BIOL10005 Lecture Notes - Lecture 11: Missense Mutation, Frameshift Mutation, Stop Codon

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plumrabbit83

31 Oct 2018

School

University of Melbourne

Department

Biology

Course

BIOL10005

Professor

Dawn Gleeson

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Document Summary

Different forms of dna sequence: mutation. Spontaneous, induced (e. g. radiation, uv damage, chemicals, x-ray), etc. Mutations can occur in both somatic/germ cells. When mutation occurs at coding region -> affects gene product. Non-coding region -> expression of gene: single base pair substitution. Silent: no change in the gene product. Changes a codon to a different codon for the same amino acid. Usually a change in the 3rd nucleotide in the codon. Missense: amino acid substitution in the gene product. Different amino acid is used in formation of protein (2nd position in codon) Nonsense: premature termination of translation (chain termination) Converts a codon for amino acid to termination codon. Protein is prematurely terminated: deletion/insertion of base pairs. Whe(cid:374) it is(cid:374)(cid:859)t -> the reading frame is out of shift -> entire sequence from downstream changes: triplet repeat mutations. Loss/gain of genetic information -> aneuploidy/polyploidy: chromosome number/structure alteration. Can be due to deletion or duplication of entire chromosome.

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

1. An occurrence of a gene made larger by trinucleotide repeats is:

Allelic expansion

Nucleotide expansion

Translocation mutation

Transformation

2. a chemical that can damage and/or change DNA is called a/an:

Allele

Endonuclease

Vector

Mutagen

3. An occurrence when a section of a chromosome relocates itself to an entirely different (non-homologous) chromosome is called a/an:

Inversion mutation

Translocation mutation

Transformation mutation

Duplication mutation

4. The tandem repeat in the sequence GGGAAGGGAAGGGAAGGGAAGGGAAG is:

GGA

GGGAA

GGAAG

GGAAGGG

A disease characterized by abnormally shaped hemoglobin is called:

Cystic Fibrosis

Sickle Cell Anemia

Marfan Syndrome

Leukemia

5. A point mutation that causes a substitution of a stop codon with an amino acid and leads to the formation of a longer protein is a:

Nonsense mutation

Missense mutation

Sense mutation

Frameshift mutation

6. Addition or deletion of nucleotides in a DNA sequence is known as a:

Nonsense mutation

Missense mutation

Sense mutation

Frameshift mutation

7. The least severe type of chromosomal mutation is:

Point

Frameshift

Inversion

Translocation

8. Chemicals inserting themselves into DNA can cause a:

Missense mutation

Nonsense mutation

Sense mutation

Frameshift mutation

9. A genetic condition caused by allelic expansion is:

Familial hypercholesterolemia

Fragile X syndrome

Alkaptonuria

Galactosemia

10. Which of the following is most likely the original DNA strand if the mutated DNA strand is ATAGUUGATGUA ?

ATAGAAGATGAA

ATAGCCGATGCA

ATAGGGGATGGA

ATAGTTGATGTA

11. An unbalanced chromosomal mutation would include a/an:

duplication (insertion)

inversion

translocation

denaturation

12. Many translocation mutations are found to be involved with:

cancers

sickle cell anemia

Huntington disease

cystic fibrosis

13. A common repeat throughout the human genome that is approximately 300 bases in length is called a/an:

EcoRI repeat

Hind repeat

Exo repeat

Alu repeat

14. A balanced chromosomal mutation includes:

imprintation

denaturation

inversion

deletion

salmondinosaur263

DNA and Genes Lab Activity
Complete your answers in the spaces provided. USE YOUR OWN WORDS â Yes even
for definitions! Remember to add your last name and first initial to the file name prior to
saving and submitting your completed assignment through Canvas.
Use your textbook, notes and these websites to answer the pre lab questions.
http://learn.genetics.utah.edu/content/molecules/transcribe/
http://www.vcbio.science.ru.nl/en/virtuallessons/cellcycle/trans/
Pre Lab Questions:
1. What is the product of transcription?
2. What is the region of DNA called where transcription begins?
3. What is the product of translation?
4. In your own words define each of the following:
Silent mutation
Missense mutation
Nonsense mutation
Frame shift mutation
5. Where in the cell does translation take place?
Click on the link below to access the online lab.
http://www.mhhe.com/biosci/genbio/virtual_labs_2K8/pages/DNA_And_Genes.html
Download and print the instructions for reference as you work through the lab. As you work through the lab fill in the table below. Use this information to answer the questions that follow contained in this document.
First read through the mutation guide. Once you close the guide you will see the buttons to begin the simulation. Note, you will be translating the mRNA strand into a protein. As you work through each of the mutations fill in the charts below. You must complete 4 mutations for this lab activity. Itâs good practice working with the codon table .
â Aris labs calls the codon table the âGenetic Code Chartâ. Use the amino acid abbreviation for the protein sequence. For example the amino acid proline is abbreviated as pro.
You have to fill in all the letters AND the resulting amino acid sequence by dragging and dropping before you click the [check] button. Abrieviate STOP as either STP or END.
For each of the three mutations you will complete, fill in the table in this lab document with the original mRNA and amino acid sequence and the mRNA sequence and the resulting amino acid sequence RESULTING FROM the mutation as outlined in the mutation rule.
The various mutations represent missense, nonsense, silent and frame shift mutations. You must complete one of each. The lab will not necessarily present the mutations in this order. You must do the mutation and identify which type it is and make sure you do one of each.
6. Frame Shift Mutation example:
Provide the mutation rule you are following.
Original A. Acids
Original mRNA
Mutated mRNA
Mutated A. Acids
7. Missense Mutation example:
Provide the mutation rule you are following.
Original A. Acids
Original mRNA
Mutated mRNA
Mutated A. Acids
8. Nonsense Mutation example:
Provide the mutation rule you are following.
Original A. Acids
Original mRNA
Mutated mRNA
Mutated A. Acids
9. Silent Mutation example:
Provide the mutation rule you are following.
Original A. Acids
Original mRNA
Mutated mRNA
Mutated A. Acids
Post Lab Questions
10. From the mutations you have explored, which one is the least severe. Explain your answer.
11. From the mutations you have explored, which one is the most severe. Why?
12. Aside from silent mutations which have no effect on amino acid sequence, are all mutations bad? Explain your answer.

champagnerat497

BIOL10005 Lecture Notes - Lecture 11: Missense Mutation, Frameshift Mutation, Stop Codon

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