Exercise 3 — Microbiology of Pond Water & Prokaryote/Eukaryote Survey

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

What is the most recent method of classifying organisms based on evolutionary relationships?

Molecular phylogeny, which compares molecular information such as DNA and RNA to determine evolutionary relationships.

Which eukaryotic organisms are studied by microbiologists?

Fungi, protozoa, algae, and some helminths.

Which organisms belong to the domain Eukarya?

Fungi, animals, plants, algae, and protozoa.

What is the main difference between prokaryotic and eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles; eukaryotic cells have a nucleus and membrane-bound organelles.

Are fungi eukaryotic or prokaryotic?

Eukaryotic.

What is yeast?

A unicellular fungus, usually made of single round or oval cells.

What are molds?

Multicellular fungi made of long, threadlike structures called hyphae.

What are mushrooms?

Multicellular fungi that produce visible reproductive structures.

What is the difference between yeast, molds, and mushrooms?

Yeast are unicellular fungi; molds are multicellular fungi made of hyphae; mushrooms are multicellular fungi that form visible reproductive structures.

What is Candida?

A genus of yeast-like fungi that can normally live on the body but can also cause fungal infections.

How can you identify Candida under the microscope?

Look for oval or round yeast cells, often showing budding; some species can also form pseudohyphae.

What are hyphae?

Long, threadlike structures that make up the body of many multicellular fungi.

What is mycelium?

A mass or network of hyphae that makes up the main body of a mold or other filamentous fungus.

What is the difference between a hypha and mycelium?

A hypha is one threadlike structure; mycelium is a network of many hyphae.

What is Rhizopus and how can you identify it microscopically?

Rhizopus is a mold commonly known as bread mold; it can be identified by its large, round sporangia containing spores.

How can you identify Penicillium under the microscope?

Penicillium has a brush-like arrangement of structures that produce spores.

How can you identify Aspergillus under the microscope?

Aspergillus has a rounded or conical spore-producing structure at the end of a stalk, with spores arranged around it.

How can you distinguish Rhizopus, Penicillium, and Aspergillus by their spores?

Rhizopus has spores inside a round sporangium; Penicillium has spores in a brush-like structure; Aspergillus has spores arranged around a rounded or conical structure.

What are saprophytes?

Organisms that obtain nutrients by breaking down and absorbing nutrients from dead or decaying organic matter.

Give examples of saprophytic organisms.

Many fungi, including molds such as Rhizopus, are saprophytes.

How can you distinguish a bacterial colony from a fungal colony?

Bacterial colonies are usually smooth, shiny, or moist; fungal colonies are often fuzzy, cottony, powdery, or filamentous.

What are mycoses?

Fungal infections or diseases caused by fungi.

What are mycorrhizae?

Mutualistic relationships between fungi and plant roots.

What benefit do mycorrhizae provide to plants?

The fungi help plants absorb water and minerals, especially phosphorus, from the soil; the plant provides nutrients to the fungus.

What are lichens?

A mutualistic association between a fungus and a photosynthetic partner, usually an alga or cyanobacterium.

What are the benefits to the fungal and algal partners in a lichen?

The fungus provides structure, protection, water, and minerals; the alga or cyanobacterium provides sugars made through photosynthesis.

What type of reproduction is commonly seen in yeasts, molds, and mushrooms?

Fungi can reproduce both sexually and asexually, depending on the species and conditions.

How do yeast commonly reproduce asexually?

By budding, in which a smaller daughter cell grows from the parent cell.

How are bacteria classified based on the shape of their cells?

Coccus = spherical; bacillus = rod-shaped; spirillum = spiral-shaped; vibrio = curved or comma-shaped.

What are the identifying characteristics of bacteria?

Bacteria are unicellular prokaryotes that lack a nucleus and membrane-bound organelles; most have a cell wall and can be identified by their shape and arrangement.

What is peptidoglycan?

A strong material in the bacterial cell wall that helps maintain cell shape and prevents the cell from bursting.

What is binary fission?

The process in which a bacterial cell copies its DNA and divides into two genetically similar daughter cells.

How do bacteria obtain nutrition?

Bacteria can absorb nutrients from organic matter, obtain energy from inorganic chemicals, or produce their own food through photosynthesis or other energy-producing processes.

What are the identifying characteristics of Archaea?

Archaea are unicellular prokaryotes that lack a nucleus and have cell membranes and cell walls that differ from bacteria.

Why are some archaea referred to as extremophiles?

Many archaea can survive and grow in extreme environments such as very hot, salty, acidic, or oxygen-free environments.

How do archaea obtain nutrition?

Archaea can absorb nutrients or obtain energy through chemical reactions; some use inorganic chemicals as energy sources.

Where can archaea be found?

Archaea can be found in soil, water, the human body, hot springs, highly salty water, and oxygen-free environments.

Are archaea prokaryotic or eukaryotic?

Prokaryotic.

What are the identifying characteristics of protozoa?

Protozoa are generally unicellular eukaryotes that lack a rigid cell wall and usually obtain nutrients by consuming or absorbing organic material.

What are the three major mechanisms of motility displayed by protozoa?

Flagella, cilia, and pseudopodia.

What are pseudopodia?

Temporary extensions of a cell used for movement and obtaining food.

What are the identifying characteristics of algae?

Algae are eukaryotic organisms with photosynthetic pigments that can produce their own food through photosynthesis; they can be unicellular or multicellular.

What are the identifying characteristics of cyanobacteria?

Cyanobacteria are prokaryotic bacteria that perform photosynthesis and contain photosynthetic pigments.

Are cyanobacteria bacteria or algae?

Bacteria; cyanobacteria are photosynthetic prokaryotes in the domain Bacteria.

In which domain are bacteria classified?

Domain Bacteria.

In which domain are archaea classified?

Domain Archaea.

In which domain are algae classified?

Most algae studied in introductory microbiology are eukaryotes in Domain Eukarya.

In which domain are protozoa classified?

Domain Eukarya.

In which domain are fungi classified?

Domain Eukarya.

In which domain are cyanobacteria classified?

Domain Bacteria.

Which domain do bacteria belong to?

Bacteria.

Which domain do archaea belong to?

Archaea.

Which domain do algae belong to?

Eukarya.

Which domain do protozoa belong to?

Eukarya.

Which domain do fungi belong to?

Eukarya.

Which domain do cyanobacteria belong to?

Bacteria.

What is the mode of nutrition for protozoa?

Protozoa are generally heterotrophic and obtain nutrients by consuming or absorbing organic material.

What is the mode of nutrition for algae?

Most algae are autotrophic and produce their own food through photosynthesis.

What is the mode of nutrition for fungi?

Fungi are heterotrophs that secrete enzymes and absorb nutrients from organic material.

What is the mode of nutrition for helminths?

Helminths are heterotrophs that obtain nutrients from their hosts or environment.

If helminths are macroscopic, why do microbiologists study them?

Their eggs and larvae are microscopic, and many helminths cause infectious diseases in humans.

What are some modes of transmission of helminthiases?

Contaminated food or water, contaminated soil, insect vectors, and direct contact, depending on the species.

What are some examples of helminths?

Tapeworms, roundworms, and flukes.

What are helminths?

Parasitic worms that can infect humans and other animals.

What are viruses?

Acellular infectious agents made of genetic material surrounded by a protein coat that cannot reproduce independently.

How are viruses different from other microorganisms?

Viruses are not cells, do not have cellular structures or their own metabolism, and must infect a host cell to reproduce.

What is an obligate parasite?

An organism or infectious agent that must live in or on a host to survive and/or reproduce.

What is a bacteriophage?

A virus that infects bacteria.

What is the basic structure of a virus?

Genetic material (DNA or RNA) surrounded by a protein coat called a capsid; some viruses also have an outer envelope.

What type of genetic material can a virus contain?

DNA or RNA, but not both as its genome.

An organism is unicellular, has no nucleus, and has peptidoglycan in its cell wall. What is it most likely?

Bacteria.

An organism is unicellular, has no nucleus, lacks peptidoglycan, and lives in a very salty environment. What is it most likely?

Archaea.

An organism is eukaryotic, has a cell wall, and obtains nutrients by absorbing organic material. What is it most likely?

Fungus.

An organism is eukaryotic and photosynthetic. What is it most likely?

Algae or another photosynthetic eukaryote, depending on the characteristics given.

An organism is a unicellular eukaryote that moves using cilia, flagella, or pseudopodia. What is it most likely?

Protozoan.

An organism is a prokaryote that performs photosynthesis. What is it most likely?

Cyanobacterium.

You see a fuzzy colony growing on an agar plate. Is it more likely bacterial or fungal?

Fungal, because fungal colonies often have a fuzzy, cottony, or filamentous appearance caused by hyphae.

You see a fungus with a brush-like arrangement of spores. What is it?

Penicillium.

You see a fungus with spores inside a large, round sporangium. What is it?

Rhizopus.

You see a fungus with spores arranged around a rounded structure at the end of a stalk. What is it?

Aspergillus.

You see individual oval cells, some with smaller cells budding from them. What type of fungus is this likely to be?

Yeast.

Which organisms from this exercise are prokaryotic?

Bacteria, cyanobacteria, and archaea.

Which organisms from this exercise are eukaryotic?

Fungi, protozoa, algae, and helminths.

What is the biggest difference between a virus and a microorganism such as a bacterium?

A bacterium is a living cell, while a virus is acellular and must use a host cell to reproduce.

What are the three biggest categories to use when identifying an unknown microorganism?

Determine whether it is prokaryotic or eukaryotic, examine its cell or body structure, and determine how it obtains nutrients or energy.