What happens when a cell-surface receptor activates a G protein?
The alpha subunit exchanges its bound GDP for GTP
T or F: Motor proteins move in a directional fashion along microtubules by using inherent structural polarity of protofilamen
True
T or F: Centromere nucleates microtubules in mitotic spindle
False; it's the centrosome
T or F: Because microtubules are subject to dynamic instability, they're used only for transient structures in a cell
False; although microtubules are subject to dynamic instability, their interaction with microtubule-binding proteins can stabilize them so they can be used to form stable structures like cilia and flagella
T or F: ATP hydrolysis by tubulin heterodimer is important for controlling growth of microtubules
False; GTP (not ATP) hydrolysis is important for controlling growth of microtubule
T or F: Nucleation of new filaments near the leading end pushes plasma membrane forward
True
T or F: ARP proteins nucleate branched actin filaments in the lamellipodia
True
T or F: Capping proteins bind to the minus end of actin filaments
False; Capping proteins bind to the plus end of actin filaments, preventing further assembly or disassembly from growing end
T or F: There's more ATP-bound actin at the leading edge than in actin filaments away from the leading edge
True
Which genetic change can't convert a proto-oncogene into an oncogene?
a. mutation that introduces a stop codon immediately after codon for initiator
b. mutation is in coding sequence that makes the protein hyperactive
c. amplification of number of copies
a
T or F: Tyrosine phosphorylation builds binding sites for other proteins to bind to receptor tyrosine kinases.
True
The protein Ras:
a. has one membrane-spanning a helix
b. is a protein kinase
c. binds directly to phosphorylated tyrosine residues on a variety of receptor proteins
d. is required for both the growth and differentiation of many different types of cells
d
Hormones are made by _____ cells and are carried to their target cells by ______.
Endocrine; the bloodstream
The growth factor RGF stimulates proliferation of cultured rat cells. The receptor that binds RGF is a receptor tyrosine kinase called RGFR. Which of the following types of mutations would be most likely to prevent receptor dimerization?
a. mutation that
b
T or F: IP3 is produced directly by cleavage of an inositol phospholipid without the incorporation of an additional phosphate group
True
T or F: Calmodulin regulates the concentration of intracellular Ca2+
False
T or F: Different signals originating from the plasma membrane can be integrated by cross-talk between different signaling pathways inside the cell.
True
T or F: the extracellular signal molecule acetylcholine has different effects on different cell types in an animal. It often binds to different kinds of cell-surface receptors on different cell types
True
The following happens when a cell-surface receptor activates a G protein:
a. the a subunit exchanges its bound GTP for GDP
b. the GDP bound to the a subunit is phosphorylated to form bound GTP
c. the a subunit exchanges its bound GDP for GTP
d. it activat
c
Are intermediate filaments found in plant cells, animal cells, or both?
animal cells
Are cell walls found in plant cells, animal cells, or both?
plant cells
Are microtubules found in plant cells, animal cells, or both?
both
Is cellulose found in plant cells, animal cells, or both?
plant cells
Is collagen found in plant cells, animal cells, or both?
animal cells
A major distinction between the connective tissues in an animal and other main tissue types such as epithelium, nervous tissue, or muscle is:
a. the ability of connective tissue cells such as fibroblasts to change shape
b. the amount of extracellular matr
b
Fibroblasts organize the collagen of the extracellular matrix by:
a. cutting and rejoining fibrils together inside of the cell for secretion
b. processing pro collagen into collagen inside of the cell for secretion
c. twirling fibrils together to make rop
d
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: monomer that binds ATP
actin filaments
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: includes keratin and neurofilaments
intermediate filaments
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: important for formation of the contractile ring during cytokinesis
actin filaments
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: supports and strengthens that nuclear envelop
Intermediate filaments
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: their stability involves a GTP cap
Microtubules
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: used in the eukaryotic flagellum
Microtubules
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: a component of the mitotic spindle
Microtubules
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: can be connected through desmosomes
Intermediate filaments
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: directly involved in muscle contraction
actin filaments
Indicate which of the three major types of classes of cytoskeletal elements the statement refers to: abundant in filopodia
Actin filaments
Indicate whether the statement refers to a ciliary microtubule, a microtubule of the mitotic spindle, both types of microtubules, or neither type: the basal body is the organizing center
Ciliary microtubules
Indicate whether the statement refers to a ciliary microtubule, a microtubule of the mitotic spindle, both types of microtubules, or neither type: the monomer is sequestered by profilin
Neither
Indicate whether the statement refers to a ciliary microtubule, a microtubule of the mitotic spindle, both types of microtubules, or neither type: it is arranged in a '9 + 2' array
Ciliary microtubules
Indicate whether the statement refers to a ciliary microtubule, a microtubule of the mitotic spindle, both types of microtubules, or neither type: it is nucleated at the centrosome
Mitotic spindle microtubules
Indicate whether the statement refers to a ciliary microtubule, a microtubule of the mitotic spindle, both types of microtubules, or neither type: it uses dyne in motors
Both
Indicate whether the statement refers to a ciliary microtubule, a microtubule of the mitotic spindle, both types of microtubules, or neither type: it's involved in moving fluid over the surface of cells
Ciliary microtubules
What is the function/feature of aster microtubules?
Interact with the cell cortex
What is the function/feature of kinetochore microtubules?
Link chromosomes to a spindle pole
What is the function/feature of interpolar microtubules?
Grow at plus ends to push spindle poles apart during anaphase
Cell movement involves the coordination of many events in the cell. Which of the following phenomena are NOT required for cell motility?
a. myosin-mediated contraction at the rear of the moving cell
b. integrin association with the extracellular environme
d
The hydrolysis of GTP to GDP carried out by tubulin molecules:
a. provides energy needed for tubulin to polymerize
b. occurs because the pool of free GDP has run out
c. tips the balance in favor of microtubule assembly
d. allows the behavior of microtubul
d
Which of the following conditions below is likely to decrease the likelihood of skeletal muscle contraction?
a. partial depolarization of the T-tubule membrane, such that the resting potential is closer to zero
b. a mutation in tropomyosin that decreased
d