Ch 12 DNA and RNA. Frederick Griffith's Experiment. DNA Structureand REplication.notebook. May 02, 2012

Transcription

1 Ch 12 NA and RNA 12.1 NA A. Genetics Study of Inheritance and the passing down of Inherited Characteristics. NA is passed down from parents to offspring on Chromosomes= Long strands of NA B. In order to understand how NA functions as the molecule of Inheritance we must first know its structure Obj: To understand how technology enhanced our understanding of Genetics C. iscovering NA Structure 1. Thomas Hunt Morgan= Using a microscope...discovered chromosomes Chroma Soma ark Body 2. Frederick Griffith (1928) Transformation Experiment Searching for a cure for neumonia Two types of neumonia Bacteria Smooth/Encapsulated isease causing Rough/Nonencapsulated Non disease causing Frederick Griffith's Experiment Searching for a cure for neumonia= Transformation Factor (id not know it was NA) 3. Oswald Avery (1944) Repeated Griffith's experiment but with new technology. Used enzymes to denature chemicals they knew existed in pneumonococcus bacteria Carbs, roteins, lipids, RNA None of these showed any change NA Transormation was blocked By using emergent technology he was able to identify Griffith's Transforming Factor as NA 1

2 4. Hershey and Chase (1952) Used emerging technology to verify the work of Avery and Griffith and positively identify NA as the genetic molecule Virologists study the effect of Virus's Bacteriophage type of virus that destroys bacteria Bacteriophage attacking E. Coli bacteria Knew a Virus was made of two chemicals rotein and NA rotein contains a high amount of Sulfer (S) NA contains a high amount of hosphorous () Both of these chemicals have radioactive isotopes unstable forms of the element that give of energy that can be traced (Markers) Used 32 and S 35 to label the rotein and the NA of the Virus T2 At the end of the experiment they looked to see which chemical was in the E. Coli Bacteria. They found the 32 in the Bacteria What does that Mean? 2

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4 The Hershey Chase Experiment 5. Erwin Chargaff and Chargaff's Rules rior to its discovery as the genetic molecule a chemist by the name of Chargaff was studying NA He determined that NA was made up of four chemicals called Nucleotides They were Adenine (A) Guanine (G) Cytosine (C) Thymine (T) He also determined that the amount of Adenine was equal to the amount of Thymine and the amount of Guanine was equal to the amount of Cytosine A=T G=C 4

5 6. Rosalind Franklin (Early ) Used new technology known as x ray imagery to take a photo of the NA molecule F. Watson and Crick (1953) Saw Franklin's photo and knew Chargaff's rules and immediately knew what it meant The structure of NA was a ouble Helix ouble stranded molecule made up of eoxyribose sugar and hosphate backbone with Nitrogenous bases as the cross pieces. Its structure immediately showed how it could be replicated during Mitosis and Meiosis 5

6 12.2 NA Structure and Replication A. NA Structure " ouble Helix" 2 Main Areas: 1. Backbone hosphates Groups eoxyribose Sugar 2. Rungs= Nitrogenous Bases Adenine (A) A Guanine (G) G Cytosine (C) C Thymine (T) T These things form the monomers of NA= A Nucleotide Backbone Rung Nucleotide Adenine A NA is ouble stranded the two strands are held together by a weak hydrogen bond Base airing: 5' 3 ' G C 3 ' 5' A always base pairs with T G always base pairs with C T A Two strands are Antiparallel A T C G T A 5' 3 ' G C 3 ' 5' 6

7 NA Replication: NA must be copied prior to its passing down to offspring (Mitosis and Meiosis) Three Step rocess 1. Supercoiled NA is unwound and unzipped by an enzyme Helicase 2. Complementary bases are added according to the rules of base pairing. The new strand is synthesized in 5' to 3' direction NA olymerase 3. Two new molecules are completed Each strand contains a parent strand and a daughter strand Simplified Overview of Replication Replicated NA contains an original strand (Template Strand) and a newly synthesized complementary strand (aughter Strand) NA Replication does not begin at one end and end at the other Happens at many locations at one time known as Replication Bubbles 7

8 12.3 RNA and rotein Synthesis A. Flow of Genetic Information NA RNA rotein Central ogma All living things play by the same genetic rules and read the same genetic code B. RNA NA is the original copy of all the genetic information and therefor must be protected It cannot leave the nucleus= roblem roteins are made in the Ribosomes which are located outside the nucleus It requires a messenger= RNA RNA is different form NA in 3 ways 1. Single stranded 2. Ribose sugar 3. Uracil replaces Thymine (Same function slightly different shape) 3 Types of RNA 1. mrna (Messenger) carries NA instructions to Ribosomes 2. rrna (Ribosomal) made in Ribosomes to help construct Ribosomes 3. trna (Transfer) used to aid in building roteins 8

9 C. Transcription rocess by which NA is converted to mrna Very similar to NA Replication roduce single stranded mrna Molecule Transcription is carried out by the enzyme RNA olymerase It will identify the region of the gene to begin at= romoter 9

10 . Translation Uses trna to arrange amino acids in the correct order according to mrna sequence Builds a functional rotein Ribosome has three sites A Attachment (where trna attaches) olypepetide (where rotein is assembled) E Exit (where trna exits to get more amino acids) trna structure 10

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13 E. Enzymes Involved in NA Replication 13

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15 mrna to Amino Acid ictionary 15

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