LS7C Week 1 RQs & CQs
A decrease in cell adhesion, by the introduction of an experimental substance to a tissue, compromises the strengthe of the tissue. Which cell junction would most likely be affected if a tissue is treated with this experimental substance? A. adherens junctions B. gap junctions C. hemidesmosomes D.tight junctions
Adherens junctions
Intermediate filaments: have a diameter that is larger than a microfilament, but smaller than a microtubule. undergo little change in length in comparison to microtubules and microfilaments. play an important role in maintaining cell shape. All of these choices are correct. play an important role in preventing skin from tearing by shear stress.
All these choices are correct.
Microtubules form from dimers of _____BLANK and ______BLANK subunits that polymerize into a ____________BLANK. Question 1 choices Choice A., +tubulin; −tubulin; double helix Choice B., beta-tubulin; gamma-tubulin; beta sheet Choice C., alpha-tubulin; beta-tubulin; hollow tube , Choice D., an amino acid; phosphate; double helix
Alpha-tubulin; beta-tubulin; hollow tube
The plus ends of both microtubules and microfilaments differentiate from the minus ends: Question 5 choices Choice A., in that new tubulin or actin subunits are added rather than removed. Choice B., in that new tubulin or actin subunits are added more quickly. Choice C., in that the end that always grows in the direction the cell is moving.
B, in that new tubulin or actin subunits are added more quickly.
Which lettered item in the figure above is similar to the payload on a transport vehicle? Question 4 choices Choice A., oval a Choice B., oval b Choice C., oval c Choice D., oval d Choice E., oval e
B, oval b
In the image of a microtubule shown above, the plus and minus ends are labeled. If the motor protein shown is dynein, what can you say about the direction in which the vesicle is being carried? Question 6 choices Choice A., It can go in either direction on microtubules. Choice B., It is going to the right (toward the plus end). Choice C., It is going to the left (toward the minus end). Choice D., The direction cannot be determined from the data provided.
C, It is going to the left (toward the minus end).
Cell movement can be faciliated by microfilaments in what way? A. by gliding past each other using energy from ATP B. By bending according to transmembrane signals C. By dynamic growing and shrinking at the ends
C, by dynamic growing and shrinking at the ends
Contraction of muscles is an example of how the motor protein _______BLANK interacts with the cytoskeletal elements called _____________BLANK to produce movement. Question 1 choices Choice A., actin; dynein Choice B., myosin; dynein Choice C., myosin; actin filaments Choice D., dynein; microtubules Choice E., kinesin; microtubules
C, myosin; actin filaments
Which lettered item in the figure above is the motor protein? Question 5 choices Choice A., oval a Choice B., oval b Choice C., oval c Choice D., oval d Choice E., oval e
C, oval c
If a mutation occurred in the cadherin gene so that the cytoplasmic domain no longer attached to the cytoskeleton, which of the following would occur? Cadherins in hemidesmosomes would no longer be anchored to intermediate filaments. Cadherins in adherens junctions would no longer be anchored to microtubules. Cadherins in desmosomes would no longer be anchored to intermediate filaments. Cadherins in desmosomes would no longer be anchored to microfilaments. Instructional Guidance: This question assesses knowledge and understanding of specific associations among cytoskeletal elements, cell adhesion molecules, and the various junctional complexes in animal cells.
Cadherins in desmosomes would no longer be anchored to intermediate filaments.
An epithelial tissue is defined as a: collection of contractile cells. collection of cells that lines cavities or outside surfaces. network of cells that use chemical communication. few cells embedded into an extensive extracellular matrix.
Collection of cells that lines cavities or outside surfaces.
Microtubules can grow by addition of tubulin dimers to _______________BLANK, and they can shorten by removal of dimers from ______________BLANK. Question 4 choices Choice A., the plus end; the minus end Choice B., the minus end; the plus end Choice C., both plus and minus ends; the minus end Choice D., both plus and minus ends; both plus and minus ends Choice E., the plus end; both plus and minus ends
D, both plus and minus ends; both plus and minus ends
A stem cell is fate determined once it has received the Self Renewal signal. As result, which genes are newly expressed? (Check all that apply) DET genes DIFF (neural) genes ID genes DIV genes DIFF (skin) genes SR genes
DET genes ID genes DIV genes
What kind(s) of cell-to-cell junctions would be most useful for anchoring these cells together to form a strong tissue? A. gap junction B. Tight junction C. Any of the above E. None of the above
Desmosomes (molecules (food and waste) can still get in between neighboring cells
The basis for movement of cilia and flagella is the interaction of the motor protein __________BLANK with the cytoskeletal elements called ____________BLANK. Question 2 choices Choice A., dynein; actin filaments Choice B., tubulin; dynein Choice C., myosin; actin filaments Choice D., dynein; microtubules Choice E., kinesin; microtubules
Dynein; microtubules
Which lettered item in the figure above represents a tubulin dimer? Question 3 choices Choice A., oval a Choice B., oval b Choice C., oval c Choice D., oval d Choice E., oval e
E, oval e
Older individuals have fragile skin that causes bed sores. The outer layer of skin can detach and blister in response to friction. Increased susceptibility to blister formation is caused by the loss of which component in the skin? A. skin signal pathway transducers B. Cell cytoskeleton proteins C. Cell adhesion molecules D. Extracellular matrix proteins
Extracellular matrix proteins
A mutation in dynein would cause vesicles to accumulate in the neuron's cell body.
False
As cells become differentiated, they delete the DNA for genes they no longer need.
False
The plus ends of both microtubules and microfilaments differentiate from the minus ends: Question 5 choices Choice A., in that new tubulin or actin subunits are added rather than removed. Choice B., in that new tubulin or actin subunits are added more quickly. Choice C., in that the end that always grows in the direction the cell is moving.
In that new tubulin or actin subunits are added more quickly
Structures known as microvilli are associated with: increased surface area for nutrient absorption. communication between cells. increased surface area for gas exchange. adhesion to the extracellular matrix.
Increased surface area for nutrient absorption
In skin, the cells of the epidermis connect to the basal lamina through cellular junctions known as hemidesmosomes. Select the cytoskeletal element that helps maintain the integrity of this connection. both intermediate filaments and microfilaments microtubules microfilaments intermediate filaments
Intermediate filaments
What is the BEST characterization of the minus end of a dynamic filament? It is fast growing. It loses subunits quickly. It is slow growing, and also loses its subunits quickly. It is slow growing.
It is slow growing
Which one of the following statements about intracellular transport is TRUE? Kinesin and myosin move substances along microtubules. Kinesin moves substances along microfilaments. Kinesin and dynein move substances along microfilaments. Kinesin and dynein move substances along microtubules.
Kinesin and dynein move substances along microtubules.
Microfilaments help a cell_____ A. strengthen the plasma membrane B. Maintain its size and shape C. Separate chromosomes during anaphase of mitosis
Maintain its size and shape
Myosin is a motor protein that associates with: intermediate filaments. microtubules. microfilaments. vimentin
Microfilaments
Could an isolated melanin granule move along an actin microfilament? Yes, motor proteins all use ATP to cause a conformation change. None of the other answer options is correct. No, motor proteins are specific for the type of filament they bind. Yes, melanin granules have motor proteins.
No, motor proteins are specific for the type of filament they bind
The property of dynamic instability implies that the individual protein subunits of microtubules are held together by: noncovalent interactions. covalent bonds. All of these choices are correct. disulfide bonds.
Noncovalent interactions
In complex multicellular organisms, bulk flow is an important physiologic character. Why is bulk flow a necessary condition of complex multicellularity? Bulk flow is necessary to move large amounts of liquid through the organism depending on physiologic needs. The tissues can all receive necessary nutrients from the environment, but bulk flow speeds the rate of diffusion. Complex multicellularity is related to the increase in oxygen in the environment. Because bulk flow systems are only related to the delivery of oxygen to tissues, higher environmental oxygen selected for individuals with bulk flow systems. Complex multicellularity reflects cell adhesion between cells, and this cannot happen without bulk flow of signaling molecules from the environment. Organisms exhibiting complex multicellularity are large and have cells/tissues that are not in contact with their environment. Systems that can overcome the limits of diffusion must occur for basic physiologic processes to occur.
Organisms exhibiting complex multicellularity are large and have cells/tissues that are not in contact with their environment. Systems that can overcome the limits of diffusion must occur for basic physiologic processes to occur.
Microfilaments are compose of ____ in_____arrangement. A. polyers of actin protein, a hollow tube-like B. repeating actin subunits; a thin double-helix C. Polymers of tubulin; a double-helix D. alpha and beta dimer subunits; a double-helix
Repeating actin subunits; a thin double-helix
Motor proteins cause movement by: (1) undergoing a conformational change, (2) harnessing energy from ATP, and (3) binding to the cytoskeleton. Statements (1) and (3) are correct. Statements (1) and (2) are correct. Statements (1), (2), and (3) are correct. Statements (2) and (3) are correct.
Statements (1), (2), and (3) are correct.
Imagine that you are examining a mouse that does not produce basal lamina in the skin. How will this mouse be different from a normal, wild-type mouse? The epidermis will not be connected to the dermis. Cellular junctions will fail to form between the cells of the epidermis. All of these choices are correct. The epidermis and dermis will be strongly connected. The dermis will be disorganized and will lack blood vessels.
The epidermis will not be connected to the dermis.
The MOST likely reason(s) a metastatic tumor cell might lose its connection to the basal lamina would be: the loss of integrin proteins from the cell's surface, or a change in the type of integrin proteins present on the cell's surface. the loss of integrin proteins from the cell's surface. a change in the type of integrin proteins present on the cell's surface. a change in the composition of the basal lamina.
The loss of integrin proteins from the cell's surface, or a change in the type of integrin proteins present on the cell's surface.
Consider Figure 20.25. Imagine that there is a mutation in the gene for the Notch receptor in the progenitor cell. How does mutation affect vulva development? The progenitor cell will remain a type 1 cell. The progenitor cell will become a type 2 cell. The EGF receptor cannot bind its ligand. The type 2 cell will differentiate into a type 1 cell.
The progenitor cell will remain a type 1 cell.
Gap junctions and plasmodesmata have what feature in common? They both attach to the cytoskeleton. They are both found in plant cells. They both allow direct transport of materials between cells. They both are made up of protein subunits located in the plasma membrane.
They both allow direct transport of materials between cells.
Which of the following best describes a role that microfilaments play in the structure and function of red blood cells? Question 5 choices Choice A., They anchor and orient the O2-bearing hemoglobin protein molecules. Choice B., They provide a track for directing O2 to the proper cellular locations. Choice C., They maintain the biconcave shape to maximize gas exchange.
They maintain the biconcave shape to maximize gas exchange.
A cell in a chick embryo is tested to determine whether it is a stem cell of some kind. These tests find: 1. The SR receptor is present 2. DIV genes are on 3. The DIFF (skin) genes are blocked 4. TF of the neural pathway is in the cytoplasm 5. Transducer 2 of the skin pathway is not phosphorylated Based on these results, the transcription factor of the Skin pathway is in the cytoplasm
True
Based on the diagram below, secretory vesicles are transported toward the plus ends of microtubules in neurons.
True
Some cell junctions allow materials to pass between adjacent cells so that they work together as a unit.
True
Vascular endothelial growth factor (abbreviated VEGF and pronounced "Veg-F") is a peptide signaling molecule related to platelet-derived growth factor. VEGF is important in the formation of the circulatory system because its signaling pathway causes the formation of blood vessels in developing embryos during normal development. Tumors also produce and secrete VEGF, causing the formation of new blood vessels that supply these tumors. Given what you know about the different kinds of cell signaling and VEGF, which one of the following statements is TRUE? VEGF is an endocrine-signaling molecule because it circulates through the bloodstream inside of platelets. VEGF is a paracrine signaling molecule because it binds to receptors on cells at the site where new blood vessels are needed. VEGF is an endocrine-signaling molecule because it is released from platelets into the bloodstream and is carried throughout the body, causing widespread activation of platelet-derived growth factor receptors on cells in a variety of tissues.
VEGF is a paracrine signaling molecule because it binds to receptors on cells at the site where new blood vessels are needed.
The basal lamina is: a specialized form of the extracellular matrix found beneath all epithelial tissues. an area found wherever two different types of tissues meet. an area found beneath all connective tissues that helps them adhere to underlying muscle. a specialized form of the extracellular matrix found only in the skin.
a specialized form of the extracellular matrix found beneath all epithelial tissues.
Signal transduction is the process by which: transcription factors bind to cis-regulatory regions of DNA and either activate or repress transcription. None of the answer options is correct. a specific combination of transcription factors determines the developmental pathway in a cell or group of cells. a single master gene, or signal, activates a series of downstream genes that lead to cell differentiation. an extracellular molecule activates a membrane protein, which in turn activates molecules inside the cell.
an extracellular molecule activates a membrane protein, which in turn activates molecules inside the cell.
Cadherins are: (Select all that apply.) proteins involved in attachment of cells to the extracellular matrix. cell adhesion molecules found in cell junctions. proteins involved in attachment of cells to neighboring cells. proteins that provide a pathway for molecules to move between cells.
cell adhesion molecules found in cell junctions. proteins involved in attachment of cells to neighboring cells.
Which of the following is a component of the extracellular matrix produced by an animal cell? collagen cellulose cadherin All of these choices are correct.
collagen
The extracellular matrix is particularly important for which type of tissue? A, nervous B, muscle C, connective D, epithelial
connective
A pathologist is carrying out an autopsy. Upon opening the chest cavity, the pathologist sees a thick, fibrous tissue surrounding the heart. This is likely: connective tissue. neural tissue. epithelial tissue. muscle tissue.
connective tissue
The ability of microtubules to undergo rapid ___________BLANK and slower ____________BLANK is associated with the ability of the ______________BLANK to explore the cell and locate chromosomes. Question 3 choices Choice A., polymerization; depolymerization; microtubules , [Your answer, incorrect] Choice B., depolymerization; polymerization; spindle apparatus , Choice C., synthesis; hydrolysis; cytoskeleton elements Choice D., synthesis; hydrolysis; microtubules
depolymerization, polymerization, spindle apparatus
Microtubules are __________BLANK because they __________BLANK and depolymerize at their ends. Question 2 choices Choice A., unstable; hydrolyze Choice B., stable; polymerize Choice C., dynamic; polymerize Choice D., dynamic; hydrolyze
dynamic; polymerize
Which of the following CORRECTLY matches a cell or group of cells with its ability to differentiate into different specialized cells? endoderm: multipotent fertilized egg: pluripotent fertilized egg: multipotent ectoderm: totipotent mesoderm: pluripotent
endoderm: multipotent
The muscle cells and nerve cells in a mouse look very different and serve very different functions in the mouse's body. These differences are because the muscle cells and nerve cells in the mouse: express different genes. have different genes. have different ribosomes. copy different genes. have different chromosomes. use different genetic codes.
express different genes
Dynamic instability is a: feature of microtubules. feature of microfilaments. feature of intermediate filaments. universal feature of the cytoskeleton. feature of microtubules and microfilaments.
feature of microtubules
Cells differentiate through: gene regulation. growth. timing. the cell cycle.
gene regulation
In many cells, the adhesion to the extracellular matrix through integrins causes the activation of kinases in the cytoplasm. This suggests that: integrins are kinases. extracellular matrix proteins are receptors and integrins are ligands. integrins promote the activation of signal-transduction pathways. Instructional Guidance: Students draw on what they know about receptor-ligand interaction and receptor activation of signaling pathways.
integrins promote the activation of signal-transduction pathways.
The basal lamina: is a specialized extracellular matrix found beneath epithelial tissues. All of these choices are correct. links to epithelial cells through tight junctions. is found on top of the epidermis of the skin. is a cell-rich layer.
is a specialized extracellular matrix found beneath epithelial tissues.
The fertilized egg is totipotent, which means: it can give rise to a complete organism. it only contains genetic material from the female. it can be removed and donated to a surrogate womb. the Y chromosome does not create interference to the expression of X-linked genes. it forms the membranes that surround and support the developing embryo.
it can give rise to a complete organism.
Which ligand acts as a signal resulting in gene U being active and V inactive? ligand M ligand H ligand K None of the other answer options is correct. ligand L
ligand H
Shown here are four ligands (M, H, K, and L) and their corresponding receptors along with three genes (U, V, and W) whose activity the receptor controls through signal transduction. The arrows indicate gene activation, the T-bars indicate gene repression. If either U or V is required to activate W, which ligand (or ligands) result in W being active? (Select all that apply.) ligand H None of the answer options is correct. ligand K ligand L ligand M
ligand H Ligand K Ligand M
Shown here are four ligands (M, H, K, and L) and their corresponding receptors along with four genes (S, T, U, and V) whose activity the receptor controls through signal transduction. The arrows indicate gene activation, the T-bars indicate gene repression. Which ligand acts as a signal resulting in gene U being inactive and V being active? ligand H None of the other answer options is correct. ligand K ligand M
ligand K
Which of the following would be more likely to cause development of a microvillus on an intestinal epothelial cell? A. Plus + end growth of microfilaments at the tip of the microvillus and shrinkage at the minus - end B. Plus + end growth of microfilaments at the tip of the microvillus but no shrinkahe at the minus - end C. Minus end growth of microfilaments at the tip of the microvillus and shrinkage at the plus + end
plus + end growth of microfilaments at the tip of the microvillus but no shrinkage at the minus - end
The extracellular matrix is a network of: channel proteins found in the cellular membrane that allow for communication. proteins and polysaccharides inside the cell that keep organelles in place. proteins found in the cellular membrane that allow for substances to enter the cell. proteins and polysaccharides outside the cell that play a role in structural support.
proteins and polysaccarides outside the cell that play a role in structural support.
If the vesicle being carried in the figure above (in an animal cell) contains content that is to be excreted from the cell at the plasma membrane, it is probably being transported toward the __________BLANK by the motor protein ____________BLANK. Question 7 choices Choice A., left; dynein Choice B., left; kinesin Choice C., right; dynein Choice D., right; kinesin
right; kinesin
Signal transduction in development is often amplified by: opening and closing of nuclear pores. sequential phosphoryation of proteins in the cytoplasm. methylation of the target cell's DNA. histone modification in chromosomes.
sequential phosphoryation of proteins in the cytoplasm.
Which of the following is the diffusible extracellular element in the process of vulval cell differentiation? the Notch receptor the EGF receptor the Notch ligand the EGF ligand
the EGF ligand
Figure 9.15 shows how normal signaling works with a Ras protein acting downstream of a receptor kinase. You examine a cell line in which Ras is always activated even in the absence of a signaling molecule. This causes constant activation of the kinases in the MAP kinase pathway. Which of the following conditions would be MOST likely to turn off this abnormally active signaling pathway? the addition of a drug that prevents the dimerization of the receptor kinase the addition of a drug that increases the binding affinity of Ras for MAP kinase enzymes in the cytoplasm the addition of a drug that prevents the phosphorylation of the receptor kinase the addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus
the addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus
Which of the following cell junctions is involved in creating a barrier between cells? desmosome adherens junction tight junction
tight junction
Which of the following junctions would you predict to be most important for the function of the bladder? A. adherens junctions B. gap junctions C. hemidesmosomes D. tight junctions
tight junctions
Each answer option below lists terms that classify cell types according to their developmental potential. Which of the options lists the terms from those capable of differentiating into the greatest number of different specialized cells to those capable of differentiating into the least number of different specialized cells? totipotent, pluripotent, multipotent totipotent, multipotent, pluripotent multipotent, totipotent, pluripotent multipotent, pluripotent, totipotent pluripotent, totipotent, multipotent
totipotent, pluripotent, multipotent
Cadherins bind to which type of cytoskeletal element(s)? microfilaments intermediate filaments microtubules both intermediate filaments and microfilaments
both intermediate filaments and microfilaments
A constitutively active receptor will do what in the presence of its ligand? turn off remain activated be down-regulated be inhibited
remain activated
How do cells connect to the extracellular matrix? through integrins through tight junctions through gap junctions through cadherins
through integrins
The strength of collagen comes from its: triple helical structure and bundling. triple helical structure and bundling, as well as its amino acid sequence. amino acid sequence. ability to bind to polysaccharide molecules.
triple helical structure and bundling
Cellular differentiation progressively restricts cell fate because the unexpressed genes in the cell: become more densely packed with nucleosomes. accumulate both point mutations and deletions. accumulate point mutations. undergo irreversible repression. accumulate deletions.
undergo irreversible repression
