Question

QUESTION 2 Which type of chromosome abnormality would be most likely to result in the least severe phenotype? a. A duplication of 1/4 of a chromosome b. A monosomy G. A trisomy d. A deletion of 1/4 of a chromosome e. A balanced Translocation QUESTION 3 A woman with albinism (an X-linked recessive gene) has a child with a man who has normal pigment. Their child is heterozygous for albinism with Klinefelter's syndrome (XXY). Where did the non-disjunction event occur? a. Could have occurred in either the mother or the father b. Could only have occurred in the father C. Could only have occurred in the mother d. Can't determine from the information given. QUESTION 4 A woman with albinism (an X-linked recessive gene) has a child with a man who has normal pigment. Their child does not have albinism but has Turner's syndrome (XO). Where did the non-disjunction event occur? O a. Could have occurred in either the mother or the father b. Could only have occurred in the mother c. Can't determine from the information given. d. Could only have occurred in the father QUESTION 5 Click Save and Submit to save and submit. Click Save All Answers to save all answers. Save

Answer 1

1. Chromosomal mutations or aberrations are different from gene mutations in that a gene mutation affects only the function of a gene and mostly be limited to a few nucleotides. Whereas, chromosomal mutations are due to aberrations in a large number of nucleotides such that it will affect the structure of the entire chromosome.

Chromosomal mutations are broadly classified into the following types:

1. Numerical aberrations:

a) Aneuploidy - here an organism lacks one of the chromosomes or have an additional copy of any of the chromosomes. Aneuploidy can be Monosomy (ex: Turner Syndrome) or Trisomy (ex: Down Syndrome)

b) Polyploidy - here an organism will have an additional complete set of chromosomes.

Having extra copies of a chromosome means that individuals have additional copies of each of its genes instead of the normal number, making it difficult for cells to properly control the amount of proteis made. Producing too much or too little protein can have serious consequences on the cellular functions.

2. Structural aberrations: leads to alteration in the structure and therefore functions of the chromosomes (genes in the chromosomes). Structural aberrations in chromosomes are of the following types:

a) Deletions: here a portion of the chromosome is missing or deleted. Wolf-Hirschhorn Syndrome in humans is caused due to deletions from chromosome 4.

b) Duplications: here a portion of the chromosome is duplicated, resulting in the presence of additional genetic material. Charcot-Marie-Tooth disease is caused by a duplication of a gene on chromosome 17.

c) Translocations: here a portion of one chromosome is transferred to another chromosome. There are 2 types of translocations- Reciprocal (where segments from two different chromosomes are exchanged) and Robertsonian translocation (where an entire chromosome gets attached to another chromosome at the centromere). Some types of cancer, like Leukemia is caused due to certain translocations.

d) Inversions: here a portion of the chromosome is broken off, turned upside down, and reattached, thus making the genetic material inverted.

All types of chromosomal aberrations will have an effect on the phenotype of the organism. However a balanced translocation, since it does not lead to the loss or gain of any protein function, will only have a minor effect on the phenotype of the individual. So the chromosome abnormality that is likely to have the least severe phenotype is option (e)- a balanced translocation.

(Kindly post the rest of the questions as separate questions. The Chegg policy is to answer the first question in case of multiple questions.)