Prokaryotes and Eukaryotes chaper 4

Vocabulary flashcards covering key terms from Chapter 4 on prokaryotic and eukaryotic cell structure and function.

Prokaryote

A cell type whose name means “prenucleus”; lacks a membrane-bound nucleus.

Eukaryote

A cell type whose name means “true nucleus”; possesses a membrane-bound nucleus.

Flagella (eukaryotic)

Long, whip-like projections, few in number, used for locomotion or to move substances along the cell surface.

Cilia

Short, numerous projections that beat rhythmically to propel a cell or move material across its surface.

Cell wall (eukaryotic)

Rigid outer layer found in plants, algae, and fungi; composed of specific carbohydrates such as cellulose, chitin, glucan, or mannan.

Cellulose

The polysaccharide that forms the principal component of plant cell walls.

Chitin

A polysaccharide that forms the main component of fungal cell walls.

Glucan and Mannan

Carbohydrate polymers that reinforce the cell walls of yeasts.

Glycocalyx (eukaryotic)

Carbohydrate layer covalently bonded to membrane proteins and lipids in animal cells; strengthens the surface, aids attachment, and mediates cell–cell recognition.

Plasma (cytoplasmic) membrane

Phospholipid bilayer with integral and peripheral proteins that encloses cytoplasm; functions in selective permeability and transport.

Sterols

Complex membrane lipids present in eukaryotic plasma membranes that add rigidity and stability.

Endocytosis

Energy-using process in which the plasma membrane engulfs material to bring it into the cell.

Phagocytosis

Type of endocytosis in which pseudopods extend around and engulf large particles or cells.

Pinocytosis

Type of endocytosis in which the membrane folds inward, bringing extracellular fluid and dissolved solutes into the cell.

Receptor-mediated endocytosis

Highly specific form of endocytosis in which binding of ligands to surface receptors triggers vesicle formation.

Cytoplasm

The material inside the plasma membrane and outside the nucleus of a eukaryotic cell.

Cytosol

The fluid portion of the cytoplasm in which organelles are suspended.

Cytoskeleton

Network of microfilaments, intermediate filaments, and microtubules that provides shape, support, and intracellular transport.

Cytoplasmic streaming

The directed flow of cytoplasm that circulates materials throughout a cell.

Ribosome

Cellular structure that carries out protein synthesis by translating mRNA.

80S ribosome

Eukaryotic cytoplasmic ribosome composed of a 60S large subunit and a 40S small subunit; may be membrane-bound or free.

70S ribosome

Prokaryotic-type ribosome found in bacteria, mitochondria, and chloroplasts.

Organelle

Membrane-bound cellular structure with a specialized function, found in eukaryotic cells.

Nucleus

Double-membrane organelle (nuclear envelope) that houses DNA complexed with histones as chromatin; forms chromosomes during cell division.

Rough endoplasmic reticulum (RER)

Folded membranous network studded with ribosomes; synthesizes and processes proteins for export or membranes.

Smooth endoplasmic reticulum (SER)

Membranous network lacking ribosomes; synthesizes lipids, hormones, and membranes.

Golgi complex

Stack of flattened membranes that modifies, sorts, and packages proteins from the ER into secretory vesicles.

Lysosome

Golgi-derived vesicle containing hydrolytic enzymes for intracellular digestion.

Vacuole

Membrane-bounded cavity formed by the Golgi or endocytosis; stores nutrients, waste, or provides shape in certain cells.

Mitochondrion

Double-membrane organelle with inner folds (cristae) and matrix that generates ATP through cellular respiration; contains its own circular DNA and 70S ribosomes.

Chloroplast

Photosynthetic organelle containing thylakoid membranes with chlorophyll, circular DNA, and 70S ribosomes.

Peroxisome

Organelle that oxidizes fatty acids and detoxifies harmful substances.

Centrosome

Organelle consisting of a pericentriolar matrix and two centrioles; organizes the mitotic spindle during cell division.

Endosymbiotic theory

Theory proposing that eukaryotic organelles originated when ancestral cells engulfed certain bacteria that became symbiotic residents.

Evidence for endosymbiotic theory

Mitochondria and chloroplasts resemble bacteria in size/shape, possess circular DNA, reproduce independently, contain 70S ribosomes, and have double membranes.