Human Anatomy and Physiology - Chapter 3: The Cell Flashcards

Vocabulary flashcards covering cell structure, transport mechanisms, organelles, cytoskeleton, protein synthesis, and cell cycle based on Chapter 3 lecture notes.

Cell Metabolism

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

Cytosol

The intracellular fluid (ICF) consisting of a watery gel with proteins, dissolved solutes, and different forms of RNA within the intracellular space.

Organelles

Molecular machines within a cell that perform and compartmentalize specific cellular functions.

Cytoskeleton

A network of protein filaments that supports the cell, maintains its shape, holds organelles in place, and provides intracellular transport.

Phospholipid Bilayer

A double layer formed by phospholipids with polar hydrophilic phosphate heads and nonpolar hydrophobic fatty acid tails that separates the ECF from the cytosol.

Integral Proteins

Membrane proteins that span the entire width of the plasma membrane, also known as transmembrane proteins when reaching both sides.

Peripheral Proteins

Membrane proteins located on only $1$ side of the plasma membrane.

Agonists

Drugs that bind to membrane receptors and mimic the natural ligand's actions.

Antagonists

Drugs that bind to membrane receptors and inhibit the ligand's effects.

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 where nonpolar solutes and gases pass straight through the phospholipid bilayer without needing a membrane protein.

Facilitated Diffusion

Passive transport where charged or polar solutes cross the phospholipid bilayer with the help of a channel or carrier protein.

Osmosis

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

Aquaporins

Water channels in the plasma membrane through which water molecules pass 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 force that water exerts on the walls of its container.

Tonicity

A measure used to compare the solute concentrations of $2$ solutions based on solutes that cannot freely cross the plasma membrane.

Hypertonic Extracellular Solution

An ECF solution with a higher solute concentration than cytosol, causing the cell to lose water and shrivel (crenate).

Hypotonic Extracellular Solution

An ECF solution with a lower solute concentration than cytosol, causing the cell to gain water, swell, and potentially rupture (lyse).

Primary Active Transport

A transport process where a carrier pump moves a solute against its concentration gradient using energy directly from the hydrolysis of ATP.

Sodium-Potassium Pump

A primary active transport pump ($\text{Na}^+/\text{K}^+$ ATPase) that moves $3$ sodium ions out of the cell for every $2$ potassium ions it brings into the cell.

Secondary Active Transport

A transport mechanism in which ATP is used to establish a concentration gradient of one substance, whose potential energy then powers the active transport of another substance.

Resting Membrane Potential

The electrical potential across the plasma membrane when a cell is at rest, measured in millivolts ($\text{mV}$).

Phagocytosis

A form of endocytosis ('cell eating') in which specialized immune cells called phagocytes ingest large particles, such as bacteria or cell debris.

Pinocytosis

A form of endocytosis ('cell drinking') in which a cell brings ECF fluid droplets and dissolved nutrients into the cytosol via protein-coated pits.

Receptor-Mediated Endocytosis

A specialized type of pinocytosis where specific ligands bind to unique receptors in protein-coated pits to be imported into transport vesicles.

Exocytosis

The vesicular transport process by which substances are released from the cell and components are added to the plasma membrane.

Transcytosis

A pathway in which substances are brought into a cell by endocytosis, transported through the cell, and released on the opposite side by exocytosis.

Peroxisomes

Membrane-enclosed organelles that use oxygen to oxidize organic compounds, producing hydrogen peroxide to detoxify substances, metabolize fatty acids, and synthesize phospholipids.

Ribosomes

Non-membrane-enclosed organelles composed of $2$ subunits of ribosomal RNA (rRNA) and proteins that serve as the site of protein synthesis.

Rough Endoplasmic Reticulum

A network of saclike membranes studded with bound ribosomes that modifies and folds proteins and manufactures most plasma membrane components.

Smooth Endoplasmic Reticulum

A tubular membrane network lacking ribosomes that stores calcium ions, synthesizes lipids, and detoxifies drugs and harmful substances.

Golgi Apparatus

A stack of flattened, membrane-enclosed sacs that modifies, sorts, and packages proteins and lipids synthesized by the ER.

Lysosomes

Membrane-enclosed sacs containing acid hydrolases that digest macromolecules, recycle worn-out organelles via autophagy, and destroy bacteria.

Actin Filaments

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

Intermediate Filaments

Ropelike cytoskeletal filaments made of fibrous proteins like keratin that give mechanical strength to the cell, support the nuclear envelope, and withstand mechanical stress.

Microtubules

Hollow cytoskeletal rods composed of tubulin subunits that maintain cell architecture, position organelles, form the core of cilia and flagella, and move vesicles via motor proteins.

Microvilli

Finger-like extensions of the plasma membrane supported by actin filaments that increase cell surface area by $30\text{ to }40$ times.

Cilia

Short, hair-like surface extensions containing a core of $9$ pairs of microtubules surrounding $2$ central microtubules that move in a coordinated beating motion.

Flagella

A single, long cellular extension containing microtubules that moves in a whiplike motion to propel a cell.

Nucleolus

A structure within the nucleoplasm of the nucleus that houses RNA and assembles ribosomes.

Chromatin

A structural form of DNA in non-dividing cells consisting of one long DNA strand wrapped around histone proteins.

Nucleosomes

Structural units of chromatin where DNA is wrapped around histone proteins, resembling 'beads' on a string.

Transcription

The first step of gene expression in which RNA polymerase copies a gene's DNA code to synthesize a complementary mRNA transcript.

Translation

The process of protein synthesis where ribosomes read mRNA codons and assemble a corresponding sequence of amino acids brought by tRNA.

Codon

A three-nucleotide sequence on an mRNA transcript that specifies a particular amino acid in the genetic code.

Exons

The coding portions of a gene that remain in the final mRNA transcript after processing.

Introns

The noncoding portions of a gene that are removed during pre-mRNA splicing.

Semiconservative Replication

The process of DNA synthesis in which each original DNA strand serves as a template to build a new complementary strand.

Apoptosis

Programmed cell death that occurs when a cell fails cell cycle checkpoints or as part of normal developmental processes.