Cytoskeleton Flashcards
The inside of a cells is basically an _________ ________ _________
organized super highway
Give a brief history of cytoskeleton discovery (2 dates)
1903: Nikolai Kolstov first described cytoskeleton as a network of tubules that control shape
1931: Paul Wintrebert coined cytoskeleton
What are the 3 main types of cytoskeletons?
Microfilaments (actin)
Intermediate filaments
Microtubules
Describe the shape of the 3 types of cytoskeletons
Microfilaments: 2 strands intertwined
Intermediate filaments: Like a strong rope (many strands intertwined)
Microtubules: Hollow cylinder
What are microfilaments made of?
Linear polymers of G-actin
What are microfilaments used for?
- Generate force when the growing end bashes against the membrane
- Act as a scaffold for myosin motor proteins to walk along
- muscle contraction, cell movement, intracellular transport, maintenance of eukaryotic cell shape, cytokinesis (cell division), cytoplasmic streaming.
What are intermediate filaments made of?
Tetramers of red-like proteins that are tightly bundled into long ropelike filaments
What are intermediate filaments used for?
- Provide internal scaffold to help anchor organelles and the nucleus and organize 3D structure of cell
- Maintain overall cell shape and form part of the cell-cell connections that allow cells to communicate with each other
What are mutations intermediate filaments linked to?
Premature again and muscular dystrophy
What are microtubules made of?
Hollow cylinders composed of tubulin protein monomers
How do microtubules grow?
They grow at the positive and and shrink at the negative end
What are microtubules used for?
They form part of motile structures such as cilia and flagella
Crucial for cell division
Transport organelles along their length
How did scientists discover the functions of the cytoskeleton?
Direct observations of the cytoskeleton
Effects of mutations in cytoskeleton structure or function
How the cytoskeleton responded to various conditions
What are the 3 main function of the cytoskeleton?
- Structural support
- Motility
- Regulate biochemical activities
What makes the cytoskeleton good for maintaining cell shape?
Quick to dismantle and reassemble in another part of the cell
How do nutrient absorbing epithelial cells in the small intestine use cytoskeletons?
They use microfilaments to form microvilli, which increases the surface area of the cells
In the small intestine, what kind of diseases can effect the microvilli? why is this bad?
Celiac disease triggers an immune response that damages the intestines’ lining. This is bad because it prevents the absorption of some nutrients
Another main use of the microfilaments is the cell division _________ ring
contractile
Describe the Brownian ratchet
It’s a way for cells to expand
G-actin is only added to the end of a microfilament when there is space and energy (via ATP). Space is made via brown movements, which is tiny vibrations. Once space is made, the cytoskeleton can expand and change the direction or shape of the cell
Cell motility comes from the interaction of the cytoskeleton and _____
motor proteins
What can motor proteins do?
Walk along the cytoskeleton, form cross-links with transmembrane proteins, vesicles, or other cytoskeleton filaments
How do animal cells change shape to move?
microfilaments reorganize to create cellular extensions. This extension combined with the interactions of the plasma membrane (or the proteins in it) and external substrate help to move the cell
What is an example of animal cells moving?
Wound healing: fibroblast cells migrate to the site of injury to aid in tissue repair
What is phagocytosis?
The process by which a cell extension surrounds and engulfs a foreign object.
What are macrophages? How do they help?
They are immune cells. They help my engulfing and destroying dead and dying cells, as well as pathogens like bacteria, viruses and other foreign objects
What is the difference between cilia and flagella?
Cells that have cilia have many short cilia
Flagellated cells possess 1-3 long flagella
What is the use of cilia and flagella?
Propel single-celled organisms through fluid or move fluid over the surface of multicellular tissues
What examples of cilia and flagella?
Cilia and windpipe to sweep mucus with debris out the lungs
Cilia on a woman’s oviduct’s to move an egg toward the uterus
Sperm of many animals, algae, and some plants have flagella
What are the movements of cilia and flagella?
Cilia rows
Flagella uses and undulatory movement
How do microtubules form cilia and flagella
microtubules run the length of these structures. 9 doublet microtubules around the circumference and 2 microtubules in the center.
Dynein moto proteins walk along the outer microtubules doublets
Nexin Proteins cross-link the microtubules doublets together
What is the bending of cilia and flagella driven by?
Dynein motor proteins
What is the rotation of flagella driven by?
Proton gradients
What is Kartagener’s syndrome caused by? What can it cause?
Caused by defects in the microtubule-based movement of cilia and flagella
They are sterile due to immobile sperm
Tend to suffer lung infections
Frequently have organs on the wrong side of the body (due to incorrect cilia-based signaling during embryogenesis
What type of cytoskeleton creates muscle cells? Do they have motor proteins on them.
actin filaments. Yes
What is the purpose of the myosin motor proteins in the muscle cells?
The walking of the protein brings the filaments closer together, causing muscle contraction
How do cytoskeletons help vesicles?
Vesicles and other organelles travel along the cytoskeleton scaffold. Some motor proteins can walk along the scaffold and carry their cargo that way
Vesicles containing _______ travel along the microtubules. For example, a frog’s ____ ______ depends on the distribution of the above
pigments, skin colour
How do neurotransmitters travel from one side of the axon to the end?
Kinesin motor proteins move vesicles containing neurotransmitters
Dynein motor proteins move the empty vesicles back towards the cell body
In the neuron axon, ______ _______ travel in specific direction along the microtubules
motor proteins
What is ALS caused by?
Defects in axonal transport associated with motor neuron diseases
