2.4 Understanding Cellular Structure And Function Flashcards
Basis for the study of biology
Cells
Robert Hooke
First discovered cells in 1665 when observing a cork under a microscope.
Divisions within the cork looked similar to cells, or living spaces, inhabited by monks
Anton van Leeuwenhoek
Advanced understanding of cells when in 1674 became the first person to witness a live cell using a microscope
Electron microscopes
EMs increase magnification to approx 100,000x the actual size of a sample, making it possible to see the internal structures within a cell
Scanning electron microscopes (SEMs) and Transmission electron microscopes (TEMs)
can be used to see smaller structures such a proteins, lipids, and even atoms but must be nonliving due to prep with strong chemical and physical treatments
Matthias Schleiden and Theodore Schwann
Developed cell theory in 1838
Modern Cell Theory
- All living organisms are made of cells
- Cells are the basic unit of life
- All cells arise from preexisting cells
- Hereditary information is passed from cell to cell
- All cells have the same basic chemical composition
- Energy flow occurs within cells
Four key components of cells
- Plasma membrane
- Cytosol
- DNA
- Ribosomes
Cytosol
Jelly-like fluid in which intracellular organelles are suspended
Organelles
Specialized cellular structures that have specific functions within the cell
Cytoplasm
Space within the cell that contains the cytosol and cytoskeleton
Ribosomes
Sphere shaped structures in cytoplasm, composed of RNA and protein
Synthesize proteins
Cells that have higher rates of protein synthesis contain more ribosomes
Prokaryotes
- Don’t have a nucleus or other membrane bound organelles
- Unicellular
- Divided into two major domains: Archaea and Bacteria
Pili (pilus)
Hair-like appendages found on cell surface of many bacteria
Help bacteria adhere
Cell wall
Rigid layer of sugar based molecules surrounding most bacteria and archaea (and plnt cells)
Provides structural support and protection from dehydration
Capsule
Sugar-containing layer considered part of bacterial cell membrane
AKA slime layer
Nucleoid
Irregularly shaped region within prokaryotes that contains ost DNA. Not surrounded by nuclear membrane
Flagellum
Microscopic, tail-like appendage found on many bacterial cells, enables movement
Prokaryotic chromosome
Single, circular double stranded DNA
Peptidoglycan
Made of sugars and proteins, cell wall component
Phospholipid bilayer
Plasma membrane
Selectively permeable, controls flow of molecules, ions, proteins
Typical prokaryotic cell diameter
0.5-1.0 micrometers
Typical range of eukaryotic cell diameter
10-100 micrometers
Extremeophiles
Organisms capable of thriving in very harsh environments
Key defining features of eukaryotes
- Membrane-bound nucleus
- Membrane-bound organelles
- Multiple rod-shaped chromosomes where DNA is stored
Nucleus
Highly specialized organelle that serves as the information-processing center, directs cellular activities, and controls DNA transcription and synthesis