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Bio - Unit 3
3.7-3.10
| Question | Answer |
|---|---|
| translation | genetic info encoded in mrna is used to assemble a specific polypeptide chain occurs on a ribosome |
| anticodon | 3 nucleotide loop complementary to codon |
| amino acid attachement site | located at 3' end - holds a specific aminoacid |
| aminoacylation | before trna can participate in translation it must be charged with its correct amino acid - redult is aminoacul-trna |
| A site, P site, E site | A -arrival site (new trna enters) P - polupeptide sire (trna has polypeptide chain) E - empty trna leaves |
| stages of translation | 1. initiation 2. elongation 3. termination |
| initiation in translation | initiator met-trna forma complex with small ribosomal subunit -complex scans the mrna unit it finds the start codon -large ribosomal subunit binds to complex -met-trna is at P site |
| elongation in translation | aminoacyl-trna w anticodon to the A site binds to ribosome -peptidyl transferase cleaves aminoacid from trna in P site -polypeptide bond forms betweens aminoacid and new aminoacid in the A site |
| termination in translation | elongation continues until stop cdon enters the A site -protein relase factor binds to A site -bidnign triggers cleavage of the polypeptide chain |
| polysomes | allow the cell to produce many copies of a protein from a single mrna template very quickly |
| post translational processing | polypeptide must fold into correct 3D conformation |
| 4 levels of eukaryotic gene control | 1. transcriptional - regualte which genes are transcribed or controls rate 2.post-transcriptional - change mrna in nucleus before translation occurs 3.translational - control length of time translation takes 4.post-translational - control how long unti |
| housekeeping genes | regulate essential processes like metabolism and growth |
| operon model | cluster of genes that contains the dna sequences to regualte a specific metabolic pathway |
| structural genes | genes that code for a specific protein |
| repressor protein | a protein that binds to the operon to repress gene expression |
| low lactose | repressor protein can be found (active repressor) |
| high lactose | increased levels of lactose bind to repressor protein -repressor can no longer bind to dna and blockr na pol. (inactive repressor) |
| low tryptophan | repressor is inactive because tryptophan is needed (operon is free to translate these genes) |
| high tryptophan | tryp starts to bind incresingly to trp repressor (making it active) |
| small scale mutations | 1.subsitution 2.insertion 3.deletion 4.inversion |
| missense mutation | causes diff. aminoa cid code -can change protein function |
| nonsense mutation | causews a premature stop codon |
| silent mutation | does not alter any amino acid |
| frameshift mutation | insert/deletion leading to a reading frame shift |
| large scale mutations | 1. amplification 2.deletion 3.translocation 4.inversion 5.trinucleotide repeat expansion |
| amplification | gene is coped in the chromosome (occurs more than once) |
| translocation | entire gene moves from one chromosome to another |
| inversion (large scale) | a portion of dna molecules reverses its direction int he genome |
| trinucleotide repeat expansion | normal sequence of trinucleotide repeats and becomes unstable and expands uncontrollably |
| spontaneous mutation | error in dna replication |
| induced mutation | caused by an environmental factor |
| centromeres | found in the place where two chromosomes are held togehter once theyre copied |
| pseudogenes | mutated, vestigial version of older genes that have lost evolutionary value -serve no function -two types: LINES and SINES |
| LINES | long interspersed nuclear elements - repetitive sequences approx. 6500 BP in length |
| SINES | short interspersed nuclear elements - repeptitive sequences approx. less than 500 BP long |
| transposons | small segments of dna that moce about genome into different chromosomes |
| viral dna | significatn portion of genome comes from ancient viral infections -viruses can add thei dna randomly into genome |
Created by:
gracie.elisabeth