7.3 microevolution

microevolution

small-scale changes in a pop over time

requires genetic variation

alleles

different versions of a gene at a specific locus

point mutations

copying errors and environmental factors

endogenous (internal) mutations - point mutations

DNA damaged due to oxidative stress from metabolic processes - mostly corrected by repair enzymes

exogenous (external) mutations - point mutations

mutagens causing harmful mutations

ex. cigarette smoke, UV radiation

silent mutation

no change in protein

missense mutation

conservative minimal impact

non-conservative can be harmful (sickle-cell disease)

nonsense mutation

creates a STOP codon, leading to incomplete proteins

frameshift mutations (chromosomal)

insertation or deletion of nucleotides (not multi of 3)

alters all codons post mutation

ex. tay-sachs disease (4-base insertation)

deletions (chromosomal)

segment of DNA is lost

duplications (chromosomal)

extra copies of genes, allowing for evolutionary changes

inversions (chromosomal)

gene sequence flips direction

insertations and translocations (chromosomal)

dna moves between chroms

mutation effects

neutral - no effect

harmful - can cause disease (ex. cystic fibrosis)

advantageous - rare - can drive evolution

sexual reproduction

largest source of genetic variation

independent assortment (repro)

random chrom distribution during meiosis

crossing over (repro)

exchange of genetic material between homologous chroms

fertilization (repro)

unique sperm-egg combination increases diversity

variation in existing alleles

horizontal gene transfer (in bacteria)

transduction (allele vari)

viruses transfer DNA between bacteria

transformation (allele vari)

bacteria take of free DNA from enviornment

conjunction (allele vari)

direct DNA transfer via a pilus between bacteria