Exam 2 Flashcards
Name the nucleating ABPs
Formin
- forms parallel filaments and remains associated with the growing plus end
Arp 2/3 Complex
- forms branched filaments and remains associated with the minus end
Name the actin subunit binding proteins
Profilin
- binds subunits, speeds elongation
Thymosin
- binds subunits, prevents assembly
Name the actin cross-linking proteins
Fimbrin
- forms tight, parallel bundles found in filopodium
Arp 2/3 Complex
- forms dendritic network found in lamellipodium
α-Actinin
- forms contractile bundles found in stress fibers
Filamin
- forms gel-like network found in cell cortex
Name the ABPs that promote depolymerization
Cofilin
- binds ADP-actin filaments, accelerates disassembly by inducing twisting
Gelsolin
- severs filaments and binds to plus end
Indicate if each of the following structures is based on actin filaments (A), microtubules (M), or intermediate filaments (I). Your answer would be a five-letter string composed of letters A, M, and I only; e.g. AAAMM.
( ) The cell cortex
( ) The mitotic spindle
( ) The nuclear lamina
( ) Cilia
( ) Filopodia
AMIMA
Indicate if each of the following changes occurring during mitosis in a fibroblast is the result of the reorganization of actin filaments (A), microtubules (M), or intermediate filaments (I). Your answer would be a five-letter string composed of letters A, M, and I only; e.g. AIAAM.
( ) The cell rounds up.
( ) The endoplasmic reticulum collapses.
( ) The Golgi apparatus fragments.
( ) The primary cilium is resorbed (disappears).
( ) The contractile ring forms and constricts.
AMMMA
Which of the following cytoskeletal filaments are abundant in an animal cell nucleus?
A. Microfilaments
B. Microtubules
C. Septins
D. Intermediate filaments
E. Spectrin filaments
D
From left to right, indicate if each of the following schematic drawings represents the typical overall organization of actin filaments (A), microtubules (M), or intermediate filaments (I) in an animal cell. Your answer would be a three-letter string composed of letters A, M, and I only; e.g. AMI.
MIA
Indicate true (T) and false (F) statements below regarding the cell cytoskeleton. Your answer would be a four-letter string composed of letters T and F only; e.g. TTFF.
( ) The three major building blocks of cytoskeletal filaments can bind to and hydrolyze nucleotides.
( ) The building blocks of microfilaments and microtubules are globular proteins, whereas those of intermediate filaments are themselves filamentous proteins.
( ) Intermediate filaments are typically thicker than actin filaments but thinner than microtubules.
( ) Plant cells lack microtubules.
FTTF
Fill in the blank: Each microtubule is typically made of thirteen parallel …. that associate laterally to form a hollow tube.
protofilaments
Indicate if each of the following descriptions matches actin filaments (A), microtubules (M), or intermediate filaments (I). Your answer would be a four-letter string composed of letters A, M, and I only; e.g. AAMM.
( ) They form hollow structures with multiple lateral interactions.
( ) They form strong structures that are more resilient than the other two cytoskeletal filaments.
( ) Their subunits bind GTP and hydrolyze it.
( ) They form coiled-coil interactions between the subunits.
MIMI
