Cytoplasm Flashcards
Microfilaments- size , structural elements, function and relationship with other organelles
8nm
composed of very fine actin subunits and distrubuted around the edges of the cell, just under the plasma membrane
-muscle cells are loaded with actin filaments and another microfilament, myosin
Function- provide movement and mechanical support - giving shape and strength to cells
Work with microtubules
Intermediate filaments
10-12um
- such as keratin and neurofilaments are slightly thicker and
-composed of several different protein subunits
Function- contribute to cell strength helping to stabilise the organelles
- also used for cell-cell adherence.
Microtubules
- 25nm thickest of cytoskeletal
- consist of long tubes composed of tubulin protein subunits
- they extend during cell division and into cilia and flagella and axon terminals during synaptic transission
- contribute to cell shape and structure and movement of organelles
e. g secretory vesicles and flagella and chromosomes during cell division
Centrioles
- 2 width
- 4um length
- 9 Sets of three microtubules ; perpendicular to eachother (right angles)
- responsible for the formation and growth of miotic spindles which radiate from centrosome during mitosis
- Contribute to the growth and formation of microtubules.
Cilia
- fine hair like, extensions of the surface of cell
- allows fluid to move its contents across the surface of the cells
- similar to centrioles
- includes microtubules into each cilium
Microvilli
- tubular extensions of the plasma membrane at the apical surface of cell.
- immobile and have actin at their core
- increase surface area of a cell for absorption
- Absorptive cells of the intestines and kidneys.
Ribosomes
- composed of ribosomal RNA
- produced seperately in the nucleoulous
- either free in cytoplasm or bound to E.R
- free ribosomes synthesise proteins for use of that cell and others for export.
Rough E.R
Continuous with nuclear envelope - ribsomes covering its external surface
- synthesize proteins such as hormones, enzymes, antibodies, blood proteins, and integral proteins, which are then deposited inside the cisternae to be processed and sorted.
- Newly synthesized proteins are later either secreted from the cell or inserted into the plasma membrane.
Smooth e.r
- contain unique enzymes on the surface which catalyse reactions
Golgi cis
- Faces the R.E.R where the vesicles fuse with the cis face to enter the golgi complex
- It recieves and modifies proteins from R.E.R
Lumen of Golgi
- space within cisternae where proteins pass through entry etc
- site of phosphorylation of proteins
Cisternae
- small , flattened membrane bound sacs which are curved at the centre and have bulbous ends
- they add carbs to proteins forming glycoproteins and lipids to carbs to form glycolipids
Golgi trans
- Vesicles fuse with the trans face to exit the golgi complex to be exported to other cells
- further modifies molecules and sorts them into vesicles for transport to the plasma membrane
Vesicles
- spherical , membrane bound sacs bud off from R.E.R or cisternae
- transport substances between organelles and out of the cells
Lysosomes
- membrane bound vesicles that bud off from golgi
- contain various digestive and hydrolytic enzymes which break down large molecules as they fuse with other vesicles
- function- digest worn out components of cell
- digest large molecules
- break down bone releasing calcium ions into blood
- destroy bacteria
