Cell ultrastructure Flashcards
What is the relationship between resolution and wavelength
-Indirectly proportional -> the lower the wavelength the higher the resolution
Define limit of resolution
The minimum distance at which two objects can be distinguished
Why do electron microscopes have a higher resolution then light microscopes and which kind has the highest?
- EMs have a shorter wavelength as they use electrons whose wavelength depends on the accelerating voltage used
- Transmission EM have a higher resolution then Scanning EM as they have a shorter wavelength
Why do prokaryotes not exhibit compartmentalisation?
-They have an external membrane but no internal membranes, i.e. all the biochemical processes occur in the same compartment
What is the structure and function of cell membranes?
- Phospholipid bilayer with free mobile proteins as well as proteins anchored to the cytoskeleton
- Contains cholesterol
- Is amphipathic (hydrophillic and hydrophobic)
- Impermeable selective barrier
- adherence and recognition
- signal transduction
- has a glycocalyx for biochemical specificity
In what cells is the nucleus not present?
- RBCs
- Stratum Corneum
- Lens fibre cells
How is heterochromatin packaged?
-selenoids
How is euchromatin packaged?
-Nucleosomes
What is the function of the nucleolus?
-RNA synthesis and ribosomal assembly
What are the functions of the cytoskeleton?
- Cell morphology and movement (within the cell)
- Structural support
- To enable locomotion (Cilia)
Describe microfilaments of cytoskeleton and give an example of where they are found
- actin fibres twisted together
- contractile
- dymanic (assemble/deassemble)
- intestinal microvilli
Describe intermediate filaments of the cytoskeleton and give an example of where they are found
- Non-dynamic
- Supporting meshwork in cytoplasm
- nerve, neuroglia and keratin
Describe microtubules of cytoskeleton and give an example of where they are found
- Polymers of tubulin
- Hollow
- Motile
- Mitotic spindle/cilia
What is the function of the sER in the liver and mammory glands?
-Lipid synthesis
What is the function of the sER in the ovarys, testes and adrenal glands?
-Steroidogenesis
Name some hydrolytic enzymes found in lysosomes?
- Protease
- Nuclease
- Lipase
What are residual bodies?
-Lysosomes which have digested cellular contents but contain undigestible remnants
Why are lysosomes not broken down by the hydrolytic enzymes they contain?
-Lysosome membrane is heavily glycosylated for protection
Why does the golgi exhibit polarity?
-To cause proteins in vesicles to migrate from the convex face to the concave face of the golgi
Which two organelles are self-replicating and which contains its own genome?
- Peroxisome - doesn’t have genome
- mitochondria - has genome
Where are there high amounts of peroxisome and why?
-Kidney tubules and parenchymal cells of liver for detoxification
Of what lineage is mitochondria?
-maternal
