Biology Tutorials > Genetics and Evolution > Chromosome Mutations – II

Chromosome Mutations – II

Genetic Mutations

Mutations involving changes in the nucleotide


Reviewed by: Mary Anne Clark, Ph.D.


This page is a continuation of the previous tutorial, Chromosome Mutations – I.

Alteration of a DNA Sequence

The previous examples of mutation have investigated changes at the chromosome level. The sequence of nucleotides on a DNA sequence are also susceptible to mutation.

  • Deletion
    Here, certain nucleotides are deleted, which affects the coding of proteins that use this DNA sequence. If for example, a gene coded for alanine, with a genetic sequence of C-G-G, and the cytosine nucleotide was deleted, then the alanine amino acid would not be able to be created, and any other amino acids that are supposed to be coded from this DNA sequence will also be unable to be produced because each successive nucleotide after the deleted nucleotide will be out of place.
  • Insertion
    Similar to the effects of deletion, where a nucleotide is inserted into a genetic sequence and therefore alters the chain thereafter. This alteration of a nucleotide sequence is known as frameshift
  • Inversion
    Where a particular nucleotide sequence is reversed, and is not as serious as the above mutations. This is because the nucleotides that have been reversed in order only affect a small portion of the sequence at large
  • Substitution
    A certain nucleotide is replaced with another, which will affect any amino acid to be synthesized from this sequence due to this change. If the gene is essential, i.e. for the coding of hemoglobin then the effects are serious, and organisms in this instance suffer from a condition called sickle cell anemia.

All of the genetic mutations looked at through the last 2 pages more or less have a negative impact and are undesired, however, in some cases they can prove advantageous.

Genetic mutations increase genetic diversity and therefore have an important part to play. They are also the reason many people inherit diseases.

The next tutorial looks at the mutation at the gene level.

 

Gene and chromosome mutations explained. Credit: Amoeba Sisters

 

CHROMOSOMAL MUTATION MATCH-UP ACTIVITY (pdf)

CHROMOSOMAL MUTATION MATCH-UP ACTIVITY (pdf)

CHROMOSOMAL MUTATION MATCH-UP ACTIVITY

A critical-thinking match-up activity on chromosomal mutation! This matching-type test is useful in tracking the student’s skills in recognizing the different kinds of chromosomal mutations.

Subjects: Genetics & Evolution
Lesson: Mutations
Grades: 9th, 10th, 11th, 12th
Type: Worksheet

Quiz

True or false: select true if the statement is correct and false if the statement is incorrect.

1. Nucleotides were inserted into the DNA sequence altering the sequence of a polypeptide chain. This is an inversion type of mutation.
2. Nucleotides in the DNA sequence are missing resulting in the absence of amino acid in a polypeptide chain. This type of mutation is deletion.
3. The new DNA sequence contains a nucleotide replaced with an amino acid. This is a substitution-type of mutation.
4. Mutations increase genetic diversity.
5. All mutations cause genetic disorders or diseases.

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Biology Tutorials > Genetics and Evolution > Chromosome Mutations – II

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