Mutations Flashcards
(31 cards)
Species
Group of individuals with similar characteristics capable of interbreeding and producing fertile offspring.
Variation
The difference between individuals within a species such as height, hair, and eye color.
Alleles
Alternative forms of a gene. Occur in pairs. Determine characteristics (genotype and phenotype) in individuals
Gene pool
Sum total of genes, with all their variations, possessed by a particular species at a time.
Mutations
Sudden and permanent change of the DNA sequence within a gene/chromosome of an organism resulting in the creation of a new character or trait not found in the parent’s
Mutant
Organism with a mutation
Heritability of mutations
- Gene mutations
- Chromosomal mutations
Mutations are caused by
- Spontaneous mutations (naturally occurring)
- Induced mutations (caused by mutagens)
Mutagens
Also called a mutagenic agent, increases the rate at which mutations occur.
Different types of mutagens
- Ionizing radiation
- Viruses and microorganisms
- Environmental poisons/chemicals
- Temperature
Ionizing radiation
Nuclear, ultraviolet radiation X-rays and gamma rays. The radiation passing through the DNA could cause disruptions in the code sequence.
Viruses and microorganisms
Some viruses integrate into the chromosome, upsetting the genes and triggering cancers.
Environmental poisons/chemicals
Natural or synthetic chemicals that cause changes in DNA. These include asbestos, some dyes, tobacco, coal, tars, agent orange, and mustard gas, sulfur dioxide and some antibiotics.
Temperature
Sudden increase can cause disruptions
Heritability of mutations
1) Germline mutations
2) Somatic mutations
Germline mutations
For the mutation to be passed on to the offspring, the change must occur in a gamete. If the mutation is advantageous for a particular environmental condition, they can be important in natural selection.
How germline mutations work
Occur in gametes, e.g. egg or sperm and have the potential to alter the genetic make-up of the species as they are inherited by the offspring.
e.g. phenylketonuria
Somatic mutations
Mutations which occur during an individual’s life but NOT found in their primary sex organs (ovaries or testes.) Cannot be passed on
How somatic mutations work
Occur in a body cell. They do not have the potential to alter the genetic makeup of the species and cannot be inherited by offspring, the mutation only affects the individual.
Mutations effect classifications
- Missense mutations
- Nonsense mutations
- Neutral mutations
- Silent mutations
Missense mutations
Cause a change in the amino acid, and therefore in the protein produced
Nonsense mutations
Change the base sequence to the code to STOP. This means that synthesis of the protein will stop, and so a shorter protein is produced that is unlikely to be able to fulfill its function.
Neutral mutations
Cause a change in an amino acid, however the amino acid is of the same type, and does not change the structure of the protein enough to change it’s function.
