Hydrogen bonds hold the bases together 2 between A and T 3 between G and C

DNA: made of nucleotides O O=P-O OPhosphate Group Group N Nitrogenous base (A, T, G, C) (A, T, G, C) CH2 O C1C1 C4C4 C3C3 C2C2 5 Sugar Sugar(deoxyribose) DRAW THIS!!!

DNA - double helix P P P O O O P P P O O O G C TATA

The two strands of DNA are attached and twisted, forming what we call a double helix. The shape and structure of DNA were determined by James Watson and Francis Crick in 1953.

Base Pair Rule One side: A T A T C A T G C G G G Other side:

Let's Review What We Know About DNA 1. DNA stands for: De _____ ribo ______ acid 2. What is the shape of DNA? _______________ 3. Who established the structure of DNA? ____________ 4. Adenine always pairs with _______________ 5. The sides of the DNA ladder are deoxyribose and _____ 6. Guanine always pairs with _____________ 7. What is the complimentary sequence: A A T G C A 8. The two sides of DNA are held together by _______ bonds. 9. DNA is composed of repeating subunits called ______________________ 10. What are the 4 bases that make up the rungs of the DNA ladder? _______________________________________

Let's Review What We Know About DNA 1. DNA stands for: De _____ ribo ______ acid 2. What is the shape of DNA? _______________ 3. Who established the structure of DNA? ____________ 4. Adenine always pairs with _______________ 5. The sides of the DNA ladder are deoxyribose and _____ 6. Guanine always pairs with _____________ 7. What is the complimentary sequence: A A T G C A 8. The two sides of DNA are held together by _______ bonds. 9. DNA is composed of repeating subunits called ______________________ 10. What are the 4 bases that make up the rungs of the DNA ladder? _______________________________________ oxy Double-helix se nucleic Watson & Crick phophates Thymine nucleotides cytosine hydrogen T T A C G T Adenine, guanine= purines (double-ring) guanine, cytosine= pyrimidines (single-ring)

DNA Replication DNA must replicate in order for all genetic material to be passed from one generation to the next. DNA replication results in two molecules of DNA, each containing one original strand and one new strand. Special enzymes are used to “unzip” the two original strands, allowing free nucleotides to pair with those on the original strand, A with T and G with C. The original strand serves as a pattern for the new strand. The original strands then bond with the new strands and two molecules are formed.

DNA REPLICATION the process by which DNA makes a copy of itself (happens in the S phase of the cell cycle) SEMI-CONSERVATIVE - half of the old strand is saved

DNA Replication DNA unzips by breaking the Hydrogen bonds between the nitrogen bases DNA Polymerase: enzyme that makes the new strand of DNA Each strand gets a new complimentary strand, synthesized from free-floating nucleotides. Each strand synthesized 5’ to 3’ direction; one strand made in one direction and other strand in opposite direction Two identical strands of DNA are made

Mini-Assessment Section 12-1: Pre-Watson and Crick Read about the beginnings of Genetic Research. 1.Describe the experiments of Frederick Griffith. Date? Nationality? Define TRANSFORMATION. What was Griffith’s primary discovery? 2.Describe the experiments of Oswald Avery. Date? Nationality? What was Avery’s primary discovery? 3.Describe the experiments of Alfred Hershey and Martha Chase. Date? Nationality? Define BACTERIOPHAGE. What was Hershey and Chase’s primary discovery? 4.Define NUCLEOTIDES. What are the 4 nucleotides that make up DNA? How do these nucleotides pair in DNA?

Textbook Assignment Read Section Define HISTONE. 2.Define REPLICATION. What is a replication fork? 3.Define DNA POLYMERASE. What role does this chemical play in DNA replication? 4.Draw a diagram of a piece of DNA undergoing replication. Label the replication fork, and show the complimentary new strand of DNA that would be produced, using the letters A, C, G, T and what you know about how they pair with each other.