Chapter 3: Cellular Structure and Function

Vocabulary flashcards covering the key terms and definitions from Chapter 3: Cellular Structure and Function.

Plasma membrane

Protective phospholipid barrier that regulates what enters and exits the cell.

Cytoplasm

Jelly-like cytosol filling the cell interior; site of many metabolic activities and organelles.

DNA

Genetic blueprint stored as chromosomes (condensed) or chromatin (relaxed).

Ribosome

Protein-synthesizing particle found free in cytoplasm or bound to rough ER.

Phospholipid

Molecule with hydrophilic head and hydrophobic tails; basic building block of membranes.

Phospholipid bilayer

Double layer of phospholipids forming the structural framework of cell membranes.

Nucleoid

Non-membrane-bound region in prokaryotes that contains DNA.

Prokaryotic cell

Cell lacking a nucleus and membrane-bound organelles; includes Bacteria and Archaea.

Peptidoglycan

Structural polymer in bacterial cell walls that provides shape and protection.

Cell wall

Rigid layer outside the plasma membrane; made of peptidoglycan in bacteria and cellulose in plants.

Flagellum

Long, whip-like appendage used for locomotion in many prokaryotes.

Thermophile

Archaean that thrives in extremely hot environments.

Halophile

Archaean that lives in high-salt environments.

Eukaryotic cell

Cell containing a nucleus and membrane-bound organelles; found in plants, animals, fungi, and protists.

Organelle

Membrane-bound structure within a eukaryotic cell that performs a specific function.

Nucleus

Organelle that houses DNA and contains the nucleolus.

Nucleolus

Dense region inside the nucleus where ribosomes are assembled.

Rough endoplasmic reticulum (RER)

Network studded with ribosomes; folds and processes proteins for transport.

Smooth endoplasmic reticulum (SER)

Ribosome-free ER that synthesizes lipids, especially phospholipids.

Golgi apparatus

Stacked membranes that package, tag, and ship proteins and lipids—“UPS” of the cell.

Mitochondrion

Organelle that generates ATP from glucose; inner folds are called cristae.

Cristae

Infoldings of the inner mitochondrial membrane that increase surface area for ATP production.

Chloroplast

Plant organelle that converts light energy into glucose via photosynthesis.

Central vacuole

Large plant organelle that stores water and helps keep the cell plump.

Cellulose

Polysaccharide that forms the structural component of plant cell walls.

Lysosome

Animal cell organelle filled with digestive enzymes that break down waste and invaders.

Passive transport

Movement across a membrane along the concentration gradient without energy input.

Simple diffusion

Passive movement of small, non-polar molecules directly through the membrane.

Facilitated diffusion

Passive transport of larger or polar molecules via specific protein channels.

Osmosis

Diffusion of water from low solute to high solute concentration across a membrane.

Active transport

Energy-requiring movement of substances against their concentration gradient.

Protein pump

Membrane protein that uses ATP to push molecules against the gradient.

Endocytosis

Active process where the cell engulfs large substances by forming an inward vesicle.

Exocytosis

Active process where a vesicle fuses with the membrane to release contents outside the cell.

ATP (adenosine triphosphate)

Primary energy currency of the cell; hydrolysis to ADP releases usable energy.