Lecture 5 Flashcards
what is the function of the cytoskeleton
Maintains cell shape and position of organelles within cells
why is the cytoskeleton a dynamic structure
because it can rapidly disassemble and reassemble to change the cell shape while providing stability
what are the three main components of the cytoskeleton
microtubules, microfilaments and intermediate filaments
what are microtubules
composed of tubulin subunits, may radiate out from an organising centre(centrosome)
what are the functions of microtubules
they resist compression- to help maintain cell shape
what is the motility of microtubules
flagella-snake-like motion
Cilia-rowing-like motion
if the cell is fixed then cilia move fluid past
ATP motor proteins can move organelles to target specific cells
what are microfilaments
a double chain of actin symbols that form linear strands, 3 dimensional networks
what are the functions of microfilaments
resist tension, the cortical network under the plasma membrane helps make this region less fluid and maintains cell shape
what do interactions between actin and motor proteins such as myosin allow
muscle contraction
support cell movement
amoeboid movement
cytoplasmic streaming in plants
what proteins make up intermediate filaments
keratins in hair
lamins in nucleus
neurofilaments in neurons
what are the characteristics of intermediate filaments
supercoiled into cables
less dynamic than microtubules and microfilaments
form relatively permanent cellular structures
help maintain cell shape and anchor organelles
may remain after the cell that made them dies
What are the three types of Cell Junctions
Tight Junction, Desmosomes, Gap Junction
What is the function of tight junctions
Hold neighbouring cells tightly pressed together
prevent movement of fluid across cell layers
what is the function of Desmosomes
Anchoring Junction
work as rivets to provide attachment between sheets of cells and are connected into the cell by intermediate filaments
What is the function of Gap Junction
A point of cytoplasmic contact between two cells
allows ions and small molecules to pass from cell to cell and intercellular communication
