Prokaryotes vs. Eukaryotes Quiz

Study Notes

Prokaryotic cells (bacteria and archaea) lack a true nucleus and membrane-bound organelles.
DNA is in a nucleoid region and typically a single circular chromosome.
Generally smaller and simpler, often single-celled.
Eukaryotic cells (animals, plants, fungi, and protists) have a defined nucleus with a nuclear membrane.
DNA is organized into linear chromosomes.
Possess many membrane-bound organelles (mitochondria, endoplasmic reticulum, Golgi apparatus) for compartmentalized functions.
Generally larger and can be single-celled or multicellular.

Among the most diverse groups of bacteria on Earth.
Seemingly simple cell structure.
Can be chain-forming or unicellular.
Important nitrogen fixers, contributing to ocean productivity and nutrient cycling (crucial in nutrient-poor regions).
Plant chloroplasts likely evolved from cyanobacteria (endosymbiosis theory).
Essential in Earth's history, fundamental to oxygenation.

Major light-harvesting pigment is chlorophyll a.
Absorbs red light.
Also contain carotenoids (e.g., beta-carotene).
Phycobiliproteins (like phycocyanin and phycoerythrin) change concentration based on light quality and quantity; form phycobilisomes.
Can perform photosynthesis in aerobic and anaerobic conditions.

Diazotrophs fix atmospheric nitrogen (N2).
Nitrogenase is responsible, but sensitive to oxygen.
Photosynthesis occurs during the day, and significant nitrogen fixation often occurs at night to separate the two processes.

Found in oceans, freshwater, and terrestrial environments (including hot springs, extreme environments etc.)
Essential components of several extreme environments such as oceans, hot springs, salt marshes, etc.
Bloom formers in some regions especially during late summer.
Primary colonisers.
Crucial in many symbiotic relationships (lichens, root nodules).

Open ocean: picophytoplankton (e.g., Synechococcus, Prochlorococcus).
Filamentous: Trichodesmium.
Littoral zones: encrusting or biofilm-forming species.
Importance to stromatolites and beachrock formation.
Different colours (e.g., black & pink types) are adapted to different conditions. This is indicated by their desiccation capacity, response to high and low tide environments.

Desiccation (water removal) is a significant issue.
Cyanobacteria mats are poikilohydric (can withstand desiccation by entering a dormant state).
Pink biofilm holds water better than the black biofilm and thus are better suited for the intertidal zones and have better desiccation tolerance.