The Fundamental Unit of Life: Cell Theory, Types, and Organelles

Vocabulary flashcards covering the major concepts, terms, and organelles related to cells, their discovery, types, structures, and basic transport processes.

Cell

The basic structural and functional unit of life; all organisms are made of one or more cells; vital activities occur inside cells.

Cell Theory

Principle that (a) all organisms are composed of cells, (b) cells are the basic unit of life, and (c) new cells arise from pre-existing cells.

Prokaryotic cell

Organisms without a defined nucleus or membrane-bound organelles; include bacteria; nucleoid region contains genetic material.

Eukaryotic cell

Organisms with a defined nucleus enclosed by a nuclear membrane and membrane-bound organelles.

Nucleus

Control center of the cell containing DNA and the nucleolus; surrounded by a double membrane called the nuclear envelope.

Nucleolus

Dense region inside the nucleus where ribosomal RNA (rRNA) synthesis occurs.

Chromatin

DNA-protein complex in the nucleus that condenses to form chromosomes during cell division.

Chromosome

Condensed DNA-protein structure that carries genetic information; visible during cell division.

DNA

Deoxyribonucleic acid; genetic material that stores hereditary information.

Nuclear envelope

Double membrane surrounding the nucleus with nuclear pores that regulate transport.

Nuclear pore

Channels in the nuclear envelope that regulate movement between the nucleus and cytoplasm.

Nucleoplasm

Fluid inside the nucleus.

Nucleoid

Region in prokaryotic cells where DNA is located; not bounded by a membrane.

Plasma membrane

Phospholipid bilayer that encloses the cell and controls entry/exit of substances; semi-permeable.

Cell wall

Rigid external layer in plants (and some bacteria) that provides support and protection.

Ribosome

Small particles where protein synthesis occurs; can be free or attached to rough ER.

Endoplasmic reticulum

Network of membranous tubules; rough ER has ribosomes for protein synthesis, smooth ER lacks ribosomes and synthesizes lipids.

Golgi apparatus

Stack of flattened sacs that modifies, sorts, and packages proteins and lipids for transport.

Mitochondrion

Powerhouse of the cell; site of ATP production; contains its own circular DNA.

Chloroplast

Plastid in plants/algae where photosynthesis occurs; contains chlorophyll and thylakoid membranes.

Chromoplast

Plastid that synthesizes pigments, giving color to flowers and fruits.

Leucoplast

Colorless plastid used for storage (starch, lipids, or proteins) in non-photosynthetic tissues.

Plastids

Family of plant organelles including chloroplasts, chromoplasts, and leucoplasts; often contain DNA and ribosomes.

Vacuole

Storage sac; large central vacuole in plant cells maintains turgor; stores substances.

Lysosome

Digestive organelle containing enzymes; known as suicide bags because rupture can digest the cell.

Diffusion

Spontaneous movement of molecules from high to low concentration.

Osmosis

Diffusion of water across a semipermeable membrane from higher to lower water concentration.

Hypertonic solution

Surrounding solution with lower water concentration than inside the cell; water leaves the cell.

Isotonic solution

Surrounding solution with equal water concentration as inside the cell; no net water movement.

Hypotonic solution

Surrounding solution with higher water concentration than inside the cell; water enters and the cell may swell.

Endocytosis

Process by which cells take in materials by engulfing them with the plasma membrane (common in animals).

Cell

The basic structural and functional unit of life; all organisms are made of one or more cells; vital activities occur inside cells.

Cell Theory

Principle that (a) all organisms are composed of cells, (b) cells are the basic unit of life, and (c) new cells arise from pre-existing cells.

Prokaryotic cell

Organisms without a defined nucleus or membrane-bound organelles; include bacteria; nucleoid region contains genetic material.

Eukaryotic cell

Organisms with a defined nucleus enclosed by a nuclear membrane and membrane-bound organelles.

Nucleus

Control center of the cell containing DNA and the nucleolus; surrounded by a double membrane called the nuclear envelope.

Nucleolus

Dense region inside the nucleus where ribosomal RNA (rRNA) synthesis occurs.

Chromatin

DNA-protein complex in the nucleus that condenses to form chromosomes during cell division.

Chromosome

Condensed DNA-protein structure that carries genetic information; visible during cell division.

DNA

Deoxyribonucleic acid; genetic material that stores hereditary information.

Nuclear envelope

Double membrane surrounding the nucleus with nuclear pores that regulate transport.

Nuclear pore

Channels in the nuclear envelope that regulate movement between the nucleus and cytoplasm.

Nucleoplasm

Fluid inside the nucleus.

Nucleoid

Region in prokaryotic cells where DNA is located; not bounded by a membrane.

Plasma membrane

Phospholipid bilayer that encloses the cell and controls entry/exit of substances; semi-permeable.

Cell wall

Rigid external layer in plants (and some bacteria) that provides support and protection.

Ribosome

Small particles where protein synthesis occurs; can be free or attached to rough ER.

Endoplasmic reticulum

Network of membranous tubules; rough ER has ribosomes for protein synthesis, smooth ER lacks ribosomes and synthesizes lipids.

Golgi apparatus

Stack of flattened sacs that modifies, sorts, and packages proteins and lipids for transport.

Mitochondrion

Powerhouse of the cell; site of ATP production; contains its own circular DNA.

Chloroplast

Plastid in plants/algae where photosynthesis occurs; contains chlorophyll and thylakoid membranes.

Chromoplast

Plastid that synthesizes pigments, giving color to flowers and fruits.

Leucoplast

Colorless plastid used for storage (starch, lipids, or proteins) in non-photosynthetic tissues.

Plastids

Family of plant organelles including chloroplasts, chromoplasts, and leucoplasts; often contain DNA and ribosomes.

Vacuole

Storage sac; large central vacuole in plant cells maintains turgor; stores substances.

Lysosome

Digestive organelle containing enzymes; known as suicide bags because rupture can digest the cell.

Diffusion

Spontaneous movement of molecules from high to low concentration.

Osmosis

Diffusion of water across a semipermeable membrane from higher to lower water concentration.

Hypertonic solution

Surrounding solution with lower water concentration than inside the cell; water leaves the cell.

Isotonic solution

Surrounding solution with equal water concentration as inside the cell; no net water movement.

Hypotonic solution

Surrounding solution with higher water concentration than inside the cell; water enters and the cell may swell.

Endocytosis

Process by which cells take in materials by engulfing them with the plasma membrane (common in animals).

Cytoplasm

The entire contents within the cell membrane, excluding the nucleus; includes cytosol and organelles.

Cytosol

The jelly-like fluid portion of the cytoplasm where organelles are suspended.

Exocytosis

Process by which cells release substances to the outside by fusing vesicles with the plasma membrane.

Active transport

Movement of molecules across a membrane against their concentration gradient, requiring energy (ATP) and carrier proteins.

Cellular respiration

Metabolic process that converts glucose into ATP (energy) for the cell, primarily occurring in the mitochondria.

Photosynthesis

Process used by plants, algae, and cyanobacteria to convert light energy into chemical energy (glucose), occurring in chloroplasts.