modification of genes and proteins

MODIFICATION OF GENES AND PROTEINS Brian Fitzgerald, Sam Kutana, and George Rakushkin

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.

Summery of Transcription and Translation

Transcription starts when RNA polymerase attaches itself to the promoter region of the DNA

Initiation of Transcription

After initiation, RNA polymerase unwinds the double helix of DNA. The unwound strand becomes a template on which a new RNA strand is synthesized

Elongation

After the pre-mRNA is created with transcription, it is processed by enzymes in the nucleus

Transcript Processing

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

Translation

An unfolded amino-acid chain folds itself as hydrophobic (black) peptides flee the watery cytoplasm.

Spontaneous Protein Folding

Because proteins are so complex, they must follow specific intermediate steps in order to achieve a complete folding

Intermediate Steps

Direct reversal is being used to repair damage done to a piece of DNA. Direct reversal is also used to reverse methylation

Direct Reversal

When nucleotides on only one side of a DNA strand are damaged, the cell can use the other side as a template for

replacement

Single- Strand Repair

Homologous recombination is being utilized to repair a double-strand break. Blue indicates broken DNA and red indicates that DNA’s sister chromatid

Double – Strand Break Repair

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

RNA Interference

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

Cellular response to double stranded RNA (dsRNA)

Medical Applications of RNAi - Cancer - Lou Gehrig’s Disease - Huntington’s -Alzheimers

- Gene Identification