L14 GRQs Flow of Genetic information II Reading Objectives Summarize the flow of information from DNA to RNA to protein Predict how specific types of mutations in DNA will lead to alterations in the structure and function of protein Module 10 15 Review The flow of genetic information in the cell is DNARNAProtein 1 What part of the flow of information occurs in the nucleus Transcription 2 What occurs in the cytoplasm Translation 3 Review name all the molecular players involved in the function of transcription DNA template strand RNA polymerase Transcription factors promoters and enhancers nucleotides 4 Review name all the molecular players involved in the function of translation mRNA ribosomes tRNA amino acids release factors for termination 5 Explain in your own words how understanding this flow of information links genotype to phenotype Genotype is the sequence of DNA this determines the mRNA sequence Translation occurs which results in a protein Proteins carry out functions build structures in our bodies This ultimately leads to observable traits Phenotype Module 10 16 Mutations can affect genes 1 Mutations or variations can occur during DNA replication before a cell divides Define mutation A mutation is a change in the DNA sequence of a gene 2 What is the consequence of a single nucleotide substitution in the DNA of a gene It can cause either a missense mutation or a silent mutation And also if the mutation creates a stop codon this results in a nonsense mutation 3 Contrast this with a single nucleotide insertion or deletion in the DNA of a gene Insertions or deletions cause frameshift mutations this changes the entire reading frame of the protein this often causes a non functional protein to be made 4 How can a single nucleotide result in a shortened protein product if the mutation introduces a stop codon prematurely by a nonsense mutation this would cause translation to be stopped early 5 Compare different changes at the DNA level that affect primary structure of a protein Missense mutation substitutes one amino acid for another Frameshift mutation Shifts the reading frame which changes the entire downstream amino acid sequence Nonsense mutation This introduces a stop codon too early on 6 Use this DNA sequence and make three different types of mutations by illustrating what the mRNA and protein would look like if you mutated a DNA sequence you design the DNA template strand Missense Nonsense Frameshift wildtype DNA TAC GGA TGC CAT TAC GGA TGC CAT TAC GGA TGC CAT mutated DNA TAC GGA TTT CAT TAC TGA TGC CAT TAC CGC ATG CCA mRNA AUG CCU AAA CUA AUG ACU ACG GUA AUG GCG UAC GGU protein Met Pro Lys Val Met Thr Stop Met Ala Tyr Gly 7 What are some mutagens that can damage DNA UV radiation Chemicals Xrays Viruses 8 How do mutations relate to evolution Mutations cause genetic variation There could also be some beneficial mutations that can improve survival and reproduction Then also harmful mutations may be removed from the population over time Real World application Visit https www pri org stories 2012 03 28 gene test offers whiff hope listen to the story and answer these questions 1 What is trimethylaminurea TMAU disorder A disorder where the body can t beak down trimethylamine which causes a fishy odor 2 The gene that is mutated in the disease codes for a protein with what kind of function An enzyme that is involved in the break down of trimethylamine 3 In what secretions will the odor be found Sweat using breath 4 Why did the gene test to confirm the diagnosis of TMAU in Graham provide hope and then disappointment There was hope when they identified the mutation but then disappointment when they found out that the disorder was genetic 5 What is the problem with research dollars and really rare or non life threatening disorders Funding is mostly prioritised for more common or life threatening diseases leaving the rare disorders with less research 6 Graham finds out that he has passed the gene onto his daughter Think about if you knew you had inherited a gene like this but had not yet showed symptoms What is the dilemma with knowing this It could provide an opportunity for early monitoring however graham will have anxiety about future symptoms
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