Cellular Transport and Cell Cycle Vocabulary

30 vocabulary flashcards covering key cellular transport mechanisms and cell-cycle concepts from Lessons 6-8.

Plasma Membrane (Cell Membrane)

Dynamic phospholipid bilayer with embedded proteins that regulates substances moving into and out of the cell.

Classical Plasma Membrane Model (Davson–Danielli)

Early model proposing a phospholipid bilayer sandwiched between two continuous protein layers.

Fluid Mosaic Model

Modern concept describing the membrane as a fluid phospholipid sea in which proteins, cholesterol, and carbohydrates float and move laterally.

Passive Transport

Movement of substances down their concentration gradient across a membrane without cellular energy expenditure.

Osmosis

Diffusion of water across a selectively permeable membrane from a hypotonic region to a hypertonic region.

Hypotonic Solution

Solution with lower solute concentration than another; tends to gain water and can cause animal cells to swell or burst.

Isotonic Solution

Two solutions having equal solute and water concentrations, allowing cells to maintain normal shape and function.

Hypertonic Solution

Solution with higher solute concentration than another; draws water out of cells, causing them to shrink.

Facilitated Diffusion

Passive movement of polar or charged molecules through membrane proteins (channels or carriers) down a concentration gradient.

Carrier Protein

Membrane protein that transports specific molecules by changing shape after binding and releasing its cargo.

Channel Protein

Hydrophilic pore–forming membrane protein that opens or closes in response to stimuli to allow specific ions or molecules to pass.

Active Transport

Energy-requiring process that moves solutes against their concentration gradient via membrane transport proteins.

Sodium–Potassium Pump

ATP-driven transporter that exports 3 Na⁺ and imports 2 K⁺ ions to maintain electrochemical gradients across the plasma membrane.

Bulk Transport

Vesicle-mediated movement of large particles or volumes across membranes via exocytosis or endocytosis.

Exocytosis

Process in which intracellular vesicles fuse with the plasma membrane to secrete their contents outside the cell.

Endocytosis

Uptake of materials by engulfing them with the plasma membrane to form intracellular vesicles.

Phagocytosis

"Cell eating"; endocytic engulfment of solid particles such as bacteria or debris into large vesicles.

Pinocytosis

"Cell drinking"; nonspecific uptake of extracellular fluid and dissolved solutes into small vesicles.

Interphase

Longest portion of the cell cycle (G1, S, G2) involving cell growth, DNA replication, and preparation for division.

Gap 1 (G1) Phase

First interphase stage characterized by cell growth, organelle duplication, protein synthesis, and DNA damage check.

Synthesis (S) Phase

Interphase stage where DNA is replicated, doubling the chromosome content in preparation for mitosis or meiosis.

Gap 2 (G2) Phase

Second growth stage involving additional cell growth, protein synthesis, and final DNA integrity checks before mitosis.

Gap 0 (G0) Phase

Non-dividing state where cells are metabolically active but temporarily or permanently exit the cell cycle.

Internal Regulators

Intracellular proteins that control cell-cycle progression, ensuring each phase begins only after the previous one is properly completed.

External Regulators

Extracellular signals, such as growth factors and nutrient cues, that influence the rate or timing of cell division.

Mitosis

Eukaryotic cell division producing two genetically identical diploid daughter cells from one parent cell.

Meiosis

Two-part division in germ cells that yields four genetically distinct haploid gametes, halving the chromosome number.

Synapsis

Pairing of homologous chromosomes during prophase I of meiosis, forming tetrads.

Crossing Over

Exchange of genetic material between non-sister chromatids within homologous pairs, increasing genetic variability.

Aneuploidy

Condition of having an abnormal number of chromosomes, often caused by non-disjunction during meiosis.