Lecture 9 Flashcards
What does the cytoskeleton do?
Supports & maintains cell shape
What are the three main types of fibres that make up the cytoskeleton?
Microtubules, intermediate filaments & microfilaments. (in descending order of diameter)
What is the structure of microtubules?
Composed of tubulin subunits which form hollow tubes - radiate from centrosomes
What is the function of microtubules?
Maintains cell shape, resists compression, cell motility: whole cell or organelle movement
Microtubules provide cell motility through flagella & cilia structures? Describe these structures?
Flagella - “snake like” motions in the direction of movement
Cilia - “ rowing like” motion perpendicular to the direction of movement. When cells are fixed in place beating of cilia move ECF
What is the structure of microfilaments?
Two intertwined strands of actin - form 3D networks
What is the function of microfilaments?
muscle contraction
support movement
What is the structure of intermediate filaments?
Fibrous proteins ( e.g keratin) coiled into cables
What is the function of intermediate filaments?
Support cell shape
Anchorage of organelles
What do cell junctions do?
Connect neighbouring cells
What are they 3 major types of cell junction?
Tight junction
Desmosomes
Gap functions
A tight junction is when:
the plasma membrane of neighbouring cells are tightly pressed against each other
What does a tight junction do? (function)
Forms a continuous seal - a barriers that prevents leakage of ECF - prevents movement of fluid across cell layers
A desmosome is when?
cells are fastened together in strong sheets -
anchoring junction attachments btw sheets of cell e.g attaches muscle cells to each other
A gap junction is?
A point of cytoplasmic contact btw cells - provides channels from one cell to adjacent cells: allows ions & molecules to pass from cell to cell
