Prokaryotic & Eukaryotic Cells and Major Cell Types

Vocabulary flashcards that cover major terms, structures, and cell types discussed in the lecture on prokaryotic and eukaryotic cells, their differences, and specialized cell types in animals and plants.

Prokaryote

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

Eukaryote

Organism whose cells contain a true nucleus and membrane-bound organelles; includes animals, plants, fungi, and protists.

Domain Bacteria

Group of prokaryotes with unbranched fatty-acid membranes and peptidoglycan cell walls; sensitive to many antibiotics.

Domain Archaea

Prokaryotic domain characterized by branched-chain membrane lipids and cell walls without peptidoglycan; often extremophilic.

Extremophile

Organism, typically archaeal, that thrives in extreme environments such as hot springs or hydrothermal vents.

Peptidoglycan

Complex polymer forming the rigid cell wall of most bacteria.

Capsule (bacterial)

Gelatinous outer layer that retains moisture and helps bacteria adhere to surfaces.

Plasma Membrane

Phospholipid bilayer regulating substance flow into and out of a cell.

Cytoplasm

Gel-like intracellular fluid containing enzymes, salts, organelles, and other molecules.

Ribosome

Cell structure—free or membrane-bound—that synthesizes proteins.

Cell Wall (prokaryotic)

Rigid outer covering that protects bacterial cells and maintains shape.

Pili

Hair-like surface appendages that aid in attachment and conjugation in bacteria.

Flagellum

Long, whip-like projection providing cellular locomotion.

Nucleoid

Region in prokaryotes where the single circular DNA molecule is located.

True Nucleus

Membrane-bound compartment housing DNA in eukaryotic cells.

Form Follows Function

Biological principle stating that cellular structure is adapted to perform specific functions.

Genetic Recombination (eukaryotes)

Exchange of genetic material via meiosis and gamete fusion, increasing diversity.

Microtubules

Cytoskeletal filaments that aid in cell shape, transport, and chromosome movement.

Endoplasmic Reticulum

Membranous network involved in protein (rough ER) and lipid (smooth ER) synthesis.

Mitochondria

Energy-producing organelles where aerobic respiration generates ATP.

Cytoskeleton

Network of protein fibers (microfilaments, intermediate filaments, microtubules) that supports cell shape and movement.

Vacuole

Membrane-bound sac for storage and regulation of water and solutes; large and central in plant cells.

Plasma Membrane with Sterols

Eukaryotic membrane feature that increases fluidity and stability via cholesterol or similar sterols.

Stem Cell

Undifferentiated cell capable of self-renewal and giving rise to specialized cell types.

Cell Differentiation

Process by which stem cells mature into specific cell types with specialized functions.

Adult (Somatic) Stem Cell

Multipotent stem cell found in tissues such as bone marrow, skin, and liver for repair and maintenance.

Embryonic Stem Cell

Pluripotent cell derived from early embryos that can differentiate into almost any cell type.

Pluripotent

Ability of a cell to develop into nearly all cell types of the body.

Red Blood Cell (Erythrocyte)

Biconcave, flexible cell that transports oxygen using hemoglobin; helps buffer blood pH.

Hemoglobin

Iron-containing protein in red blood cells that binds and carries oxygen.

Carbonic Anhydrase

Enzyme in red blood cells that catalyzes conversion of CO₂ and water, aiding pH balance and CO₂ transport.

White Blood Cell (Leukocyte)

Immune cell group that defends the body against pathogens and foreign substances.

Neutrophil

Most abundant granulocyte; phagocytizes pathogens and releases digestive enzymes.

Eosinophil

Granulocyte releasing histaminase and arylsulfatase B; active in allergies and parasitic infections.

Basophil

Least common granulocyte; secretes anticoagulants and antibodies involved in hypersensitivity reactions.

Natural Killer (NK) Cell

Lymphocyte that destroys virus-infected or tumor cells without prior sensitization.

Monocyte

Agranulocyte that differentiates into macrophages to phagocytize debris and microbes.

Macrophage

Large phagocytic cell derived from monocytes; engulfs pathogens and dead cells in tissues.

Lymphocyte

White blood cell that includes B cells, T cells, and NK cells for adaptive immunity.

Helper T Cell

T lymphocyte that activates B cells and cytotoxic T cells during immune responses.

Killer T Cell (Cytotoxic T)

T lymphocyte that directly destroys virus-infected or cancerous cells.

Memory T Cell

Long-lived T cell that provides quicker response upon re-exposure to the same antigen.

B Cell

Lymphocyte that differentiates into plasma cells to produce antibodies.

Plasma Cell

Activated B cell that secretes large quantities of specific antibodies.

Memory B Cell

B cell that persists after infection to enable rapid antibody production on re-infection.

Platelet (Thrombocyte)

Cell fragment derived from megakaryocytes that is essential for blood clotting.

Neuron

Excitable cell that transmits nerve impulses; composed of soma, dendrites, axon, and terminals.

Glial Cell (Neuroglia)

Non-neuronal nervous-system cell that supports, protects, and nourishes neurons.

Astrocyte

Star-shaped glial cell maintaining the chemical environment for neuronal signaling.

Oligodendrocyte

Glial cell that forms myelin sheaths around CNS axons to speed impulse conduction.

Microglial Cell

Small glial cell that removes debris and pathogens from nervous tissue.

Ependymal Cell

Glial cell lining brain ventricles; produces and circulates cerebrospinal fluid.

Myocyte (Muscle Cell)

Cell rich in actin and myosin; includes skeletal, cardiac, and smooth muscle types.

Osteoclast

Large cell that resorbs bone tissue by secreting acids and enzymes.

Osteoblast

Bone-forming cell responsible for depositing new bone matrix.

Osteocyte

Mature bone cell that maintains bone matrix and signals remodeling.

Lining Cell (Bone)

Flat cell covering bone surface; releases calcium into blood when levels fall.

Keratinocyte

Skin cell producing keratin; blocks toxins, pathogens, and prevents water loss.

Melanocyte

Skin cell synthesizing melanin pigment that determines skin color and absorbs UV.

Merkel Cell

Mechanoreceptor skin cell involved in the sense of touch.

Gamete

Sex cell (sperm or ovum) that fuses during fertilization to form a zygote.

Spermatozoon

Motile male gamete contributing paternal DNA during fertilization.

Ovum (Egg)

Non-motile female gamete contributing maternal DNA and cytoplasm to the zygote.

Parenchyma Cell

General plant cell type involved in photosynthesis, storage, and metabolism.

Collenchyma Cell

Flexible plant support cell with thickened primary walls but no lignin; allows growth.

Sclerenchyma Cell

Rigid plant support cell with secondary walls hardened by lignin.

Palisade Parenchyma

Columnar parenchyma tissue rich in chloroplasts; main site of leaf photosynthesis.

Spongy Parenchyma

Loosely arranged parenchyma tissue with air spaces facilitating gas exchange.

Chloroplast

Plant organelle containing chlorophyll where photosynthesis occurs.

Bacterial Capsule

Sticky polysaccharide layer aiding bacterial adhesion and protection.