The Cell: Organelles, Energetics, and Membrane Transport

Vocabulary practice flashcards covering prokaryotic and eukaryotic cell organelles, cellular energetics (respiration and photosynthesis), and membrane transport mechanisms (diffusion, osmosis, active transport, endocytosis, and exocytosis).

Prokaryotic Cell

A cell lacking membrane-bound organelles that contains a cell wall, plasma membrane, cytoplasm, ribosomes, a bacterial chromosome (nucleoid), and optionally pili, flagella, and a capsule.

Nucleus

The eukaryotic organelle responsible for DNA storage; in the factory analogy, it serves as the files and blueprints management.

Mitochondrion

The eukaryotic organelle responsible for cellular respiration and energy production, harvesting chemical energy from food to produce $ATP$; serves as the cell's powerplant.

Mitochondrial Matrix

The internal compartment enclosed by the inner membrane of the mitochondrion where materials necessary for $ATP$ generation are located.

Cellular Respiration

The process accomplished in eukaryotic mitochondria that converts chemical energy in food into chemical energy in $ATP$, represented by: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$.

Ribosome

The cellular structure responsible for protein synthesis; analogized as the machine that produces toys in a factory.

Rough Endoplasmic Reticulum (Rough ER)

An organelle that carries out protein production and modification; analogized as the coordination and decoration of the toy production line in a factory.

Smooth Endoplasmic Reticulum (Smooth ER)

An organelle responsible for lipid production and detoxification; analogized as accessory production in a factory.

Golgi Apparatus

The organelle responsible for protein transportation and export; analogized as the factory's packaging and shipping department.

Peroxisome

An organelle that carries out lipid breakdown and redox reactions; analogized as hazardous chemical handling in a factory.

Lysosome

An organelle responsible for protein destruction and cellular waste breakdown; analogized as the recycling department in a factory.

Cytoskeleton

A network comprising microtubules, intermediate filaments, and microfilaments that facilitates cell movement and intracellular transportation; analogized as a factory conveyor system.

Plastids

A class of plant and algal organelles that includes chloroplasts, chromoplasts, and leucoplasts.

Chloroplast

The photosynthesizing organelle of plant and algal cells that converts solar energy into chemical energy, partitioned into the stroma, thylakoids, and grana; analogized as solar panels.

Photosynthesis

The biological process in which light energy is converted into the chemical energy of sugar molecules: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$.

Vacuole

A plant cell organelle dedicated to storage and water regulation; analogized as storage spaces in a factory.

Passive Transport

The movement of small molecules down a concentration gradient (from high to low concentration) across the cell membrane without the expenditure of cellular energy ($ATP$).

Simple Diffusion

A passive transport process where molecules disperse across the lipid bilayer from an area of high concentration to an area of low concentration.

Factors Affecting the Rate of Diffusion

Seven key factors controlling diffusion speed: size of the molecules (inversely proportional to molecular weight, e.g., $O_2$ diffuses faster than $CO_2$), temperature, solubility, charged or uncharged condition, concentration gradient, pressure, and membrane permeability.

Osmosis

The passive diffusion of water through a selectively permeable membrane from an area of high water concentration (low solute) to an area of low water concentration (high solute).

Hypotonic Solution

A solution with a lower solute concentration (e.g., $0\%$ sucrose) than the cell interior, causing net water entry that lyses animal cells (hemolysis) and makes plant cells turgid.

Hypertonic Solution

A solution with a higher solute concentration (e.g., $10\%$ sucrose) than the cell interior, causing net water loss that shrivels animal cells and causes plasmolysis in plant cells.

Isotonic Solution

A solution having the same solute concentration (e.g., $2\%$ sucrose) as the cell interior, causing no net movement of water, leaving animal cells normal and plant cells flaccid.

Active Transport

The movement of molecules against their concentration gradient (from low to high concentration) that requires cellular energy ($ATP$), transport proteins, and enzymes, observed only in living cells.

Endocytosis

A bulk transport process that brings large molecules or particles into the cell via vesicle formation, including phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Phagocytosis

Cellular eating; a form of endocytosis in which a cell engulfs large solid particles into a phagosome (food vacuole), such as white blood cells ingesting bacteria.

Pinocytosis

Cellular drinking; a form of endocytosis where the cell takes in droplets of extracellular fluid containing dissolved solutes into small vesicles.

Exocytosis

A form of bulk active transport that forces materials out of the cell by fusing intracellular vesicles with the plasma membrane, requiring energy and cell shape changes (e.g., releasing hormones or wastes).