For "JOYMERCY" Only!!! Assign #4

12/16/2011

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Central Dogma An extremely important theory in biology.

 The relationship between nucleic acids and proteins.

 Genotype → Phenotype

 DNA → RNA → Proteins

 This was first proposed by Watson and Crick.

12/16/2011

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Be able to compare DNA with RNA.

DNA

Adenine

Guanine

Cytosine

Thymine

RNA

Adenine

Guanine

Cytosine

Uracil

Genes don’t always express themselves.

 It wasn’t long after DNA was discovered that researchers found “controls” of genes.

 Repressor genes

 Any element that controls gene expression.

 Promotor genes  Any element that initiates gene expression.

12/16/2011

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Making proteins in your cell.  You are a eukaryote.

 Your cells have a nucleus and a cytoplasm.

 Your DNA is in your nucleus.

 Your proteins are made in your cytoplasm.

 Problem: Getting the genetic information from your nucleus to your cytoplasm.

Building proteins has two steps.  Transcription  Occurs in the nucleus.

 Takes the message in DNA, and turns it into RNA.

 Translation  Occurs in the cytoplasm.

 Takes the RNA message and makes proteins.

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Transcription  The part of the DNA which codes for the needed protein

has to be exposed.

 RNA Polymerase reads DNA, and places correct RNA nucleotides into place.

 This message must be sent to the cytoplasm.

Major types of RNA:

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First step: The gene needs to be exposed…

Promotor region is identified. The needed gene.

OK.. Lets make proteins! Three steps in transcription.

 Initiation  This is when protein synthesis is started.  “Start codon” AUG

 Elongation

 This is when the protein grows as it is being built.

 Termination

 This is when the protein is finished.  “Stop codons” UAA, UAG, UGA

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Initiation The promoter region is flagged.

RNA Polymerase can then begin.

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More than one mRNA can be made.

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RNA has been made… now what?

 The RNA molecule has to be modified.

 hnRNA → mRNA

 This is called “Eukaryotic Processing”

Eukaryotic Processing

 Exons are cut out.

 Introns are “glued” together.

 The “head” and “tail” regions are modified.

 The hnRNA has now been converted into the mRNA.