L2: Non-Membranous organelles & cell inclusion Flashcards
(50 cards)
what are ribosomes?
They are non-membranous organelles that are responsible for protein synthesis.
How are ribosomes seen under LM?
spherical small particles and they are basophilic as they contain phosphate groups in the RNA.
How are Ribosomes seen under EM?
electron-dense granules of a diameter of 20-30 nm which consists of two subunits, each one consists of protein associated with rRNA.
what is the function of ribosomes?
synthesis of protein.
what are the types of ribosomes?
free ribosomes: responsible for protein synthesis within the cell for its usage.
attached ribosomes; Responsible for protein synthesis that are segregated in rER and transported to the outside of the cell.
what are cytoplasmic fibres?
non-membranous organelles in the form of thread-like structures.
what are the types of cytoplasmic filaments?
thin
thick
intermediate
thin cytoplasmic filaments
Structure Actin
Diameter 6-7 nm
Contractility Contractile
Distribution & function Microvilli for their movement.
In cleavage furrow during cell division.
In muscles for contraction.
thick cytoplasmic filaments
Structure Myosin
Diameter Variable(12-16nm)
Contractility Contractile
Distribution & function In muscle associated with actin filaments
Intermediate cytoplasmic filaments
Structure 5 types
Diameter 10-12nm
Contractility Non-Contractile
Distribution&function
In muscles (desmin), nerve cells (neurofilaments), and epithelial cells (cytokeratin).
Support and maintain the shape of the cell.
Important for identification of tumors.
can be used as cell type specific markers for different types of tumors.
What are microtubules?
They are non-membranous organelles in a pipe-like structure.
what is the structure of microtubules?
tubulin protein
what is the distribution and function of microtubules?
All over the cytoplasm and it is used in many functions like
Components of the cytoskeleton which support, maintain, and stabilize the shape of the cell.
They act as guiding tracks for transporting vesicles and organelles.
Mitotic spindle formation.
The main structural component of cilia, flagella and
centriole
what is the length and diameter of microtubules?
25 nm in diameter but variable in length.
How do cytotoxic drugs work?
They prevent the formation of new microtubules so they lead to the stoppage of mitosis and consequently the growth of cancer cells.
what are centrioles?
They are non-membranous organelles that are responsible for cell division.
how are centrioles seen under LM?
-they are seen as dark blue stained granules by iron hematoxylin.
what is the site of centioles?
in non-dividing cells, it is present as a pair of centrioles in a juxtanuclear position associated with Golgi bodies.
how are centrioles seen under EM?
- Each centriole is a short cylinder. (Perp. To each other)
-The wall of the cylinder is composed of 27 microtubules longitudinally arranged in 9 (nine) bundles.
-Each bundle consists of three micro-tubules (triplets) which are surrounded by fibrillar electron dense material.
what are the functions of centrioles?
- Play an important role in cell division.
-In non-dividing cells, it serves as a center about which other cell organelles are polarized.
- Its location plays a key role in the three-dimensional organization of the cell as it regulates the location of the nucleus and different organelles.
- In ciliated cells, act as basal bodies of the cilia.
what is cilia?
-they are Hair like processes projecting from the free surface of certain epithelial cells.
what is the site of cilia?
-Respiratory system; trachea and bronchioles.
-Female genital system; uterus and fallopian tube.
How are cilia seen under LM?
- Could be seen vaguely on the surface of the cell facing the lumen or cavity.
what is the length and number of cilia?
10-15 micrometer - several hundred per cell
