Muscles Flashcards
What is another word for cell?
Myocytes
Did muscles evolve before or after the sponge? And why?
Muscles probably developed after the sponges since sponges do not have muscles, and they are the only animals that lack muscles.
What animal did muscles evolve from?
Cnidarians, which include hydra and corals.
What can the initial invention of muscles be described as?
the ability to organize basic cytoskeletal machinery into arrangements that permitted the cells to change shape.
How can cells move? And how does this connect with the initial evolution of muscles from Cnidarians?
Cells can be moved by changing how cytoskeletal proteins interact with each other.
Cnidarians probably first was arrange these proteins into a complex matrix.
What are the 3 main filaments in the cytoskeleton?
Microtubules: are made of tubulin
Intermediate Filaments: made up of lots of different things
Actin filaments:
*each of these filaments have a role in structure.
What are stress fibers?
collections of actin into more rigid structures that are importsnt for changing the shape of the cell.
What do we focus on when talking about cellular movement?
Microtubules and actin, as they serve as tracks over which motor proteins walk.
What does it mean when a structure has polarity?
the polymer is arranged in a way that has two distinct ends, which we call positive or negative.
What is the main function of microtubules?
maintenance of cell shape (compression resisting), cell motility (as cilia or flagella), chromosome movements in cell division, organelle movements. Made up of tubulin.
What is the main function of microfilaments (Actin filaments)?
maintenance of cell shape (tension bearing elements), changes in cell shape, muscle contractions, cytoplasmic streaming in plant cells, cell motility, division of animal cells. Made up of actin.
What is the main function of microfilaments (Actin filaments)?
maintenance of cell shape (tension bearing elements), changes in cell shape, muscle contractions, cytoplasmic streaming in plant cells, cell motility, division of animal cells. Made up of actin.
What is the main function of intermediate filaments?
maintenance of cell shape (tension bearing elements), anchorage of nucleus and certain other organelles, formation of nuclear lamina. They are made up of several different proteins (such as keratins).
How do motor proteins change their shape?
motor proteins use the energy of ATP hydrolysis to change their three dimensional shape.
What are 3 main motor proteins? What makes them relevant?
Kinesin, dynein, and myosin.
Each of them has a head that id the part that walks on the track, and a tail that binds something to be moved. Kinesin and dynein are motor proteins that walk along their microtubule tracks. This is as they recognize the polarity of a microtubule, one walks toward the positive end and one on the negative end. Myosin walks over actin, and they are in all eukaryotic cells and all animal cells as part of the cytoskeleton.
What back and forth process do kinesin and dynein mediate?
Underneath axons are microtubules. the vesicles of neurotransmitters are constructed in the cell body, then carried to the axon termini. When emptied they are carried back to the cell body to get remade. The back and forth of this process if when Kinesin and dynein mediate.
What is a homodimer? And what is an example of one?
it is a protein composed of two polypeptide chains that are identical in the order, number, and kind of their amino acid residues. It has two subunits of the same protein.
Myosin can be an example of one (the type II one).
What do proteins along the neck of myosin II do?
The proteins on the neck between the head and long tail of the myosin motor helps to regulate the catalytic properties of this myosin.
Why might there be confusion with the myosin II motor?
the single subunit is called myosin, the homodimer is called myosin, and the heterohexamer is also called myosin. Therefore, you have to know context to be able to talk about its structure and function.
How individual myosins exist within cells?
They often exist with their tails attached to the other proteins, and through those connections, the cell membrane. The myosin head binds the microfilament and when it hydrolyzes ATP, it bends at the neck and pulls the actin toward its own tail. As well, within muscle actin does the same sort of movement, and the bending triggers a different kind of more complicated movement.