Cell Theory and History Quiz

Study Notes

Early studies described cells as protoplasm (primary substance) containing a nucleus surrounded by a membrane.
The protoplasm surrounding the nucleus is called cytoplasm, while the protoplasm within the nucleus is called nucleoplasm.
Electron microscopy (EM) revealed two basic cell types: prokaryotes and eukaryotes.
Prokaryotes are simpler, without a nuclear envelope or compartments.
Eukaryotes are more complex and contain a nuclear envelope and compartments called organelles.

Feature	Prokaryotic	Eukaryotic
Nucleus	Absent	Present
Membrane-enclosed organelles	Absent	Present
DNA	Circular chromosome	Linear chromosomes
Cell division	Binary fission	Mitosis or meiosis

Size: Prokaryotic cells are typically 0.2-2.0 μm in diameter; eukaryotic cells are typically 10-100 μm in diameter.
Nucleus: Prokaryotes lack a nucleus; eukaryotes have a true nucleus with a membrane and nucleolus.
Membrane-enclosed organelles: Prokaryotes lack them; eukaryotes have various membrane-bound organelles (e.g., mitochondria, Golgi apparatus, endoplasmic reticulum).
Flagella/Cilia: Can be present in both prokaryotes and eukaryotes; structures for movement.
Glycocalyx: Present in some prokaryotes as a capsule or slime layer; in some eukaryotes.
Cell Wall: Usually present in prokaryotes (typically peptidoglycan); can be present in eukaryotes (e.g., plants, fungi; composed of cellulose or chitin).
Plasma membrane: Both types of cells have this structure; surrounds the cytoplasm.
Cytoplasm: The contents of a cell between the nucleus and the plasma membrane.
Cytoskeleton: More complex in eukaryotes; involved in cell structure and shape.
Ribosomes: Found in both types of cells but different in size (70S vs 80S)
Chromosome: Usually single circular in prokaryotes; multiple linear in eukaryotes
Cell Division: Binary fission (prokaryotes); mitosis (eukaryotes)
Sexual Recombination: Absent/only transfer of DNA (prokaryotes); Present (eukaryotes)

Manufacturing: Involves the nucleus, ribosomes, endoplasmic reticulum, and Golgi apparatus. This includes synthesis of proteins, like enzymes.
Breakdown: Includes lysosomes, vacuoles, and peroxisomes; responsible for digesting food, bacteria, and cellular waste.
Energy-processing: Involves mitochondria (in animal cells), which generate energy to power cellular function in the form of ATP.
Structural support, movement, and communication: Cytoskeleton and plasma membrane involved in cell structure, movement, and communication with other cells

Composition: Made of a mix of proteins and lipids.
Proteins:
- Transmembrane proteins: Span the bilayer
- Peripheral proteins: Located on the surfaces of the bilayer
Carbohydrates:
- Attached to protein (glycoproteins) or lipids (glycolipids); involved in cell recognition.
Phospholipid bilayer: Main component; composed of two layers (bilayer) of phospholipid molecules. Phospholipids composed of fatty acid chains and a phosphate head group.

Passive transport: Movement of molecules from high concentration areas to low, without energy input - Diffusion: Movement of small molecules down the concentration gradient. Example: CO2 and H2O - Facilitated diffusion: Need protein carriers to move large molecules down the concentration gradient.
Active transport: Movement of molecules from low concentrations to high, requiring energy input; utilizes protein carriers.
Bulk transport: Movement of large molecules; requires cellular energy
- Exocytosis: Transport out of the cell
- Endocytosis: Transport into the cell; sub categories:
  - Pinocytosis: Transport of fluids
  - Phagocytosis: Transport of solids, including bacteria.