OSSF Cytoskeletal proteins UPDATED
ACTUAL Exam Questions and CORRECT
Answers
What are the 3 primary types of protein filamanets? - CORRECT ANSWER - Actin
microfilaments, intermediate filaments, microtubules
What is the thinnest, most flexible component of the cytoskeleton? - CORRECT ANSWER -
Actin filaments
What are actin filaments made of? - CORRECT ANSWER - Globular actin monomers with
their own ATP binding site
What end of an actin filament is growing? - CORRECT ANSWER - Plus end
What are hollow, nonbranching cylinders made of 13 parallel protofilaments? - CORRECT
ANSWER - Microtubules
What is at the minus end of microtubules? - CORRECT ANSWER - Alpha tubulin
What is at the plus end of microtubules? - CORRECT ANSWER - Beta tubulin
What are each beta tubulin of microtubules bound to? - CORRECT ANSWER - GTP
What end of microtubules is growing? - CORRECT ANSWER - Plus end
What is the anchoring site where actin filaments and microtubules grow from? - CORRECT
ANSWER - Nucleation site
, Where is the nucleation site for acting molecules? - CORRECT ANSWER - Plasma
membrane
Where is the nucleation site for microtubules? - CORRECT ANSWER - Microtubule
organizing centers (MOC)
The binding of subunits causes hydrolysis of ATP (actin) or GTP (microtubules) and decreases
the strength of binding causing... - CORRECT ANSWER - Dynamic instability
Which end do the ATP/ GTP molecules dissociate from? - CORRECT ANSWER - Minus end
What provides a stronger, stable actin structure? - CORRECT ANSWER - Bundling proteins
together
What regulates shape and number of actin filaments and microtubules through altering the
number of regulatory proteins? - CORRECT ANSWER - Nucleus
What acts as a scaffold for myosin (motor protein) in muscle cells and helps with vesicle
movements? - CORRECT ANSWER - Actin filaments
What are apical cell membrane projections that increase SA? - CORRECT ANSWER -
Microvilli
What are microvilli supported by? - CORRECT 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? - CORRECT ANSWER - Myosin
ACTUAL Exam Questions and CORRECT
Answers
What are the 3 primary types of protein filamanets? - CORRECT ANSWER - Actin
microfilaments, intermediate filaments, microtubules
What is the thinnest, most flexible component of the cytoskeleton? - CORRECT ANSWER -
Actin filaments
What are actin filaments made of? - CORRECT ANSWER - Globular actin monomers with
their own ATP binding site
What end of an actin filament is growing? - CORRECT ANSWER - Plus end
What are hollow, nonbranching cylinders made of 13 parallel protofilaments? - CORRECT
ANSWER - Microtubules
What is at the minus end of microtubules? - CORRECT ANSWER - Alpha tubulin
What is at the plus end of microtubules? - CORRECT ANSWER - Beta tubulin
What are each beta tubulin of microtubules bound to? - CORRECT ANSWER - GTP
What end of microtubules is growing? - CORRECT ANSWER - Plus end
What is the anchoring site where actin filaments and microtubules grow from? - CORRECT
ANSWER - Nucleation site
, Where is the nucleation site for acting molecules? - CORRECT ANSWER - Plasma
membrane
Where is the nucleation site for microtubules? - CORRECT ANSWER - Microtubule
organizing centers (MOC)
The binding of subunits causes hydrolysis of ATP (actin) or GTP (microtubules) and decreases
the strength of binding causing... - CORRECT ANSWER - Dynamic instability
Which end do the ATP/ GTP molecules dissociate from? - CORRECT ANSWER - Minus end
What provides a stronger, stable actin structure? - CORRECT ANSWER - Bundling proteins
together
What regulates shape and number of actin filaments and microtubules through altering the
number of regulatory proteins? - CORRECT ANSWER - Nucleus
What acts as a scaffold for myosin (motor protein) in muscle cells and helps with vesicle
movements? - CORRECT ANSWER - Actin filaments
What are apical cell membrane projections that increase SA? - CORRECT ANSWER -
Microvilli
What are microvilli supported by? - CORRECT 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? - CORRECT ANSWER - Myosin
