10/15 Unicellular Organisms

What are the three domains of life?

Bacteria, Archea, and Eukaryotes. Bacteria and archea are prokaryotes.

Prokaryotes are the basis of all…

eukaryotic metabolism

Who are the Archaea?

They can inhabit extreme environments; methanogens, halophiles, thermophiles, acidophiles

Binary Fissions

the process by which prokaryotes reproduce asexually (similar to mitosis)

Horizontal Gene Transfer

the process where an organism transfers genetic material to another organism that is not its offspring

4.6 bya, Earth was…

hot, barren, with low oxygen. Over time, it cooled and oceans formed.

Photosynthesis

converts solar energy from the sun into chemical energy (energy stored in bonds)

Photosynthesis is followed by one of two forms of respiration

Anaerobic - without oxygen (med 2 ATP per glucose molecule)

Aerobic - with oxygen (more efficient; new 38 ATP per glucose molecule)

Respiration

chemical process of releasing energy from food

Which came first, photosynthesis or anaerobic respiration?

Anaerobic respiration came before photosynthesis

Protists

a catch-all category for things that act like animals but are usually unicellular

What kind of phylogenetic grouping is “Protists?”

a polyphyletic group and a traditional grouping that has been proved meaningless, but it useful to have category names to use!

How do protists get food?

some eat organic matter and some do photosynthesis

How do protists reproduce?

asexually (binary fission, budding) and sexually

Examples of beneficial protists

Phytoplankton are important sources of food in aquatic ecosystems

Examples of harmful protists

• Diatoms and dinoflagellates can reproduce in enormous numbers when conditions are favorable

• Toxins produced by these organisms can kill or harm vertebrates, including fish and humans!

Properties of simple multicellularity

• Adhesion molecules present (stick + stay together!)

• Most/all cells retain a full range of functions, including reproduction

• Every cell is in contact with the external environment

  • Lack a complex 3-D structure that encloses some cells