Question

All of the following are true of mutations EXCEPT:

1. Chromosomal mutations involve moving many genes to a new location
2. Point mutations affect only one gene.
3. Mutations that occur in the regulatory regions of a gene can change how much, where or when a gene is expressed.
4. The only mutations that are important are the ones that occur in the coding regions of genes.

Answer 1

a- Chromosomal mutation is a mutation that changes a part of chromosome.There are four types of chromosomal mutation-

Deletion- In this a section or a part of chomosome is removed.

Translocation- In this mutation a part of chromosome is added to other chromosome that is not its homologous partner. In translocation many genes move from one position to another as the option a says.

Inversion- A part of chromosome is reversed.

Duplication- In this a part of chromosome is added from its homologous partner.

Main cause of chromosomal mutation is the error in cell division. Chromosomal mutation are lethal as they alter the chromosomal structure.

So option a is correct.

b- Point mutation- Point mutation is a mutation that affects only a single nucleotide or a single gene of nucleic acid DNA or RNA. A single nucleotide base is changed inserted or deleted from the sequence of DNA or RNA. Types of point mutation-

1-Base substitution- In this a single base is substituted. Glu------>Val which causes sickel cell disease. Base substitution is of two types-

Transition- It occurs when purine is substituted from purine and pyrimidine is substituted from pyrimidine.

Transversion- It occurs when pyrimidine replaces purine and vice versa.

Point mutation can occurs in DNA sequence encoding protein are either silent, missence or nonsence.

2-Deletion- Deletion occurs when a part of DNA is loss.

Insertion- Insertion occurs when aditional base pairs are added in the sequence.

So b option is correct.

c- Mutation in the regulatory region can change the gene expression and finally it alters the protein synthesis. Mutation in the non coding DNA can cause protein to be expressed in the wrong place, at the wrong time or can reduce or diminish the exression of resulting protein. So it results in the health problems.

So option c is also correct.

d- Non coding mutation or mutation in the regulatory part are very important as they play role in controling the gene activity. Mutation in the non coding regions are linked with the developmental disorder like isolated Pierre Robin sequence. It is caused by change in inhancer elements that control the activity of SOX9 gene.

So option d is only incorrect .