MicrobiologyLesson 3 of 3 in the course An Invisible World

Microbial Diversity, Infectious Agents, and Research Ethics

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

Save course
Lesson progress
0 / 5

Your progress is kept in this browser only.Sign up to save it

Summary

Microorganisms vary widely in size and organization. This lesson introduces the scale of microscopic life and the broad classification systems used to describe it.

An object generally needs to be about 100 micrometers across to be visible to the unaided eye. A typical animal cell is about 10 μm\mu m across, while many bacterial cells are about 1 μm\mu m. Viruses can be roughly ten times smaller than bacteria. Most microbes therefore require magnification, although a few single-celled organisms are visible without a microscope and some microscopic organisms are multicellular.

All flashcards

What is a micrometer?
A unit of length equal to one-millionth of a meter, or 10−610^{-6} meters; it is commonly used to describe cells and bacteria.
How does a nanometer compare with a micrometer?
A nanometer is one-thousandth of a micrometer and equals 10−910^{-9} meters.
What distinguishes a prokaryote from a eukaryote?
A prokaryote lacks a nucleus enclosing its DNA, while a eukaryote has a nucleus.
What are the three domains of cellular life?
Archaea, Bacteria, and Eukarya.
Why are viruses called acellular?
They are not composed of cells, and they are not classified within any of the three domains of life.

Quiz questions

  1. Which substance is found in most bacterial cell walls?Answer: Peptidoglycan
  2. Which statement describes yeasts in comparison with molds?Answer: Yeasts are unicellular fungi, while molds are multicellular.
  3. Which combination describes algal protists?Answer: They photosynthesize and have cell walls containing cellulose.
  4. Which statement describes the genetic material in a virus?Answer: A virus contains DNA or RNA, but not both.
  5. What are prions made of?Answer: Infectious abnormal proteins without genetic material.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

More in Microbiology

All Microbiology lessons
MicrobiologyBacterial Culture Media: Composition, Selection, and Differential Tests5 flashcards · 5 quiz questions · 4 gamesPlay free →MicrobiologyMicrobial Temperature Growth, Adaptations, and Food Safety5 flashcards · 5 quiz questions · 4 gamesPlay free →MicrobiologyClinical Features, Transmission, and Time Courses of Infectious Disease5 flashcards · 5 quiz questions · 4 gamesPlay free →MicrobiologyMicrobial Growth, Enumeration, Reproduction, and Biofilms5 flashcards · 5 quiz questions · 4 gamesPlay free →MicrobiologyDeeply Branching Bacteria: Phylogenetic Position and Extreme Adaptations5 flashcards · 5 quiz questions · 4 gamesPlay free →MicrobiologyFrom Ancient Fermentation to the Foundations of Microbiology5 flashcards · 5 quiz questions · 4 gamesPlay free →