2 Cytoskeleton

Question 1

Functions

Answer 1

maintaining the shape of cells=

It can actively contract to deform the cell and allow migration

Question 2

Involved in?

Answer 2

cell signal pathways
cytokinesis (division into 2 daughter cells)
endocytosis
intracellular transport (movement of organelles within the cell)

Question 3

Found?

Answer 3

Found in both Eukaryotic and Prokaryotic cells, but is more abundant in Eukaryotic cells.
Homologous (similar) proteins have been found in both cell types

Question 4

Structure: four main components

Answer 4

Microtubules (Tubulin), Microfilaments (Actin), Intermediate Filaments, and Centrioles

Question 5

Structure: Microtubules (Tubulin)

Answer 5

• consists of 2 polypeptides which join to form strands of protofilaments, 13 of these form a microtubule.
• Microtubules change constantly with uneven growth at either end, the faster one is the plus end while the slower one is the minus end
• The minus ends are anchored in microtubule organizing centers (MTOC), the biggest being the centrosome, usually near the nucleus

Question 6

Structure: Microfilaments (Actin)

Answer 6

• Actin microfilaments consist of actin proteins arranged in a spiral chain
  
  • Also has plus and minus ends, with ATP growth at the plus end
  • Often found beneath cell cortex, mesh of membrane proteins that support the plasma membrane; allow cell to hold complex shapes
  • Involved in cell movement and cytokinesis

Question 7

Structure: Intermediate Filaments

Answer 7

• Intermediate Filaments are present in all cells with varying protein subunits
  
  • Types depend on cell: specifically neurons (neurofilaments), muscle (desmin), epithelial (keratin), or generally vimentin (near microtubules), lamins (reinforce nuclear membrane)
  • Strong Rope Like shape that helps provide strength and support for microtubules

Question 8

Structure: Centrioles

Answer 8

• Centrioles have a cylindrical shape and play a role in the formation of cilia and flagella
  
  • Located near the nucleus, they consist of a ring of 9 evenly spaced bundles of 3 microtubules
  • In animal cell division, the mitotic spindle forms between centrioles, allowing for the separation of chromosomes during cell division
  • Cilia and flagella move by sliding microtubules along each other

Question 9

Faulty Organelles

Answer 9

• A faulty cytoskeleton is known to be the cause of various cardiovascular diseases, neurodegeneration, cancer, cirrhosis, and skin diseases
• The issues of a faulty cytoskeleton are generally caused by protein aberrations, which can negatively affect functionality of the entire cell