1. Your first patient is an individual who turns out to beheterozygous for an in
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Question
1. Your first patient is an individual who turns out to beheterozygous for an inversion in chromosome . Which of thefollowing might be consequences of being heterozygous for thatinversion?
(1) Reduced fertility
(2) Increased fertility
(3) No effect on fertility
(1) Loss of one chromosome pair, so the individual onlyhas 21 and not 22 pairs of autosomes
(2) Presence of three copies of chromosome 21 in theindividual with Down’s
(3) Nondisjunction during gamete formation in eitherparent
(4) Nondisjunction during gamete formation in only themother
(5) Answers (2) and (3)
(6) Answers (2) and (4)
3. Which of the following genetic phenomena are consequences ofthe presence of transposable genetic elements in DNA?
(1) Deletions
(2) Inversions
(3) Duplications
(4) Transformations
(5) Mutations
(6) All the above
(7) Answers (1) and (4)
(8) Answers (1), (2), and (3)
(9) Answers (1), (2), (3), and (5)
.5. You are working for a company, “Your DNA” thatprovides individuals with their genome sequence that is printed ona tee shirt. You have sequenced the DNA of an individual andidentify a number of different transposable genetic elements. Thecustomer has not heard of these DNA sequences and asks how youdetermined that their DNA contains transposable genetics elements.Which of the following are characteristics that permitted you todetermine that the individual’s DNA contained transposablegenetic elements?
(1) They are sequences terminated at both ends byinverted repeats
(2) They are sequences flanked by direct repeats of atarget chromosomal sequence
(3) They are sequences that encode for a transposase,responsible for catalyzing transposition
(4) They are sequences only found in circular DNA, notlinear chromosomal DNA
(5) All the above
(6) Answers (1) and (2)
(7) Answers (1), (2), and (3)
(8) Answers (2), (3), and (4)
Explanation / Answer
1.Reduced fertility
inversions usually do not cause any abnormalities incarriers as long as the rearrangement is balanced with no extra ormissing genetic information. However, in individuals which areheterozygous for an inversion, there is an increased production ofabnormal chromatids (this occurs when crossing-over occurs withinthe span of the inversion). This leads to lowered fertility due toproduction of unbalanced gametes.so abnormal gametes reduces thefertility
2.(5) Answers (2) and (3)
downs syndrome is caused by hree copies of chromosome 21in the individual .it may come from the Nondisjunction duringgamete formation in either parent
3. answer 9
Types of transposable elements which comprise largediscrete segments of deoxyribonucleic acid (DNA) capable of movingfrom one chromosome site to a new location. In bacteria, thetransposable elements can be grouped into two classes, theinsertion sequences and the transposons.
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