Cell Structure and Function: Prokaryotes and Eukaryotes - Vocabulary

Vocabulary flashcards covering key terms and definitions from the lecture notes on cell structure and function (prokaryotes vs eukaryotes, organelles, and related concepts).

Prokaryotic cell

A cell lacking a membrane-bound nucleus; DNA is located in the nucleoid and it has no membrane-bound organelles.

Eukaryotic cell

A cell with a true nucleus and membrane-bound organelles; contains linear DNA organized into chromosomes.

Plasma membrane

The phospholipid bilayer that separates the living cell from its environment and regulates entry/exit of substances.

Cytoplasm

The jelly-like interior of the cell where organelles reside and metabolism occurs.

DNA

Deoxyribonucleic acid; genetic material of the cell; in prokaryotes it is a naked circular molecule, in eukaryotes linear and organized into chromosomes.

Nucleus

Brain of the cell; a double-membrane organelle that stores DNA and coordinates genes; contains nuclear pores, envelope, and nucleolus.

Nucleoid

Region in a prokaryotic cell where the circular DNA is located, not surrounded by a membrane.

Chromatin

DNA packaged with proteins in the nucleus; becomes visible as chromosomes during cell division.

Ribosome

Molecular machine for protein synthesis; consists of a large and small subunit and is not membrane-bound.

80S ribosome

Ribosome type in eukaryotic cells, larger subunit (proteins + rRNA) involved in protein synthesis.

60S ribosome

One component of the prokaryotic ribosome (as noted in notes); part of the ribosome responsible for protein synthesis.

Endomembrane system

Interconnected membranes (ER, Golgi, vesicles) that synthesize, modify, and transport proteins and lipids.

Smooth Endoplasmic Reticulum (SER)

Endoplasmic reticulum lacking ribosomes; synthesizes lipids, stores Ca2+, detoxifies compounds, and metabolizes carbohydrates.

Rough Endoplasmic Reticulum (RER)

Endoplasmic reticulum with ribosomes on the surface; synthesizes proteins and glycosylates them; inserts proteins into membranes.

Golgi apparatus

Packaging and shipping center of the cell; receives, modifies (glycosylation), sorts, and dispatches proteins in vesicles.

Vesicle

Small membrane-bound sac that transports substances between organelles or to the plasma membrane.

Lysosome

Organelle containing digestive enzymes that break down macromolecules and cellular waste in acidic conditions.

Peroxisome

Organelle that breaks down peroxide and participates in lipid metabolism and detoxification.

Mitochondrion

Cellular energy generator; has outer/inner membranes, intermembrane space, and matrix; site of ATP production.

Cristae

Folded inner membrane of mitochondria that increases surface area for the electron transport chain.

Matrix

Fluid inside the mitochondrion that contains enzymes of the Krebs cycle and mitochondrial DNA/ribosomes.

Chloroplast

Solar energy organelle in plants/algae; conducts photosynthesis; contains grana, thylakoids, and stroma.

Grana

Stacks of thylakoids in chloroplasts where the light reactions of photosynthesis occur.

Thylakoid

Flattened membrane-bound sacs within chloroplasts that contain chlorophyll for light reactions.

Stroma

The fluid surrounding thylakoids in chloroplasts; contains enzymes for the Calvin cycle.

Chloroplast DNA

Circular DNA within chloroplasts, with prokaryotic-like gene structure.

Mitochondrial DNA

Circular DNA within mitochondria, similar to bacterial DNA.

Semiautonomous

Organelles like mitochondria and chloroplasts that contain DNA and ribosomes but rely on the cell for some functions.

Endosymbiont theory

Idea that mitochondria and chloroplasts originated from engulfed bacteria becoming symbiotic organelles.

Cyanobacteria

Photosynthetic bacteria; ancestors of chloroplasts according to the endosymbiont theory.

Purple nonsulfur bacteria

Ancestral aerobic bacteria related to mitochondrial origin as proposed in endosymbiont theory.

Cell wall

Rigid layer outside the plasma membrane; provides structure; composition varies (cellulose in plants, chitin in fungi, peptidoglycan in bacteria).

Middle lamella

Gluing layer between plant cell walls composed of calcium pectate/pectin.

Plasmodesmata

Cytoplasmic channels between plant cells that allow transport and communication.

Extracellular matrix (ECM)

Noncellular framework outside the plasma membrane made of proteoglycans, collagen, fibronectin, and integrins; links to the cytoskeleton.

Collagen

A major structural protein in the ECM that provides strength and support.

Proteoglycan

Protein-polysaccharide complex in the ECM that binds water and provides cushioning.

Integrin

Transmembrane receptor in the ECM that connects ECM to the cytoskeleton.

Glycosylation

Addition of sugars to proteins in the Golgi apparatus as part of protein processing.

Cytoskeleton

Network of protein filaments (actin, intermediate filaments, microtubules) that support the cell and enable movement.

Actin (microfilaments)

Thin filaments beneath the plasma membrane involved in shape maintenance and movement.

Intermediate filaments

Tough, fibrous filaments (e.g., keratin) that provide structural support.

Microtubules

Hollow tubules made of tubulin that guide intracellular transport and form spindle apparatus; extend to cilia/flagella.

Kinesin

Motor protein that moves cargo along microtubules toward the plus end.

Cilia

Short, hair-like projections with microtubules that move liquid past a cell surface.

Flagella

Long, whip-like projections with microtubules that propel cells.

Centrosome

Microtubule-organizing center in animal cells, typically containing a pair of centrioles.

Turgor pressure

Pressure of the cell contents against the cell wall in plant cells, maintained by the central vacuole.

Central vacuole

Large plant cell vacuole that stores water, maintains turgor, and stores substances.

Vacuole types (central/contractile/food)

Central vacuole in plants; contractile vacuoles in some protists; food vacuoles for digestion.