Cell Structure and Function (Chapters 4 and 5)

Comprehensive vocabulary flashcards covering cell theory, prokaryotic and eukaryotic structures, membrane transport, energy processes including photosynthesis and cellular respiration, and protist diversity based on Chapters 4 and 5.

Cell Theory

The foundational biological principle stating that all living things are made of cells, cells are the smallest unit of life, and all cells arise from preexisting cells.

Robert Hooke

The scientist who first observed cell structures in cork and coined the term "cells".

Matthias Schleiden

The scientist who contributed to cell theory by discovering and stating that all plants are composed of cells.

Theodor Schwann

The zoologist who contributed to cell theory by concluding that all animals are made of cells.

Rudolf Virchow

The scientist who proposed that new cells are produced only from preexisting cells through cellular division.

Prokaryotic Cell

A smaller, simpler cell type lacking a nucleus and membrane-bound organelles that contains a single circular chromosome in a nucleoid region, having first evolved approximately $3.5\text{ billion}$ years ago.

Eukaryotic Cell

A larger, complex cell type featuring membrane-bound organelles and a membrane-enclosed nucleus containing linear chromosomes, first evolving approximately $2.1\text{ billion}$ years ago.

Nucleoid

The non-membrane-enclosed region in a prokaryotic cell where its single circular chromosome of "naked" DNA is concentrated.

Total Magnification

The combined magnifying power of a compound light microscope, calculated using the formula: $\text{Total Magnification} = \text{ocular magnification} \times \text{objective magnification}$.

Plasma Membrane

The selectively permeable outer barrier present in all cells that encloses the cytoplasm and consists of a phospholipid bilayer with embedded proteins.

Phospholipid Bilayer

The structural basis of the cell membrane, arranged with hydrophilic heads facing the watery exterior and interior environments and hydrophobic tails pointing toward each other inward.

Ribosome

A non-membrane-bound cellular structure found in both prokaryotes and eukaryotes that synthesizes proteins by linking amino acids into polypeptides using instructions from DNA.

Endomembrane System

The interconnected collection of internal membranous organelles, including the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles, that synthesize, modify, and package cell products.

Rough Endoplasmic Reticulum

A portion of the endoplasmic reticulum studded with ribosomes where newly synthesized polypeptides enter to be modified and packaged into transport vesicles.

Smooth Endoplasmic Reticulum

A network of interconnected membranous tubules lacking attached ribosomes that synthesizes lipids and performs diverse metabolic functions.

Golgi Apparatus

A stack of membranous sacs possessing "receiving" and "shipping" faces that receives transport vesicles from the rough ER, modifies the contents, and ships them onward in newly budded vesicles.

Lysosome

A membrane-enclosed digestive organelle containing enzymes that break down macromolecules, old cellular components, and foreign materials.

Chloroplast

A photosynthetic organelle found in plant cells and other autotrophs that captures light energy to build sugars.

Mitochondria

Double-membraned organelles found in all eukaryotic cells that perform cellular respiration to break down sugars and produce ATP.

Cytoskeleton

A dynamic network of protein fibers and microtubules that maintains cell shape and enables cell movement, such as the crawling motility of an Amoeba.

Adenosine Triphosphate (ATP)

The primary energy currency for cellular work, consisting of adenosine bonded to three phosphate groups, which releases usable energy when hydrolyzed to ADP and a phosphate group.

Passive Transport

The movement of substances across a biological membrane down their concentration gradient without any input of cellular energy.

Diffusion

The spontaneous net movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient until dynamic equilibrium is reached.

Facilitated Transport

Passive transport down a concentration gradient that is assisted by specific transmembrane proteins, requiring no expenditure of cellular ATP.

Aquaporin

A dedicated transmembrane channel protein that facilitates the rapid diffusion of water molecules across the cell membrane.

Osmosis

The diffusion of water across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration.

Isotonic Solution

A solution that has an equal solute concentration compared to the cell cytoplasm, resulting in no net movement of water.

Hypotonic Solution

A solution with a lower solute concentration than the cytoplasm of the cell, causing net water entry into the cell.

Hypertonic Solution

A solution with a higher solute concentration than the cytoplasm of the cell, causing net water loss and cell shrinkage.

Turgor Pressure

The pressure exerted by the fluid contents of the central vacuole against the rigid plant cell wall, creating a turgid, healthy state and preventing wilting.

Active Transport

The movement of a substance across a membrane against its concentration gradient (from low to high concentration), which requires energy in the form of ATP.

Sodium-Potassium Pump

An active transport carrier protein that uses energy from ATP to export three sodium ions ($3\,Na^+$) out of the cell and import two potassium ions ($2\,K^+$) into the cell.

Endocytosis

The active transport process in which the cell membrane invaginates around external materials to enclose them in a vesicle and bring them inside the cell.

Exocytosis

The active transport process where an intracellular transport vesicle fuses with the plasma membrane to discharge its contents outside the cell.

Light Reactions

The initial stage of photosynthesis occurring in the thylakoid membranes of chloroplasts, capturing solar energy with pigments to split $H_2O$, release $O_2$, and generate ATP and NADPH.

Calvin Cycle

The light-independent reactions of photosynthesis occurring in the chloroplast stroma, using chemical energy from ATP and NADPH to fix $CO_2$ into glucose.

Stomata

Microscopic pores on leaf surfaces regulated by guard cells that open and close to facilitate the uptake of $CO_2$ and the release of $O_2$ and water vapor.

Photosynthesis Equation

The balanced chemical summary of photosynthesis: $6\,CO_2 + 6\,H_2O \xrightarrow{\text{Light energy}} C_6H_{12}O_6 + 6\,O_2$.

Cellular Respiration Equation

The overall chemical reaction of aerobic cellular respiration: $C_6H_{12}O_6 + 6\,O_2 \rightarrow 6\,CO_2 + 6\,H_2O + \approx 32\,\text{ATP} + \text{heat}$.

Glycolysis

The first step of cellular respiration occurring in the cytoplasm, which splits one glucose molecule into two pyruvic acid molecules, yielding a net gain of $2\,\text{ATP}$ and $2\,\text{NADH}$.

Citric Acid Cycle (Krebs Cycle)

An aerobic stage of cellular respiration that takes place within the mitochondrial matrix, breaking down pyruvate derivatives to generate electron carriers and ATP.

Electron Transport Chain

The final stage of aerobic respiration located in the inner mitochondrial membrane, transferring electrons from NADH to produce the majority of cellular ATP while releasing $H_2O$.

Lactic Acid Fermentation

An anaerobic process occurring in human muscle tissue during oxygen debt and in bacteria such as Lactobacillus, converting pyruvate directly into lactic acid to regenerate $NAD^+$ for glycolysis.

Alcoholic Fermentation

An anaerobic process carried out by yeasts (Saccharomyces) and bacteria that converts glucose into ethyl alcohol and $CO_2$ while recycling $NAD^+$.

Kingdom Protista

A diverse group of single-celled or simple multicellular eukaryotic organisms displaying animal-like, plant-like, or fungus-like lifestyles.

Amoeba

A single-celled eukaryotic protist that moves and feeds via pseudopodia through continuous cytoskeletal microtubule and filament remodeling.

Euglena

A unicellular, flagellated green protist characterized by an elongated, spindle-like shape and photosynthetic chloroplasts.

Paramecium

A slipper-shaped, ciliated freshwater protist that utilizes coordinated surface cilia for locomotion and feeding.

Volvox

A colonial green alga that forms hollow, spherical green colonies containing multiple embedded daughter colonies.

Spirogyra

A freshwater filamentous green alga named for the distinctive spiral arrangement of its chloroplast ribbons within elongated cylindrical cells.