Topic 11: origin of eukaryotes Flashcards

• what was toxic to most early prokaryotes

  oxygen
• what caused the oxygen revolution

  photosynthetic cyanobacteria
• how long after the oxygen revolution did eukaryotic cells arise

  100 million years after the oxygen revolution
• what are the 6 ways eukaryotes differ from prokaryotic cells

  1. DNA in linear chromosomes in a membrane bound nucleus2. membrane-bound organelles3. eukaryote cells are generally much larger4. cytoskeleton 5. have dynamic membranes6. sexual reproduction promotes genetic diversity
• Eukaryotic genomes are larger than those of prokaryotes allowing for what


  allowing for evolution of new mechanisms of gene regulation
• compartmentalizing machinery for energy metabolism frees the cell to what


  to interact with the environment in novel ways not available to prokaryotes
• What does the cytoskeleton in eukaryotes do?

  allows them to change shape, move, and transfer substances in and out of the cell-allows engulfing particles by phagocytosis
• why do eukaryotes have dynamic membranes

  facilitate movement and feeding
• meiosis creates what

  unique gametes
• how does meiosis create unique gametes

  through chromosome recombination and independent assortment of alleles
• fertilization fuses what

  fuses gametes at random creating unique combinations of alleles
• alternation of meiosis and fertilization is common to what

  all sexually reproducing organisms
• three main types of sexual life cycles differ in what

  in timing of meiosis and fertilization
• life cycles of single celled eukaryotes differ in proportion of what


  of time spent as haploid (1n) versus diploid (2n) cells
• life cycles of multicellular eukaryotes have many what

  mitotic divisions between formation of the zygote and meiosis
• the endosymbiont theory states that


  mitochondria and plastids were formerly small prokaryotes living within larger host cells
• what is a plastid

  chloroplasts and related organelles
• What is endosymbiosis?


  is a relationship between two species in which one organism lives inside the cell or cells of another organism, thus become an endosymbiont
• what is an endosymbiont


  a cell that lives within a host cell
• how did prokaryotic ancestors of mitochondria and plastids most likely enter the host cell

  entered as undigested pray (phagocytosis) or as internal parasites
• In the process of becoming more interdependent, host and endosymbionts would become what

  a single cell
• Endosymbiont theory supported by what

  physical, biochemical, and genetic similarities between chloroplasts & cyanobacteria, and between mitochondria & alpha-proteobacteria.
• Ancestral prokaryote cells developed structures gradually by what

  by infoldings of the plasma membrane, including:- Endoplasmic reticulum. - Nuclear envelope.
• in serial endosymbiosis the ancestral prokaryote may have been a what

  been an archaeon
• ancestral prokaryote cells took on what kind of endosymbiotic prokaryote

  an aerobic heterotrophic prokaryote-probably and alpha-proteobacteria
• at what point was a cell a true eukaryote (3)

  -prokaryote cells took on an endosymbiotic aerobic heterotrophic alpha-proteobacteria-uses oxygen and organic matter to generate energy-eventually became the mitochondrion
• other ancestral heterotrophic eukaryote lineages engulfed what

  photosynthetic prokaryotes-most likely cyanobacteria
• ancestral photosynthetic eukaryote gave rise to what (2)

  to photosynthetic protists and plants
• ancestral heterotrophic eukaryotes gave rise to what (3)

  animals, fungi, and many protists
• serial endosymbiosis hypothesizes that


  that mitochondria evolved before plastids through a sequence of primary endosymbiotic events.
• Although all eukaryotes have mitochondria (or remnants of these organelles), they do not all have what


  plastids (chloroplasts and related organelles).
• Primary (1°) endosymbiosis is what

  prokaryotes are taken up as endosymbionts by prokaryotic or eukaryotic cells.
• Secondary (2°) endosymbiosis is what

  eukaryotic cells are taken up as endosymbionts by other eukaryotic cells.
• what are the 5 points of evidence supporting the endosymbiotic origin of mitochondria and plastids

  1. The organelle's inner membranes are homologous to plasma membranes of prokaryotes.2. Mitochondria and chloroplasts have their own small, circular DNA, which they replicate, transcribe, and translate independently of nuclear DNA. 3. Division is similar in these organelles and prokaryotes (binary fission). 4. The organelle ribosomes are more similar to prokaryotic than eukaryotic ribosomes. 5. The organelles resemble prokaryotes in size and structure.
• Some unicellular eukaryotes evolved to interact with one another, giving rise to what

  a variety of multicellular forms.
• multicellularity evolved independently multiple times, giving rise to what (4)

  algaeplantsfungianimals
• The oldest known fossils of multicellular eukaryotes that can be resolved taxonomically are what

  small algae that lived about 1.2 bya.
• Larger and more diverse multicellular eukaryotes do not appear in the fossil record until about how long ago

  600 mya (the Ediacaran biota that lived from 600 to 535 mya
• Early taxonomists classified all species as either what

  plants or animals
• what used to be the 5 kingdoms to classify organisms

  Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia.