Chapter 3: The Cellular Level of Organization - Vocabulary Flashcards

Vocabulary practice flashcards generated from Chapter 3: The Cellular Level of Organization.

Plasma Membrane

A flexible yet sturdy barrier surrounding and containing the cytoplasm of a cell, composed of a phospholipid bilayer with embedded proteins.

Integral Proteins

Membrane proteins that extend into or through the lipid bilayer and are firmly embedded within it.

Peripheral Proteins

Proteins attached to the inner or outer surface of the lipid bilayer that do not extend through the membrane.

Cholesterol (Membrane)

A lipid molecule present in the plasma membrane that functions to stabilize the membrane structure and reduce membrane fluidity.

Electrochemical Gradient

The combined influence of a concentration gradient and an electrical gradient across the plasma membrane.

Simple Diffusion

A passive movement of nonpolar, hydrophobic substances down their concentration gradient directly through the lipid bilayer without transport proteins.

Facilitated Diffusion

Passive movement of polar or charged solutes down a concentration gradient aided by transmembrane proteins functioning as channels or carriers.

Osmosis

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

Isotonic Solution

A solution in which solute concentration is equal on both sides of the plasma membrane, allowing cells to maintain their normal shape.

Hypotonic Solution

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

Hypertonic Solution

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

Primary Active Transport

An active transport process in which energy derived from ATP hydrolysis changes the shape of a carrier protein to pump a substance across a membrane against its concentration gradient.

Secondary Active Transport

Coupled transport that moves a substance against its concentration gradient using energy stored in a $\text{Na}^+$ or $\text{H}^+$ concentration gradient created by primary active transport.

Antiporters

Transporters in secondary active transport that move $\text{Na}^+$ (or $\text{H}^+$) and another substance in opposite directions across the plasma membrane.

Symporters

Transporters in secondary active transport that move $\text{Na}^+$ (or $\text{H}^+$) and another substance in the same direction across the plasma membrane.

Receptor-Mediated Endocytosis

A highly selective active process where ligand-receptor complexes trigger infolding of clathrin-coated pits to form vesicles containing imported ligands.

Phagocytosis

A type of vesicular transport ('cell eating') in which a cell extends pseudopods to engulf solid particles like bacteria, viruses, or dead cells into a phagosome.

Bulk-Phase Endocytosis (Pinocytosis)

A type of vesicular transport ('cell drinking') involving nonselective infolding of the plasma membrane to form vesicles containing extracellular fluid and dissolved solutes.

Exocytosis

An active transport process in which membrane-enclosed secretory vesicles fuse with the plasma membrane to release their contents into the extracellular fluid.

Transcytosis

An active transport process combining endocytosis on one side of a cell and exocytosis on the opposite side to move substances across the cell.

Cytosol

The fluid portion of cytoplasm (intracellular fluid) containing water, solutes, suspended particles, lipid droplets, and glycogen granules.

Cytoskeleton

A protein filament network in the cytoplasm consisting of microfilaments, intermediate filaments, and microtubules that maintains cell shape and enables cellular movement.

Centrosome

An organelle consisting of a pair of centrioles and a pericentriolar matrix that contains tubulins used for microtubule formation and growth of the mitotic spindle.

Cilia

Short, motile cell surface projections that contain microtubules and function to sweep fluids over the cell's surface.

Flagella

Long, motile cell surface projections that contain microtubules and function to propel an entire cell forward.

Ribosome

An organelle composed of two subunits containing ribosomal RNA and proteins that serves as the site of protein synthesis.

Rough Endoplasmic Reticulum (Rough ER)

A membranous network studded with ribosomes attached to the nuclear envelope that synthesizes glycoproteins and phospholipids.

Smooth Endoplasmic Reticulum (Smooth ER)

A membranous network lacking ribosomes that synthesizes fatty acids and steroids, detoxifies drugs, and stores calcium ions in muscle cells.

Golgi Complex

An organelle composed of 3–20 flattened membranous sacs (saccules) divided into entry (cis) face, medial saccules, and exit (trans) face, which modifies, sorts, and packages proteins.

Lysosome

A digestive vesicle formed from the Golgi complex containing hydrolytic enzymes that digest endocytosed substances, worn-out organelles, or whole cells.

Autophagy

The process by which lysosomal enzymes digest worn-out cellular organelles.

Autolysis

The destruction of an entire cell by its own lysosomal enzymes.

Peroxisome

A cell vesicle containing oxidases and catalase that oxidizes amino acids and fatty acids, and detoxifies harmful substances such as hydrogen peroxide.

Proteasome

A tiny barrel-shaped structure containing proteases that degrades unneeded, damaged, or faulty proteins by cutting them into small peptides.

Mitochondrion

A double-membrane organelle containing cristae and matrix that acts as the site of aerobic cellular respiration reactions producing most of a cell's ATP.

Nucleus

The organelle consisting of a nuclear envelope with pores, nucleoli, and chromatin that houses genes controlling cellular structure and directing cellular activities.

Transcription

The process occurring in the nucleus whereby genetic information encoded in DNA is copied onto a strand of RNA to direct protein synthesis.

Translation

The process occurring in the cytoplasm in which the nucleotide sequence of mRNA is read by ribosomes to assemble a specific sequence of amino acids into a protein.

Interphase

The period of the cell cycle between divisions consisting of $\text{G}_1$, $\text{S}$, and $\text{G}_2$ phases, during which the cell grows, duplicates organelles, and replicates DNA.

Mitosis

Nuclear division resulting in the distribution of two identical sets of chromosomes into two separate, identical nuclei.

Prophase

The first phase of mitosis during which chromatin condenses into visible chromosomes, the nucleolus and nuclear envelope disappear, and centrosomes move to opposite poles.

Metaphase

The stage of mitosis in which centromeres of chromatid pairs align along the metaphase plate in the center of the cell.

Anaphase

The phase of mitosis in which centromeres split and identical sets of sister chromatids move toward opposite poles of the cell.

Telophase

The final phase of mitosis where nuclear envelopes and nucleoli reappear, chromosomes uncoil into chromatin, and the mitotic spindle dissolves.

Cytokinesis

The division of a parent cell's cytoplasm where a contractile ring forms a cleavage furrow, splitting the cytoplasm into separate and equal portions.

Meiosis

Reproductive cell division that produces gametes containing a haploid ($n$) number of chromosomes through two successive nuclear divisions.