Prokaryotes vs. Eukaryotes. I. Structure, function, and reproduction of prokaryotes A . Most prokaryotes are unicellular. 1.Some species form aggregates of two or more individuals . B . Three (3) common shapes: cocci (round); bacilli ( rod); helical (spiral).
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A. Most prokaryotes are unicellular.
1.Some species form aggregates of two or more individuals.
B. Three (3) common shapes: cocci (round); bacilli (rod); helical (spiral)
Caused by a spirochete
1. The sticky protective layer secreted by prokaryotes is called the capsule.
2. Some prokaryotes adhere to substrates using Pili.(Pili are thin, protein tubes originating from the cytoplasmic membrane)
a. Some Pili are specialized for DNA transfer. This process is called conjugation; note for later in class.
1. Cell walls maintain cell shape.
2. Cell walls are composed of peptidoglycan.(a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria, forming the cell wall)
1.Prokaryotes have no nucleus.
2. The nucleoidregion in a prokaryotic cell consists of a concentrated mass of DNA. This mass of DNA is usually one thousand times less than what is found in a eukaryote.
Photosynthesis evolved early in prokaryotic life
Cyanobacteria started to produce O2 about 2.7 billion years ago
Contrasting hypotheses for the taxonomic distribution of photosynthesis among prokaryotes.
- Parasitic; survive only within cells of animals
- Some cause STDs e.g.Chlamydia
- Helical heterotrophs
- Some cause STDs e.g. syphilis
- Oxygenic photosynthesis, and chloroplasts evolved from them.
A. Prokaryotes are links in the recycling of chemical elements
B. Many prokaryotes are symbiotic (2 organisms living in direct contact with each other).
Mutualism– both symbiotic organisms benefit
- e.g. Nitrogen-fixing bacteria like Rhizobium: plant obtain organic nitrogen, Rhizobium gets energy in the form of sugars that the plant produces.
Are all prokaryotes disease producing germs?
Without prokaryotes ecosystems would collapse!
Chemical & Medical production
Research (genetic engineering, etc.)
Prokaryote = without a nucleus
Eukaryote = with a nucleus
Have membranes surrounding organelles
Have cell wall
Are mostly bacteria
Include all plant and animal cells