(VAB) Viruses and Bacteria Module Overview

BiologyOverview_Banner.png

Alien Invasion

"If an alien visited Earth, they would take some note of humans, but probably spend most of their time trying to understand the dominant form of life on our planet - microorganisms like bacteria and viruses." -Nathan Wolfe

BIO19_AlienBacteria.png

Microbiology: The study of microscopic, unicellular organisms which include both prokaryotes and viruses (as well as Protists and Fungi). In this module, we will be focusing on prokaryotes (bacteria) and viruses.

Module Lessons Preview

In this module, we will study the following topics:

  • Viruses
  • Bacteria: Archaebacteria and Eubacteria
  • Bacteria Reproduction
  • Human Effects: Harmful & Helpful

Module Key Terms

Key Terms

  • Microbes- things that are too small to be seen with the naked eye, including viruses and bacteria. Many are also called germs or pathogens
  • Pathogen - disease-causing agent (virus, bacteria, protist, or fungi)
  • Bacteria (sing. bacterium) – one of the two Domains of prokaryotes and are single-celled organisms that lack nuclei
  • Virus (pl. viruses) – infectious agent composed of a core of DNA or RNA surrounded by a protein coat
  • Host - the organism that houses a disease-causing entity (virus, bacteria). The disease-causing entity would reproduce within the host (example:you may be the host of E.Coli if you have a stomach flu
  • Viroid - plant pathogen.Their genome is composed of very short, circular RNA.
  • Prion - an infectious particle made of protein (rather than DNA or RNA) that has been mis-folded. It may induce other proteins to fold in a similar manner to itself
  • Prokaryote - single-celled microorganisms that lack a nucleus. All bacteria are prokaryotes.
  • Archaebacteria - ancient forms of bacteria that survive extreme heat, acidity, salinity, or even methane
  • Eubacteria - slightly more advanced bacteria found in three common shapes – bacilli, cocci, and spirilla and range from mutualistic and beneficial forms to extremely deadly parasitic forms
  • Peptidoglycan - a polymer of sugars and amino acids, which protects the cell from injury and determines its shape
  • Capsule - outer layer of some bacteria that protect some bacteria from drying out and being eaten
  • Pili (singular: pilus) - hairline projections often used in bacterial conjugation. One type helps in motility
  • Nucleoid - bacterial genome (DNA)
  • Plasmid - tiny, circular pieces of DNA (separate from the bacterial genome) found in bacteria that typically contains antibiotic resistant genes or other genes beneficial to the bacteria
  • Flagellum -a whip-like structure that some prokaryotes (and eukaryotes) use for motility
  • Cocci (singular: coccus) - sphere-shaped bacterium
  • Bacilli (singular: bacillus) - rod-shaped bacterium
  • Spirilli (singular: spirillum) - spiral-shaped bacterium
  • Filamentous - elongated shape for a bacterium
  • Gram stain - technique for identifying eubacteria based on their cell wall structure and involves dyeing and rinsing the cells
  • Gram positive - bacteria with thick peptidoglycan layer that remain violet colored after gram staining
  • Gram negative - bacteria with thin peptidoglycan layer that remain red/pink colored after gram staining
  • Photoautotroph - organism that obtains energy directly from the sun
  • Chemoautotroph - organism that obtains energy from using chemicals in the environment
  • Photoheterotroph – heterotrophic phototrophs; they use energy from the sun, but need compounds in the environment to make their own food
  • Taxes (singular: taxis) – movement towards or away from a stimulus (phototaxis, chemotaxis, and magnetotaxis types exist in bacteria)
  • Obligate aerobes - organisms that require a constant supply of oxygen to live
  • Obligate anaerobes - organisms that do not require oxygen to live; can even be poisoned by it
  • Facultative anaerobes - organisms that do not require oxygen, but can switch from cellular respiration and fermentation. They can live anywhere.
  • Binary fission - asexual cell division in bacteria that results in two identical daughter cells (this also occurs in some cell organelles, such as mitochondria)
  • Bacterial conjugation - when a bacterium transfers genetic material (such as plasmid) to another bacterium by physical contact with another cell. It usually involves direct cell to cell contact and/or a bridge between cells
  • Endospore - tough, protective form of bacteria that is usually triggered by low-nutrient conditions. It allows the bacteria to remain dormant until favorable conditions for growth arise
  • Pasteurization - a process of heating and cooling food products repeatedly so that the endospore that breaks out of dormancy into regular bacteria form during cooling will be killed if heated again
  • Sterilization -an effective means of removing or killing pathogens and it may involve using heat, chemicals, irradiation, pressure
  • Antibiotic - compound that kills or stops the growth and reproduction of bacteria
  • Zones of inhibition (ZOI) - in bacterial culture, an area where bacteria are not growing because of a chemical agent (antibiotic, for example) is inhibiting their growth
  • Bioremediation - a process where bacteria are used to clean up waste water, oil spills, or convert garbage to compost
  • Nitrogen fixation - the process of converting nitrogen gas into a chemical form the plant can use
  • Capsid - the outer boundary of a virus, composed of protein
  • Retrovirus - a virus that stores its genetic information in RNA
  • Bacteriophage - a virus that infects bacteria
  • Lytic (Lytic Cycle) – a type of viral reproduction or infection in which the viral cell releases its DNA into the host cell and the host cell makes new viruses by reading viral DNA. The host cell bursts, releasing the manufactured viruses. Viruses that use the lytic cycle are called virulent.
  • Lysis - a process of breaking apart or bursting a cell
  • Lysogenic (Lysogenic Cycle) - a type of viral reproduction or infection in which the host cell integrates copies of the viral DNA within its own genome and the viral DNA is copied into daughter cells and part of the normal bacterial reproduction. The host cell does not lyse. Viruses that use the lysogenic cycle are called temperate because they do not immediately cause disease.
  • Interferon - a protein produced by cells when exposed to a virus. This protein binds to the cell membranes of neighboring cells and “interferes” with the ability of a virus to enter the cell
  • Vaccine - part of a virus (or bacterium) that has been permanently damaged or attenuated (weakened) used to prevent infection by exposing a host to it. It’s role is to stimulate the body’s immune system so that it destroys and then records information about the invader, should it return again.

Science_OverviewBottomBanner.png