Modification of Genes and Proteins - sharonap-cellrepro-p3

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Transcript Modification of Genes and Proteins - sharonap-cellrepro-p3

Brian Fitzgerald, Sam Kutana, and George Rakushkin
Summery of Transcription and Translation
mRNA is synthesized in the nucleus using unwound DNA, travels to tRNA in the
cytoplasm, and is “decoded” to create a chain of amino acids.
Initiation of Transcription
Transcription starts when RNA polymerase attaches itself to the promoter region of
the DNA
After initiation, RNA polymerase unwinds the double helix of DNA. The unwound strand
becomes a template on which a new RNA strand is synthesized
Transcript Processing
After the pre-mRNA is created with transcription, it is processed by enzymes in the
After the mRNA is synthesized and released, it is fed through tRNA and creates a
chain of amino acids based on codons in the mRNA
Spontaneous Protein Folding
An unfolded amino-acid chain folds itself as hydrophobic (black) peptides flee the
watery cytoplasm.
Intermediate Steps
Because proteins are so complex, they must follow specific intermediate steps in
order to achieve a complete folding
Direct Reversal
Direct reversal is being used to repair damage done to a piece of DNA. Direct
reversal is also used to reverse methylation
Single- Strand Repair
When nucleotides on only one side of a DNA strand are damaged, the cell can use
the other side as a template for replacement
Double – Strand Break Repair
Homologous recombination is being utilized to repair a double-strand break. Blue
indicates broken DNA and red indicates that DNA’s sister chromatid
RNA Interference
If “fishy” mRNA is discovered in a cell, all copies of the gene that would produce
the mRNA are destroyed. This protects against viral duplication
Cellular response to double stranded RNA (dsRNA)
When a cell comes in contact with dsRNA, it is chopped up into smaller segments and
then used to identify and destroy any RNA produced by the dsRNA
Medical Applications of RNAi
- Cancer
- Lou Gehrig’s Disease
- Huntington’s
- Gene Identification