Chapter 16: Cell Structure and Function (Lessons 16.1 & 16.2)

Comprehensive vocabulary flashcards covering the key terms, scientific discoveries, microscopes, cell types, organelles, and membrane properties from Chapter 16 (Lessons 16.1 & 16.2).

Cell

The smallest living unit of any organism.

Robert Hooke

An English scientist who, in 1665, observed thin slices of cork under an early microscope and coined the term 'cells' because the empty chambers reminded him of a monastery's rooms.

Anton van Leeuwenhoek

A Dutch microscopist who used a single-lens microscope to first observe living microorganisms in pond water and from his own mouth.

Cell Theory

A fundamental concept of biology stating that: 1. All living things are made up of cells; 2. Cells are the basic units of structure and function in living things; and 3. New cells are produced from existing cells.

Matthias Schleiden

A German botanist who concluded in 1838 that all plants are made of cells.

Theodor Schwann

A German biologist who stated in 1839 that all animals are made of cells.

Rudolf Virchow

A German physician who published the idea in 1855 that new cells can be produced only from the division of existing cells.

Compound Light Microscope

A microscope that allows light to pass through a specimen and uses two lenses (the objective lens and ocular lens) to form an image, producing clear images up to a magnification of about $1000$ times.

Fluorescence

A property of certain dyes that give off light of a particular color when viewed under specific wavelengths of light, used to locate and track molecules within living cells.

Transmission Electron Microscope (TEM)

An electron microscope that passes a beam of electrons through ultra-thin slices of chemically preserved samples, producing flat, two-dimensional images of internal cell structures and large protein molecules.

Scanning Electron Microscope (SEM)

An electron microscope that scans a pencil-like beam of electrons over the surface of a specimen, forming three-dimensional images of the surface without requiring thin slicing.

Micrograph

A photograph of an object seen through a microscope.

Cell Membrane

A thin, flexible barrier that surrounds all cells, regulating what enters and leaves the cell while providing protection and support; also known as the plasma membrane.

Nucleus

A large, membrane-enclosed structure found in eukaryotic cells that contains genetic material in the form of DNA and controls many cellular activities.

Eukaryote

An organism whose cells enclose their genetic material (DNA) within a nucleus.

Prokaryote

A unicellular organism whose cells lack a nucleus and do not enclose their genetic material within a membrane.

Cytoplasm

In eukaryotic cells, the portion of the cell outside the nucleus; in prokaryotic cells, the entire interior of the cell.

Organelle

A specialized structure that performs important cellular functions within a cell; literally translates to 'little organ.'

Nuclear Envelope

A structure composed of two membranes surrounding the nucleus, dotted with thousands of nuclear pores that allow materials like proteins and RNA to move into and out of the nucleus.

Chromatin

A complex of DNA bound to proteins that is spread throughout the nucleus of a cell when it is not actively dividing.

Nucleolus

A small, dense region within the nucleus where the assembly of ribosomes begins.

Ribosome

A cellular structure composed of RNA and protein found throughout the cytoplasm in both eukaryotes and prokaryotes that synthesizes proteins by following instructions from DNA.

Endoplasmic Reticulum (ER)

An internal membrane system in eukaryotic cells where lipids are synthesized along with proteins and other materials that are exported from the cell.

Rough Endoplasmic Reticulum

The portion of the ER covered with ribosomes on its surface, responsible for chemically modifying and assembling proteins destined for export, the cell membrane, or specialized locations within the cell.

Smooth Endoplasmic Reticulum

The portion of the ER that lacks ribosomes on its surface and contains specialized enzymes involved in lipid synthesis, drug detoxification, and carbohydrate synthesis.

Golgi Apparatus

An organelle composed of a stack of flattened membranes that modifies, sorts, and packages proteins and other materials from the ER into vesicles for cellular storage or secretion.

Vacuole

A large, saclike, membrane-enclosed organelle that stores materials like water, salts, proteins, and carbohydrates.

Central Vacuole

A single, large liquid-filled vacuole found in many plant cells that provides internal pressure and rigidity to help support heavy structures like leaves and flowers.

Vesicle

A small, membrane-enclosed structure that stores and moves materials between cell organelles, as well as to and from the cell surface.

Lysosome

A small organelle filled with enzymes that breaks down lipids, carbohydrates, and proteins into usable molecules and removes clutter or worn-out organelles from the cell.

Cytoskeleton

A network of protein filaments in eukaryotic cells that supports cell shape, provides internal organization, and assists in cellular transport and whole-cell movement.

Microfilaments

Threadlike cytoskeletal structures made of the protein actin that create a tough, flexible framework to support the cell and drive movements such as amoeboid crawling.

Microtubules

Hollow cytoskeletal tubes made of tubulin proteins that maintain cell shape, form the mitotic spindle during cell division, and assemble into cilia and flagella.

Centriole

A paired organelle located near the nucleus in animal cells, formed from tubulins, that helps organize cell division; absent in plant cells.

Chloroplast

An organelle found in plant cells and other photosynthetic organisms that captures energy from sunlight and converts it into chemical energy stored in food.

Mitochondrion

A double-membrane organelle found in nearly all eukaryotic cells that converts chemical energy stored in food into compounds more convenient for cellular use.

Endosymbiotic Theory

The hypothesis proposed by Lynn Margulis stating that mitochondria and chloroplasts originated from free-living prokaryotic ancestors that entered into mutualistic relationships with ancestral eukaryotic cells.

Cell Wall

A rigid, supporting layer outside the cell membrane found in plants, fungi, and most prokaryotes that shapes, supports, and protects the cell; composed mainly of cellulose in plants.

Lipid Bilayer

A double-layered sheet of lipid molecules with hydrophilic heads exposed outward and hydrophobic fatty acid tails tucked inward, forming the flexible, structural foundation of biological membranes.

Selectively Permeable

A property of biological membranes that allows certain substances to cross while blocking others; also referred to as semipermeable.

Fluid Mosaic Model

A model of cell membrane structure describing it as a dynamic, flexible lipid bilayer embedded with floating proteins and attached carbohydrates that can move laterally.

Leber's Hereditary Optic Neuropathy (LHON)

An inherited disease caused by defective mitochondria that results in the deterioration of optic nerve cells and permanent vision loss, passed to offspring exclusively by females.