OSSF CYTOSKELETAL PROTEINS
EXAM 2024-2025
What are the 3 primary types of protein filaments? - ANSWER Actin
microfilaments, intermediate filaments, microtubules
What is the thinnest, most flexible component of the cytoskeleton? -
ANSWER Actin filaments
What are actin filaments made of? - ANSWER Globular actin monomers
with their own ATP binding site
What end of an actin filament is growing? - ANSWER Plus end
What are hollow, nonbranching cylinders made of 13 parallel
protofilaments? - ANSWER Microtubules
What is at the minus end of microtubules? - ANSWER Alpha tubulin
What is at the plus end of microtubules? - ANSWER Beta tubulin
What are each beta tubulin of microtubules bound to? - ANSWER GTP
What end of microtubules is growing? - ANSWER Plus end
What is the anchoring site where actin filaments and microtubules grow
from? - ANSWER Nucleation site
Where is the nucleation site for acting molecules? - ANSWER Plasma
membrane
Where is the nucleation site for microtubules? - ANSWER Microtubule
organizing centers (MOC)
, The binding of subunits causes hydrolysis of ATP (actin) or GTP
(microtubules) and decreases the strength of binding causing... -
ANSWER Dynamic instability
Which end do the ATP/ GTP molecules dissociate from? - ANSWER
Minus end
What provides a stronger, stable actin structure? - ANSWER Bundling
proteins together
What regulates shape and number of actin filaments and microtubules
through altering the number of regulatory proteins? - ANSWER Nucleus
What acts as a scaffold for myosin (motor protein) in muscle cells and
helps with vesicle movements? - ANSWER Actin filaments
What are apical cell membrane projections that increase SA? -
ANSWER Microvilli
What are microvilli supported by? - ANSWER Actin bundles- in the core
and anchored to terminal web of actin at the base
What produces cellular contraction (and cellular movement) by sliding
actin filaments in opposite directions and hydrolyzing ATP in the
process? - ANSWER Myosin
What are the 4 main functions of microtubules in the cell? - ANSWER
Mitotic spindle, cilia and flagella, anchor organelles, motor proteins
(dynein and kinesin) move vesicles along
What are the sites that localize microtubule minus ends? - ANSWER
Microtubule organizing centers (MTOC)
What is used by all cells for generating the mitotic spindle during mitosis
and meiosis? - ANSWER Centrosome
What serve as poles for the mitotic spindle during mitosis? - ANSWER
Duplicated centrosomes
EXAM 2024-2025
What are the 3 primary types of protein filaments? - ANSWER Actin
microfilaments, intermediate filaments, microtubules
What is the thinnest, most flexible component of the cytoskeleton? -
ANSWER Actin filaments
What are actin filaments made of? - ANSWER Globular actin monomers
with their own ATP binding site
What end of an actin filament is growing? - ANSWER Plus end
What are hollow, nonbranching cylinders made of 13 parallel
protofilaments? - ANSWER Microtubules
What is at the minus end of microtubules? - ANSWER Alpha tubulin
What is at the plus end of microtubules? - ANSWER Beta tubulin
What are each beta tubulin of microtubules bound to? - ANSWER GTP
What end of microtubules is growing? - ANSWER Plus end
What is the anchoring site where actin filaments and microtubules grow
from? - ANSWER Nucleation site
Where is the nucleation site for acting molecules? - ANSWER Plasma
membrane
Where is the nucleation site for microtubules? - ANSWER Microtubule
organizing centers (MOC)
, The binding of subunits causes hydrolysis of ATP (actin) or GTP
(microtubules) and decreases the strength of binding causing... -
ANSWER Dynamic instability
Which end do the ATP/ GTP molecules dissociate from? - ANSWER
Minus end
What provides a stronger, stable actin structure? - ANSWER Bundling
proteins together
What regulates shape and number of actin filaments and microtubules
through altering the number of regulatory proteins? - ANSWER Nucleus
What acts as a scaffold for myosin (motor protein) in muscle cells and
helps with vesicle movements? - ANSWER Actin filaments
What are apical cell membrane projections that increase SA? -
ANSWER Microvilli
What are microvilli supported by? - ANSWER Actin bundles- in the core
and anchored to terminal web of actin at the base
What produces cellular contraction (and cellular movement) by sliding
actin filaments in opposite directions and hydrolyzing ATP in the
process? - ANSWER Myosin
What are the 4 main functions of microtubules in the cell? - ANSWER
Mitotic spindle, cilia and flagella, anchor organelles, motor proteins
(dynein and kinesin) move vesicles along
What are the sites that localize microtubule minus ends? - ANSWER
Microtubule organizing centers (MTOC)
What is used by all cells for generating the mitotic spindle during mitosis
and meiosis? - ANSWER Centrosome
What serve as poles for the mitotic spindle during mitosis? - ANSWER
Duplicated centrosomes
