BIOL 2200 Units 1–2: Microbial World and Cell Structure

Bacteria

single-celled organisms that lack a nucleus; prokaryotes

Archaea

Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan

Eukarya

Domain of all organisms whose cells have nuclei, including protists, plants, fungi, and animals

Virus

A tiny, nonliving particle that invades and then reproduces inside a living cell.

Protist

Kingdom composed of eukaryotes that are not classified as plants, animals, or fungi

fungus

any member of a distinct biological kingdom of eukaryotic organisms

endosymbiosis

A theorized process in which early eukaryotic cells were formed from simpler prokaryotes.

biological species concept

Species is a group of populations whose members have the potential to produce fertile offspring.

Phylogeny

Evolutionary history of a species

phylogenetic tree

A family tree that shows the evolutionary relationships thought to exist among groups of organisms

ribosome

site of protein synthesis

16S rRNA

RNA component of the small (30S) subunit of prokaryotic ribosomes

cell morphology

Study of cell shape and size.

nitrogen fixation

Process of converting nitrogen gas into ammonia

microbiome

the microorganisms in a particular environment

Bacteriophage

A virus that infects bacteria

lytic cycle

a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses

Lysogeny

a state in which phage DNA is incorporated into the host cell without lysis

bright field microscopy

generates a dark image of an object over a light background

Phase Contrast Microscopy

Enhances contrast in transparent specimens.

Fluorescence Microscopy

Uses UV light, Fluorescent substances absorb UV light and emit visible light

simple staining

the use of a single stain to color a bacterial cell

differential staining

using specific stains to distinguish different types of cell.

cell wall

strong, supporting layer around the cell membrane in some cells

peptidoglycan

Cell wall of prokaryotes made of a sugar polymer and polypeptide. AKA murein

Phospholipids

a lipid containing a phosphate group in its molecule

diester

Compound with two ester functional groups.

Diether

Compound with two ether functional groups

Flagella

A long, whip-like filament that helps in cell motility.

Endospores

bacterial spore that can survive harsh conditions

Pili

short, hairlike protein structures on the surface of some bacteria

Glycocalyx

The external surface of a plasma membrane that is important for cell-to-cell communication

Antibiotics

Drugs that block the growth and reproduction of bacteria

flagellar motility

occurs by rotary motion of helical flagella. Run-and-tumble

Chemotaxis

Cell movement that occurs in response to chemical stimulus

methyl-accepting chemotaxis proteins

bind attractant or repellent and initiate flagellar rotation

Signal Transduction

A series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell.

two-component signal transduction

sensor kinase and response regulator

twitching motility

use pili to drag themselves across a surface

Nucleoid

A dense region of DNA in a prokaryotic cell.

Chromosome

A threadlike structure of nucleic acids and protein found in the nucleus of most living cells.

Supercoiling

twisting in the opposite direction to the turns of the double helix during the first stage of mitosis.

Gyrase

unwinds DNA

Topoisomerase

corrects "overwinding" ahead of replication forks by breaking, swiveling, and rejoining DNA strands

Endospores

bacterial spore that can survive harsh conditions

Pili

Appendages that allow bacteria to attach to each other and to transfer DNA

capsule

Covers the cell wall in prokaryotes.