Unit 4 9A: Mutations Flashcards
Genotype
the genetic makeup or alleles of an organism
Phenotype
A physical characteristic determined by genotype and environment
Genetic diversity
The genetic variability within a species
Adaptations
The behavioural, physiological, biochemical and structural features of an organism that help them survive in an environment
Population
A group of individuals of the same species living in the same region at a given time
Species
A group of organisms that can interbreed, producing fertile and viable offspring
Gene pool
The sum total of alleles present in a population of organisms
Allele frequency
The proportion of a particular allele within a population
Evolution
A change in the allele frequencies of a population over time
Mutation
A permanent change in the nucleotide sequence of a section of DNA
Mutagenic agents
Agents known to cause mutations; for example, some radiation sources and chemicals; also called mutagens
Point mutation
A change to one base in the nucleotide sequence of a section of DNA; includes base substitutions and frameshift mutations
Substitution mutations
A type of point mutation that occurs when one nitrogenous base in a gene is replaced with another base; includes silent, missense and nonsense mutations
Silent mutation
A mutation where the change in the nucleotide sequence doesn’t change the amino acid that is coded for
Missense mutation
A mutation in which the base change in the nucleotide sequence of the DNA changes the amino acid that is coded for; a type of substitution point mutation
Nonsense mutation
A mutation that occurs when the base change in the nucleotide sequence of the DNA codes for a STOP codon, prematurely halting the production of the polypeptide; a type of substitution point mutation
Frameshift mutation
A type of point mutation that occurs when one base is inserted into or deleted from a gene, causing an incorrect reading of the codons due to a shift in the reading frame
Block mutation
A type of mutation that affects large sections of DNA, typically containing multiple genes; also called chromosome mutation
Types of block mutations
DDIT
- Deletion
- Duplication
- inversion
- Insertion
- Translocation
What is a deletion block mutation
Description and effects on the individual
A section of DNA is removed from the chromosome
Leads to disrupted/missing genes.
Large impact on growth and development, sometimes fatal
What is a Duplication block mutation
Description and effects on the individual
A section of chromosome is repeated multiple times (sometimes thousands of times) on the same chromosome
Can lead to an increase in gene expression
What is an Inversion block mutation
Description and effects on the individual
A section of chromosome is removed, rotated 180 degrees and reattached in reverse order.
Can be as small as two bases, or as large as several genes
Usually does not cause abnormalities, but can cause lowered fertility
What is a Translocation block mutation
Description and effects on the individual
A section of one chromosome ataches to a non-homologous chromosome or sections are exchanged between the two.
Leads to disruptions in gene sequences or interruptions in gene regulation
Can cause some cancers
Chromosome abnormality
Mutation that involves a whole chromosome or a change in the number of chromosomes, which can be identified using a karyotype;
examples are aneuploidy and polyploidy
Karyotype
a pictorial representation of chromosomes that allows the determination of diploid number, gender and chromosomal abnormalities
Aneuploidy
When a cell has one more or one less chromosome than expected, usually due to non-disjunction during meiosis
What is non-disjunction
In meiosis
When the chromosomes fail to separate. The result is daughter cells of gametes forming with an incorrect number of chromosomes.
Polyploidy
A condition in which an organism has more than two full sets of chromosomes in its cells; more common in plants than animals
What is an insertion mutation
a type of mutation that involves the addition of one or more nucleotides(nitrogenous bases) into a segment of DNA.
