Microbiology Chapter 3: Cell Structure and Function

Comprehensive vocabulary flashcards covering the processes of life, prokaryotic and eukaryotic structures, bacterial cell wall types, transport mechanisms, and organelles based on the lecture transcript.

Metabolism

Controlled chemical reactions of organisms; one of the four processes of life occurring in all bacteria, archaea, and eukaryotes.

Prokaryotes

Organisms that lack a nucleus and internal structures bound with phospholipid membranes, can read DNA and make protein simultaneously, and are typically $1.0\,\mu m$ in diameter or smaller.

Eukaryotes

Organisms that have a nucleus and internal membrane-bound organelles, are typically $10\text{--}100\,\mu m$ in diameter, and include algae, protozoa, fungi, animals, and plants.

Glycocalyx

A gelatinous, sticky substance surrounding the outside of a cell, composed of polysaccharides, polypeptides, or both.

Capsule

A type of glycocalyx composed of organized repeating units of organic chemicals that is firmly attached to the cell surface and may prevent recognition by a host.

Slime layer

A loosely attached, water-soluble glycocalyx that allows prokaryotes to attach to surfaces.

Flagella

Long structures responsible for movement that extend beyond the cell surface; they are composed of a filament, hook, and basal body.

Taxis

The movement of bacteria in response to environmental stimuli, characterized by "runs" and "tumbles."

Fimbriae

Sticky, bristlelike projections used by bacteria to adhere to one another and to substances in the environment; they are shorter than flagella.

Pili

Also known as conjugation pili; a special type of fimbriae used to transfer DNA from one cell to another.

Peptidoglycan

The primary component of bacterial cell walls, consisting of a meshwork of sugar chains (NAG and NAM) and amino acid crossbridges.

Gram-positive Bacterial Cell Walls

Characterized by a relatively thick layer of peptidoglycan and unique chemicals called teichoic acids; they appear purple following Gram staining.

Mycolic acid

A substance found in up to $60\%$ of the cell walls of acid-fast bacteria that helps the cells survive desiccation.

Lipid A

The portion of lipopolysaccharide (LPS) in Gram-negative bacteria that can cause fever, vasodilation, inflammation, shock, and blood clotting.

Fluid mosaic model

Descriptive term for the phospholipid bilayer membrane structure, composed of lipids and associated integral and peripheral proteins.

Osmosis

The passive diffusion of water molecules down their concentration gradient across a selectively permeable membrane.

Group translocation

An active transport process in bacteria where a substance (such as glucose) is chemically modified during transport across the membrane.

Inclusions

Reserve deposits of chemicals sometimes found within the liquid cytosol of bacterial cytoplasm.

Endospores

Unique structures produced by some bacteria as a defensive strategy against unfavorable conditions; they are resistant to heat, radiation, and chemicals.

Hami

Fimbria-like structures produced by some archaea that function to attach the organism to surfaces.

Endocytosis

An active transport process found only in eukaryotes where substances are surrounded by pseudopods and brought into the cell; includes phagocytosis and pinocytosis.

Exocytosis

The eukaryotic process of exporting substances, such as wastes or secretions, by fusing internal vesicles with the cytoplasmic membrane.

Nucleoplasm

The semiliquid portion of the eukaryotic nucleus which contains chromatin and nucleoli.

Golgi body

A eukaryotic organelle composed of flattened hollow sacs that receives, processes, and packages large molecules for export in secretory vesicles.

Peroxisomes

Eukaryotic organelles containing enzymes that degrade poisonous wastes.

Endosymbiotic Theory

The theory that eukaryotes formed from the union of small aerobic prokaryotes with larger anaerobic prokaryotes, eventually evolving into mitochondria and chloroplasts.

70S Ribosomes

The size of ribosomes found in prokaryotes, as well as within the mitochondria and chloroplasts of eukaryotes.

80S Ribosomes

The size of ribosomes found in the cytosol and on the Rough Endoplasmic Reticulum of eukaryotic cells.