Analogy Video Central Dogma Analogy Video (Resources Page)

From Genotype to Phenotype The DNA inherited by an organism leads to specific traits, but how? Proteins are the links between genotype and phenotype. Gene Expression- the process by which DNA directs protein synthesis. Includes two stages: Transcription and Translation.

Central Dogma DNA  RNA  Protein RNA is the bridge between genes and the proteins they code for. Transcription is the synthesis of RNA using information in DNA (DNA messenger RNA) Translation is the synthesis of a polypeptide using the information in the mRNA.

Central Dogma

Transcription RNA synthesis is catalyzed by RNA polymerase which uses the DNA strands as a template to make a RNA compliment. RNA synthesis follows the same base pairing rules as DNA, except that uracil (U) substitutes for thymine (T). Transcription occurs in the nucleus of the cell.

Transcription The DNA sequence where RNA polymerase attaches is called the promoter and the sequence ending the transcription is called the terminator The stretch of DNA that is transcribed is called a transcription unit.

Three Stages of Transcription Initiation is the first stage of transcription. Transcription factors mediate the binding of RNA polymerase at the promoter and the initiation of transcription. All of the transcription factors and RNA polymerase bound to a promoter is called a transcription initiation complex. A promoter called a TATA box (a sequence of A’s and T’s) is crucial in forming the initiation complex in eukaryotes.

Three Stages of Transcription The second stage of transcription is elongation. The RNA polymerase moves along the DNA strand, untwisting it 10-20 bases at a time and creating the RNA compliment.

Three Stages of Transcription Termination is the third stage of transcription. Termination works differently in bacteria and eukaryotes. In bacteria, the polymerase stops at the end of the terminator. In eukaryotes, RNA polymerase transcribes the polyadenylation signal sequence and is released after.

Modifying RNA after Transcription Eukaryotes modify the mRNA after transcription in RNA Processing before the mRNA is sent to the cytoplasm. Both ends of the mRNA are usually altered. Some interior parts are removed while others are spliced together.

Modifications to the Ends The 5’ end of the mRNA has a 5’ cap added to it. Helps the ribosome attach to this end in translation. The 3’ end of the mRNA gets a poly-A tail Like the 5’ cap, this helps protect mRNA from hydrolytic enzymes

RNA Splicing Most eukaryotes have long non coding stretches in their genes that lie between coding regions. In RNA splicing the noncoding regions called introns are removed and the exons that code for genes that are expressed are put together. Spliceosomes consist of a variety of proteins that carry out RNA Splicing.

RNA Splicing

Animation Transcription Animation- McGraw Hill (Resources Page) http://highered.mheducation.com/sites/0072507470/student_view0/chapter3/animation__mrna_synthesis__transcription___quiz_1_.html

Modeling Central Dogma Interactive- Concord (Resources Page) Model the process of Transcription with the modeling kit provided. Write a summary of transcription after, including the steps and the enzymes involved. http://lab.concord.org/embeddable.html#interactives/sam/DNA-to-proteins/1-dna-to-protein.json