PCB 3023 Exam 2: Transcription and Translation Questions And Answers Graded A+

alternative splicing - - Splicing of introns in a pre-mRNA that occurs in different ways - leads to different mRNAs that code for different proteins - Increases the diversity of proteins. dna transcription vs replication - - replication synthesizes new (daughter) DNA - transcription of DNA forms RNA does the structure of the DNA (nucleosomes) impact the ability of the RNA polymerase to transcribe genes? - - yes - tightly bound nucleosomes, it's harder to get to the DNA so there is less expression - DNA is more exposed when the histones aren't packed together so tightly what direction does transcription proceed? - RNA is synthesized 5' to 3' what nucleotides are used in RNA synthesis? - - adenine - guanine - cytosine - uracil what is a promoter in RNA transcription? why is it important? - - promoter: a sequence in the DNA where the transcription is initiated - importance: control the binding of RNA polymerase to DNA Transcription steps - 1. Initiation 2. Elongation 3. Terminationwhat is an intron? - - a segment of a DNA or RNA molecule that does not code for proteins and interrupts the sequence of genes. what is an exon? - - An expressed sequence of DNA; codes for a protein is it true that one gene codes for one protein? - - no, genes can code for a number of proteins what happens after mRNA as been transcribed in euks? - - mRNA is exported to the cytosol for processing which includes: capping of the 5' end, splicing, and polyadenylation of the 3' end what is alternative splicing? how does this impact the protein which will be produced by the transcript - - mRNA processing events that lead to different combinations of exons being spliced together - the protein will be changed binding proteins - - stabilize separate strands - TFIIH, TFIID -> TBP general transcription factors - - TATA box in the promoter - binding proteins - RNA polymerases mRNA - - messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome tRNA - - transfer RNA; type of RNA that carries amino acids to the ribosome rRNA - - ribosomal RNA; type of RNA that combines with proteins to form ribosomessnRNA - small nuclear RNA; Found only in the nucleus of eukaryotes and functions to remove introns from mRNA promoter - - specific region of a gene where RNA polymerase can bind and begin transcription coding region - - part of a gene that contains the coded information for making a polypeptide chain terminator - - A special sequence of nucleotides in DNA that marks the end of a gene - It signals RNA polymerase to release the newly made RNA molecule, which then departs from the gene