Biology 1002B Lecture Notes - Fall 2018 Lecture 18 - Biochemical cascade, Homeobox, Eukaryote

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greyyak215

21 Sep 2018

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Missense mutation: mutated base pair (snp) leads to altered sense codon leads to altered amino acid. Silent mutation: it"s perfectly possible to su er a mutated base pair (snp) that would have no e ect on which amino acid is coded for. Nonsense mutation: mutated base pair (snp) from normal, codon changed to stop, premature termination of polypeptide. Frameshift mutation: insertion or deletion of a single base pair can have devastating e ects because it shifts the reading frame of a gene (codons come in groups of 3, everything downstream of an in/del mutation is wrong) *in/del is therefore more troublesome than a snp. Consider a single base pair insertion into the dna coding for the rst exon of an mrna sequence. The resulting protein is likely to be too short if the insertion results in a premature stop codon. The resulting protein is likely to be too long if the insertion causes a frameshift and collapses the stop codon.

Related Questions

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

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

PART C IS THE PART I NEED HELP WITH PLEASE

Below is a partial mRNA sequence. Use it to answer the following questions.

5' - GCCGAUCGAACU - 3'

What is the correct reading frame for this mRNA?

5' - G | CCG | AUC | GAA | CU - 3'

If a single base-pair deletion occurred in the part of the gene that corresponds to the mRNA above and the resulting partial amino acid sequence was (N-term-...P-M-N...-C-term), which new partial mRNA sequence would be consistent with this change?

5' - G | CCG | AUG | AAC | U - 3'

Part C

The amino acids in the original partial sequence (N-term-...P-I-E...-C-term) have little to no impact on protein structure and function. However the amino acid sequence near the C-terminal end of the protein is required for normal function. Any amino acid changes in this region of the protein will result in a nonfunctional protein.

Given this information, which reversion mutation in the gene would restore the normal function of the protein?

Select all that apply.

Insertion of 2 base-pairs in the region of the proline codon

Deletion of 5 base-pairs in the region of the proline codon

Deletion of 2 base-pairs in the region of the proline codon

Deletion of 1 base-pair in the region of the proline codon

Insertion of 1 base-pair in the region of the proline codon

Insertion of 4 base-pairs in the region of the proline codon

tanbadger888

Biology 1002B Lecture Notes - Fall 2018 Lecture 18 - Biochemical cascade, Homeobox, Eukaryote

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