BIO 2133 Lecture Notes - Lecture 1: Foxp2, Speech Disorder, Mutation

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amberherring744

8 May 2016

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Document Summary

Phenotype is one of the biggest concepts in this course. It is the expression of our genes or traits. This is possible thanks to the mechanisms of transcription and translation. Anything we can see with our own two eyes or can be put on display. Example: there is a mutation that deals with cf, one mutation causes a recessive mutation and one mutation causes the dominant mutation. If it is recessive you need two copies for it to be expressed. If it is dominant you only need one copy of the allele. It is involved in the development of speech. On the slide (4) it shows the normal speech pattern development. Slide 5 shows a pedigree representing males as squares and females as circles. Doctors ask you about family history of the disorder to put together a pedigree to see if there is any hereditary condition to the disorder.

Related Questions

1.) Choose the best response for each.

a.) The Ames test is commonly used to test whether a particular chemical is mutagenic. When you conduct an Ames test, you need two groups of plates. One group of plates contains bacteria that are exposed to the chemical of interest, while the other plates contain bacteria that are not exposed to the chemical. Why is the latter group needed if you are just interested in the rate of mutation caused by the chemical?

The group without the chemical can be exposed to mammalian liver extract to see the effects of liver enzymes on the bacteria.

Having two groups allows researchers to compare the effects of different environments on the mutation rate

It is important to compare the rate of mutations with the chemical to the normal background mutation rate. Mutations occur spontaneously even without the presence of a mutagen.

The second group is used as a control to make sure that the replica plating technique is done correctly.

b.) Frameshift mutations can be very severe. What is one reason why they are often so serious?

When a frameshift mutation occurs, it causes transition mutations to occur. These are particularly severe.

When a frameshift mutation occurs, it causes changes in many bases downstream and can affect many of the amino acids in the protein.

Frameshift mutations always occur in the regulatory region, so they cause a gene to be turned off and then the protein is not produced at all.

When a frameshift mutation occurs, it causes changes in many bases upstream and can affect many of the amino acids in the protein.

c.) An organism that cannot synthesize methionine is called __________.

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.