Chapter 3: The Cellular Level of Organization Vocabulary Flashcards

Vocabulary flashcards covering cellular structures, transport mechanisms, organelles, genetic processes, and cell cycle regulation based on BIO 2403 Chapter 3.

Phospholipid Molecule

A molecule consisting of a polar phosphate head that is hydrophilic and a non-polar lipid tail that is hydrophobic, forming a bilayer sheet in cell membranes.

Simple Diffusion

The passive movement of substances like oxygen and carbon dioxide across a semi-permeable cell membrane down their concentration gradient, from higher to lower concentration.

Facilitated Diffusion

The movement of substances across a cell membrane down their concentration gradient using channel or carrier proteins when simple diffusion is prevented by large size, charge, or polarity.

Channel Proteins

Membrane proteins that form pores to help transport ions or water into and out of the cell, discriminating cargo mildly based on size and charge.

Carrier Proteins

Selective membrane proteins with specific binding sites that bind and shuttle target molecules across the cell membrane.

Aquaporins

Specific channel proteins in cell membranes that quickly facilitate the flow of water into or out of cells to maintain fluid balance and blood pressure.

CFTR (Cystic Fibrosis Transmembrane Conductance Regulator)

A chloride channel protein that, when mutated, blocks chloride and water transport across epithelial cells, causing thick, sticky mucus buildup in the lungs and digestive tract.

Hypertonic Solution

A solution with a higher solute concentration than the fluid inside the cell, causing water to move out of the cell and leading to cell shrinkage.

Isotonic Solution

A solution with equal solute concentration inside and outside the cell, maintaining normal cell volume.

Hypotonic Solution

A solution with a lower solute concentration than inside the cell, causing water to move into the cell, which leads to cell swelling and potential bursting.

Endocytosis

A form of active transport in which a cell envelopes extracellular materials using its cell membrane to bring them inside.

Phagocytosis

A relatively nonselective form of endocytosis where the cell engulfs a large particle.

Pinocytosis

A form of endocytosis where the cell ingests fluid containing small particles.

Receptor-Mediated Endocytosis

A selective form of endocytosis initiated when specific extracellular ligands bind to cell membrane receptors.

Exocytosis

The active process where export-destined material packaged in a vesicle fuses with the cell membrane to release contents into the extracellular space.

Rough Endoplasmic Reticulum (Rough ER)

A winding network of thin membranous sacs studded with ribosomes that serves as a primary site for protein synthesis.

Smooth Endoplasmic Reticulum (Smooth ER)

A membranous organelle that synthesizes phospholipids and steroid hormones, regulates cellular $\text{Ca}^{++}$ concentration, metabolizes carbohydrates, and breaks down toxins.

Golgi Apparatus

An organelle that organizes, modifies, packages, and tags products from the rough ER for transport or exocytosis, and produces new lysosomes.

Mitochondrion

A membranous, bean-shaped organelle known as the energy transformer of the cell, which converts energy from glucose into ATP along its inner membrane during cellular respiration.

Nucleus

The control center of the cell containing genetic material (DNA) that determines cell structure and function; site of DNA replication and RNA transcription.

Multinucleated

Describing a cell containing multiple nuclei, such as a mature skeletal muscle fiber formed by the fusion of smaller precursor cells during development.

Chromatin

Strands of DNA wrapped around supporting histone proteins that condense into tightly packed chromosomes when a cell prepares to divide.

DNA Replication

The semiconservative duplication of the cell's entire genome carried out by enzymes including helicase, primase, DNA polymerase, and ligase.

Semiconservative Replication

A mode of DNA replication where each daughter DNA molecule consists of one preexisting template strand and one newly synthesized strand.

Triplet

A sequence of three DNA bases in a row that codes for a specific amino acid.

Transcription

The process occurring within the cell nucleus in which DNA is used as a template to synthesize an mRNA molecule.

Translation

The process in the cytoplasm where an mRNA transcript is decoded into an amino acid sequence of a protein with the help of ribosomes and tRNA.

Cell Cycle

The sequence of events from a cell's formation following cell division until it divides into two new cells, consisting of Interphase ($\text{G}_0$, $\text{G}_1$, $\text{S}$, $\text{G}_2$) and Mitosis ($\text{M}$ phase).

Homologous Chromosomes

A pair of chromosomes separately inherited from each parent, each bound to an identical sister chromatid resulting from DNA replication.

Cyclins and Cyclin-Dependent Kinases

Regulatory molecules that control cell cycle progression by determining whether a cell is prepared to move to the next stage.

Stem Cells

Unspecialized cells that retain the capacity to differentiate into specialized cell types, offering therapeutic applications for replacing damaged tissue cells.