Prokaryotes

 A group of organisms that lack a cell nucleus (= karyon), or any other membrane-bound organelles.

(True or False)

Most prokaryotes are unicellular but some can aggregate temporarily or permanently in colonies.

True!

What is the average size range of a prokaryotic organism?

0.5 - 5 micrometers

What are the three most common shapes shapes of prokaryotes?

Spheres (cocci), Spirals, Rods (bacilli)

Staphylo-

Grape-like cluster arrangement of prokayotes.

(eg. staphylococci)

Strepto-

Chain-like arrangement of prokaryotic cells.

(eg. Streptobacilli)

(True or False)

Nearly all prokaryotic cells have a cell wall which maintains cell shape, provides protection, and prevents the cell from bursting in hypotonic solutions.

True!

This person developed gram staining.

Hans Christian Gram 

Peptidoglycan

A network of modified sugar polymers that make up the cell wall of bacterial (but not archeal) cells.

Gram-postive

(stain purple/violet)

The cell wall is made up entirely of a thick, simple wall with a lot of peptidoglycan.

Gram-negative

(stain pink/red)

These cells have a thin layer of peptidoglycan sandwiched between two layers of membrane (the plasma membrane and an outer membrane containing lipopolysaccharides).

Capsule

A sticky layer of polysaccharide that surrounds the prokaryote and enables it to stick to substrates and to other prokaryotes (like in a colony).

Fimbriae

(attachment pili)

Hair-like protein structures that allow some prokaryotes to attach to surfaces or other prokaryotes.

Sex Pili

An appendage that pulls two cells together prior to DNA transfer from one cell to another.

[image]

Flagella

A tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and functions in locomotion.

Taxis

Movement toward or away from a stimulus.

Chemotaxis

Movement in response to chemicals like nutrients, oxygen and poisons.

Positive vs. Negative Taxis

Postive - movement towards

Negative - movement away from

(True or False)

In the majority of prokaryotes, the genome consists of a single circular chromosome and smaller rings of DNA called plasmids. 

True!

Nucleoid

Region of cytoplasm where the chromosome of a prokaryote is located.

Binary Fission

Method by which prokaryote reproduce. 

Transformation

The genotype and phenotype of a prokaryotic cell is altered by the uptake of foreign DNA from its surroundings.

Transduction

Bacteriophages carry bacterial genes from one host cell to another.

This is a type of horizontal gene transfer!

Recombinant

A cell whose chromosome contains DNA derived from two different cells.

Conjugation

Genetic material is transferred between two bacterial cells that are temporarily joined by sex pili.

This is also a method of horizontal gene transfer.

Endospores

A dormant, tough, and temporarily non-reproductive structure produced by certain bacteria.

Heterotroph

Autotroph

An organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) from simple inorganic molecules using energy from light (by photosynthesis) or inorganic chemical reactions (chemosynthesis).

Photoautotroph

Uses light energy and sythesizes organic compounds from carbon dioxide. 

Eg. Cyanobacteria, plants and certain protist like algae.

Photoheterotroph

Use light energy and organic compounds (from consumption) to derive nutrition.

exclusive to certain prokaryotes

Chemoautotrophs

Derives energy from inorganic chemicals and carbon from carbon dioxide.

exclusive to certain prokaryotes. (sulfolobus)

Chemoheterotroph

Derives both energy and carbon from organic compounds.

(many prokaryotes and protists, animals and some plants.)

Aerobic

Requires oxygen for respiration.

Anaerobic

Does not require oxygen.

Obligate Aerobe

Cannot grow without oxygen for cellular respiration.

Obligate Anaerobes

Are poisoned in the presence of oxygen.

Facultative Anaerobes

Will use oxygen if it's present but can also carryout anaerobic respiration or fermentation in the lack of oxygen.

Free-Living Ecological Relationship

An organism that is not directly dependent on another organism for survival. 

Pathogenic Ecological Relationship

A form of parasitism that causes disease in the host cell.

Mutualistic

An interaction between two species in which both benefit. 

Commensalism

Relationship in which one species benefits but the other is neither harmed not helped. 

Decomposers

Organisms that break down dead or decaying organisms, and in doing so carry out the natural process of decomposition.

Biofilms

An aggregate of microorganisms in which cells adhere to each other and/or to a surface. 

Extremophiles

Extreme Halophiles

Archaea that live in highly saline environments.

Extreme Thermophiles

Archaea that thrive in very hot environments.

eg. sulfolobus (volcanic springs)

Methanogens

Obtain energy by using carbon dioxide to oxidize hydrogen gas, releasing methane as a waste product. 

Strict anaerobes, decomposers and the cause of swamp gas.

Non-Extreme Archaea

May live in non-extreme environments like farm soil, lake sediments and the surface of the ocean.

include Crenarchaeota, Korarchaeota and Nanoarchaeota.

Eubacteria

The most familiar bacteria. 

[image]

Proteobacteria

Diverse clade of gram-negative bacteria. 

Example: E.coli (gamma proteobacteria)

Spirochetes

Helical heterotrophs that spiral through their environments using internal flagellum.

Gram Positive Bacteria

Include actinomycetes (cause tuberculosis and leprosy), bacillus anthracis (anthrax), clostridium botulinum (botulism), and staphylococcus.

Mycoplasmas

The tiniest of all not cells and the only known bacteria to lack cell walls.