Topic 11
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What was toxic to most early prokaryotes?
Oxygen
What are the six ways eukaryotic cells differ from prokaryotes?
i) DNA in linear chromosomes in a membrane-bound nucleus ii) Membrane-bound organelles iii) Much larger iv) Cytoskeleton v) Dynamic membranes vi) Sexual reproduction
Why is sexual reproduction important?
It promotes genetic diversity in eukaryotic populations
What creates unique gametes and what fuses them together at random to create unique combinations of alleles?
Meiosis and fertilization
What is the endosymbiont theory?
It proposes mitochondria and plastids (chloroplasts) were formerly small prokaryotes living within larger host cells
What is the process in which a unicellular organism engulfs another cell becoming an endosymbiont and eventually an organelle?
Endosymbiosis
What is a cell that lives within a host cell?
An endosymbiont
What are the three steps to the origin of eukaryotic cells?
i) Prokaryotic cells developed structures like the nuclear envelope and endoplasmic reticulum by infoldings of the plasma membrane ii) Took in an endosymbiotic aerobic, heterotrophic prokaryote that became the mitochondrion iii) Other eukaryotes took in photosynthetic prokaryotes
What is a sequence of first mitochondria and then plastids by primary endosymbiosis?
Serial endosymbiosis
What is the difference between Primary and Secondary endosymbiosis?
Primary symbiosis involves prokaryotes taken up by prokaryotic or eukaryotic cells and secondary involves the engulfing of eukaryotic cells by other eukaryotic cells
What are the five points of evidence supporting the endosymbiotic origin of mitochondria and plastids?
i) Mito and chloro have their own circular DNA ii) Division is similar in organelles to some prokaryotes iii) Organelle’s inner membranes are homologous to plasma membranes of prokaryotes iv) Ribosomes are more similar to prokaryotes v) Resemble bacteria in size and structure
What is the movement of genes between genomes of different species?
Horizontal gene transfer
What is the informal name of a taxonomically diverse group of mostly unicellular eukaryotes?
Protist (paraphyletic group)
How do protists differ to other eukaryotes?
More structural, nutritional and functional diversity Some asexual reproduction
What is the diversity of protists caused by?
Endosymbiosis