Untitled Quiz

Study Notes

Prokaryotic Cells: Simple, single-celled organisms
- Lack a nucleus and membrane-bound organelles
- Examples include bacteria and archaea
Eukaryotic Cells: More complex cells
- Possess a nucleus and various membrane-bound organelles
- Can be single-celled or part of multicellular organisms (plants, animals, fungi, protists)

Nucleus:
- Prokaryotic: No true nucleus; DNA floats in the cytoplasm
- Eukaryotic: Has a defined nucleus containing DNA
Organelles:
- Prokaryotic: Lack membrane-bound organelles
- Eukaryotic: Contain membrane-bound organelles (mitochondria, endoplasmic reticulum)
Size:
- Prokaryotic: Generally smaller (1-10 µm)
- Eukaryotic: Larger (10-100 µm)
Ribosomes:
- Prokaryotic: Smaller (70S)
- Eukaryotic: Larger (80S)
Reproduction:
- Prokaryotic: Binary fission
- Eukaryotic: Mitosis and meiosis

Nucleus:
- Contains genetic material (DNA) and controls cell activities
Mitochondria:
- "Powerhouse" of the cell
- Generates ATP through cellular respiration.
Ribosomes:
- Synthesize proteins
Endoplasmic Reticulum (ER):
- Rough ER: Studded with ribosomes; synthesizes proteins
- Smooth ER: Synthesizes lipids and detoxifies drugs
Golgi Apparatus:
- Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles
Lysosomes:
- Contain digestive enzymes to break down waste materials and cellular debris
Chloroplasts (in plant cells):
- Conduct photosynthesis
Cell Membrane:
- Regulates the movement of substances in and out of the cell
Cytoskeleton:
- Provides structure and shape
- Facilitates movement

Cell Division: Process by which a cell divides into two new daughter cells
Mitosis:
- Division of a eukaryotic cell nucleus
- Results in two genetically identical daughter cells
Meiosis:
- Reductive division leading to the production of gametes with half the chromosome number
Cell Cycle:
- Series of stages (G1, S, G2, and M) that cells go through as they grow and divide
  - G1 Phase: Cell growth and protein synthesis
  - S Phase: DNA replication
  - G2 Phase: Preparation for mitosis
  - M Phase: Mitosis and cytokinesis occur
Regulation:
- Controlled by checkpoints (G1, G2, M) and proteins like cyclins and cyclin-dependent kinases (CDKs)

Cell Junctions:
- Tight Junctions: Seals gaps between epithelial cells
- Desmosomes: Anchoring junctions that prevent cells from being pulled apart
- Gap Junctions: Allow communication between cells by permitting the passage of molecules and ions
Signal Transduction:
- Cells communicate through chemical signals that trigger specific pathways

Abiogenesis: Theory that life originated from non-living matter
- Hypotheses: Primordial soup, deep-sea hydrothermal vents, and extraterrestrial origins

Disproved theory that life can arise from nonliving matter spontaneously
Key Experiments:
- Francisco Redi (1668): Demonstrated that maggots on meat came from fly eggs, not the meat itself
- Louis Pasteur (1859): Proved that microorganisms in air cause fermentation and spoilage, refuting spontaneous generation via his swan-neck flask experiment.