Cells: Evolution

Question 1

Evolution of Cells

Answer 1

= existing cells are the products of evolution
... billions of years ago:
4.5: Earth created
3.5: first prokaryotes (anaerobic)
2.5: first photosynthesising prokaryotes
1.5: first eukaryotes
.480: first plants
.225: first mammals

Question 2

Miller-Urey Experiment (1953)

Answer 2

• produced organic compounds from inorganic compounds

- results support theory that life arose as a product of chemical reactions (after 1 week: amino acids, adenine, ribose)

Question 3

Evidence of Evolution

Answer 3

1. calcified bacteria (fossil rocks)
   - stromatolites (bacterial mats growing in salt water) in WA are 3-4 billion years old
2. infolding of plasma membrane
   - formed: E.R., nucleus, Golgi bodies, most other organelles
3. endosymbiosis: mutually beneficial relationship where larger prokaryote engulfs smaller cell by phagocytosis
   - smaller cell not destroyed/digested, able to respire aerobically/photosynthesise
   - larger cell able to carry more cellular activities than before

Question 4

Evidence of Endosymbiosis

Answer 4

chloroplasts (cyanobacteria) & mitochondria (aerobic bacteria)…

1. own circular loop of DNA (resemble prokaryote - no proteins, introns)
2. own ribosomes (resemble bacterial ribosomes)
3. able to self-replicate independently (binary fission)
4. distinctly different double membrane (outer similar to host, inner similar to bacteria)