Genetics Test Bank If the DNA sequence on one strand is : 5'- ATGCCGTTA- 3' i) What is the complementary strand? ii) What does 5' and 3' mean? - CORRECT ANSWERS3'-TACGGCACT-5', the beginning and end of the strand

Genetics Test Bank If the DNA sequence on one strand is : 5'- ATGCCGTTA- 3' i) What is the complementary strand? ii) What does 5' and 3' mean? - CORRECT ANSWERS3'-TACGGCACT-5', the beginning and end of the strand. During DNA replication, the DNA is split, and paired up with a replicated strand of complementary base pairs. Sometimes, this doesn't happen correctly. What errors might occur during this process? - CORRECT ANSWERSnucleotide bases may be inserted, deleted, or mismatched into the DNA strand incorrectly Why is DNA replication important for cell reproduction? Why is it important for the newly replicated daughter strand of DNA to have the same information as the parent strands? - CORRECT ANSWERSBecause all cells need DNA to function, it is important that the DNA from the parent cell is copied to allow that same parent cell to divide into daughter cells. It is pertinent that the DNA is the same in all the cells produced. Explain how the leading and lagging strands of DNA are replicated. Include a drawing. Be sure to explain why the lagging strand is more complicated to replicate. - CORRECT ANSWERSBoth act as templates Replication fork moves down strand in 1 direction: leading strand (continuous) is replicated into the fork and lagging strand goes in the opposite direction. Why is DNA repair necessary? If DNA repair does not take place what could happen? - CORRECT ANSWERSDNA provides the blueprint for the proteins our cells need to function. Serious damage could occur, including cancer. How are multiple strands of mRNA synthesized? Why is it advantageous to make multiple mRNA strands? - CORRECT ANSWERSMultiple stands of mRNA can be made from a code found in our DNA. If multiple mRNA strands are made an abundance of a specific protein will be formed using the mRNA strand as the template to translate it into a protein Would errors in transcription or errors in replication be more damaging? Explain your answer. - CORRECT ANSWERSErrors in replication would be more damaging since this means the error would be in the DNA. DNA is our code for hereditary/genetic information, as well as ultimately the code for proteins. If the DNA is damaged and not properly fixed this change will "stick", every time the DNA is replicated the error will be replicated and this could lead to a mutation. Errors in transcription (DNA to RNA) would mean that the error is in the RNA strand, this will impact the protein that should be translated from this mRNA strand, however the "real" code is still present and available in our DNA to hopefully be transcribed correctly next time. What is the role of tRNA in translation? Why is there not a specific tRNA molecule for each possible codon? - CORRECT ANSWERSused as anticodon to convert into amino acid. There is not a specific tRNA molecule for each possible codon because several codons code for the same amino acid. If one tRNA recognizes each amino acid, then it can work efficiently by recognizing all the codons that code for it. There are many more codons than there are amino acids, but a unique tRNA molecule is not needed for each one. Using words and/or diagrams, explain the process of translating mRNA to a polypeptide - CORRECT ANSWERSThe ribosome binds to mRNA at a specific area. The ribosome starts matching tRNA anticodon sequences to the mRNA codon sequence. Each time a new tRNA comes into the ribosome, the amino acid that it was carrying gets added to the elongating polypeptide chain. The ribosome continues until it hits a stop sequence, then it releases the polypeptide and the mRNA. The polypeptide forms into its native shape and starts acting as a functional protein in the cell. One of your friends tells you that he thinks biology is hard, and really doesn't get genetics. How do you explain DNA replication, transcription and translation in a way that will help him make sense of these very abstract concepts - CORRECT ANSWERSTranscription is the first step in gene expression. It involves copying a gene's DNA sequence to make an RNA performed by enzymes called RNA polymerases, which links nitrogenous bases to form an RNA strand (using a DNA strand as a template). Describe the state of the trp operon system if the level of tryptophan is high. (discuss all enzymes and proteins in the system). What would happen if tryptophan levels fall? - CORRECT ANSWERSWhen trp is high there is no need to make more, so the repressor which has trp bound to it will attach to the operator stopping RNA polymerase from transcribing the gene (trp is not made). When trp is low, trp will be made. Trp will fall off of the repressor causing it to change shape and fall off the operator, allowing RNA polymerase to transcribe the gene (make Trp) Identify the similarities and the differences between the lac operon and the trp operon systems. - CORRECT ANSWERSSame level of gene control (transcriptional). They are both regulated/controlled genes Affected/altered by the amount of product present/available in the cell The regulatory gene is where the repressor comes from