Problems on mutational changes
Problem B.1
Construct a matrix of the set {A, C, T, G} to illustrate the characteristic of the transition and transversion mutations.
(Hint: You may use a score of 100 % to depict the element of the matrix pertinent to no mutation - for example for 100% for A-to-A as shown; and, use prorated percentages to represent other elements illustrating the characteristic as above. The spontaneous base substitutions ratio of transitions to transversions is approximately 2:1. Therefore each transition should have a probability of 2/3 and each transversion 1/3).
Answer:
Problem # B.2 (a)
A strand is presumably mutated at a location underlined in the sequences shown below. In each case, (i) write down the eventual resulting strand for the following additional mutations happening in succession:
1) Inversion of some subsequence part
2) Deletion of some subsequence part
3) Transpose ofsome subsequence part
4) Duplication of a base-pair in the sequence
5) Point mutation of one base into another
(Hint: The answers may depend on subjective selection as required)
a).....TTAAGGGGGGCCTTTTGAAA....
Example answer: (5) GGGG → GGCG
(b)....,,AAAAGGGGGGCCTTGGGACC....
(c) ......CCAAGGGTGTCCTTTTGAGG....
(ii) In each case, also write down the corresponding final resulting duplex strands at preRNA level
1. GGCG
Example answer: CCGC
2. AAATAA
3. TCCT
4. CGTTA
Problem B. 2(b)
Consider an ancestral sequence:
...ACCCTAC ...
Suppose a sequence of changes occur on this segment as follows: Single substitution, no change, multiple substitutions, back substitution, parallel substitutions, coincidental substitutions and convergent substitutions.
Write down two possible resulting sequences.
1) Initial - ACCCTAC
Single Sub - (A→G)CCCTAC (Example answer)
No Change -
Multiple Sub -
Back Sub -
Parallel Sub -
Coincidental Sub-
Convergent Sub -
2) Initial - ACCCTAC
Single Sub -
No Change -
Multiple Sub - A(C→T→A)CCTTC (Example answer)
Back Sub -
Parallel Sub -
Coincidental Sub-
Convergent Sub -
Problem B.3
Given a sequence:
X: 5' - TAC GGA TCG AAT GCT CCC GTA ATC - 3'
Suppose the following mutations have occurred in succession: A single point mutation, deletion of a triplet and duplication of a triplet twice in succession; and, the resulting complementary strand is found to be:
Y: 3' - ATG CCT AAC TTA CGG CAT CAT CAT TAG - 5'
Find
Single Point Mutation - (Example answer: Highlight in YELLOW. In triplet 3, the second base C was changed to T. ....GGA TCG .... to ....CCT AAC ....)
Deletion of a Triplet - Highlight in RED.
Duplication of a Triplet - Highlight in GREEN.