1 Geneticists refer to human chromosomes by the numbers 122

1. Geneticists refer to human chromosomes by the numbers 1-22, and the sex chromosomes. Which of the following mutations has the greatest probability of being harmful to a cell?

A. 2,000 bases are duplicated within chromosome number 3.

B. A nucleotide base T is changed to a nucleotide base C on chromosome number 19.

C. A nucleotide base G is missing from the Y chromosome.

D. Three extra nucleotides are added to chromosome 12.

E. The cell has an extra copy of chromosome number 2.

2. What typically happens to a gene to turn it on?

A. the gene is transported out of the nucleus through a nuclear pore.

B. a protein molecule binds to the gene.

C. the gene’s position gets flipped around on the chromosome.

D. a nerve sends a signal to the gene.

E. the gene is detached from the chromosome.

3. Does a cell in your big toe contain a gene for insulin?

A. Yes.

B. Maybe – it depends on whether the cell needs insulin.

C. No. The gene for insulin is only found in pancreas cells.

4.A gene known as MITF codes for a protein called MITF protein. MITF protein binds to another gene called TYR, turning it on. When TYR is turned on, the pigment melanin is produced in the cell. Given this information, the MITF gene is:

A. Mutated

B. an oncogene

C. a regulatory gene

D. universal

E. redundant

Solution

1. Answer is E.

The cell havaing an extra copy of chromosome number 2 is likely to not survive. It happens beause the chromosome 2 is one of the largest chromosome. Thus, the chances of carrying harmful/unsuitable genes become greater. Now, if an extra copy of this chromosome is added, the chances of occurance of harmful genes further increase reducing the life expectancy further.