Answer all questions. Provide reasoning for the right answer. Provide reasoning

Question

Answer all questions. Provide reasoning for the right answer. Provide reasoning for wrong options as well.

7) Marfan syndrome (MFS) is an autosomal dominant hereditary disorder of connective tissue. It is caused by mutations in the glycoprotein gene, fibrillin-1 (FBN1). This syndrome can be described as a type of _______.

a. epistasis

b. haploinsufficiency

c. aneuploidy

d. trisomy

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8) Please refer to the following DNA sequence: 5’ GAGGCCTTAAATTT 3’

Which one of the changes listed below would be a structural chromosomal mutation to the sequence above?

a. If first adenine is substituted with guanine.

b. If the second cytosine deleted.

c. If the sequence 5’ GAGGCCTTAAATTT 3’ changed to 5’ GAGGCCTTTTTAAA 3’

d. If the sequence 5’ GAGGCCTTAAATTT 3’ changed to 5’ GAGGGAGGCCTTAAATTT 3’

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9) Which of the following is true regarding lethal mutations?

a. A recessive lethal mutation can behave as a dominant lethal mutation if the mutated gene is x-linked.

b. Cystic fibrosis is a disease caused by a heterozygous dominant lethal mutation

c. Huntington’s disease is caused by a single point mutation in a single gene

d. The scalloped wing (sd) mutation is Drosophila is lethal in the heterozygous condition.

Explanation / Answer

Ans 7..B...haploinsufficiency

In.marfan syndrome their is haploinsufficiency.

Haploinsufficiency is when a diploid organism has lost one copy of a gene and is left with single functional copy of that gene .their is loss of function mutation.the single copy of gene is unable to to pruduce wild type phenotypic character.same occurs with the FBN1 gene on Chromosome 15 which encode fibrillin which is defective here.fibrillin is responsible for proper formation if extracellular matrix and elastic fibre function.due to deficiency of fibrillin here symptoms of marfan syndrome occur

Elistasis ,aneuploidy and trisomy are not the feature of marfan syndrome

Ans 8.b...if second cytosine gets deleted

.. structural chromosomal mutation mean any of the following if occur

Imsertion

Deletion

Inversion

Translocation

In 2nd option deletion if cytosine will cause structural chromosomal mutation

In option one their is substitution which is not a feature of structural chromosomal mutation

C option also has substittion

In d option the insertion is not in between the given sequence it is before that so no chage in the given chromosomal structure

Ans 9...a..

A recessive lethal mutation can behave as dominant if it is X linked .in males it will behave as dominant bacuase their is only one X-chromosome

Other options are wrong because

Cystic fibrosis is autosomal recessive

Huntington is an inherited disease

Scalloped wing mutation in drosophillais leghal in homozygous condition

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