study guide 1 - learning objectives

Ways microbes shaped environment + history

• Produced oxygen through photosynthesis (cyanobacteria).

• Decomposed waste, recycling nutrients.

• Caused and prevented disease (plagues, vaccines, antibiotics).

• Food/beverage production (bread, beer, cheese).

Timeline of microbiology discoveries

• 1600s – Leeuwenhoek sees microbes with microscope.

• 1800s – Pasteur disproves spontaneous generation; Germ Theory develops.

• Late 1800s – Koch proves microbes cause specific diseases.

• 1900s – DNA discovered as genetic material; molecular biology revolution.

Evidence for Endosymbiotic Theory

• Mitochondria & chloroplasts have their own DNA and ribosomes.

• They reproduce by binary fission (like bacteria).

• Double membranes suggest engulfing process.

Supporting evidence:

• Mitochondria and chloroplasts have their own DNA (similar to bacterial DNA).

• They replicate by binary fission, like bacteria.

• Their ribosomes resemble bacterial ribosomes.

• DNA sequence & chromosome structure strongly match bacteria.

• Genes have been transferred from organelles → host nucleus.

Three domains of life

• Bacteria – prokaryotes with peptidoglycan cell walls.

• Archaea – prokaryotes, extreme environments, unique membrane lipids.

• Eukarya – eukaryotes with nucleus and organelles.

Phylogenetic trees

• Closer branches = more closely related.

• Root shows common ancestor.

• Can compare genetic markers (like rRNA).