L3 - cells in their environment Flashcards

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1
Q

why is it believed that all cell types evolved from a common ancestor

A

cell types all share many features eg
cell membranes
utilise same classes of macromolecules
similarities in genetic code

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2
Q

what is the one common ancestor believed to be

A

ancestral prokaryote

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3
Q

what is LUCA

A

Last Universal Common Ancestor

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4
Q

explain the evolution of LUCA

A
  1. simple chemicals in prehistoric warm oceans reacted via catalysis to form simple RNA’s (could store info)
  2. these folded and formed ribozymes which had enzymatic activity (more complex RNA’s which could carry genetic info and catalyse their own reproduction)
  3. DNA was formed, more stable
  4. bilayers were formed (amphipathic lipids spontaneously form vesicles)
  5. a DNA molecule could have been trapped in one of these vesicles
  6. first cell
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5
Q

what simple molecules were thought to exist first

A

minerals , catalysts , phosphates, HCN etc

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6
Q

specialisation of a prokaryote

A

flagella
acidophiles / thermophiles etc
can use different energy sources (H, methane etc)

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7
Q

what is the endosymbiotic theory

A
  1. eukaryotes were originally anaerobic however were invaded by mitochondria via a symbiotic relationship between archaea and bacteria
  2. also the crossing of photosystem 1 and 2 to form photosynthetic bacteria, and then this crossing into plants
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8
Q

examples of single celled eukaryotes

A
  1. protozoans eg gregarina (slime mould)

2. yeast

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9
Q

examples of multicellular eukaryotes

A

plants

animals

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10
Q

explain concept of cellular specialisation

A

in multicellular organisms cells can be specialised to perform a particular function

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