Mutations Flashcards
Define evolution.
The change in characteristics of a species overtime.
Define Genotype.
The genetic makeup of an organism.
Define phenotype.
The observable characteristics in an individual resulting from the expression of genes.
Define population.
A group of organisms of the sam e species living together in a particular place at a particular time.
Define gene pool.
The grouping of genotypes and the sum of all alleles in a given population.
Define allele frequencies.
Is how common an allele is in a given population.
What are the two types of mutations?
- Gene mutations
- Chromosomal mutations
What are mutations?
Are changes in the DNA sequence of an organism.
What are gene mutations?
Change in a single gene so that the traits normally produced by that gene are destroyed or changed.
What are chromosomal mutations?
All or part of a chromosome is affected. A mutation involving a long segment of DNA or chromosomes. It can occur when the number of chromosomes increases or decreases in a genome as well as when chromosome structure change occurs.
What are the causes of mutations?
Mutagenic agents or mutagens.
What are 5 examples of mutagens/mutagenic agents?
- Mustard gas
- Formaldenyde
- Sulfur dioxide
- Some antibiotics and ionizing radiation (UV + X-rays)
- Radiation
What are induced mutations?
Are caused by mutagens.
What are spontaneous mutations?
They are random errors in meiosis or mitosis.
What are the 4 classifications of mutations?
- Cause of the mutation.
- Heritability of the mutation.
- Effect of mutations.
- Extent of the mutation.
What do you talk about in terms of the cause of a mutation?
Whether its induced or sponatanous.
What do you talk about in terms of the heritability of a mutation?
Whether it is a somatic or germline mutation.
What do you talk about in terms of the effect of a mutation?
Whether it is a missense, nonsense, neutral or silent mutation.
Describe somatic mutations.
These mutations cannot be passed into offspring. Only tissues derived from the mutated cell are affected.
What is an example of somatic mutations?
Cancer.
Describe germline mutations.
Occur in gametes and can be passed onto offspring. Every cell in the entire organsim can be affected.
What is an example of germline mutations?
PKU preventing the breakdown of the amino acid phenylalanine.
What is a point mutation?
Are changes in a single base pair usually during DNA replication.
What are the 4 types of point mutations?
- Missense
- Nonsense
- Neutral
- SIlent
What are missense mutations?
Cause a change in the amino acid and therefore the protein.
What are nonsense mutations?
Change in the base sequence to code for a stop codon. This means the synthesis of the protein will stop, so a shorter protein will be produced that will not fulfil its function.
What are neutral mutations?
Cause a change in the amino acid but it is of the same type which does not change the structure of the protein and its function.
What are silent mutations?
Does not cause a change in the amino acid and therefore the protein is produced.
What causes point mutations?
Due to nucleotides being -
1. Inserted - a new nucleotide is added.
2. Deleted - a nucleotide is removed from the DNA strands.
3. Substituted - An existing nucleotide is replaced with another one.
What causes frameshift mutations?
Insertions and deletions.
What are frameshift mutations?
Occur when a base is inserted or deleted and this changes the reading frame of DNA codons.
What causes missense, nonsense, neutral and silent mutations?
Substitutions.
What causes chromosomal mutations?
- Errors during mitosis, meiosis or fertilisation.
- Mutagens.
What are the 4 types of chromosomal mutations?
- Duplication.
- Deletion.
- Inversion.
- Translocation.
What is duplication?
A section of chromosomes occur twice.
What is a deletion?
A section of DNA is removed.
What is an inversion?
A break in the chromosome occurs and then is reattached the wrong way.
What is translocation?
Part of the chromosome breaks off and reattaches to the wrong chromosome.
What is non-disjunction?
During meiosis a chromosome pair does not separate and so one daughter cell has an extra chromosome and one daughter cell has one less than the normal number.
What is non-disjunction also referred to as?
Aneuploidy.
