Chapter 15 General Biology 1

Chapter 15: General Biology 1 • Alkaptonuria is an inherited disease and the patients with this disease produce urine that contains homogentisic acid. • If an arginine nutritional mutant can grow on minimal media, supplemented with ornithine, we can conclude which of the following? This mutant has a mutation in the argE gene. • Which of the following refers to the RNA-to-protein step in the expression of genes? Translation • In transcription, the DNA strand that is not copied is called the coding strand. • Translation, which takes place on the ribosome, is the synthesis of protein from an RNA transcript • Archibald Garrod concluded that patients suffering from alkaptonuria lack the enzyme necessary to catalyze the breakdown of homogentisic acid. • Consider the pathway for synthesis of arginine from glutamate by Neurospora)crassa. A mutant for the argG gene will be able to grow on minimal media supplemented with which of the following? Arginine and Arginosuccinate • In transcription, which DNA strand has a sequence that is identical to the produced RNA (except RNA contains U and DNA contains T)? The sense strands • Identify the physician who, in the early 1900s, proposed a relationship between genes and the production of enzymes. Archibald Garrod • When scientists synthesized an RNA molecule made of U (polyU) and translated it in cell-free translation systems, they produced a protein made of a string of the same amino acid • Ribosomes cannot directly process DNA to synthesize polypeptides; they can only translate a specific type of RNA transcript, the messenger RNA • The universality of the genetic code is one of the strongest pieces of evidence suggesting that all living things share a common evolutionary heritage • How many nucleotide bases are in one codon? 3 • How was the genetic code deciphered? By using cell-free biochemical systems to produce proteins based on synthetic mRNAs • In a bacterial transcription unit, the role of the promoter is to form a recognition and binding site for the RNA polymerase • The region containing the RNA polymerase, the DNA template, and the growing RNA transcript is called the transcription bubble • What is the nature of terminators in bacteria? They are specific sequences in DNA • How many RNA polymerases are found in prokaryotes (please answer by only entering a number)? 1 • The genetic code is read in groups of three nucleotide bases known as codons • In prokaryotes, how do translation and transcription occur? They are coupled • What is the function of the promoter in a bacterial transcription unit? To form a recognition and binding site for RNA polymerase • Choose all statements that accurately describe the transcription bubble: It contains an RNADNA hybrid, about 9 nt long; the growing RNA strand protrudes from the bubble; and it moves along the DNA at a rate of about 50 nt/sec • The end of a bacterial transcription unit is marked by a terminator sequence • Transcription and translation of an mRNA molecule occur simultaneously in prokaryotes • Before it can bind to the promoter, a eukaryotic RNA polymerase II has to be recruited by several transcription factors • In the transcription elongation complex of eukaryotes, what is the function of the CTD? It acts as a platform, which recruits elongation factors and RNA-modifying enzymes • Most mature eukaryotic mRNAs have a string of nucleotides referred to as a poly-A tail • In the transcription elongation complex of eukaryotes, what is the CTD made of? It consists of 7 amino acids repeated many times • Eukaryotic genes may contain non-coding regions known as introns because they interrupt the sequence of a gene • To create a functional RNA, the pre-mRNA undergoes a process known as splicing. During the splicing process, the introns are removed and the remaining exons are connected to each other • The start codon of an mRNA specifies which of the following amino acids? Methionine • Select the functions of the ribosome: Forming peptide bonds and decoding the transcribed message • Which of these is not a modification of eukaryotic transcripts? 3'cap • Charged tRNAs are brought to the A site in the ribosome by an elongation factor called EF-Tu • In translation termination, stop codons are recognized by a protein known as a release factor • Which of the following describes how proteins are targeted for translation to the rough ER? The initial amino acid sequence of these proteins serves as a signal sequence that targets them to the rough ER • What type of mutation happens when a single base in DNA is substituted with another base, for example, an A becomes a G? Point mutation • Chromosomal mutations are changes that alter the structure of the chromosome itself • 1) SNV mutations, 2) Indels, 3)Mobile element insertion, 4)CNV mutation