Biology Chapter: Cells and Organisms

Study Notes

Romans experimented with glass in the first century, creating lenses.
Zacharias Janssen invented the first compound microscope around 1595, likely with help from his father, Hans.
Robert Hooke observed cork under a microscope in 1665, describing its structure as "cells."
Anton van Leeuwenhoek was the first to observe live cells, inventing microscopes with lenses that could magnify objects 270-300 times.

Matthias Jakob Schleiden (1838) stated that cells are the building blocks of plants.
Theodor Schwann (1839) declared that cells are fundamental units of animals, merging plant and animal cell structure concepts.
Rudolf Virchow (1855) presented "Omnis cellula e cellula," asserting all cells come from existing cells.

Suggests organisms can arise from non-living sources.
Francesco Redi's experiments with jars and meat demonstrated that maggots do not spontaneously generate.
John Needham's chicken broth experiment appeared to support spontaneous generation.
Lazzaro Spallanzani countered Needham, showing no microorganisms grew in sealed broths.
Louis Pasteur confirmed that microorganisms originate from the air through his S-shaped flask experiment.

Cell Wall: Protects and supports plant cells; prevents excessive water uptake.
Cell Membrane: Protects cells; is semipermeable, controlling substance movement.
Nucleus: Acts as the cell's control center, managing all activities.
Cytoplasm: Site of physiological processes, supporting organelles.
Ribosomes: Sites for protein synthesis and assembly.
Golgi Body: Packages proteins for transport outside the cell.
Endoplasmic Reticulum (ER): Transports materials; rough ER has ribosomes, while smooth ER detoxifies substances.
Lysosomes: Break down old organelles; termed "suicide bags" of the cell.
Chloroplasts: Found in plant cells; contain chlorophyll for photosynthesis.
Vacuoles: Storage for food, water, and waste materials.
Mitochondria: Powerhouses of the cell, generating ATP energy.
Flagella and Cilia: Aid in locomotion and movement of cells.
Centrioles: Assist with cell division and organization of microtubules.
Peroxisomes: Conduct oxidative reactions and recycle molecules.

Plantae: Capable of photosynthesis; contains cell walls made of cellulose.
Fungi: Decomposers; reproduce via spores/budding; composed of hyphae.
Animalia: Most complex, multicellular organisms with diverse cell types (e.g., osteocytes, neurons).
Protista: Mostly unicellular; includes protozoa with various locomotion strategies.
Eubacteria: Comprising complex, unicellular organisms in different shapes (cocci, bacilli, spirilla); includes extremophiles.

Cell specialization occurs post-division, allowing cells to effectively perform their functions.
Apical Modifications: Features like pseudopods, flagella, cilia, and microvilli enhance movement and absorption.
Lateral Modifications: Gap junctions, tight junctions, and adhering junctions facilitate communication and structural integrity.
Basal Modifications: Desmosomes and hemidesmosomes stabilize cell connections with the substrate.
Specialized cells in plants include root hairs and guard cells.

Prokaryotes: Lack a nucleus; divide via binary fission, no endocytosis/exocytosis.
Eukaryotes: Possess a nucleus and are genetically diverse; includes animals, fungi, plants, and protists.