What is a mutation?
Spontaneous change in the amount or structure of DNA.
An alteration in a gene will likely change its sequence of bases, therefore correct proteins can no longer be formed.
Are all mutations harmful? Provide some examples.
Some mutations can be beneficial to a species, allowing it to produce a better protein than the original one, it becomes a source of evolution.
Some somatic mutations can cause harm (eg. increase the rate of mitosis which can cause a tumor).
What is a mutagen? Provide some examples
A mutagen is a factor that causes a mutation.
Eg. Radiation (UV or X-rays), Chemicals (cigarette smoke, preservatives, barbecuing), Infectious agents (HPV, helicobacter pylori)
Causes of mutations
Mutagens or may arise naturally when a DNA fails to produce exact copies of itself (Spontaneous mutations).
What is a somatic and germline mutation?
Somatic: Occurs in non-reproductive cells and are not passed to offspring.
Germline: Occur in germ cells, which give rise in egg/sperm, hence can be passed to offspring.
What are point mutations? Provide some examples.
mutation that alters, adds or removes only ONE or VERY FEW nucleotides from a sequences of DNA or RNA.
Substitution One nucleotide is replaced by another.
Frameshift One or two nucleotides being either added or removed from the nucleotide sequence from the point onwards. This includes insertion and deletion.
Provide an example of a gene mutation
Sickle cell anemia
- Inherited blood disorder caused by mutation in the haemoglobin gene (recessive allele)
- Causes blood cell to change shape into a sickle
What are chromosome mutations? What are the four main types of chromosomal mutations?
Large change in structure or number of one or more chromosomes.
- Deletion: loss of chromosome segment
- Duplication: extra copies of segment
- Inversion: A piece of chromosome drips out, rotates 180 degrees and is rejoined.
- Translocation: segment moves to different chromosome
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Chromosomal Mutations/abnormalities
What is a aneuploidy? Example of a disorder.
When one or more copies of an entire chromosome is made or is missing.
Eg. Down syndrome where an individuals has an extra copy of chromosome 21.
Chromosomal Mutations/Abnormalities
What is polyploidy? What happens if this occurs in humans? What about in plants?
When an organism contain more that two full sets of chromosomes due to error during meiosis.
In humans, plolypoid zygotes don’t survive. However it is common in plants such as strawberries.
What happens in the body when a mutation occurs?
Proteins in the cell will remove the damaged section of DNA and replace it with correct sequences of bases.
