Bio 004,CH15, College of the Desert

• All major animal groups evolved before the end of the Cambrian Period.
• Extensive animal diversity in 10 million years All major animal groups evolved before the end of the Cambrian period.

Belief that life arises from non-living material.

• Principle in that life arises only by the reproduction of pre-existing life
• In a series of experiments, Louis Pasteur proves biogenesis over spontaneous generation (1862).

• Four Stage Hypothesis – Origin of Life
• 1) The abiotic synthesis of small organic molecules (amino acids, nucleotides, etc.).
• 2) The joining of small organic molecule into large organic molecules (polymers) forming proteins and nucleic acids.
• 3) The origin of self-replicating molecules (RNA & DNA) that ultimately makes inheritance possible.
• 4) The packaging of all these molecules into precursors to cells.

Way in which organic molecules could have been synthesized around deep sea vents and lava flows.

• Prokaryotes [Bacteria]
• A. General Characteristics
• 1. Ubiquitous - outnumbering all other species
• 2. Thrive in extreme conditions
• 3. Responsible for serious illness
• 4. Responsible for human existence

• 1. Archaea
• a) Extremophiles: thrive in extreme conditions (extreme heat, pH, salinity, etc.)
• b) Methanogens: thrive in anaerobic conditions (digestive tracts of herbivores), producing methane gas.

2. Bacteria Consist of the more familiar bacteria – those that interact directly or indirectly with humans.

• 1. Most are unicellular and very small
• 2. Nucleus/complex organelles absent
• 3. Cell walls (different than plant cell walls)
• 4. Occur in three basic shapes: coccus (round), bacillus (rod), and spirillum (spiral).

• Endospores: Thick-coated protective cell produced within a bacterial cell when exposed to harsh conditions.
• a. Remain dormant for centuries.
• b. Can even withstand boiling water.
• c. Example: Clostridium botulinum.

Asexual reproduction in which the parent cell divides into two cells of approximate equal size. Some bacteria populations double in size every 20 minutes; in 48 hours this would result in a colony consisting of 2.2 x 1043. Colonies are limited in size by the amount of natural resources and by the build-up of waste products.

• Disease-causing organism.
• Exotoxins - poisonous proteins secreted by bacterial cells (example: Staphylococcus)
• Endotoxins - poisonous chemical components within bacterial cells (example: Salmonella)

Prokaryotes derive energy from light and chemicals depending on their habitat.

Organisms that break down dead and decaying organic material. Recycle nutrients back into living organisms. [decomposers]

Use of organisms to remove pollutants from water, air, and soil.

• 1. Unicellular to multicellular.
• 2. Nucleus/complex organelles present.
• 3. Cell walls present in algae, fungi, and plantsOccur in many diverse shapes.

Close association of 2 species in which one lives inside another.

• a) Contain DNA & RNA.
• b) Synthesize proteins using ribosomesReproduce by binary fission.

Eukaryotic, unicellular organisms.

Animal – like protists

Fungus – like protists

• Plant-like protists (photo-synthetic)
• a) Plankton: Communities of microscopic organ-isms that drift or swim near pond, lake, and ocean surfaces.
• b) Diatoms: Unicellular algae with cell walls com-posed of silica (glass); diatomaceous earth
• c) Green algae: Most closely related to green plants (ancestors?); possess cell walls and chloroplasts.

Large, multicellular, marine algae. Grows along rocky shores and just beyond the surf with adaptations for existence. Classified based partly on pigments present: green, red, brown (kelp). Food source and as a thickening agent in pudding, ice cream, and salad dressing.