Unit #8: Gene Expression Flashcards
How do cells communicate locally?
Through gap junctions/plasmodesmata, direct cell to cell interactions and interstitial fluid.
How do cells communicate long distance?
Through hormones, in animals, they travel through blood.
What are the three stages of signalling?
Reception, Transduction and Response.
Where does reception occur?
In the cell membrane when a signaling molecule binds to a receptor protein.
What is transduction?
The information from the signaling molecule travelling down a phosphorylation cascade, which continues until the target protein is reached.
What is the response?
Turning the gene on and off.
In transcription, what direction is the RNA synthesized if the DNA is read 3’ to 5’?
5’ to 3’
What direction does the ribosome read the RNA in?
5’ to 3’
Describe transcription initiation.
Transcription factors bind to promoters which allow for the binding of RNA Polymerase.
Describe transcription elongation.
RNA Polymerase unwinds the DNA, and adds nucleotides to the 3’ end of the RNA.
Describe RNA Modification.
Introns cut out by spliceosomes, the 5’ cap is added and the Poly-A-Tail is added at the 3’ end.
Where do transcription and mRNA modification occur?
Nucleus
What are spliceosomes?
Enzymes made up of snRNPs that splice mRNA.
How many anticodons are there?
61
What is the difference between peptidyl-tRNA and aminoacyl-tRNA.
Peptidyl-tRNA contains peptide chain while aminoacyl-tRNA contains single a^2.
What is Aminoacyl-tRNA Synthetase
Enzyme that loads aminoacyl-tRNA with appropriate a^2
How many Aminoacyl-tRNA Synthetase are there?
20, a unique one for each a^2
What occurs when a STOP codon is reached in translation?
Release factors enter the A space in the ribosome, hydrolyzing the complex, breaking it apart, and releasing the peptide.
How are proteins destined for the endomembrane system differentiated?
Tagged with a signal peptide, which will then recognize a signal recognition particle on the membrane which “escorts” the peptide into endomembrane system.
Where does posttranslational modification occur if the protein is meant to stay in the endomembrane system? Where if its not meant to?
Golgi if stays in endomembrane system if not, then cytoplasm.
