GCU BIO 181- Study Guide Topic 7 (Chapters 17 & 18) latest updated

Transcription Factors - ANSWER-mediate the binding of RNA polymerase and the initiation of transcription Transcription - ANSWER-synthesis of an RNA molecule from a DNA template TATA box - ANSWER-A promoter that is crucial in forming the initiation complex in eukaryotes Introns - ANSWER-a non-coding, intervening sequence within a eukaryotic gene Exons - ANSWER-Expressed, usually translated into amino acid sequences within a eukaryotic gene Spliceosomes - ANSWER-consists of a variety of proteins and several small nuclear ribonucleoproteins (snRNPs) that recognize the splice sites Spliceosome catalytic activity - ANSWER-The RNAs of the spliceosome catalyze the splicing reaction Ribozyme - ANSWER-Catalytic RNA molecules that function as enzymes and can splice RNA Alternative RNA splicing - ANSWER-some genes encoding more than one kind of polypetide, depending on which segments are treated as exons during splicing Transfer RNA (tRNA) - ANSWER-A cell translates an mRNA message into protein with the help of __________ (tRNA) - ANSWER-transfer amino acid to the growing polypeptide in a ribosome aminoacyl-tRNA synthetase - ANSWER-First step in accurate translation by an enzyme that corrects match between a tRNA and an amino acid Wobble - ANSWER-Flexible pairing at the third base of a codon and allows some tRNS to bind to more than one codon ribosomal RNA (rRNA) - ANSWER-the two ribosomal subunits (large and small) are made of proteins and _________________ signal peptide - ANSWER-marks polypeptides destined for the ER or for secretion signal-recognition particle (SRP) - ANSWER-binds to the signal peptide, brings the signal peptide and its ribosome to the ER missense mutations - ANSWER-codes for an amino acid, but not the correct amino acid nonsense mutations - ANSWER-change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein silent mutations - ANSWER-have no effect on the amino acid produced by a codon because of redundancy in the genetic code frameshift mutation - ANSWER-produced by insertion or deletion of nucleotides may alter the reading frame Effect of mutation on a resulting protein - ANSWER-these mutations have a disastrous effect on the resulting protein more often than substitutions do George Beadle and Edward Tatum - ANSWER-developed one gene-one enzyme hypothesis accuracy transcription - ANSWER-synthesis of RNA using information, produces messenger RNA (mRNA) Translation - ANSWER-synthesis of a polypeptide, using information in the mRNA, ribosomes are the sites RNA polymerase - ANSWER-pries the DNA strands apart an joins together the RNA nuceotides, complementary to the DNA template strand, does not need any primer, follows the same base-pairing rules as DNA, except that uracil substitutes for thymine. Codon - ANSWER-mRNA base triplets are read in the 5'-3' direction during translation. Specifies the amino acid (one of 20) to be placed at the corresponding positions along a polypeptide. How many tRNA codons are there? - ANSWER-64 codons, 61 code for amino acids, 3 triplet are "stop" signals to end translation How many mRNA codons are there? - ANSWER-20 codons importance of the 3' end of the tRNA - ANSWER-nucleotides are added to the 3' end of the growing RNA molecule tryptophan - ANSWER-by default is on and the genes synthesized are transcribed, when present, it binds to the repressor protein, which turns the operon off repressible operon - ANSWER-negative gene regulation, one that is usually on, binding of a repressor to the operator shuts off transcription inducible operon - ANSWER-negative gene regulation, one that is usually off, a molecule called an inducer inactivates the repressor and turns on transcription Lactose operon - ANSWER-an inducible operon and contains genes that code for enzymes used in the hydrolysis and metabolism of lactose Epigenetic inheritance - ANSWER-the inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence examples of epigenetic inheritance - ANSWER-DNA methylation, x inactivation proximal control - ANSWER-elements that are located close to the promoter distal control elements - ANSWER-groupings of which are called enhancers, may be far away from a gene or even located in an intron repressor - ANSWER-can be in an active or inactive form depending on the presence of other molecules prevents gene transcription by binding to the operator and blocking RNA polymerase Regulatory gene prducts - ANSWER-a seperate gene that produces the repressor prokaryotic vs. eukaryotic gene expression - ANSWER-prokaryotes and eukaryotes precisely regulate gene expression in response to environmental conditions