BIO 121 Lecture Notes - Lecture 14: Sister Chromatids, Cleavage Furrow, Centromere
23 Mar 2018
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Document Summary
A ribosome has three binding sites for trna. The p site holds the trna that carries the growing polypeptide. The a site holds the trna that carries the next amino acid to be added to the chain. The e site is the exit site, where discharged trna"s leave the ribosome. Translation proceeds along the mrna in a 5" to 3 direction. The ribosome and mrna move relative to each other codon by codon. The elongation cycles takes less than a tenth of a second. Elongation continues until a stop codon in the mrna reaches the a site of the ribosome. Mutations are changes in the genetic information of a cell. Point mutations are changes in just one nucleotide paro of a gene. The changes of a single nucleotide in a dna template strand can lead to the production of an abnormal protein. Substitutions: nucleotide pair substitution replaces on nucleotide and its partner with another pair of nucleotides.
