IndietroConcepts for review
Termini in questo insieme (8)
Polyploidy
A condition in which an organism has more than two complete sets of chromosomes; a common mechanism of sympatric speciation, especially in plants.
Autopolyploid
An individual with more than two chromosome sets, all derived from a single species (typically from a failure of cell division that doubles its own chromosome number).
Allopolyploid
An individual with multiple chromosome sets derived from two or more different species, typically resulting from hybridization followed by chromosome doubling.
Heterochrony
An evolutionary change in the rate or timing of developmental events, which can result in substantial changes to an adult organism’s body form even without large-scale changes in the genes themselves.
Homeotic genes
A class of regulatory genes that control the overall body plan of an organism during development by determining the identity and placement of body structures; a subset of these genes contain a DNA sequence called the homeobox.
Effects of gene sequence changes
Changes in the genes that control development (regulatory genes) can have large effects on an organism’s form, even from relatively small changes in DNA sequence, because such genes often control the expression of many other genes during development.
Serial endosymbiosis
The hypothesis that mitochondria and chloroplasts originated through a sequence of endosymbiotic events, in which ancestral prokaryotic cells were engulfed by larger host cells and eventually evolved into these organelles.
Evidence supporting endosymbiotic theory
Mitochondria and chloroplasts share several features with free-living prokaryotes, including their own circular DNA, bacteria-like ribosomes, a double membrane, and the ability to grow and reproduce somewhat independently within the cell — all supporting their origin as engulfed prokaryotic cells.