Cell Structure & Function – Lecture Vocabulary

Vocabulary flashcards summarizing key terms from the lecture on prokaryotic vs. eukaryotic cell structure and organelle functions.

Plasma Membrane

Semi-permeable phospholipid bilayer that encloses the cytosol and defines the cell’s outer boundary.

Phospholipid

Amphipathic molecule (glycerol-phosphate head + fatty-acid or isoprenoid tails) forming cellular membranes.

Cytosol

Aqueous interior of the cell containing water, ions, proteins, and organelles.

Prokaryote

Single-celled organism lacking a membrane-bound nucleus; includes Bacteria and Archaea.

Eukaryote

Organism whose cells possess a membrane-bound nucleus and numerous organelles.

Domain Bacteria

Prokaryotic lineage with fatty-acid phospholipids and peptidoglycan cell walls.

Domain Archaea

Prokaryotic lineage with isoprenoid-based phospholipids; many live in extreme environments.

Nucleus

Double-membrane organelle in eukaryotes that stores linear chromosomes (DNA library).

Chromosome

DNA molecule carrying genes; usually single and circular in bacteria, 23 pairs in humans.

Nucleoid

Region in prokaryotes where the chromosome resides without a surrounding membrane.

Plasmid

Small circular DNA in bacteria that confers extra traits (e.g., antibiotic resistance).

Ribosome

RNA-protein complex (large + small subunit) that translates mRNA into polypeptides.

Cytoskeleton

Network of protein filaments providing shape, support, and intracellular transport tracks.

Peptidoglycan

Sugar-peptide polymer forming strong bacterial cell walls.

Cell Wall

Rigid extracellular layer; peptidoglycan in bacteria, cellulose in plants, adds shape & protection.

Flagellum

Long, rotating appendage that propels many bacteria through liquid environments.

Fimbriae

Short, needle-like projections helping bacteria adhere to host tissues (Velcro-like).

Supercoiling

Compaction of prokaryotic DNA into a dense, manageable structure inside the cell.

Photosynthetic Membrane

Internal membrane folds in some bacteria containing pigments and enzymes for photosynthesis.

Chlorophyll

Green pigment that absorbs light energy for photosynthesis in chloroplasts and photosynthetic bacteria.

Membrane Infolding

Process by which cells increase internal surface area by folding the plasma membrane inward.

Surface Area-to-Volume Ratio

Measure influencing diffusion efficiency; higher ratios (small size, infoldings) favor metabolism.

Slime Mold

Unusual organism forming one large multinucleate cell instead of many small cells.

Organelle

Membrane-bound compartment in eukaryotic cells with specialized functions.

Rough Endoplasmic Reticulum (Rough ER)

ER region studded with ribosomes; synthesizes proteins for membranes, secretion, or organelles.

Smooth Endoplasmic Reticulum (Smooth ER)

Ribosome-free ER region that synthesizes lipids and participates in detoxification.

Golgi Apparatus

Stacked membrane sacs that modify, sort, and package proteins and lipids for delivery.

Vacuole

Large storage organelle in plant cells that holds water, ions, and nutrients (e.g., sugars).

Chloroplast

Double-membrane organelle in plants/algae where photosynthesis occurs; contains its own DNA.

Mitochondrion

Organelle that performs aerobic respiration and ATP production; present in both plants and animals.

Peroxisome

Organelle housing oxidative enzymes for fatty-acid breakdown and detoxification.

Lysosome

Acidic vesicle containing hydrolytic enzymes that digest macromolecules and worn-out organelles.