Chapter 3: The Cell Vocabulary Flashcards

Vocabulary flashcards covering cellular processes, membrane transport, organelles, cytoskeleton, protein synthesis, and the cell cycle from Chapter 3.

Cell Metabolism

The chemical reactions that a cell carries out to maintain life, including anabolic, catabolic, and oxidation-reduction reactions.

Cytosol

The watery gel within the cytoplasm containing proteins, dissolved solutes, inclusions, and various forms of RNA.

Fluid Mosaic Model

The model describing the plasma membrane as a dynamic mosaic of phospholipids, proteins, lipids, and carbohydrates that move laterally within the bilayer.

Integral Proteins

Membrane proteins that span the entire width of the plasma membrane; also known as transmembrane proteins when they reach both sides.

Peripheral Proteins

Membrane proteins located on only one side of the plasma membrane that may float freely or be anchored by the cytoskeleton.

Agonist

A drug or chemical that binds to a membrane receptor and mimics the action of a natural ligand.

Antagonist

A drug or chemical that binds to a membrane receptor and inhibits or blocks the action of a natural ligand.

Diffusion

The movement of solute molecules from an area of higher solute concentration to an area of lower solute concentration driven by a concentration gradient.

Simple Diffusion

Passive transport of nonpolar solutes and gases directly through the phospholipid bilayer without the aid of a membrane protein.

Facilitated Diffusion

Passive transport of charged or polar solutes across the membrane via a channel or carrier protein.

Osmosis

The movement of solvent (water) across a selectively permeable membrane from a solution of lower solute concentration to one of higher solute concentration.

Aquaporins

Protein channels in the plasma membrane through which water passes during osmosis.

Osmotic Pressure

The pressure that must be applied to a solution to prevent water from moving into it by osmosis.

Hydrostatic Pressure

The physical force exerted by fluid on the walls of its container.

Tonicity

A measure of the ability of an extracellular solution to cause osmosis and alter cell volume based on non-penetrating solute concentration.

Isotonic Solution

An extracellular solution that has the same solute concentration and ability to cause osmosis as the cytosol of a cell, resulting in no net water movement.

Hypertonic Solution

An extracellular solution with a higher solute concentration than the cytosol, causing water to leave the cell and leading to crenation.

Hypotonic Solution

An extracellular solution with a lower solute concentration than the cytosol, causing water to enter the cell and leading to swelling or lysis.

Sodium-Potassium Pump

A primary active transport pump ($\text{Na}^+/\text{K}^+$ ATPase) that moves 3 $\text{Na}^+$ ions out of the cell and 2 $\text{K}^+$ ions into the cell against their concentration gradients using ATP hydrolysis.

Secondary Active Transport

A transport process in which an ATPase pump creates an ion concentration gradient, and the potential energy of that gradient is used to drive the active transport of another substance.

Resting Membrane Potential

The electrical potential across the plasma membrane when a cell is at rest, resulting from an excess of positive charges in the ECF and negative charges in the cytosol.

Phagocytosis

A form of endocytosis known as 'cell eating,' in which specialized cells ingest large particles or bacteria using pseudopods to form a phagosome.

Pinocytosis

A form of endocytosis known as 'cell drinking,' in which a cell brings dissolved solutes and fluid from the ECF into transport vesicles formed from protein-coated pits.

Receptor-Mediated Endocytosis

A specialized form of endocytosis in which specific ligands bind to surface receptors in protein-coated pits to be internalized in high concentration.

Exocytosis

The process by which substances enclosed in exocytic transport vesicles fuse with the plasma membrane to release their contents into the ECF.

Transcytosis

A cellular process in which a substance enters a cell via endocytosis, moves through the cytoplasm, and is released on the opposite side via exocytosis.

Cristae

The inner folds of the inner mitochondrial membrane that increase surface area for oxidative catabolism and ATP synthesis.

Peroxisomes

Membrane-enclosed organelles that use oxygen to oxidize toxic substances, break down fatty acids, and synthesize specific phospholipids.

Ribosomes

Non-membrane-enclosed organelles composed of large and small subunits made of rRNA and proteins that serve as the sites of protein synthesis.

Rough Endoplasmic Reticulum (RER)

A series of saclike membranes studded with bound ribosomes that modifies and folds proteins made by ribosomes and manufactures membrane components.

Smooth Endoplasmic Reticulum (SER)

A tubular membrane system lacking ribosomes that stores calcium ions, synthesizes lipids, and carries out detoxification reactions.

Golgi Apparatus

A stack of flattened membranous sacs that sorts, modifies, and packages proteins and lipids received from the ER for transport.

Lysosomes

Membrane-enclosed organelles filled with acid hydrolases that digest endocytosed substances, break down worn-out cellular parts, and function at an optimal pH of around 5.0.

Autophagy

The lysosomal process of degrading and recycling old or damaged organelles and cellular components.

Actin Filaments

Thin cytoskeletal filaments composed of intertwined actin subunits that support the plasma membrane, form the core of microvilli, and interact with myosin for cell movement.

Intermediate Filaments

Ropelike cytoskeletal filaments made of fibrous proteins like keratin that give mechanical strength to cells and tissues and support the nuclear lamina.

Microtubules

Hollow cytoskeletal tubes made of tubulin subunits that maintain organelle positioning, move vesicles via motor proteins (dynein and kinesin), and form the core of cilia and flagella.

Centrosome

A cellular region containing a tubulin gel matrix and a pair of centrioles arranged at right angles, serving as the microtubule-organizing center.

Microvilli

Finger-like extensions of the plasma membrane supported by actin filaments that form a brush border to increase surface area for absorption.

Cilia

Short, hair-like cellular extensions with a 9+2 microtubule core that beat in a coordinated motion to move substances past the cell surface.

Flagella

Long, single cellular extensions containing a 9+2 microtubule structure that propel the entire cell through liquid using a whiplike motion.

Nuclear Envelope

A double membrane enclosing the nucleus containing nuclear pores, with an outer membrane continuous with the RER and an inner membrane supported by the nuclear lamina.

Chromatin

A complex of a long DNA strand wound around histone proteins into nucleosomes, forming a compact structure when the cell is not dividing.

Chromosomes

Tightly condensed, bar-like structures of DNA and histones formed during cell division, consisting of identical sister chromatids joined at a centromere.

Transcription

The process in which RNA polymerase synthesizes a complementary strand of messenger RNA (mRNA) from a DNA gene template inside the nucleus.

Translation

The process in which ribosomes read the mRNA nucleotide sequence and synthesize a polypeptide chain using amino acids brought by tRNAs.

Codon

A three-nucleotide sequence on an mRNA strand that specifies a particular amino acid or stop signal in the genetic code.

Anticodon

A three-nucleotide sequence on a tRNA molecule that is complementary to a specific mRNA codon.

Exons

The coding regions of a gene that remain in the mRNA transcript after RNA processing and are translated into protein.

Introns

The noncoding regions of a gene that are removed from pre-mRNA during RNA processing prior to translation.

Semiconservative Replication

The mechanism of DNA synthesis in which two new identical double helices are produced, each containing one original parent strand and one newly synthesized strand.

Mitosis

The division of genetic material during the M phase of the cell cycle, consisting of prophase, metaphase, anaphase, and telophase.

Cytokinesis

The division of the cytoplasm, organelles, and cytosol into two distinct daughter cells, beginning in late anaphase and ending in telophase with a cleavage furrow.

Apoptosis

Programmed cell death that removes unrepairable, damaged, or unneeded cells during development and cell cycle control.

Metastasis

The process by which malignant cancer cells break away from a primary tumor and spread to other tissues in the body.