1. Summary

Point mutations are random changes in the DNA code that involve a single pair of nucleotides, causing the evolution of new genetic information in a population without changing the amount of genetic information present. While most point mutations usually have a neutral effect on the organism, some mutations can have a negative or a positive effect on the organism’s ability to reproduce and, thus, survival. Changes due to point mutations can be so dramatic that they can give rise to long-furred dogs and enable poison immunity in predators.

2. Why Watch This Video?

• Have you ever wondered if your unique features were caused by mutations in your genes?
• Would you like to know how genetic information evolves?
• Have you ever been confused by how all living things on earth evolved from one common, very simple ancestor?

3. Key Terms

• Genetic Information – the information stored in genes that helps determine the size, shape and behaviour of an organism
• Point Mutations – a genetic mutation where one nucleotide, or DNA base pair, in the DNA sequence is altered
• Evolution – the diversification of a species, caused by the inheritance of changes/mutations in individuals of a population from generation to generation.

4. Loose Ends

Loose end #1: Types of point mutations

This video does not elaborate of the different types of point mutations that can occur. There are three types of point mutations: substitution, insertion and deletion. Substitution point mutations occur when one base pair is substituted for another. Substitution mutations can lead to the production of abnormal proteins. Insertion point mutations occur when an extra base pair is added to a sequence. Deletion point mutations are the opposite of insertion mutations and occur when a base pair is deleted from the DNA sequence. Both insertion and deletion mutations cause drastic changes in the DNA sequence as they addition or deletion of a base pair can drastically affect the chain of amino acids produced and thus, change the structure and function of the protein.

Loose end #2: Point mutations in humans

This video addresses the changes point mutations have made in bacteria/microorganisms, dogs and amphibians but does not talk about some changes point mutations have made in humans. One example of a point mutation in humans is the origin of Sickle Cell Anemia. Sickle cell anemia is a recessive genetic disorder caused by the substitution of one base pair in the gene that is responsible for producing hemoglobin. Hemoglobin is a protein that transports oxygen in the blood. This substitution results in the production of the amino acid valine, rather than the normally produced amino acid glutamic acid. When an individual carries two copies of this mutation, their red blood cells become thin and sickle-shaped and are unable to carry oxygen properly.

Loose end #3: Point mutations aren’t the only way genetic material changes

This video made it clear that while point mutations are a source of new genetic information to a population, they do not increase the amount of overall genetic information in the genetic code of an organism. Point mutations essentially ‘edit’ the DNA sequence, meaning that when new information in produced, old information is lost. So how did every creature on Earth evolve from a single common ancestor that had far less genetic material than any living thing alive today? How did the increase in the genome and complexity of organisms occur? These questions can be answered by recognizing that point mutations are just one of the mechanisms biologists have discovered to be involved in the increase of genetic information and diversity of species. Point mutations are also the simplest of all the mechanisms. Other mechanisms, such as duplication events in the genome, directly increase the length of the genome. Environmental events and natural selection work alongside genetic mechanisms to increase the diversification of species over time.

5. Self-Test Questions