Chapter 4: Introduction to Cells and Cellular Structures

Vocabulary practice flashcards covering cell biology fundamentals, historical developments in microscopy, microscopy techniques, cellular theory, and eukaryotic organelle functions.

Robert Hoch (1665)

The scientist who examined tree bark in 1665 using a crude microscope and described the structures as "little rooms," derived from the Latin root cellulae, which originated the term cells.

Antonio Van Nguyen Hooke

The historical figure who refined the crude microscope by combining lenses and placing them further apart to increase magnification and view specimens closer.

Light microscope

A microscope that utilizes a light bulb or a rotated piece of glass to reflect light through a specimen for viewing.

Scanning electron microscope

A type of electron microscope that uses beams of electrons to study the external topography of a specimen after it has been coated with a metal, frequently gold.

Transmission electron microscope

An electron microscope used to view internal cellular details at high magnification by passing beams of electrons through thin, bread-like sliced sections of a cell.

Magnification

The property or process of increasing the apparent size of an object under observation.

Resolution

The clarity of an image and the ability of a microscope to identify two adjacent objects as distinct from one another, typically distinguishing items separated by at least $0.1$ to $0.2\,\mu\text{m}$.

Cell theory

The biological principle introduced in the early 1800s stating that "cells beget cells," meaning that any living cell must originate from a pre-existing cell.

Spontaneous generation

The disproven historical belief that living organisms arise from nothing or non-living matter, exemplified by the ancient misconception that flies and larvae spontaneously emerge from unrefrigerated meat.

Luca

The Last Universal Common Ancestor to which all phylogenetic branches of life—including archaea, bacteria, and eukaryotes—trace back.

Plasma membrane

A phospholipid bilayer containing embedded proteins, lipids, sugars, glycoproteins, and lipoproteins that encloses the cell and regulates transport.

Cytosol

The fluid portion of the cytoplasm that has been strained of ions, proteins, and cellular structures.

Prokaryote

A unicellular organism, such as a bacterium, that lacks a membrane-bound nucleus and true membrane-enclosed organelles.

Eukaryote

A cell type—found in organisms such as plants and animals—characterized by the presence of a true, membrane-bound nucleus and membrane-bound organelles.

Genetic control center

The functional cellular category composed of the nucleus and ribosomes, responsible for directing protein synthesis and housing genetic instructions.

Manufacturing, distribution, and breakdown group

The functional cellular grouping consisting of the endoplasmic reticulum, lysosomes, vacuoles, peroxisomes, and the Golgi apparatus.

Energy processing group

The functional cellular grouping that carries out energy conversions, comprised of mitochondria and chloroplasts.

Structural support, movement, and communication group

The functional cellular grouping composed of the cytoskeleton, plasma membrane, and plant cell wall.

Plant cell wall

A rigid outer barrier in plant cells that acts like a brick wall and possesses preformed holes to allow substances to travel in and out.

Central vacuole

A prominent organelle found in plant cells that serves as a storage compartment for water, nutrients, or toxins.

Nucleus

The double-membrane-bound genetic control center of eukaryotic cells that directs protein synthesis and contains cellular DNA.

Nuclear localization signal (NLS)

A specific molecular recognition tag that functions like an exclusive wristband to permit entry through nuclear envelope pores into the nucleus.

Chromatin

The stringy, condensed form of DNA super-coiled around histone proteins within the nucleus.

Nucleolus

The specialized, central compartment of the nucleus where ribosomes are synthesized before moving to the cytoplasm.

Ribosomes

RNA-protein complexes synthesized in the nucleolus that read messenger RNA strands to translate and produce proteins.

Rough endoplasmic reticulum (RER)

A continuous membrane network studded with ribosomes that folds synthesized proteins into secondary, tertiary, or quaternary structures and buds off transport vesicles.

Smooth endoplasmic reticulum (SER)

A tunnel-like membrane network devoid of ribosomes dedicated to synthesizing lipids and processing or removing cellular toxins.