ch. 11.1: genes are made of dna
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Ch. 11.1: Genes are made of DNAObjectives:
• Describe historic discoveries that lead to the understanding that DNA is responsible for heredity
Scientists:
Griffith, Avery, Hershey & Chase
Vocab.: virus, bacteriophageBill Nye’s Greatest Discoveries:
http://www.youtube.com/watch?v=vP_h08cT5jw
http://www.youtube.com/watch?v=p9M5xJTs-zY&feature=related
http://www.youtube.com/watch?v=x-0P_DIeHBs&feature=related
• 1928s• Result: Genetic material can be
transformed!• What molecule controls genes: Protein or
DNA?
http://www.youtube.com/watch?v=9R2Zp7IHNZo
http://www.youtube.com/watch?v=vQOdDGM5vSg&feature=related
AVERY: Determines identity of “Transforming Factor”
(enzyme that denatures proteins)
(enzyme that denatures DNA)
(Not Protein!)
Hershey & Chase: Prove DNA = Genetic material
1952: Experiments using BACTERIOPHAGE (virus that attacks bacteria)
Virus: Nucleic acid inside a protein coat (no cells)
Virus: injects its DNA into living organisms; viral DNA hijacks cells to make more viruses
Radioactively label protein coat or DNA; ONLY radioactive DNA is INSIDE DAUGHTER CELLS.
http://www.youtube.com/watch?v=YG3d77SRWZI
11.2: Structure of DNA
Objectives:
1. Identify the building blocks of DNA.
2. Describe DNA’s structure and the rules for base pairing in DNA.
Vocab: Deoxyribonucleic acid (DNA), nucleotide, Nitrogenous base, pyrimidine, purine, double helix
DNA: Deoxyribonucleic Acid
DNA structure: http://www.youtube.com/watch?v=ZGHkHMoyC5I
Bill Nye: http://www.youtube.com/watch?v=V9BZ3zx8b8I&feature=related
DNA molecule: polymer made of thousands of nucleotides.
Nucleotide: Building block (monomer)
1. 5-C sugar: Deoxyribose
2. Phosphate group
3. Nitrogen base
BasesTypes
1. Pyrimidines: single ring
• Thymine (T)
• Cytosine (C)
2. Purines: Double ring
• Adenine (A)
• Guanine (G)
Base Pairing Rules: A = T; C = G (Chargaff discovery).
H-bonds attract pairs together.
DNA StructureBackbone (Sides of “Ladder”)
1. Sugar
2. Phosphates
Rungs of Ladder
Complementary Bases
DNA Function• Store genetic info.
• Self-duplication
• Expression of genes (inherited traits)
DNA’s major function = CODE FOR PROTEINS
Double Helix
Rosalind Franklin & Maurice Wilkins (1950s)
• DNA = Helix
• X-ray crystallography to “see” structure
James Watson & Francis Crick (1950s)
• “Crack Code” …determine specifics of DNA structure.
• DOUBLE HELIX
Watson & Crick Double Helix
• 2 chains of nucleotides
• 2 strands are anti-parallel
• Backbone: sugar + phosphate
• Base pairs = rungs
DNA & Chromosomes
Prokaryotes• Circular• Very small• 1 chromo. per cell• Some enzymes &
proteins are associated w/ DNA
• Not housed in nucleus
Eukaryotes• Linear• Fairly long• Several per. Cell• Nucleosome: Loops
of DNA wrapped around histone proteins
• In nucleus
11.3: DNA Replication
Objectives:
1. Explain how the template mechanism is important in DNA replication.
2. Describe the process of DNA replication.
Vocab: DNA Replication, DNA polymerase, semi-conservative
Template Mechanism
DNA replication is SEMI-CONSERVATIVE
New copies of DNA contain:
• 1 original strand
• 1 new strand
Each strand serves as a TEMPLATE to make a complementary copy (due to base-pairing rules)
DNA Replication:Making copies of DNA
Enzymes Involved:
1. Helicase: unwinds double helix
2. DNA Polymerase: Attaches new nucleotides; can only add to the 3’Carbon
3. Ligase: join fragmented copies on “lagging” strand.
Leading Strand: continuous growingLagging Strand: Fragmented; ligase joinsNEW STRANDS GROW in 5’ --> 3’ direction!
http://www.youtube.com/watch?v=AGUuX4PGlCc&feature=relatedhttp://www.youtube.com/watch?v=4jtmOZaIvS0
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