Regulation of Animal Cell Shape Flashcards
What is the cytoskeletons role in the cell?
Support and Mobility
What do cells connect via?
Cell junctions
What does the cytoskeleton do within the cell?
helps maintain cell shape and the position of the organelles within the cell, it rapidly disassembles and reassembles and this ability allows rapid changes in cell shape, the cytoskeleton is highly dynamic but still provides stability
What are the three main components of the cytoskeleton?
Microtubules, Microfilaments, Intermediate filaments.
What are the functions of microtubules?
They are composed of tubulin subunits, they may radiate out from an organising centre, they resist compression therefore helping to maintain cell shape
How do microtubules provide cell motility?
Through flagella and cilia.
Flagella: snake-like movement.
Cilia: rowing-like motion (brushing back and forth). If they are on cells that are fixed in place, they move fluid past them
What is the function organelle motility that microtubules are involved in?
ATP-powered proteins can ‘walk’ organelles along microtubules. This allows vesicles, or other organelles to be transported to specific targets within the cell.
What are microfilaments made from?
A double chain of actin subunits
What is the function of microfilaments?
They can form linear strands and 3D networks (using branching proteins), they resist tension, the cortical network under the plasma membrane helps make this less fluid and thus maintains cell shape. (these filaments play a part in muscle contraction too)
What are intermediate filaments made from?
Various proteins (such as keratins in hair, lamins in the nucleus and neurofilaments in neurons). They are supercoiled into ‘cables’.
What are the functions of intermediate filaments?
Less dynamic than microtubules or microfimalents, they form relatively permanent cellular structures (because they are harder to break down/rebuild), help maintain cell shape and anchor organelles, may remain after the cell has died
What are the three types of cell junctions?
Tight junctions, desmosomes, gap junctions (do the hand actions to help remember??)
What do tight junctions do?
Hold neibouring cells tightly pressed together, may form a continuous seal, prevents movement of fluids across cell layers (use these to prevent things from moving between cells like water)
What do desmosomes do?
They are an anchoring junction that provides attachments between sheets of cells, they act like rivets and are connected into the cell by intermediate filaments.
What do gap junctions do?
They are a point of cytoplasmic contact between two cells, ions and small molecules can pass from cell to cell really quickly, allows rapid intercellular communication.
