Chapter 3A: Bacteria and Archaea I

Microbes

Microorganisms, including bacteria and archaea, that appeared on Earth around 3.8 billion years ago.

Eukaryotes

Organisms with a 'true nucleus'; one of the three domains of life.

Bacteria

Single-celled microorganisms that lack a true nucleus.

Archaea

Single-celled microorganisms similar to bacteria but genetically distinct.

Ribosome

Cellular structures that make proteins.

Cytoplasm

The gel-like substance within a cell, where cellular processes occur.

Cell/plasma membrane

A barrier that controls movement into and out of the cell.

Prokaryote

A type of cell that does not have a nucleus, including bacteria and archaea.

Coccus

A spherical-shaped prokaryotic cell.

Bacillus

A rod-shaped prokaryotic cell.

Spirochete

A flexible, spiral-shaped prokaryotic cell.

Vibrio

A comma-shaped prokaryotic cell.

Coccobacilli

Short, wide bacteria that are intermediate between cocci and bacilli.

Mycelium

A network of long filaments (hyphae) found in some bacterial species.

Fimbriae

Small, bristle-like fibers on bacteria that aid in attachment to surfaces.

Flagella

Threadlike appendages that provide motility to bacteria.

Glycocalyx

A coating of polysaccharide or glycoprotein units that protect bacteria.

Capsule

A dense, protective layer around some bacteria that resists phagocytosis.

Biofilm

A complex community of microorganisms that adhere to surfaces.

Chemotaxis

Movement of bacteria in response to chemical stimuli.

Positive chemotaxis

Movement toward a favorable chemical stimulus.

Negative chemotaxis

Movement away from a repellant chemical stimulus.

Nanotubes

Thin tubular extensions of the plasma membrane used for molecular exchange.

Pilus

A structure used in bacterial conjugation for genetic material transfer.

Spirillum

A rigid spiral-shaped bacterium.

Palisades

Cells that remain partially attached in a chain formation.

Dexoxpidation

Loss of water in bacterial structures.

Filament

Part of the flagellum that aids in motility.

Hook

The part of the flagellum that connects the filament to the basal body.

Basal body

The structure that anchors the flagellum in the cell membrane.

S layer

A protective surface layer made of protein produced by bacteria.

Leptospirosis

A disease caused by the bacterium Leptospira, often spread through contaminated water.

Cytoskeleton

A network of protein filaments in the cytoplasm that maintains cell shape.

Endospore

A dormant, tough, and non-reproductive structure formed by some bacteria.

Plasmid

A small, circular piece of DNA in bacteria that can be transferred between cells.

Spirilla

A type of rigid, spiral-shaped bacterium that can be found in aquatic environments.

Pilus

A structure used in bacterial conjugation for genetic material transfer.

S layer

A protective surface layer made of protein produced by bacteria.

Pleomorphism

The change in shape by bacteria of a single species due to changes in nutrient availability can be explained by this phenomenon

Sarcina

When viewing a stool sample under the microscope a group of cells arranged in a cubicle packet if eight, this is called