A2.2 Cell Structure [HL]

where are all eukaryotes evolved from

a common unicellular ancestor around 2.7 billion years ago

describe an ancestral prokaryote cell

a nucleus and sexual reproduction

describe the process of endosymbiosis

ancestral eukaryote (respired anaerobically) -> infolding of plasma membrane (nucleus forming) -> endosynthesis (aerobic bacterium + cyano bacterium) -> ancestral eukaryotes

what are the 6 evidences for endosymbiosis

size, membranes, DNA, ribosomes, division, susceptible

membranes

double membrane (inner membrane formed from plasma membrane, outer membrane from vesicle)

DNA

circular naked DNA

ribosomes

70S ribosomes

division

binary fission

susceptible to…

susceptible to some antibiotics

what is the function of cell differentiation

allows for the development of specialized tissue in multicellular organisms

what happens to the gene of unspecialized cells

all the genes are switched on this chromosome

what happens to the gene in specialized cells

different genes are switched off, only certain genes are expressed and others are not expressed

what does cell specialization results in

cells that structurally adapted for their specific function

what are the 3 evolution of multicellular

1. all plants and animals are multicellular

2. many fungi and eukaryotic algae are multicellular

3. multicellularity evolved independently

what are the three advantages of multicellularity

1. Cell specialization

2. Larger body size

3. Longer lifespan