The Cell – Lecture Overview

Vocabulary flashcards covering major scientists, cell theory principles, microscopy, prokaryotic vs eukaryotic distinctions, and subcellular organelles from the lecture notes.

Zacharias Janssen

Dutch spectacle-maker credited with inventing the first compound microscope in the early 1600s.

Robert Hooke

English scientist who coined the word “cell” in 1665 after observing cork under a microscope.

Antonie van Leeuwenhoek

Dutch microscopist who discovered single-celled “animalcules” (bacteria, protozoa, sperm, blood cells) with his handcrafted lenses.

Matthias Schleiden

German botanist who stated in 1838 that all plants are composed of cells, co-founding cell theory.

Theodor Schwann

German zoologist who extended cell theory to animals in 1839, declaring all living things cellular.

Rudolf Virchow

German physician who added the idea “Omnis cellula e cellula”—all cells arise from pre-existing cells (1855).

Ignaz Semmelweis

Hungarian physician who showed that handwashing reduces puerperal infections (1847).

Louis Pasteur

French chemist who disproved spontaneous generation, developed pasteurization, and advanced germ theory (1860s).

Robert Koch

German microbiologist who identified causative agents of diseases and formulated Koch’s Postulates.

Koch’s Postulates

Four criteria linking a specific microbe to a specific disease, involving isolation, culture, inoculation, and re-isolation.

Spontaneous Generation

Discredited idea that life arises spontaneously from non-living matter; disproved by Pasteur’s swan-neck flask experiment.

Cell Theory (classical)

1) All organisms consist of one or more cells; 2) The cell is the basic unit of life; 3) Cells arise from pre-existing cells.

Modern Cell Theory

Adds that energy flows in cells, DNA passes hereditary info, and all cells share basic chemical composition.

Prokaryotic Cell

Cell type lacking a true nucleus and membrane-bound organelles; includes Bacteria and Archaea.

Eukaryotic Cell

Cell type with a true nucleus and membrane-bound organelles; found in animals, plants, fungi, protists.

Cell Membrane (Plasma Membrane)

Phospholipid bilayer with proteins that controls transport, communication, and protection of the cell.

Cell Wall

Rigid outer layer providing support and protection; present in plants (cellulose), fungi (chitin), bacteria (peptidoglycan).

Nucleus

Membrane-bound control center that houses DNA; surrounded by nuclear envelope with pores.

Nucleolus

Dense region inside nucleus where ribosomal RNA is synthesized and ribosome assembly begins.

Chromatin

DNA-protein complex that condenses to form chromosomes and regulates gene expression.

Cytoplasm

All cellular contents outside the nucleus, including cytosol, organelles, and cytoskeleton.

Cytosol

Fluid portion of cytoplasm where metabolic reactions occur and organelles are suspended.

Ribosome

RNA-protein complex (70S in prokaryotes, 80S in eukaryotes) that synthesizes proteins from mRNA.

Endoplasmic Reticulum (ER)

Network of membranous tubules; Rough ER has ribosomes for protein synthesis, Smooth ER synthesizes lipids and detoxifies.

Golgi Apparatus

Stack of flattened sacs that modify, sort, and package proteins and lipids for secretion or delivery.

Vacuole

Membrane-bound sac for storage and turgor maintenance; large central vacuole prominent in plant cells.

Lysosome

Animal-cell organelle containing hydrolytic enzymes for intracellular digestion and recycling.

Peroxisome

Organelle that breaks down fatty acids and detoxifies hydrogen peroxide via catalase.

Mitochondrion

Double-membraned “powerhouse” generating ATP through aerobic respiration; contains its own DNA.

Chloroplast

Plant organelle with chlorophyll that carries out photosynthesis, converting light energy to glucose.

Centrosome

Animal-cell microtubule-organizing center composed of two centrioles; forms spindle in mitosis.

Cytoskeleton

Network of microfilaments, intermediate filaments, and microtubules providing structure and facilitating transport.

Microfilament

Actin filament that supports cell shape and enables muscle contraction and cell movement.

Microtubule

Tubulin hollow rod that maintains cell shape, forms cilia/flagella, and guides chromosome movement.

Flagellum

Long whip-like appendage for motility; present in some bacteria, protists, and sperm cells.

Cilium

Short hair-like projection that beats rhythmically for movement or to shift fluids across cell surfaces.

Nucleoid

Region in prokaryotes where circular DNA resides, not enclosed by membrane.

Plasmid

Small circular DNA molecule in prokaryotes that replicates independently and often carries antibiotic-resistance genes.

Capsule

Thick polysaccharide layer outside some bacterial cell walls aiding in adhesion and immune evasion.

Pilus

Long bacterial surface projection used for attachment or DNA transfer during conjugation.

Fimbria

Short, numerous bacterial surface appendage that aids in adhesion to surfaces or tissues.

Compound Microscope

Light microscope with multiple lenses (ocular and objective) achieving higher magnification.

Scanning Electron Microscope (SEM)

Microscope that scans a sample with electrons to produce detailed 3-D surface images.

Transmission Electron Microscope (TEM)

Microscope that passes electrons through thin sections for high-resolution internal structures.

Objective Lens

Lower lens of a microscope closest to the specimen; provides primary image magnification.

Ocular Lens (Eyepiece)

Upper lens of a microscope that further magnifies the primary image from the objective.

Coarse Adjustment Knob

Microscope control that moves stage/lens broadly to focus at low power.

Fine Adjustment Knob

Microscope control for precise focusing at higher magnifications.

Diaphragm (Iris)

Microscope component regulating the amount of light passing through the specimen.

Energy Flow in Cells

Concept that metabolic reactions (e.g., respiration, photosynthesis) occur within cells to supply energy.

DNA Heredity

Transmission of genetic information from parent cell to daughter cells during cell division.

Basic Chemical Composition

Principle that all cells share common biomolecules—proteins, lipids, carbohydrates, nucleic acids.

Binary Fission

Asexual reproduction method in prokaryotes where one cell divides into two identical cells.

Mitosis

Eukaryotic nuclear division producing two genetically identical diploid daughter cells.

Meiosis

Eukaryotic cell division producing four genetically varied haploid gametes.

Bacterial Shapes: Bacillus

Rod-shaped bacterial morphology.

Bacterial Shapes: Coccus

Spherical bacterial morphology.

Bacterial Shapes: Spirillum

Spiral-shaped bacterial morphology.

Chlorophyll

Green pigment in chloroplasts that absorbs light for photosynthesis.

Turgor Pressure

Internal water pressure in plant cells maintained by the central vacuole, keeping cells rigid.

Animalcule

Term used by van Leeuwenhoek to describe microscopic organisms he observed.

Germ Theory of Disease

Idea that microorganisms are the cause of many diseases, supported by Pasteur and Koch.