1.2: Classification of Cells: Prokaryotic vs Eukaryotic

Question 1

Prokaryotic is derived from Greek, meaning

Answer 1

“before kernel,”

Question 3

eukaryotic is derived from Greek, meaning

Answer 3

“true kernel.”

Question 3

a membrane enclosed region within a cell that contains the genetic material.

Answer 3

nucleus

Question 4

It is also important to simply note that as of 1990 biologists further expanded the characterization and specification of the classifications of life into three categories:

Answer 4

Bacteria, Archaea, and Eukarya.

Question 5

What two categories of cells are all comprised of prokaryotic microorganisms lacking a membrane-bound nucleus?

Answer 5

Bacteria
Archaea

Question 6

Bacteria

Answer 6

(sometimes referred to as Eubacteria, meaning ‘true bacteria’) constitute a large cohort of prokaryotic microorganisms. They can be considered the everyday bacteria and are common in human daily life. They have a variety of shapes by which they can be further classified.

Question 7

Bacteria display many distinct morphologies (shapes), the most common include:

Answer 7

coccus (round/spherical)
bacillus (rod)
vibrio (curved rod)
spirillum (spiral/corkscrew).

Question 8

coccus

Answer 8

(round/spherical)

Question 9

bacillus

Answer 9

(rod)

Question 10

vibrio

Answer 10

(curved rod)

Question 11

spirillum

Answer 11

(spiral/corkscrew).

Question 12

Archaea

Answer 12

the other prokaryotic class of microorganisms, have similar characteristics and shapes as Bacteria (Eubacteria) and yet remain genetically and compositionally distinct. Most notably, they can survive in extremely harsh environmental conditions, such as high salt levels, acid conditions, high temperatures, and oxygen-poor conditions. As such, Archaeons may also be referred to as extremophiles, based on the extreme or atypical environments in which they can be found.

Question 13

Archaeons may also be referred to as

Answer 13

extremophiles

Question 14

Eukarya

Answer 14

is a diverse category and consists of a wide range of microorganism. Due to high diversity and complexity, eukaryotes can be subdivided into multiple categories, a process still debated today. However, the unifying characteristic of all eukaryotic cells is the presence of a membrane-bound nuclear region within the cell. For the purposes of this course, eukaryotic microorganisms will be classified as either: Animalia, Plantae, Fungi, and Protista.

Question 15

eukaryotic microorganisms can be classified as either:

Answer 15

Animalia, Plantae, Fungi, and Protista.

Question 16

Animalia

Answer 16

consists of multicellular eukaryotic organisms, and, as the name suggests, includes animals, as well as humans (and their cells) in their classification. All microorganisms in this category are heterotrophic , meaning they are incapable of producing their own energy, must absorb (consume) nutrients from the environment, and have the general characteristic of motility (the ability to move).

Question 17

Fungi

Answer 17

can be either multicellular or unicellular microorganisms, and, like Animalia, they are heterotrophic. A defining characteristic of fungi is the presence of chitin, a derivative of glucose, in their cell walls. Common examples of multicellular fungi are molds and mushrooms, while perhaps the most common unicellular fungus is yeast.

Question 17

Plantae

Answer 17

are also multicellular eukaryotes, but, unlike Animalia, they can obtain most of their energy from sunlight via photosynthesis—a process that converts light energy (sunlight) into chemical energy (sugars) within the organism and fuels its activities.

Question 18

Protista

Answer 18

are unicellular microorganisms that may form as colonies. However, the colonies (seemingly multicellular) do not form tissue layers and thus retain the unicellular classification. Protista is often used as a classification for any microorganism that does not clearly fit the criteria for being considered animal, plant, or fungi. Common examples range from amoeba, known for its motility; algae, known for its plant-like characteristics; and mold, known for its fungi-like properties.

Question 19

Viruses

Answer 19

although they are considered neither prokaryotic nor eukaryotic, do play a large role in microbiology. Viruses are not considered living and do not replicate on their own, meaning they must replicate within a host. Outside of a host cell viruses have no metabolism and are essentially dormant—the virus takes up neither energy nor nutrients. Although viruses contain similar structures to the microorganisms described above, they are not cellular, and, as such, they do not fall within one of the categories described above. For instance, viruses contain a capsid , a membrane-like structure that contains genetic material, similar to the nucleus of a eukaryotic cell.