Stuvia.com https://docs.google.com/document/d/1NtscM1UiFSrmxVNuq2Gw9FazZDueySmwoeWX0untxCA/edit Biology 1404 Exam Chapter 15 -17,21 Review Course CH15 - Genes and proteins CH16 - Gene expression CH17 - Biotechnology and genomics CH21 - Viruses CH15: GENES AND PROTEINS 15.1 ❏ The central dogma in biology explains that the flow of genetic information in cells from DNA to mRNA to protein - The nucleotide -based genetic information on mRNA is translated into a protein product ❏ There are 20 amino acids and 64 (43) possible codons found in proteins ❏ Each amino acid is defined by a 3-nucleotide sequence called triplet codon , can be found on the codon table ❏ Scientists theorized that the genetic code is universal and degenerate (an amino acid can be encoded by more than one codon) ❏ Degeneracy is believed to reduce the negative impact of random mutations ❏ The insertion of one or two nucleotides could change the entire triplet reading frame/protein reading message, causing 1) Different amino acid to be inserted 2) A non -
functional protein 3) A frameshift mutat ion ❏ During translation, the codon AUG (codes for Methionine) always serves as the start codon to initiate translating, and codons UAA, UAG, and UGA are the stop codons (or nonsense codons) terminate protein synthesis and release the polypeptide from the translation machinery 15.2 ❏ Prokaryotes are single -celled organisms with circular chromosomes and no membrane -bound organelles, they do not have DNA wrapped around histones, and can have fragments of non-chromosomal DNA called plasmids ❏ Prokaryotic DNA is found in a central part of the cell: the nucleoid
functional protein 3) A frameshift mutat ion ❏ During translation, the codon AUG (codes for Methionine) always serves as the start codon to initiate translating, and codons UAA, UAG, and UGA are the stop codons (or nonsense codons) terminate protein synthesis and release the polypeptide from the translation machinery 15.2 ❏ Prokaryotes are single -celled organisms with circular chromosomes and no membrane -bound organelles, they do not have DNA wrapped around histones, and can have fragments of non-chromosomal DNA called plasmids ❏ Prokaryotic DNA is found in a central part of the cell: the nucleoid
