Biology exam 3 KU
Cellular crawling motion is accomplished by: -the polymerization of microfilaments along the leading edge in response to an activated cell surface receptor. -the depolymerization of microfilaments along the leading edge in response to an activated cell surface receptor. -the contraction of microfilaments along the leading edge in response to an activated cell surface receptor. -the polymerization of microfilaments along the trailing edge in response to an activated cell surface receptor. -All of these choices can contribute to rapid shifting of direction of crawling motion.
the polymerization of microfilaments along the leading edge in response to an activated cell surface receptor
Cellular crawling motion is accomplished by: -the polymerization of microfilaments along the leading edge with contraction of microfilaments along the trailing edge through the action of myosin. -the polymerization of microtubules along the leading edge with contraction of microfilaments along the trailing edge through the action of myosin. -the polymerization of microfilaments along the trailing edge with contraction of microfilaments along the leading edge through the action of myosin. -the polymerization of microfilaments along the leading edge with contraction of microfilaments along the trailing edge through the action of kinesin. -the polymerization of microfilaments along the leading edge with contraction of microfilaments along the trailing edge through the action of dynein.
the polymerization of microfilaments along the leading edge with contraction of microfilaments along the trailing edge through the action of myosin
Why do the functions of many receptor kinases depend on the fluid nature of the plasma membrane? -The generation of cAMP requires a fluid membrane. -Binding of ligand to the receptor requires a fluid membrane. -The receptor monomers must move together and dimerize to be activated. -Phosphorylation requires a fluid membrane.
the receptor monomers must move together and dimerize to be activated
Phosphatases are a family of enzymes that specifically remove phosphate groups from proteins that were added by protein kinases. Vanadate is an inhibitor of phosphatases in eukaryotic cells. What effect would vanadate have on the response of cells to signals received by receptor kinases? -The response of the cell would last longer than it normally would. -The response of the cell would be shorter than it normally would. -The signal would still bind the receptor, so there would be no effect
the response of the cell would last longer than it normally would.
Which of the following is NOT true about gametes? -They are formed by meiotic cell division. -They have half as many chromosomes as a somatic cell of the same individual. -They are called eggs and sperm in animals. -They fuse to form a new organism during fertilization. -They are genetically identical to other gametes formed during meiosis.
they are genetically identical to other gametes formed during meiosis
Which type of receptor is membrane-associated? (Select all correct choices.) -G protein-coupled receptor -receptor kinase -ligand-gated ion channel -nuclear receptor
-g protein-coupled receptor -receptor kinase -ligand-gated ion channel
How many copies of each gene are present in skin cells at G1 of interphase? -2 -4 -6 -8
2
A number of mutations have been described in G proteins that have profound effects on their activity. For example, some mutations greatly increase the affinity of the G protein for GDP making it very difficult to be exchanged for GTP. Other mutations prevent the hydrolysis of GTP to GDP. Which of the following scenarios would still result in a proliferation signal via the kinase cascade in the absence of ligand binding to its receptor tyrosine kinase? -A continuously active receptor and an inactive Map kinase pathway -A Ras molecule that has no GTPase activity -A continuously inactive MAP kinase pathway and an inactive Ras -A continuously active Ras and an inactive MAP kinase pathway -A continuously activated receptor in the absence of ligand
a Ras molecule that has no GTPase activity
An enzyme that attaches a phosphate group to another molecule is called ____________. -a phosphatase -a phosphorylase -a kinase -a cyclase
a kinase
Which of the following would most likely contribute to uncontrolled cell proliferation (i.e., cancer)? -A mutant CDK that was active in the absence of its cyclin binding partner. -A mutant cyclin that cannot bind to its normal CDK binding partner. -A mutant microtubule synthesis/polymerization enzyme. -A mutant DNA replication mechanism causing extra chromosome copies. -A mutant kinetochore protein that causes reduced microtubule attachment.
a mutant CDK that was active in the absence of its cyclin binding partner
A protein on a cell surface that binds to a signaling molecule is an example of which of the following elements of cellular communication? -a signaling cell -a signaling molecule -a receptor molecule -a responding cell -None of these choices are correct.
a receptor molecule
Which of the following would NOT be considered a cell-surface receptor? -a receptor that binds a nonpolar steroid hormone and activates transcription -a receptor that allows ions to enter the cell when a ligand binds -a receptor that causes GDP to be exchanged for GTP in a G protein -a receptor that must form a dimer after binding the ligand to transmit a signal
a receptor that binds a nonpolar steroid hormone and activates transcription
A cell that responds to an environmental condition by the release of a chemical is an example of which of the following elements of cellular communication? -a signaling cell -a signaling molecule -a receptor molecule -a responding cell -None of these choices are correct.
a signaling cell
A chemical that binds to a cell to cause its activity to change is an example of which of the following elements of cellular communication? -a signaling cell -a signaling molecule -a receptor molecule -a responding cell -None of these choices are correct.
a signaling molecule
Most of the significant changes in activities and functions that accompany passage through a cell cycle checkpoint are regulated by the: -activation of microtubules. -changes in membrane polarization. -activation of kinase enzymes. -activation of DNA polymerase. -inhibition of cyclin proteins.
activation of kinase enzymes
CDKs are important in the regulation of the cell cycle. They carry out their function by ____________. -adding phosphate groups to target proteins -degrading cyclin proteins -preventing the progression of a cell from one stage of the cell cycle to the next
adding phosphate groups to target proteins
A G protein: -is a component of a signal-transduction pathway that is coupled to a G protein-coupled receptor. -is composed of three subunits and is inactive when bound to GDP. -releases GDP and binds to GTP when associated with an activated receptor. -becomes deactivated when bound GTP is dephosphorylated to GDP. -All of these choices are correct.
all of these choices are correct
A cellular response to a signal can be terminated by: -depletion of the signal that activates the receptor. -inactivation of intracellular signal-transduction proteins. -automatic inactivation of proteins in the signal pathway over time. -depletion of a second messenger. -All of these choices are correct.
all of these choices are correct
Evidence that cytoskeletal elements have ancient origins comes from: -the sequence similarities of cytoskeletal elements when comparing distantly-related organisms. -the presence of cytoskeletal elements in both eukaryotes and prokaryotes. -the observation that both prokaryotes and eukaryotes use cytoskeletal elements to assist cell division. -the ability to form functional hybrid microfilaments from actin monomers taken from distantly-related organisms. -All of these choices are correct.
all of these choices are correct
Intermediate filaments: -have a diameter that is larger than a microfilament, but smaller than a microtubule. -play an important role in maintaining cell shape. -play an important role in preventing skin from tearing by shear stress. -undergo little change in length in comparison to microtubules and microfilaments. -All of these choices are correct.
all of these choices are correct
Microtubules grow longer: -more quickly at one end than the other. -by growing outward from the centrosome. -in cycles, following rapid depolymerization. -if free tubulin dimers are available. -All of these choices are correct.
all of these choices are correct
Reproduction by cell division: -results in two daughter cells that are genetically identical. -is asexual reproduction. -persists in mature plant cells for continued growth. -continues in mature adult humans to replace damaged and worn-out cells. -All of these choices are correct.
all of these choices are correct
Second messengers: -are small intracellular molecules that participate in signal transduction. -play a role in activation of intracellular signal transduction. -are removed in order to terminate a cellular signaling response. -amplify the effects of the signal. -All of these choices are correct.
all of these choices are correct
Studies of rapidly dividing embryonic animal cells revealed: -a cyclic production of certain proteins in sync with the cell cycle. -a cyclic activation of protein kinases in sync with the cell cycle. -the rapid production of cyclin proteins is trailed by an activation of CDK enzymes. -inhibition of protein production blocks mitosis. -All of these choices are correct.
all of these choices are correct
The extent and duration of cellular response to a signal depend on: -the binding affinity of the receptor to the signaling molecule. -the concentration of the signaling molecule in the vicinity of the receptor. -the level of expression of the signal-transduction proteins. -the level of expression of the terminating proteins. -All of these choices are correct.
all of these choices are correct
Types of steroids include: -sex hormones such as estrogen and testosterone. -glucocorticoids that regulate blood glucose levels. -insect molting hormones. -lipid-soluble hormones derived from cholesterol. -All of these choices are correct.
all of these choices are correct
Which of the following types of cellular activities can be a response to cell signaling? -Cell division is triggered. -Gene expression patterns are changed. -Enzyme activity patterns are changed. -Cell signals are released to communicate with other cells. -All of these choices are correct.
all of these choices are correct
Zebrafish embryos change the color of the melanophore cells in their skin to a darker shade: -by dynein motor proteins moving pigment granules outward from the center of the cell. -by kinesin motor proteins moving pigment granules outward from the center of the cell. -by dynein motor proteins moving pigment granules inward toward the center of the cell. -by kinesin motor proteins moving pigment granules inward toward the center of the cell. -by dynein motor proteins moving pigment granules inward toward the plus end of microtubules.
by kinesin motor proteins moving pigment granules outward from the center of the cell
Why are the ends of microfilaments and microtubules called "plus ends" and "minus ends"? -because monomers are added more quickly to one end (the "plus end") than they are to the other end (the "minus end") -because polymerization occurs at one end (the "plus end") and depolymerization occurs at the other end (the "minus end") -because monomers can be added to one end only (the "plus end"), and can only be removed from the other end (the "minus end") -because the actin and tubulin monomers that make up microfilaments and microtubules have evolved more rapidly than most other proteins
because monomers are added more quickly to one end (the "plus end") than they are to the other end (the "minus end")
In spite of their heterogeneity, steroid hormones: -have the same effect on different types of cells. -bind to cell-surface receptors. -bind intracellular receptors to form complexes that migrate to the nucleus. -are hydrophilic small molecules that bind to intracellular receptors. -facilitate the initiation of translation by ribosomes.
bind intracellular receptors to form complexes that migrate to the nucleus
Some cytoskeletal elements are more permanent than others. Which components of the cytoskeleton are dynamic structures? -microtubules -microfilaments -intermediate filaments -both microtubules and intermediate filaments -both microtubules and microfilaments
both microtubules and microfilaments
How are steroid hormone receptors and cell-surface receptors similar? -When bound to their ligand, both types enter the nucleus to activate transcription. -Both types cause GDP to be exchanged for GTP in a G protein. -Both types undergo a conformational change when they bind to their ligand. -When activated the signals of both types are transduced across the plasma membrane.
both types undergo a conformational change when they bind to their ligand
Myosin motor proteins use ATP energy to: -carry vesicles along a microtubule within a cell in a minus-to-plus direction. -carry vesicles along a microfilament within a cell in a minus-to-plus direction. -carry vesicles along a microtubule within a cell in a plus-to-minus direction. -carry vesicles along a microfilament within a cell in a plus-to-minus direction. -slide along intermediate filaments to contract muscle cells.
carry vesicles along a microfilament within a cell in a minus-to-plus direction
Kinesin motor proteins use ATP energy to: -carry vesicles along a microtubule within a cell in a minus-to-plus direction. -carry vesicles along a microfilament within a cell in a minus-to-plus direction. -carry vesicles along a microtubule within a cell in a plus-to-minus direction. -carry vesicles along a microfilament within a cell in a plus-to-minus direction. -slide along microfilaments to contract muscle cells.
carry vesicles along a microtubule within a cell in a minus-to-plus direction
Dynein motor proteins use ATP energy to: -carry vesicles along a microtubule within a cell in a minus-to-plus direction. -carry vesicles along a microfilament within a cell in a minus-to-plus direction. -carry vesicles along a microtubule within a cell in a plus-to-minus direction. -carry vesicles along a microfilament within a cell in a plus-to-minus direction. -slide along microfilaments to contract muscle cells.
carry vesicles along a microtubule within a cell in a plus-to-minus direction
Which of the following is capable of phosphorylating key proteins involved in regulating the cell cycle? -cyclin -CDK -phosphatase -p53 protein -cyclin-CDK complex
cyclin-CDK complex
The high variability of the types of G protein-coupled receptors allows for: -different types of cells to respond to different types of signals. -different types of signal-transduction pathways to respond to signals. -a rapid response to cell signals. -a sensitive response to cell signals. -All of these choices are correct.
different types of cells to respond to different types of signals.
Consider a diploid organism (2n) with a haploid complement (n) of four chromosomes. At Prophase I, how many total chromosomes will be present in a cell? -four, one complete set of chromosomes -eight, four pairs of homologous chromosomes -twelve, four pairs of homologous chromosomes and their haploid complement -sixteen, four pairs of homologous chromosomes and two sister chromatids per chromosome
eight, four pairs of homologous chromosomes
True or false: During meiosis, two rounds of DNA synthesis are required to form four gametes from one parent cell. -true -false
false
The FoxP2 gene is thought to be related to language in humans. At Prophase I, how many copies of the FoxP2 gene are present in a cell? Keep in mind that humans are diploid. -two copies, one on each homologous chromosome -four copies, one on each sister chromatid in a pair of homologous chromosomes -eight copies, one on each sister chromatid in a pair of homologous chromosomes -eight copies, one on each of strand of each chromatid per homologous pair
four copies, one on each sister chromatid in a pair of homologous chromosomes
Which of the following is NOT true about the eukaryotic cell cycle? -There are two stages to the cell cycle: M phase and interphase. -The M phase consists of two events: mitosis and cytokinesis. -Interphase is typically the shortest of the two stages of the cell cycle. -There are three phases of interphase: the S phase and two gap phases. -Some cells pause between M phase and S phase for more than a year.
interphase is typically the shortest of the two stages of the cell cycle.
The centrosome: -is a region of the chromosome where sister chromatids remain attached. -is a region of the chromosome where kinetochores attach. -is a region of the chromosome where microtubules attach to chromosomes during mitosis. -is the microtubule organizing center for the mitotic spindle. -All of these choices are correct.
is the microtubule organizing center for the mitotic spindle
Which one of the following statements about intracellular transport is true? -Kinesin and dynein move substances along microtubules. -Kinesin and myosin move substances along microtubules. -Kinesin and dynein move substances along microfilaments. -Kinesin moves substances along microfilaments.
kinesin and dynein move substances along microtubules
Which one of the following statements about intracellular transport is true? -Kinesin and myosin move substances along microtubules. -Kinesin and dynein move substances along microfilaments. -Myosin and dynein move substances along microfilaments. -Myosin moves substances along microfilaments.
kinesin and dynein move substances along microtubules
Which type of receptor is involved in rapid responses of muscle cells and neurons? (Select all correct choices.) -G protein-coupled receptor -receptor kinase -ligand-gated ion channel -nuclear receptor
ligand-gated ion channel
Homologous pairs of chromosomes are separated during ____________. -mitosis -meiosis I and mitosis -meiosis II and mitosis -meiosis I -meiosis II
meiosis I
Sister chromatids of replicated chromosomes are separated during ____________. -mitosis -meiosis I and mitosis -meiosis II and mitosis -meiosis I -meiosis II
meiosis II and mitosis
Cells with cilia or flagella rely mainly on ____________ to facilitate their movement. -microtubules -microfilaments -intermediate filaments
microtubules
In a study of tadpole coloration, you noticed that a certain percentage of tadpoles in a population displayed a decreased ability to shift from dark coloration at night to light coloration during the day. These individuals were studied and found to have the normal number of melanophores that produced normal amounts of melanin pigment granules. You remember reading about melanophores and pigment granule transport in cells and that it involved the cytoskeleton. Which part of the cytoskeleton would you suggest investigating as a potential source of the faulty color adjustment in these tadpoles? -intermediate filaments -microtubules -microfilaments
microtubules
Microtubules and microfilaments are said to be "dynamic" elements of the cytoskeleton. In this case, dynamic means that: -once individual microfilaments and microtubules have formed they can change shape and move around inside the cell. -they are constantly changing and are never in the same place for very long. -microtubules and microfilaments are assembled and disassembled and then reassembled again in a regulated manner.
microtubules and microfilaments are assembled and disassembled and then reassembled again in a regulated manner
The cytoskeleton of animal cells includes: -microtubules, microfilaments, and intermediate filaments. -actin, microfilaments, and intermediate filaments. -actin, microtubules, and intermediate filaments. -tubulin, microfilaments, and intermediate filaments. -microtubules and microfilaments.
microtubules, microfilaments, and intermediate filaments
Microfilaments grow longer: -more quickly at one end than the other. -by growing outward from the centrosome. -in cycles, following rapid depolymerization. -if free tubulin dimers are available. -All of these choices are correct.
more quickly at one end than the other
Which one of the following statements about intracellular transport is true? -Kinesin and myosin move substances along microtubules. -Kinesin and dynein move substances along microfilaments. -Myosin and dynein move substances along microfilaments. -Myosin moves substances along microfilaments.
myosin moves substances along microfilaments
Epidermolysis bullosa is a rare genetic disorder: -of a keratin gene that disrupts intermediate filaments, weakening epidermal cell connections. -of a microfilament gene that disrupts desmosomes, weakening epidermal cell connections. -of an intermediate filament gene that disrupts hemidesmosomes, weakening epidermal cell connections. -of a keratin gene that disrupts microfilaments, weakening epidermal cell connections. -All of these choices are correct.
of a keratin gene that disrupts intermediate filaments, weakening epidermal cell connections
Imagine that you are a medical student working in a cancer research laboratory. Your boss has given you samples of cancer cells and blood from a patient. She has told you that the cells have no mutations in any of their signaling molecule proteins (i.e., all the proteins are normal), but the cells' signaling transduction properties are not normal, causing them to be cancerous. Which of the following could account for the increased cell proliferation in the patient? -The cells taken from the patient have more growth factor receptors than normal. -The concentration of a signaling molecule in the patient is higher in the patient than usual. -The cells taken from the patient exhibit a reduced level of signal amplification. -Options 1 and 2. -Options 1, 2, and 3.
options 1 and 2
Which of the following has the most similarity in nucleotide sequence? -homologous chromosomes -non homologous chromosomes -sister chromatids -complementary strands of DNA -maternal and paternal versions of the same chromosome
sister chromatids
Which of the following statements would be true if a cell has a mutation in the p53 gene such that the p53 protein is no longer able to be phosphorylated? -The amount of p53 protein in the nucleus would remain low in the presence of DNA damage. -The amount of cytoplasmic p53 protein would increase in response to DNA damage. -The kinase activity in the nucleus would decrease in response to DNA damage.
the amount of p53 protein in the nucleus would remain low in the presence of DNA damage
Paramecium is a single-cell eukaryotic organism that can reproduce by mitotic cell division. Prior to the M phase of the cell cycle, which of the following must occur? -The cell must replicate its chromosomes. -The cell must first be fertilized. -The nucleus must divide. -Chromatids must be separated. -The nuclear envelope must disintegrate.
the cell must replicate its chromosomes
A homologous chromosome pair is best described as two chromosomes that have ____________. -the same genes in the same order but possibly with different alleles of some of the genes -the same alleles of the same genes in the same order -the same genes possibly arranged in a different order with potentially different alleles of some of the genes -different alleles of the same genes arranged in a different order -identical sequences of nucleotides
the same genes in the same order but possibly with different alleles of some of the genes
Sister chromatids are best described as two DNA molecules that have ____________. -the same genes in the same order but having different alleles. -the same alleles of the same genes in a different order. -different genes in the same order and possibly having different alleles of some genes. -different alleles of the same genes arranged in a different order. -virtually identical sequences of nucleotides.
virtually identical sequences of nucleotides
