Campbell Biology Chapter 6: A Tour of the Cell Flashcards

Comprehensive vocabulary flashcards covering cell structure, organelles, endomembrane system, energy organelles, cytoskeleton, and cell junctions based on Chapter 6 of Campbell Biology.

Cell Theory

The fundamental biological principle stating that all organisms are made of cells, the cell is the simplest collection of matter that can be alive, and all cells come from pre-existing cells.

Cytosol

The semifluid substance present in all cells in which subcellular components are suspended.

Prokaryotic Cell

A type of cell lacking a nucleus and membrane-bound organelles, characterized by DNA that is unbound in a nucleoid region, found only in the domains Bacteria and Archaea.

Eukaryotic Cell

A type of cell characterized by having DNA enclosed within a membranous nuclear envelope, numerous membrane-bound organelles, and cytoplasm between the plasma membrane and nucleus.

Plasma Membrane

A selective barrier composed of a phospholipid bilayer that regulates the passage of oxygen, nutrients, and waste to service the volume of the cell.

Surface Area to Volume Ratio ($SA:V$)

The critical physical relationship where as cell size increases, volume increases by a factor of $n^3$ while surface area increases by $n^2$, requiring cells to remain small or adapt specialized structures to ensure efficient exchange of resources and waste.

Nuclear Envelope

A double membrane consisting of lipid bilayers that encloses the nucleus, separating its contents from the cytoplasm and containing pore complexes that regulate entry and exit of molecules.

Chromatin

The complex of DNA and histone proteins found within the nucleus that condenses to form discrete chromosomes as a cell prepares to divide.

Nucleolus

A specialized structure within the nucleus responsible for the synthesis of ribosomal RNA (rRNA).

Ribosomes

Cellular particles made of ribosomal RNA and protein that carry out protein synthesis in the cytosol (free ribosomes) or attached to the rough ER or nuclear envelope (bound ribosomes).

Endomembrane System

A collection of membranous cellular structures—including the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, vesicles, and plasma membrane—that regulate protein traffic and perform metabolic functions.

Smooth Endoplasmic Reticulum (Smooth ER)

A region of the endoplasmic reticulum that lacks ribosomes on its surface, functioning in lipid synthesis and detoxification of drugs, alcohol, and poisons.

Rough Endoplasmic Reticulum (Rough ER)

A region of the endoplasmic reticulum studded with bound ribosomes on its outer surface, which compartmentalizes the cell, synthesizes secretory proteins (glycoproteins), and distributes transport vesicles.

Golgi Apparatus

An organelle consisting of flattened membranous sacs (cisternae) that modifies, sorts, and packages products from the rough ER for transport, manufactures lysosomes, and synthesizes carbohydrates.

Cis Face of Golgi Apparatus

The receiving side of the Golgi apparatus located near the ER where transport vesicles arrive and fuse with the Golgi membrane.

Trans Face of Golgi Apparatus

The shipping side of the Golgi apparatus that gives rise to transport vesicles that pinch off and travel to other sites, such as the plasma membrane.

Lysosome

A membranous sac containing hydrolytic enzymes used by animal cells to digest macromolecules, food particles, damaged organelles, or whole cells in an acidic environment.

Phagocytosis

A cellular process where a cell engulfs a particle or another cell, creating a food vacuole that subsequently fuses with a lysosome for digestion.

Autophagy

A lysosomal process in which the cell uses hydrolytic enzymes to recycle its own organic material and damaged organelles.

Apoptosis

Programmed cell death, a process mediated by lysosomal mechanisms during developmental processes, such as digit formation in human embryos.

Contractile Vacuole

A specialized organelle found in freshwater protists that pumps excess water out of the cell to maintain suitable ion and molecule concentrations.

Central Vacuole

The largest compartment in most mature plant cells, which stores inorganic ions and water and plays a major role in plant cell growth.

Endosymbiont Theory

The evolutionary theory stating that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell, eventually evolving into a single organism.

MAD DR Mnemonic

A mnemonic summarizing evidence for the endosymbiont theory: Double Membranes, Antibiotics susceptibility, Division by fission, naked circular DNA, and 70S Ribosomes.

Mitochondrion

The organelle bounded by a double membrane that serves as the site of cellular respiration, utilizing oxygen to generate ATP.

Cristae

The infoldings of the inner mitochondrial membrane that house enzymes for ATP synthesis and present a large surface area for cellular respiration.

Mitochondrial Matrix

The compartment of the mitochondrion enclosed by the inner membrane, containing mitochondrial DNA, free ribosomes, and metabolic enzymes.

Chloroplast

A photosynthetic plant and algal organelle containing chlorophyll, thylakoids, and stroma, which converts solar energy into chemical energy.

Thylakoids

Flattened, membranous sacs inside the chloroplast that contain chlorophyll and are stacked into grana; the site of the light-dependent reactions of photosynthesis.

Stroma

The dense fluid within the chloroplast surrounding the thylakoid membrane, containing chloroplast DNA, ribosomes, and enzymes for the Calvin cycle (light-independent reactions).

Cytoskeleton

A network of protein fibers extending throughout the cytoplasm that organizes structures and activities, anchors organelles, supports cell shape, and facilitates cell motility.

Microtubules

Hollow rods with a diameter of $25\,nm$ composed of tubulin dimers ($\alpha\text{-tubulin}$ and $\beta\text{-tubulin}$) that maintain cell shape, guide organelle movement, and separate chromosomes during cell division.

Microfilaments

Solid, intertwined strands of actin subunits with a diameter of $7\,nm$ that function in maintaining cell shape, muscle contraction, cytoplasmic streaming, and cell division cleavage furrow formation.

Intermediate Filaments

Fibrous protein cables (such as keratins) with diameters of $8\text{--}12\,nm$ that specialize in bearing tension, anchoring the nucleus and organelles, and forming the nuclear lamina.

Cilia

Short, numerous microtubule-containing appendages that extend from eukaryotic cells and move in a sweeping motion to propel fluids or cells.

Flagella

Long, usually solitary microtubule-containing appendages that move in an undulating motion powered by ATP to propel cells, such as sperm.

Plasmodesmata

Open channels through plant cell walls that connect the cytoplasm of adjacent cells, allowing water, small solutes, proteins, and RNA to pass freely between cells.

Tight Junctions

Intercellular junctions in animal cells where membranes of neighboring cells are pressed tightly against each other by interlocking proteins, preventing leakage of extracellular fluid across cell layers.

Desmosomes

Anchoring junctions in animal cells that function like rivets, fastening cells together into strong sheets using intermediate filaments made of keratin.

Gap Junctions

Communicating junctions in animal cells consisting of membrane proteins surrounding a pore, providing cytoplasmic channels between adjacent cells for the exchange of ions and small molecules.