Lecture 6 - Regulation Of Animal Cell Shape Flashcards
What is the cytoskeleton?
The cytoskeleton is a dynamic network that interlinks protein filaments present in the cytoplasm. It also provides stability
What is the function of the cytoskeleton?
The cytoskeleton helps maintain cell shape and position of organelles with in cells
What are the three main components of the cytoskeleton?
Microtubules
Microfilaments
Intermediate filaments
How are microtubules composed?
Microtubules are composed of subunits of the protein tubulin.
How are microtubules organised?
Microtubules either organise themselves next to each other or radiate out from an organised centre called the centrosome
What is the function of microtubules?
Microtubules resist compression (pushing force) thus helping the cell maintain its shape.
Provide cell motility
Involved in organelle movement
Describe flagella motion
Snake like motion
Sperm
Describe cilia motion
Rowing like motion
If cells are fixed in place beating of cilia and moves fluid past them (move mucus away and clear space around body)
Explain how organelle motility occurs and the function of it
Organelle motility happens due to ATP-powered motor proteins that walk the organelles along microtubules. This allows vesicles or other organelles to be transported to specific targets within the cell
What are microfilaments?
Microfilaments are a double chain of actin subunits
What do microfilaments form?
Linear strands
Three-dimensional networks (using branching proteins)
What do actin-myosin interactions allow
Support cell movement:
Muscle contraction
Amoeboid movement
Cytoplasmic streaming in plants
Why is it important that microfilaments resist tension?
So cells don’t become damaged when they move
Why is it good to have more fluidity inside the cell than the outside of the cell?
To provide tension in plasma membrane
What are some proteins that make intermediate filaments?
Keratin (hair)
Lamins (nucleus)
Neurofilaments (neurons)
What is the structure of intermediate filaments?
Intermediate filaments are tightly wound together (supercoiled) to form cables which makes them less dynamic than microtubules and microfilaments
What are intermediate filaments used in?
They are used to form the relatively permanent cellular structures because it is less dynamic which is useful for permanent features.
What is the function of intermediate filaments?
Maintain cell shape Anchor organelles (a more permanent anchoring)
How are cells joined together?
Through cell junctions
What are the 3 major types of cell junction?
Tight junctions
Desmosomes
Gap junctions
What is the role of tight junctions?
Tight junctions hold cells together and stop things going between them.
What is the role of desmosomes?
Desmosomes are the anchoring junction that anchors two cells together.
Why are desmosomes so strong?
Desmosomes act like rivets and are connected to intermediate filaments.
What is the role of gap junctions?
Gap junctions are a point of cytoplasmic contact between cells that allow ions and small particles to pass from cell to cell. It allows for rapid intercellular communication
