Cell Structure, Function & Division – Lecture Vocabulary

A comprehensive set of vocabulary flashcards covering cell anatomy, plasma membrane components, organelles, cytoskeletal elements, cellular projections, and stages of cell division.

Cell

Basic structural and functional unit of all living organisms.

Nucleus

Cell’s control center that houses DNA and directs cellular activities.

Nuclear Envelope

Double-membrane barrier surrounding the nucleus; contains nuclear pores for material exchange.

Nucleolus

Dense, non-membranous body inside the nucleus where ribosome subunits are assembled.

Chromatin

Loose network of DNA and proteins (histones) within the nucleus; condenses into chromosomes during division.

Chromosome

Condensed, rod-like form of chromatin visible during cell division, composed of two sister chromatids joined at a centromere.

DNA (Deoxyribonucleic Acid)

Genetic blueprint containing instructions for protein synthesis and cell reproduction.

Plasma Membrane

Phospholipid bilayer with embedded proteins that forms the cell’s outer boundary and regulates transport.

Phospholipid Bilayer

Two layers of phospholipids with hydrophilic heads facing water and hydrophobic tails facing inward.

Hydrophilic Head

Polar portion of a phospholipid that is water-loving and faces aqueous environments.

Hydrophobic Tail

Non-polar fatty-acid portion of a phospholipid that avoids water and forms the membrane’s interior.

Glycoprotein

Protein with attached carbohydrate chains; functions in cell recognition and signaling.

Glycocalyx

Sticky, sugar-rich coating on the cell surface formed by glycolipids and glycoproteins.

Membrane Protein

Integral or peripheral protein that acts as enzyme, receptor, channel, or carrier in the plasma membrane.

Microvillus

Finger-like plasma-membrane projection that increases surface area for absorption.

Tight Junction

Impermeable intercellular junction that fuses adjacent cell membranes to prevent leakage.

Desmosome

Anchoring junction that fastens cells together like molecular Velcro and resists mechanical stress.

Gap Junction

Communicating junction with connexon channels that allow ions and small molecules to pass directly between cells.

Cytoplasm

Cellular material between the nucleus and plasma membrane; site of most cellular activities.

Cytosol

Fluid portion of cytoplasm in which organelles are suspended.

Organelle

Specialized cellular structure (e.g., mitochondrion, ribosome) that performs a specific metabolic function.

Inclusion

Non-functional cytoplasmic substance such as lipid droplet, glycogen granule, or pigment.

Mitochondrion

Double-membrane organelle with cristae; site of ATP production—“powerhouse of the cell.”

Cristae

Shelf-like infoldings of the inner mitochondrial membrane that increase surface area for ATP synthesis.

Ribosome

Tiny particle of rRNA and protein that synthesizes proteins; free in cytosol or bound to rough ER.

Endoplasmic Reticulum (ER)

Membranous network of interconnected tubules involved in protein and lipid processing.

Rough ER

ER studded with ribosomes; synthesizes, folds, and transports proteins and produces membrane phospholipids.

Smooth ER

ER lacking ribosomes; synthesizes lipids and steroids, detoxifies drugs, and stores Ca²⁺.

Golgi Apparatus

Stack of flattened sacs that modifies, sorts, and packages proteins into vesicles for secretion or storage.

Transport Vesicle

Small membranous sac that moves proteins and other substances between cell compartments.

Lysosome

Membranous sac of acid hydrolase enzymes that digest worn-out organelles and foreign matter; “suicide sac.”

Peroxisome

Small organelle containing oxidase and catalase enzymes that neutralize toxins and break down hydrogen peroxide.

Cytoskeleton

Network of protein filaments (microfilaments, intermediate filaments, microtubules) providing support and movement.

Microfilament

Thin actin filament involved in cell motility, shape change, and muscle contraction.

Intermediate Filament

Stable, rope-like filament that resists mechanical stress and anchors organelles.

Microtubule

Hollow tubulin cylinder that maintains cell shape, forms mitotic spindle, and provides tracks for transport.

Centriole

Paired cylindrical structures of microtubule triplets that organize mitotic spindle and form cilia/flagella bases.

Cilia

Short, numerous cell projections that move substances across the cell surface.

Flagellum

Long, whip-like projection that propels an entire cell, e.g., sperm tail.

Mitosis

Division of a cell’s nucleus producing two genetically identical daughter nuclei.

Interphase

Non-dividing phase in which the cell grows, performs functions, and replicates DNA (G1, S, G2 periods).

Prophase

First mitotic stage: chromatin condenses, spindle forms, nuclear envelope dissolves.

Metaphase

Mitotic stage where chromosomes align at the cell’s equatorial metaphase plate.

Anaphase

Shortest mitotic stage; sister chromatids separate and move toward opposite poles.

Telophase

Final mitotic stage: chromosomes decondense, nuclear envelopes re-form, spindle disappears.

Cytokinesis

Division of cytoplasm by cleavage furrow, completing formation of two daughter cells.

Centromere

Region where sister chromatids are joined and where spindle fibers attach via kinetochore.

Kinetochore

Protein structure on the centromere that binds spindle microtubules during mitosis.

Cleavage Furrow

Contractile ring indentation that pinches the cell membrane during cytokinesis.