Lecture 4: Prokaryotic Cells

Flashcards on Cell Types and Prokaryotic Cells

Cell

The smallest unit of life that can function independently.

Prokaryotic Cells

Cells that lack a nucleus and other membrane-bound organelles; small and simple in structure.

Eukaryotic Cells

Cells that have a nucleus and other membrane-bound organelles; more complex and larger than prokaryotic cells.

Nucleoid

A zone of the cytoplasm where the single circular molecule of DNA is localized in prokaryotes.

Binary Fission

Cell division by which prokaryotes undergo.

Similarities between prokaryotic and eukaryotic cells

A membrane bound (plasma membrane) containing DNA as their genetic material. They both produce three types of RNA: messenger RNA, ribosomal RNA, and transfer RNA. These cells have ribosomes and obtain energy in form of ATP, furthermore they have the ability to reproduce and to synthesize cell components.

Flagella

Structures used by bacterial cells for locomotion.

Filament (Flagella)

Long, thin, helical structure composed of protein flagellin.

Hook (Flagella)

Flexible coupling between the filament and the basal body in flagella.

Basal Body (Flagella)

A stack of rings anchored in the cell wall that acts as a molecular motor for flagella rotation.

Monotrichous Flagella

A single flagellum at one end of the cell.

Lophotrichous Flagella

Small bunches of flagella emerging from the same site of the cell.

Amphitrichous Flagella

One or group of flagella at both ends of the cell

Peritrichous Flagella

Flagella over the entire surface of the cell.

Axial Filaments

Special flagella found only in spirochetes, enclosed in the space between the outer sheath and the peptidoglycan of the cell wall.

Fimbriae

Fine, proteinaceous, hairlike bristles emerging from the cell surface, important in attachment to other cells and surfaces.

Adhesins

Special adhesive molecules attached to the tips of fimbriae.

Pili

A rigid tubular structure made of protein pilin, found only in Gram-negative bacteria, mainly functioning in DNA transfer.

Glycocalyx

A layer found outside the cell wall of certain types of bacteria, made up of polysaccharide (sometimes with protein), can be a capsule or slime layer.

Capsule

Dense and well-organized glycocalyx.

Slime Layer

Loose and poorly organized glycocalyx.

Cell Envelope

Complex structure consisting of the cell wall, outer membrane (in some bacteria), and a plasma membrane.

Cell Wall

Semi-rigid layer found outside the cell membrane of most bacteria, determining the shape of the cell and preventing bursting due to osmotic pressure.

Peptidoglycan

The primary structural component of the bacterial cell wall, a polymer composed of NAG and NAM.

Teichoic Acids

Glycopolymers embedded within the peptidoglycan layers of Gram-positive bacteria, contributing to the rigidity of the cell wall.

Outer Membrane

Membrane located outside of the peptidoglycan layers found in Gram-negative bacteria, composed of phospholipids, lipoproteins, lipopolysaccharides and porins.

Lipopolysaccharides (LPS)

Anchored into the outer membrane and project from the cell into the environment.

Lipoproteins

Located in the periplasm of the outer membrane.

Periplasm

Space in Gram-negative cells between the outer membrane and cell membrane, containing peptidoglycan, digestive enzymes, and transport proteins.

Cell (Plasma) Membrane

A universal structure that separates the external environment from the internal (cytoplasmic) environment.

Integral Proteins

Proteins embedded within the cell membrane bilayer.

Peripheral Proteins

Proteins associated on the outside of the cell membrane.

Gram Stain

A differential stain used to identify Gram-positive and Gram-negative bacteria.

Gram-Positive Bacteria

Bacteria with cell walls composed predominantly of peptidoglycan and teichoic acid.

Gram-Negative Bacteria

Bacteria with a more complex cell wall containing a thin layer of peptidoglycan, an outer membrane, and lipopolysaccharides.

Mollicutes

Class of bacteria whose members lack a cell wall.

Acid-Fast Bacteria

A group of bacteria sharing the characteristic of acid fastness, with a cell wall composed of mycolic acid.

Cytoplasm

Gel-like fluid that fills each cell, providing an aqueous environment for the chemical reactions that take place in a cell.

DNA

The genetic material of the cell, localized in the nucleoid in bacterial and archaeal cells.

Plasmids

Smaller molecules of DNA existing as closed loops in the cytoplasm.

Ribosomes

Small organelles that function as a site for protein synthesis.

Bacterial Inclusions

Distinct structures located either within the cytoplasm or periplasm of the cell

Polysaccharide granules, lipid inclusions, and sulfur granules

Energy reserves.

Metachromatic granules

Used for storage of inorganic phosphate which can be used to build nucleic acids, phospholipids, and ATP.

Magnetosomes

Inclusions that contain long chains of magnetite (Fe3O4), which are used by the cell as a compass in geomagnetic fields, for orientation within their environment.

Gas vacuoles

Organelles built with a watertight protein shell.

Cytoskeleton bacterial

Proteins resembling (or analogous to) those in the eukaryotic cytoskeleton.

Endospores

A dormancy stage when the cells experience nutrient depletion.

Rod-shaped

Bacillus (plural: bacilli) is a __ cell

Spherically-shaped bacterial

Coccus (plural: cocci) is a __ cell

Spirally-shaped

Spirillum (plural: spirilla) is a __ cell

Double arrangement

Cells of many bacterial species also remain attached after division and take on cellular arrangements characteristic of the species. Diplococci is a _ arrangement

Twisted chain

Cells of many bacterial species also remain attached after division and take on cellular arrangements characteristic of the species. Streptococci is a _ arrangement

Short or long

Bacilli cells all divide in only one plane producing a single cell, strepto, or coccobacillus arrangement. The strepto arrangement may involve _ chains

Curved, rigid

Spirilla cells do not remain attached after cell division and come in one of three forms, a vibrio, a spirillum, or a spirochete. Vibrio is a _ cell