chap 9- genetic changes in a population over time Flashcards
what is a gene
section of DNA that transmits genetic information
what is an allele
different forms of a gene
what is a genotype
the alleles present in an individual
what is a phenotype
observable physical traits
what are the types of variation
structural, biochemical, behavioural, developmental, physiological and geographic
what are allele frequencies
a measure of how common a particular allele is in the gene pool of a population
what are mutations
random/unpredictable changes in DNA. creates new alleles, genes and chromosomes
what are spontaneous mutations
copying errors during DNA replication
what are mutagens
factors that induce mutation
what are somatic mutations
occur in body cells and only affect that individual
what are germline mutations
are heritable because they affect gametes and can be passed on to offspring
what are point mutations
a mutation that alters, adds or removes a single nucleotide from a sequence of DNA or RNA is called a point mutation. typically affect a single gene
what are substitution mutations
a point mutation in which one nucleotide is replaced by another type of nucleotide.
can be silent mutations, missense mutations, or nonsense mutations
what are silent mutations
the new codon still codes for the same amino acid
what is a missense mutation
the new codon codes for a different amino acid
what are nonsense mutations
the new codon is a stop codon and shortens the amino acid chain (which may have severe affects)
what is a frameshift mutation
one nucleotide being either added or removed from a nucleotide sequence. alters every codon in that sequence from that point onwards
what are block mutations
mutations that affect large sections of a chromosome (multiple genes)
when do block mutations occur
in eukaryotic cells during meiosis
what are the types of block mutations
duplication, inversion, deletion, insertion, translocation
what is a duplication mutation
results in multiple repetitions of a sequence of DNA
what is an inversion mutation
mutations involve a broken section of the sequence rotating 180 degrees before reattaching.