Lecture 2 Flashcards
IClicker Question:
What are the 3 components of phenotype of an adult organism?
Physiology, Morphology & Behaviour
IClicker Question:
Does physiology influence evolutionary changes over time?
Yes
How do animal cells generate movement?
Cytoskeleton & Motor proteins
What is a cytoskeleton?
The cytoskeleton is like a cell’s internal framework or “skeleton”. It is made up of protein fibers that help give the cell its shape, support and structure. It also works like a system of tracks that helps move things around inside the cell and is involved in cell movement
What is a motor protein?
A motor protein is a special protein in cells that moves things by “walking” along the cytoskeleton using energy from ATP. It helps transport molecules, like vesicles, within the cell and plays a key role in cell movement.
What are the four general types of cellular movement?
1.) Polymerization
2.) Mobile cytoskeleton
3.) Mobile motor
4.) Mobile motor & cytoskeleton
What are the charcteristics that define the type of cellular movement?
The type of cellular movement depends on if the cytoskleton, the motor protein, or both can move.
What is polymerization?
Polymerization is the reorganization of the cytoskeletal network - growth of the cytoskeleton in one region of the cell pushes the cell membrane outward - used in amoeboid movement
What is Mobile Cytoskeleton?
Motor proteins attached to the cell membrane pull on the cytoskeleton, moving an element of cytoskeleton. *Ratcheting action of motor proteins pull the cytoskeleton in one direction
What is Mobile Motor?
Motor proteins “walk” along relatively fixed elements of the cytoskeleton - can be used to transport cargo throughout cell.
Mobile Motor and Cytoskeleton
Motor proteins and cytoskeleton are arranged in arrays that they slide over each other, pulling the cell into a different shape. When motor proteins are activated, the cytoskeletal elements slide over each other to cause a change in cell shape
What are the 3 different types of fibers within Cytoskeleton?
1.) Microtubules
2.) Microfilaments / Actin Filaments
3.) Intermediate Filaments
What are microtubules?
Microtubules are long hollow tubes composed of repeating units of tubulin.
What is a tublin?
Tubulin is a dimer of α-tubulin and β-tubulin
Do microtubules have polarity? (Positive & Negative end)
Yes
What are the factors that influence the rate of growth and the rate of shrinkage of microtubules?
1.) Concentration of tubulin
2.) Whether or not the GTP bound by β-tublin is hydrolyzed
3.) Microtubule associated proteins (MAPS)
4.) Temperature
What does critical concentration mean in terms of Microtubules?
Critical concentration → The concentration at which microtrubules are in a dynamic equilibrium where they neither grow or shrink.
What happens to the microtubules above the critical condition?
Microtubules will grow (polymerize), as there are enough free tubulin dimers available to be added to the ends of the microtubule.
What happens to the microtubules below the critical condition?
Microtubules will shrink (depolymerize), as there are not enough free tubulin dimers available to replace those lost from the ends of the microtubule.
Does both ends of microtubules grow and shrink at the same rate?
Theplus (+) end(the rapidly growing end) has alower critical concentration, meaning tubulin is more likely to be added here compared to the minus end.
Theminus (−) endhas ahigher critical concentration, meaning it is more likely to lose tubulin subunits unless the free tubulin concentration is higher.
What is a MTOC?
Microtubule Organizing Center
Where is the MTOC located within a cell?
In most cells, MTOC is located near the nucleus
Is there polarity in MTOC?
Typically, the minus end of each microtubule is located at the MTOC while the (+) end extends out toward the cell membrane
What motor proteins work with microtubules?
Kinesin & Dynein
