Lecture 4 - Cell basics, Microscopes, Prokaryotes, and Eukaryotes Flashcards
Cell Theory,
a unifying principle
- Cells are fundamental units of life.
- All living organisms are composed of cells.
- All cells come from preexisting cells.
* Also, evolution through natural selection explains diversity of modern cells.
Implications of cell theory (3 points)
- Cell biology is similar for most living organisms.
- Life is continuous.
- Origin of life on earth was marked by origin of the cell.
Most cells are tiny. Most cell diameters are in the range of…
1-100 uM
Cells have ___ surface are to volume ratio, because…
[high], because a lot of surface area is needed for closer and more abundant cell-to-cell interaction.
_______ reveal cell features (2 points)
[Microscopes]
- Magnification (eg. human eye has 1X magnification)
- Resolution (res) is the minimum distance two objects can be apart and still be seen as two objects (eg. human eye has a resolution of 0.2 mm)
Light microscope (5 points)
- glass lenses and visible light
- passes light through living specimen
- 0.2 um res
- 1,000X magnification
- Use: cell sizes, shapes, and some internal structures
examples: bright-field, phase-contrast, differential interference-contrast, stained bright-field, fluorescence, confocal
Electron Microscope (5 points)
- Electromagnet and electrons
- Electrons directed through a vacuum toward a screen to create image
- 2 nm res
- 100,000X magnification
- Use: Subcellular structures
examples: transmission electron, scanning electron, freeze-fracture
Microscopes in pathology (3 points)
- Phase-contrast/differential interference-contrast used to determine cell size, cell shape, spread (ex. cancer)
- Dyes and bright-field used for nuclei shape and cell division characteristics
- Electron used to observe lysosome digestion of cell components
Role of plasma membrane (5 points)
- selectively permeable barrier
- allows cell to maintain a more or less constant environment
- communication with adjacent cells and receive signals from environment
- protruding proteins allow binding and adherence to adjacent cells
- use electron microscope to observe/study structure of plasma membrane.
Prokaryotic vs. Eukaryotic (3 points each)
Domains: Archaea and Bacteria
No membrane-enclosed internal compartments
No nucleus
Ex. E.coli, Archaea
Domains: Eukarya
Membrane-enclosed internal compartments called organelles
Nucleus
Ex. Human, Plant, Fungi
Prokaryotic cells (3 points)
- Diameter or length between 1-10 uM
- Smaller than eukaryotes (structurally less complex, however functionally they are just as complex)
- Found as single cells, chains, clusters
All prokaryotes have… (3)
- Plasma membrane
- traffic regulation - Nucleoid: DNA
- Cytoplasm: contains cytosol, insoluble filmanets, and particles
- Cytosol: mostly water with dissolved ions, small molecules and soluble macromolecules
- Ribosomes: complexes of RNA and protein
Many prokaryotes have… (7)
Cell wall Outer membrane, capsule, flagella, pili, fimbraie, cytoskeleton
Many prokaryotes have (detailed)… (3)
- Cell wall
- bacteria has peptidoglycan
- rigid, support, shape
- Outer membrane
- Lipopolysaccharide
- Toxin (to host)
- Capsule
- Polysaccharide
- Protection
Prokaryotic flagella (3 points)
- Appendage for motility
- composed of flagellin
- motorl proteins (spin like propellar)
Prokaryotic adherence (2 points)
- Pili
- hair-like structure
- aid attachment
- conjugative pili exchange genetic material
- Fimbriae
- shorter than pili
Prokaryotic cytoskeleton (3)
- Composed of protein filaments
- maintains cell shape by holding cell together
- rod shape cells have helical internal cytoskeleton
- important during cell division
- eg. constricts the cell
Eukaryotes are structurally ___ complex than prokaryotes
[more]
Eukaryotic cells (2)
- diameter of length between 10-100 um
- on average, 10X greater than prokaryotes
- membrane-bound compartments, called organelles, within cytoplasm.
Organelles (2)
- each has specific role
- better structural detail since early 1900’s due to electron microscope.
