MGY377H1 Midterm: Study notes for midterm

38 views2 pages

redtermite204

26 Dec 2011

School

UTSG

Department

Molecular Genetics and Microbiology

Course

MGY377H1

Professor

William Navarre

For unlimited access to Study Guides, a Grade+ subscription is required.

Document Summary

Mutation heritable change in base sequence of genome lead to change in phenotype. Base changes from inherent chemical instability of the bases or of the glycosidic bond. Alterations resulting from action of other chemicals and environmental agents including oxygen, ultraviolet light, nitrites. Incorrect base in one strand that cannot form hydrogen bonds with the corresponding base in the other strand. Neutral change in amino acid but functionally equivalent. Frameshift all downstream codons out of register. Promoter changes promoter recognition by rna polymerase and or regulatory molecules. Higher organisms with very large genomes tend to have replication error rates about tenfold lower than typical bacteria. Replication errors are usually repaired immediately by proofreading domains of dna polymerase. Methy-directed mismatch repair pathway directs repair to the newly synthesized strand of dna. Involves: muts = protein that recognizes the mismatch, muth protein that specifically recognizes hemimethylated gatc sequences, mutl links muts and muth via looping. Dna nicked on unmethylated strand: nicked strand degraded.

Related Questions

Part B

Think about the DNA coding sequence of a gene. If an A were swapped for a T, what kind of mutation could it cause and why?

a) It could cause a frameshift nonsense or frameshift missense mutation because it would change the reading frame of the codon triplet.

b) It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one.

c) It could cause a nonsense mutation because the sequence would no longer be the same, so the protein would be shorter and non-functional.

d) It could cause a silent mutation because A and T are complementary to each other so it is not really a substitution mutation.

Part C

Why is a frameshift missense mutation more likely to have a severe effect on phenotype than a nucleotide-pair substitution missense mutation in the same protein?

a) A substitution missense mutation causes the protein to be shorter and thus non-functional.

b) A frameshift missense will cause the codons to be out of order, but a substitution missense does not change the order of the codons.

c) A frameshift missense mutation will cause an early Stop codon, but a substitution missense might be silent.

d) A substitution missense affects only one codon, but a frameshift missense affects all codons downstream of the frameshift.

Part D

Which of the following sequences shows a frameshift mutation compared to the wild-type mRNA sequence?

a) wild-type	5â-AUGCAUACAUUGGAGUGA-3â
mutant	5â-AUGCAUACAGAGUGA-3â

b) wild-type	5â-AUGCAUACAUUGGAGUGA-3â
mutant	5â-AUGCAUACGUUGGAGUGA-3â

c) wild-type	5â-AUGCAUACAUUGGAGUGA-3â
mutant	5â-AUGCAUACAUCUGGAGUGA-3â

d) wild-type	5â-AUGCAUACAUUGGAGUGA-3â
mutant	5â-AUGCAUGUGACAUUGGAGUGA-3â

Part F

Suppose that the triplet of nucleotides indicated in bold (AGC) spans two codons, that is, CTA and GCC. If the triplet AGC were deleted from this DNA coding sequence, what effect would it have on the resulting protein?

5â-ATGCTAGCCTATCGTAAC-3â

a) The two flanking codons would be altered, but the rest of the amino acid sequence would be the same because there would be no frameshift.

b) The entire amino acid sequence would be altered due to the frameshift.

c) All of the amino acids after the deletion would be altered due to the frameshift.

d) All of the amino acids up to the deletion would be altered due to the frameshift.

mauvetrout554

Substitution of one base pair for another in a coding region of a gene can result in a ____ mutation where the changed codon codes for a different amino acid than was previously coded for.a.silent b.missense c.chromosomal d.nonsense e.frameshift

ivorylouse662

A mutation has resulted in changes to both the size (number of amino acids) and the amino acid composition of the protein encoded by a gene. This mutation is most likely a (an) ---------.

	A.	Deletion of the promoter
	B.	Insertion or deletion of a base pair in an exon
	C.	Single missense mutation in the transcription region
	D.	A base substitution, which has changed the start codon to 5'ACG3'
	E.	Insertion or deletion of a base in the middle of an intron

scarletplatypus922

MGY377H1 Midterm: Study notes for midterm

Document Summary

Get access

Related Documents

BMS 607 Lecture Notes - Lecture 4: Centromere, Tandem Repeat, Frameshift Mutation

BIO SCI 98 Lecture Notes - Lecture 3: Missense Mutation, Nonsense Mutation, Acridine Orange

MCB 2610 Lecture Notes - Lecture 15: Ecological Niche, Heteroduplex, Escherichia Coli

Related Questions