Chapter 4 – Cells: Organization and Communication

Vocabulary flashcards covering cell structure, membrane transport, tonicity, and cellular respiration from Chapter 4: Cells: Organization and Communication.

Eukaryotic Cell (Animal)

A fundamental membrane-bound biological unit characterized by a nucleus containing genetic material and surrounded by cytoplasm containing specialized organelles such as mitochondria, the endoplasmic reticulum, and the Golgi apparatus.

Plasma (Cell) Membrane

The outer boundary of the cell consisting of a phospholipid bilayer embedded with proteins, cholesterol, and carbohydrates that regulates the movement of substances entering and exiting the cell.

Selective Permeability

The property of the plasma membrane that allows only certain substances to pass through freely while preventing or regulating the passage of others.

Cytoplasm

The cellular material located between the plasma membrane and the nucleus, consisting of the fluid cytosol, organelles, and cytoskeleton.

Diffusion

The passive net movement of solute molecules or ions from a region of higher concentration to a region of lower concentration down a concentration gradient.

Osmosis

The net diffusion of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Facilitated Transport

The passive movement of specific substances across a plasma membrane down their concentration gradient via protein channels or carrier proteins without requiring cellular energy.

Active Transport

The energy-requiring process that moves solute molecules across a plasma membrane against their concentration gradient, typically utilizing transport proteins and $ATP$.

Endocytosis

A vesicular transport process in which the plasma membrane invaginates and pinches off to bring extracellular substances or large particles into the cell.

Exocytosis

A vesicular transport mechanism wherein intracellular vesicles fuse with the plasma membrane to secrete their contents into the extracellular fluid.

Tonicity

The ability of an extracellular solution to cause a cell to gain or lose water, demonstrated by the morphological changes in red blood cells when placed in isotonic, hypotonic, or hypertonic environments.

Isotonic Solution

A solution having the same solute concentration and water potential as the cell interior, leading to no net movement of water into or out of the cell.

Hypotonic Solution

A solution with a lower solute concentration compared to the cell interior, resulting in a net influx of water that causes the cell to swell and potentially lyse (burst).

Hypertonic Solution

A solution with a higher solute concentration compared to the cell interior, causing a net outflow of water that leads to cell shrinkage and crenation.

Cellular Respiration

The multi-stage metabolic process involving glycolysis in the cytoplasm, followed by the citric acid cycle and the electron transport chain inside the mitochondrion to produce $ATP$.

Aerobic Cellular Respiration

The oxygen-dependent metabolic pathway that fully oxidizes glucose into carbon dioxide ($CO_2$) and water ($H_2O$), yielding a high amount of $ATP$.

Lactic Acid Fermentation

An anaerobic pathway occurring in the absence of oxygen where pyruvate from glycolysis is reduced to lactic acid (lactate) in order to regenerate $NAD^+$ for continuous ATP generation.