Topic 3: Non-membranous organelles Flashcards
Name 3 of the non-membranous organelles.
- ribosomes
- centrosomes
- cytoskeleton
What are the function of ribosomes?
- sites for protein synthesis (translation)
What are the components of ribosomes? (2)
- rRNA and proteins
Where are ribosomes located?
- free in cytosol
- attached to the ER
What do ribosomes that are free in cytosol do?
- make proteins destined for cytosol, mitochondria and nucleus
What do ribosomes attached to the ER do?
- make proteins destined for all other sites
What are centrosomes?
dense area of cytoplasm
What do centrosomes contain?
- usually contains 2 centrioles (function uncertain - some cells lack them)
- also has the pericentriolar matrix
What is the function of centrosomes?
- organizes microtubules of cytoskeleton and spindle apparatus (for cell division)
What is the cytoskeleton and how are they formed?
- ALL types support cell shape and are formed from proteins
What is the function of the cytoskeleton? (3)
- important in cell movement
- cell division
- movement and anchoring of organelles + proteins (e.g. receptors, enzymes)
What are the three types of cytoskeleton??
- microfilaments
- intermediate filaments
- microtubules
What are microfilaments made of and what is their size?
made of actin
- smaller ones
What are the functions of microfilaments? (3)
- muscle contraction (with myosin)
- maintenance of cell shape and projections (e.g. microvilli)
- cytokinesis (separates cytoplasm)
What is the composition of intermediate filaments, and what is their function?
- composition is tissue specific e.g. keratin
- supports the cytoplasm (scaffolding for the cell)
- note that the size of intermediate filaments is in between the other two
What is the composition of microtubules?
-hollow tubes made of tubulin
- larger in comparison to the other two
What does the microtubules form? (4)
forms:
- centrioles
- spindle apparatus
- cilia (short) –> for cell movement (ie. fallopian tubes, throat)
- flagella (long) –> sperm
