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Biology Unit 1- Natural Selection > The Rise of Eukarya > Flashcards

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What is the advantage of organisms being ‘wall-less mutants’?

taking advantage of one of the most abundant food sources – other cells. Internal digestion is possible now. But now it is important to have lysosomes and nuclear membrane


why is an envelope necessary for wall-less mutants

DNA is at risk of enzyme degradation when food is taken in


how did mitochondria arise in eukaryotic cells?

By an engulfment process, where aerobic bacteria were enslaved to produce more energy using oxygen (Endosymbiosis theory)


what evidence is there for the arising of mitochondria in cells?

Double membrane
Own DNA (bacteria type DNA-plasmid)
Divide by what seems to be binary fission (bacterial asexual reproduction)
Pelomyxa contains no mitochondria, but instead has symbiotic bacteria inside


6 most important changes in evolution of eukaryote

- mitochondria
- motor proteins
- mitosis
- chloroplasts
- sexual reproduction
- multicellularity



- endosymbiosis theory


motor proteins

molecules that move material around the cell
provide movement for the cells
cytoplasmic streaming
thought to be a symbiotic relationship with bacteria (cilia and flagella)
allowed for behaviour to develop


mitosis (and chromosomes)

copying of genetic material to allow for the distribution of a copy to each cell
growth, repair or replace cells, asexual reproduction unicellular organisms
much more efficient than relying on the random distribution


chloroplasts (and photosynthesis)

evolved from green symbionts that live inside cells for protection, while providing the cell with food by photosynthesis
chloroplasts contain DNA, replicate like bacteria, have bacterial ribosomes, antibiotics kill them – this indicates that they likely began as a symbiotic relationship
chlorophyll molecules are found in different combinations in eukaryotic photosynthesizers
symbiotic relationships still exist (sea squirts, hydra etc)


sexual reproduction

more complexity and diversity
fusing together to exchange genes
produces genetic variety for natural selection to act on
diploid haploid cycle for new variety



colonies help to avoid predation
division of labour