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.
Differences between animal and plant cells ( MAKE TABLE)
Make table
Cell fractionation (3)
- remove plasma membrane
- separate organelle based on size or density
- biochemical analysis on isolated organelles
Eukaryotic ribosome (4)
- site for protein synthesis
- consists of two subunits (small and large)
- rRNA and protein
- In prokaryotes: float freely
- In eukaryotes: free, attached to ER, inside mitochondria or inside chloroplast.
Nucleus (4)
- contains most of a cell’s genetic information
- site of DNA replication and transcription
- nucleolus: site of ribosome assembly
- nucleoplasm: liquid portion
Chromatin (4)
- in nucleus
- fibrous complex made of DNA and protein
- contains chromosomes
- prior to cell division, chromatin condenses and individual chromosomes are observed.
Nuclear envelope (2)
- two membranes that surround nucleus
- contain nuclear pores
- outer membrane of envelope folds out and connects to ER
- Nuclear Lamina
- interior periphery, chromatin is attached to protein mesh
- maintain shape of nucleus
Endomembrane system is a group of interrelated organelles and they include… (6)
plasma membrane, nuclear envelope, ER, golgi apparatus, lysosomes, and vesicles that shuttle between.
Endoplasmic Reticulum (3)
- interconnected membranes branching through cytoplasm (tubes, flattened sacs)
- lumen: interior space
- has greater surface area than plasma membrane
Rough ER (4)
- ribosomes attached to outer surface
- receives proteins destined for lysosomes and plasma membrane
- within lumen, proteins are modified to tag them for a specific destination
- tertiary conformation of protein formation occurs
- proteins within vesicles pinch off RER
Smooth ER (6)
- no ribosome attached
- continuous with RER
- some proteins synthesized in RER are further modified in SER
- Chemically modifies small, potentially toxic molecules
- site for glycogen degradation, lipid and steroid synthesis
- stores calcium ion, which when released allows muscle contraction
Golgi apparatus (3)
- consists of stacked, flattened membranous sacs called cisternae (provides all the surface area of GA)
- cis: near nucleus RER (“receiving” side)
- trans: near plasma membrane (“transfer” side)
- receives proteins containing vesicles from ER
- modifies, concentrates, and packages and sorts proteins before sending to final destination
Lysosome (3)
- originate from golgi apparatus
- digestive enzymes hydrolyze macromolecules into monomers
- phagocytosis: process in which plasma membrane breaks off into cells engulfing lysosomes and other molecules.
Cells require energy for…
growth, reproduction, responsiveness, and movement.
Energy is harvested from…
- fuel molecules in all eukaryotes
- sunlight in plants
- energy transformations in cell membranes of prokaryotes
Mitochondria (4)
- chemical energy into ATP, energy-rich
- Process uses oxygen - called cellular respiration
- two membranes
- outer: smooth, protective
- inner: folds called cristae with protein complex
- mitochondrial matrix
- space within inner membrane (DNA, protein)
Plastid (2)
- only in plants and some protists
- chloroplast
- chlrophyll
- photosynthesis
- two membranes
- stacks (grana) of compartments (thylakoids) filled with pigments
- grana suspended in stroma (DNA, protein)
Plastid (2) cont’d
- chromoplast: synthesis and storage of red, yellow, and orange pigments
- leuocoplast: storage and starch, amyloplast
Other membrane-enclosed organelles (3)
- Peroxisome: accumulate and break down toxic peroxides
- Glyoxysome: similar to peroxisome, but only found in plants
- Vacuoles - storage, structure, reproduction, digestion, contractile
Cytoskeleton…
maintains cell structure and allows movement.
Cytoskeleton (4)
- meshwork of filaments inside cell
- support and shape
- organelle stabilization and movement
- interacts with extracellular structure (anchor)
3 components of cytoskeleton:
microfilaments, intermediate filaments, and microtubules
Microfilament (6)
- assembled from actin, double helical chain
- cell movement
- shape and support
- cytoplasmic streaming
- “pinching in” during cell division
- in animals, associated with myosin (muscle contraction)
cell shape/movements
cytoskeleton rearranges itself based on where the cell wants to go.
cell support from…
microvilli
Intermediate filmanets (3)
- tough, rope-like protein assemblages
- anchor structures in place - eg. nuclear lamina, eg. microvilli
- resist tension - maintain rigidity in body surface tissue
Microtubules (4)
- long, hollow unbranched cylinders
- dimers of tubulin (alpha and beta)
- form rigid internal skeleton
- framework (“tracks”) for motor proteins to move structures around inside cells (eg. chromosome movement)
Movable appendages (2)
- projections of plasma membrane
- cilia: shorter, move stiffly to propel cell
- flagella: longer, push/pull cell
- 9+2 array of microtubules allows bending motion
Dynein (1)
- motor protein that drives sliding of microtubules
- as___ chages shape, doublets move past each other
- nexin crosslinks doublets and limits sliding
- eg. cilium or flagella bending
Kinesin (2)
- motor protein that carries vesicles or other organelles
- ___ binds and “walks” along a microtubule
How to establish cause and effect (2)
- inhibition: use drug that inhibits cause and see if effect still occurs
- mutation: cells that lack gene for A and see if B still occurs
