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Biology 2581B Lecture Notes - Lecture 8: Null Allele, Missense Mutation, Stop Codon

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sapphirebear815
11 Feb 2017
School
Western University
Department
Biology
Course
Biology 2581B
Professor
David R Smith

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Document Summary

Allele classifications: what happens to a gene when it is mutated. Based on origin: spontaneous vs. induced. Based on molecular change: base substitutions. Based on the effect on translation: genes coding for proteins when mutate a gene on the dna level, see the effect on the protein level. Mutations happen on dna and rna level. Change a c: consequence is not much still coding for alanine. Silent mutation: the amino acid coded does not change: changes in triplets can occur but not all changes affect the amino acid that is coded by that arrangement. Some triplets code for the same amino acid: e. g anything starting with gc will code for alanine. Wobble position: the last base can wobble (cid:523)doesn"t matter what it is(cid:524), will code for the same. If it happens at this position, it is a silent mutation because there is no change at the amino acid level or protein sequence amino acid.

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Related Questions

please solve this:

Cancer Biology (Oncogenic Pathways)

The majority of malignant cells rely on dysregulation of a handful of oncogenes and their associated signaling pathways to support their abnormal proliferation and survival. The list below indicates the proteins that have become the ‘name sake’ for these key dysregulated pathways. Note that sometimes the protein listed is mutated and drives the pathway (ex. Ras), but other times it is rarely mutated (ex. Akt where PI3K and PTEN mutations predominate).

Working together in your groups, please create a portfolio of ‘profiles’ for the pathways shown below. For each pathway, include a map that links together the main proteins or molecules involved- ligands, receptors, transcription factors, etc... but always end with the ultimate effect on the cell! These pathway maps must be your own creation- do not copy other image files. For each protein or molecule you list in the map, please provide a ‘key’ that describes what it is, its specific function in the pathway, and detail where the most common pathogenic mutations occur in at least three proteins in the pathway (see below for details). Since these pathways can be extremely complex, you need not include more than three proteins or molecules at any one level in the pathway.

For information on the pathogenic mutations, use the COSMIC (catalogue of somatic muations in cancer) resource at http://cancer.sanger.ac.uk/cosmic . Enter the gene/protein name à click on the gene name in table below à under ‘Mutation Impact’ select Pathogenic à Apply. A bar graph depicting the various mutations will be shown, provide the number of confirmed mutations and the changes (DNA and amino acids) it causes at that site. For example, in the BRAF gene: 24,291 mutations have been confirmed that involve a T to A mutation at base 1799 which leads to a Valine (V) to Glutamic acid (E) amino acid substitution at position 600 (note this mutation constitutively activates the BRaf kinase).

Key Oncogenic Pathways to Profile:

Ras

Akt

Wnt

TGFB

Notch

Hedgehog

Grading will be based on aesthetic clarity, thoroughness and accuracy of the information.

Grading Rubric: 75 points total

Visuals: Aesthetic clarity 30 points

Pathways are well organized, easy to follow

activating and inhibitory relationships are readily apparent

Creative layout

Content: Thoroughness and Accuracy 30 points

All pathways completed

Essential level of detail in key

Expression vectors inprokaryotes do not make functional eukaryotic gene products inbacteria very well because

Answer Not sure which one ?!

· the codon sequence for prokaryotes is differentthan the codon sequence in eukaryotes

· there are no disulfide bridges formed in proteinsnormally made in prokaryotes

· prokaryotic expression vectors cannot translateeukarytic sequences

· eukaryotic genes have introns, and prokaryotesdon't

· eukaryotic genes have exons and prokaryotesdon't


I create a knockout mouseusing the agouti/black fur system \. When I cross the agoutioffspring of the originally engineered mouse, I find a ratio of 2agouti mice to 1 black furred mouse. What is the bestexplanation?

Answer not sure which one?!

· The gene knocked out was recessive.

· The gene knocked out was dominant.

· The gene knocked out was a lethalgene.

· The knockput was integrated into a random spot,and did not knockput the original gene.

A restriction enzyme cuts DNAand leaves the following end

xxCTGCA
xxG

Which of the following could be the sequence of the correspondingend of the other end of the cut DNA?

Answer

· xxG
xxCTGCA

· xxC
xxGTGCA

· xxCCGAT
xxG

· xxGGCTA
xxC


An SNP always occurs dueto

Answer

· a one base-pair change.

· a three base-pair change.

· a single restriction site change.

· a single amino acid change.

· None of these.


I PCR out a mutated gene in apatient with Lisenbee chorea (the inability to dance in acoordinated fashion) and I compare it to another patient with thatsame disease phenotype. One subject had a mutation on chromosome 4,and the other subject couldn't rock it because of a mutation onchromosome 5. This is an exampe of

Answer

· pleitropy

· locus heterogeneity

· allelic heterogeneity

· dominant negative mutation

· penetrance

In his experiments, Mendelnoted that when two traits are involved in a genetic cross, theyare inherited independently of each other. Though Mendel didn'tknow about chromosomes, this still holds true (mostly)because

Answer

· genes on the same chromosome are often mixedthrough meiotic crossover during the formation ofgametes.

· variant alleles of the same gene do not interferewith the phenotypic expression of the gentoype in different geneticloci.

· most higher organisms are diploid, making only twoalleles available for every genetic locus, and there is a 50/50chance of geting either allele from a single parent.

· expression of phenotypes can vary from thegenotypes because of encironmantal influences.

· chromosomes often recombine

Anticipation is caused by amutation that increases in expressivity over subsequentgenerations.

Answer

· True

· False

Question 44

I have a genotype that shouldproduce a specific phenotype, but some of the individuals with thegenotype do not demonstrate any evidence of the phenotype. I wouldconsider this an example of

Answer

· allelic heterogeneity.

· locus heterogeneity.

· penetrance.

· expressitivity.

· sheer luck.

Question

Which of the following doesnot occur during the PCR reactions?

Answer

· Changes in the reaction temperature by athermocycler

· Denaturation at high temperatures

· Synthesis of oligonucleotide primers

· Extension of primers by DNA polymerase

· Annealing of oligonucleotide primers

Question

DNA markers, or variantnon-coding regions of DNA, are DNA polymorphisms that are usefulfor genetic mapping.

Answer

· True

· False

A mosaic is an organismwith

Answer

· multiple genotypes within one organism

· multiple alleles within one genotype

· more than one color of fur

· transgenes added to the zygote beforedevelopement

· a wt phenotype but a mutated genotype

Question

Genotype causesphenotype.

Answer

· No, gentoype just influences phenotype.

· Yes, genotype is the DNA sequence that createsphenotype.

Question

A true genetic chimera can becreated by

Answer

· mutating a gene early on in the development of anorganism resulting in different alleles being present in theadult

· multiple fertilized eggs or zygotes fusing to formone embryo

· adding a transgene to the genome of an organismduring fetal development only

· adding cells of a different species to an adultorganism

· adding a transgene to the genome of an animal atany stage in development

Question

The ABO blood group can bestbe explained by the concept of _______.

Answer

· dominant traits

· recessive traits

· allelic heterogeneity

· locus heterogeneity

· vampirism

If a loss of functionmutation creates a dominant phenotype, it may be becauseof

Answer

· haploinsufficiency

· penetrance

· expressivity

· allelic heterogeneity

· locus heterogeneity

Please select the best matchfor each.

Answer

· PCR: Technique used to generatecopies of a DNA fragment

· Southern blot : Screeningprocedure used to assay DNA fragments

· RFLPs : DNA fragments generatedby restriction enzymes that vary in length betweenindividuals

· Northern blot : Screeningprocedure used to assay mRNA fragments

· Electrophoresis Movement ofmacromolecules in an electrical field

Answer

A.

Screening procedure used toassay DNA fragments

B.

Movement ofmacromolecules in an electrical field

C.

Screening procedure used toassay mRNA fragments

D.

DNA fragments generated byrestriction enzymes that vary in length betweenindividuals

E.

Technique used to generatecopies of a DNA fragment

A gene mutates, and theprotein produced has a novel way of interacting with the cell, andcreates a new phenotype because of this new functionality. This iscalled

Answer

· pleitropy

· locus heterogeneity

· allelic heterogeneity

· dominant negative mutation

· gain of function dominant mutation

Question 62

Mutations in the somaticchromosomes may be inherited by the next generation.

Answer

· True

· False


A degenerate PCR primer withmany variant sequences must be used to make multiple copies of agene

Answer

· if only the protein sequence of the gene productis known to construct the primers

· if the DNA you are using is cDNA to constructthe primers

· if the DNA you are using is genomic DNA to becopied

· if the DNA you are trying to copy iscDNA

· if the vector is prokaryotic and the transformedcell is eukarytotic

Question

Please select the best matchfor each term.

Answer

· Restriction enzyme


· PCR C

· Plasmid

· YAC A

· Dideoxynucleotide

Answer

A.

Endonuclease isolated frombacteria

B.

Eukaryotic cloningvector

C.

Method for amplification ofDNA sequences

D.

Small circular fragment ofDNA

E.

Molecule used in DNAsequencing

Question

A couple goes on MauryPovitch, and the results are in: you are not the father. But noother man impregnated the female (granted, unlikely for a MauryPovitch guest, but work with me here) and he must be the father.DNA analysis claims otherwise, though the child definitely wasmom's (poor thing). What may be going on here?

Answer

· the child is parthenogenic because the motheractually impregnated herself like a shark, and the child's DNA isall mom's

· the child had a mutation that changed the genethat is used to trace paternity

· the child is a mosaic because he is actually a setof twins fused early during fetal development, and therefore camefrom 2 eggs and 2 sperm

· the dad may have germ-line mosaicism, meaning thatthe genotype of his sperm is different from his somaticgenotype

· mitochondrial DNA only comes from mom, so there isno way to tell whobthe baby's father is