ToB S3 - Cell Ultrastructure Flashcards
Determine the term limit of resolution
The minimum distance that two objects can be distinguished as separate
List two advantages and two disadvantages of light and electron microscopy
Light microscopy
+ Cheap
+ Can use live specimens
- Higher limit of resolution
- Lower magnification
Electron microscopy
+ Lower limit of resolution
+ Capable of higher magnification
- Expensive
- Uses dead tissue only
- Black and white images
What three components make up the cytoskeleton?
1) Microfilaments
2) Intermediate filaments
3) Microtubules
What are the functions of the plasma membrane?
Cell morphology and movement selectively permeability and transport of substances
What are the functions of the SER?
- Lipid and steroid synthesis
- Helps with protein folding
- Glycosylation
- Disulphide bond formation
What is the difference between heterochromatin and euchromatin?
Heterochromatin - Chromosomes densely and coiled into solenoids, not being expressed
Euchromatin - Uncoiled DNA in form of ‘Beads on a string’, DNA is being expressed
What is the function of mitochondria?
ATP synthesis by oxidative phosphorylation
What is the function of lysosomes?
- Digestion of cell debris and waste material
- Produced by the golgi and fuse with material requiring digestion followed by the release of hydrolytic enzymes
What is the function of the nucleolus?
Ribosomes assembly and RNA modification
What are the functions of the nucleus?
- Stores the cells DNA
- It coordinates the cells activity; metabolism, growth, protein synthesis, mitosis
What is the function of peroxisomes?
a cell organelle containing catalase, peroxidase, and other oxidative enzymes and performing essential metabolic functions, as the decomposition of fatty acids and hydrogen peroxide
What are the three main types of cytoskeleton filaments?
1) Microfilaments
2) Intermediate filaments
3) Microtubules
Describe microfilament structure
- Two strings of actin twisted together
- Associated with ATP
- Can assemble and dissociate Eg a core of actin filaments allow intestinal microvilli to maintain their shape
Describe the intermediate filament structures
- Not dynamic
- Common in nerve and neurological cells
- Also common in epithelial cells made of cytokeratin.
They form tough supporting meshwork in the cytoplasm and are anchored to plasma membrane as strong intracellular junctions (desmosomes)
Describe the microtubule filament structure
- Thirteen α and β subunits polymerise to form the wall of the hollow microtubules
- They originate from the centrosome (tubular units added or subtracted)
- Found at sites where structures in cells are moved (Eg elongated cell processes such as nerve fibres, the mitotic spindle and the cores of cilia and flagella)
