ch 12 dna and rna - northern highlands regional high school · 2015-05-13 · ch 12 dna and rna...

DNA Structureand REplication.notebook

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Ch 12 DNA and RNA

12.1 DNAA. Genetics Study of Inheritance and the passing down of Inherited Characteristics.

DNA is passed down from parents to offspring on Chromosomes= Long strands of DNA

B. In order to understand how DNA functions as the molecule of Inheritance we must first know its structureObj: To understand how technology enhanced our understanding of

GeneticsC. Discovering DNA Structure

1. Thomas Hunt Morgan= Using a microscope...discovered chromosomesChroma Soma Dark Body

2. Frederick Griffith (1928) Transformation ExperimentSearching for a cure for Pneumonia

Two types of Pneumonia BacteriaSmooth/Encapsulated Disease causingRough/Nonencapsulated Nondisease causing

Searching for a cure for Pneumonia= Transformation Factor (Did not know it was DNA)

3. Oswald Avery (1944)Repeated Griffith's experiment but with new technology.Used enzymes to denature chemicals they knew existed in pneumonococcus bacteriaCarbs, Proteins, lipids, RNA None of these showed any changeDNA Transormation was blocked By using emergent technology he was able to identify Griffith's Transforming Factor as DNA

Frederick Griffith's Experiment


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Bacteriophage attacking E. Coli bacteria

4. Hershey and Chase (1952)Used emerging technology to verify the work of Avery and Griffith and positively identify

DNA as the genetic moleculeVirologists study the effect of Virus'sBacteriophage type of virus that destroys bacteria

Knew a Virus was made of two chemicals Protein and DNAProtein contains a high amount of Sulfer (S)DNA contains a high amount of Phosphorous (P)

Both of these chemicals have radioactive isotopes unstable forms of the element that give of energy that can be traced (Markers)

Used P32 and S35 to label the Protein and the DNA 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 P32 in the BacteriaWhat does that Mean?


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The HersheyChase Experiment

5. Erwin Chargaff and Chargaff's Rules Prior to its discovery as the genetic molecule a chemist by the name of Chargaff was studying DNAHe determined that DNA 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=TG=C


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6. Rosalind Franklin (Early 19511952)Used new technology known as xray imagery to take a photo of the DNA molecule

F. Watson and Crick (1953)Saw Franklin's photo and knew Chargaff's rules and immediately knew what it meantThe structure of DNA was a Double Helix

Double stranded molecule made up of Deoxyribose sugar and Phosphate backbone with Nitrogenous bases as the cross pieces.

Its structure immediately showed how it could be replicated during Mitosis and Meiosis


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A. DNA Structure " Double Helix"

2 Main Areas:1. Backbone

Phosphates GroupsDeoxyribose Sugar

2. Rungs= Nitrogenous BasesAdenine (A)

Guanine (G)

Cytosine (C)

Thymine (T)

These things form the monomers of DNA= A Nucleotide

D

P

A

G

C

T

DNA is Double stranded the two strands are held together by a weak hydrogen bond

PBackbone

DA

Nucleotide Adenine

Rung

P

D

P

D

G

T

A

C

T

G

P

D

P

D

P

D

P

D

P

D

P

D

P

D

P

D

P

D

P

D

A

A

C

C

T

G

Base Pairing:

A always base pairs with TG always base pairs with C

Two strands are Antiparallel

3'

5'

5'

3'

3'

5'

3'

5'

P

D

12.2 DNA Structure and Replication


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DNA Replication:DNA must be copied prior to its passing down to offspring (Mitosis and Meiosis)Three Step Process

1. Supercoiled DNA is unwound and unzipped by an enzyme Helicase2. Complementary bases are added according to the rules of base pairing.

The new strand is synthesized in 5' to 3' directionDNA Polymerase

3. Two new molecules are completedEach strand contains a parent strand and a daughter strand

DNA Replication does not begin at one end and end at the other

Happens at many locations at one time known as Replication Bubbles

Simplified Overview of Replication

Replicated DNA contains an original strand (Template Strand) and a newly synthesized complementary strand (Daughter Strand)


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12.3 RNA and Protein Synthesis

A. Flow of Genetic InformationDNA RNA ProteinCentral Dogma

All living things play by the same genetic rules and read the same genetic code

B. RNADNA is the original copy of all the genetic information and therefor must be protected

It cannot leave the nucleus= Problem Proteins are made in the Ribosomes which are located outside the nucleusIt requires a messenger= RNA

RNA is different form DNA in 3 ways1. Single stranded2. Ribose sugar3. Uracil replaces Thymine (Same functionslightly different shape)

3 Types of RNA1. mRNA (Messenger) carries DNA instructions to Ribosomes2. rRNA (Ribosomal) made in Ribosomes to help construct Ribosomes3. tRNA (Transfer) used to aid in building Proteins


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C. Transcription

Process by which DNA is converted to mRNAVery similar to DNA Replication

Produce single stranded mRNA Molecule

Transcription is carried out by the enzyme RNA PolymeraseIt will identify the region of the gene to begin at= Promoter


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D. TranslationUses tRNA to arrange amino acids in the correct order according to mRNA sequenceBuilds a functional Protein

Ribosome has three sitesA Attachment (where tRNA attaches)P Polypepetide (where Protein is assembled)E Exit (where tRNA exits to get more amino acids)

tRNA structure


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E. Enzymes Involved in DNA Replication


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mRNA to Amino Acid Dictionary


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ch 12 dna and rna - northern highlands regional high school · 2015-05-13 · ch 12 dna and rna...

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