Flashcards in Cell ultrastructure Deck (22)
Define limit of resolution
The minimum distance at which two objects can be distinguished
What is the relationship between resolution and wavelength
-Indirectly proportional -> the lower the wavelength the higher the resolution
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
-Is amphipathic (hydrophillic and hydrophobic)
-Impermeable selective barrier
-adherence and recognition
-has a glycocalyx for biochemical specificity
In what cells is the nucleus not present?
-Lens fibre cells
How is heterochromatin packaged?
How is euchromatin packaged?
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)
-To enable locomotion (Cilia)
Describe microfilaments of cytoskeleton and give an example of where they are found
-actin fibres twisted together
Describe intermediate filaments of the cytoskeleton and give an example of where they are found
-Supporting meshwork in cytoplasm
-nerve, neuroglia and keratin
Describe microtubules of cytoskeleton and give an example of where they are found
-Polymers of tubulin
What is the function of the sER in the liver and mammory glands?
What is the function of the sER in the ovarys, testes and adrenal glands?
Name some hydrolytic enzymes found in lysosomes?
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