Lecture 1: Introduction to Microbiology Flashcards
Understand that the scientific method requires that experiments be…
reproducible and predictive
Know how early microbiology disproved spontaneous generation.
Pasteur disproved spontaneous generation using a non-sterile liquid poured into a flask (the neck of the flask is drawn out using a flame) that is then sterilized by heating and air is forced out the open end. Tyndall fails to repeat the experiment. But Cohn discovers that endospores cannot be killed by boiling; endospores were in Tyndall’s broth.
Recognize the important properties of endospores.
The spore coat is dense and provides protection.
The cortex is responsible for heat resistance. It has peptidoglycan that has a spongy, loosely-crosslinked form that soaks up water from the core and keeps the core dry. Because the core is not wet, it is then heat resistant because hot water will not get in the core.
The core has small acid-soluble proteins and calcium-dipicolinate. The small acid-soluble proteins (SASPs) have DNA wrapped around them which allows the DNA to become non-replicative (inert, A-form DNA). This protects the DNA against mutation and prevents the spore from using energy. Calicium-dipicolinate is a salt that is found in the core which lowers water activity and keeps enzymes metabolically inactive.
Know the basic differences between prokaryotes and eukaryotes.
Prokaryotes are 0.3-2micrometers in size while eukaryotes are 5-50micrometers in size. Prokaryotes have peptidoglycan and eukaryotes do not. Prokaryotes do not have membrane-bound organelles (mitochondria, chloroplasts) but eukaryotes do.
Understand what we mean when we say prokaryotic cells are “diffusion limited”.
Size of prokaryotes is said to be “diffusion-limited” because they are limited by how fast large molecules (esp. proteins) can diffuse within cells that lack an endomembrane system.
Be able to explain why prokaryotic cells are generally smaller than eukaryotes,
Prokaryotic cells are generally smaller than eukaryotes because they do not have an endomembrane system and do not have as many internal structures as eukaryotic cells do.
Know the differences between bacteria and archaea.
Bacteria have a cytoskeleton made up of organized peptidoglycan synthases and division septum.
Archaea are more likely to be found in extreme environments.
Know the differences between algae, fungi, and protozoans.
Algae has a cellulose cell wall, chloroplasts for photosynthesis, and can have cilia.
Fungi have 2 life forms; it’s multi form is yeast and it’s singular form is mold. Fungi is also a saprophyte.
Protozoan use endocytosis for feeding and can have cilia.
Know the differences between viruses, viroids, and prions.
Viruses have no metabolism so they are not classified as living. Viruses can have DNA or RNA but never both. Viruses have a protein capsid/coat and some can have a lipid envelope. There are viruses that specifically attack either plants, phages, or animals. Viruses are kingdom specific.
Viroids are infectious RNA (no protein). They are naturally interfering RNA that usually affect plants. They are much smaller than viruses.
Prions are infectious protein (no nucleic acid). The are a manifolding template which is how they replicate. They are much smaller than viruses.
Cite some arguments for and against “phage therapy” using bacteriophage to fight infections.
Bacteriophages might be able to be used instead of antibiotics to treat bacterial infections. It is used routinely in much of the world. However, you need a different phage to kill each different bacteria. It has low efficacy in practice (50% success). Phage preparation may still contain live bacterial hosts that had been used to grow the viruses. Products released from dead bacterial cells can be toxic.
Know how bacterial, viral, and other microbial sizes compare to each other.
Bacteria: 0.2-3 um
Archaea: 0.2-3 um
Algae: 10-300 nm
Viruses: 10-100 nm
