lecture 9 Flashcards
when did the first eukaryotic organisms evolve?
2 billion years ago
what lead to the evolution of prokaryotes
increased oxygen concentration in the atmosphere due to cyanobacteria producing oxygen though photosynthesis
2 ways how some anaerobic prokaryotes survived the increase of O2 in the environment?
some lived in oxygen poor environments (water)
some formed an endosymbiotic relationship with an aerobic prokaryote
what is symbiogenesis?
the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms
what eventually led to the eukaryotic cell?
the endosymbiotic relationship between an asgard archaea and an alphaproteobacterium
what is evidence of symbiogenesis being used to make the prokaryotic cell?
evidence that the alphaproteobacterium entered the asgard superphylum and formed the mitochondria in prokaryotic cells
mitochondria has it’s own DNA, ribosomes, intermembrane and outer membrane
how did the first eukaryote evolve from the endosymbiotic relationship?
genes from the proteobacterium merged with the archaea DNA
eukaryotic DNA contains some genes that are similar to both archaea and bacteria
3 benefits of eukaryotic cells
- nucleus protects DNA (fewer mutations) and keeps cell division coordinated
- ability to reproduce sexually
- organelles keep functions separate and efficient, and allow cells to specialize and form tissues.
3 advantages to asexual reproduction
quick population growth
no need for a mate
all individuals can produce offspring
advantage to sexual reproduction
produces genetic variation (genetic recombination)
offspring more fit than parent in change in environmental conditions
from which process did meiosis evolve from?
mitosis
mitosis would have evolved in eukaryotes and meiosis evolved later
what is a haploid - dominant lifecycle?
organisms exist in a haploid stage (single celled or multicellular)
fusion only takes place right before sexual production
how do haploid dominant organisms reproduce?
asexually
what is a diploid dominant lifecycle?
organisms exist in a multicellular diploid stage for most of their life
single celled haploid gametes only produced during sexual reproduction
can diploid dominant organisms produce asexually?
no
what is haplodiplontic life cycle?
organisms alternate between a multicellular haploid stage and multicellular diploid stage
haploid gametophyte produce gametes while diploid sporophyte produce spres
