Deck 20: Cell Communities: Tissues, Stem Cells, and Cancer

Question 1

Proteoglycans in the extracellular matrix of animal tissues

A)chiefly provide tensile strength.
B)allow cartilage to resist compression.
C)are linked to microtubules through the plasma membrane.
D)are polysaccharides composed of glucose subunits.

Answer 1

B

Question 2

Which of the following statements about cellulose is FALSE?

A)Cellulose synthase enzyme complexes are integral membrane proteins.
B)An array of microtubules guides the cellulose synthase complex as it moves in the membrane.
C)The sugar monomers necessary for the synthesis of a cellulose polymer are transported across the plasma membrane.
D)Microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers.

Answer 2

D

Question 3

Which of the following statements about animal connective tissues is TRUE?

A)Enzymes embedded in the plasma membrane synthesize the collagen in the extracellular matrix extracellularly.
B)In connective tissue, the intermediate filaments within the cells are important for carrying the mechanical load.
C)Cells can attach to a collagen matrix by using fibronectin, an integral membrane protein.
D)Proteoglycans can resist compression in the extracellular matrix.

Answer 3

D

Question 4

A basal lamina

A)is a thin layer of connective-tissue cells and matrix underlying an epithelium.
B)is a thin layer of extracellular matrix underlying an epithelium.
C)is attached to the apical surface of an epithelium.
D)separates epithelial cells from each other.

Question 5

Which of the following statements about gap junctions is FALSE?

A)Gap junctions are made of connexons.
B)Molecules up to 1000 daltons in molecular mass can move across gap junctions.
C)Because gap junctions only allow uncharged molecules to pass through, they are not used for electrically coupling cells.
D)Gap junctions can close in response to extracellular signals.

Question 6

Which of the following statements is FALSE?

A)Proteoglycans can act as filters to regulate which molecules pass through the extracellular medium.
B)The negative charge associated with proteoglycans attracts cations, which cause water to be sucked into the extracellular matrix.
C)Proteoglycans are a major component of compact connective tissues but are relatively unimportant in watery tissues such as the jellylike substance in the interior of the eye.
D)Glycosaminoglycans are components of proteoglycan.

Question 7

Fibroblasts organize the collagen of the extracellular matrix by

A)cutting and rejoining the fibrils.
B)processing procollagen into collagen.
C)twisting fibrils together to make ropelike fibers.
D)pulling the collagen into sheets or cables after it has been secreted.

Question 8

A cell can crawl through a tissue because of the transmembrane __________ proteins that can bind to fibronectin outside of the cell.

A)integrin
B)collagen
C)gap junction
D)claudin

Question 9

Tight junctions

A)allow small, water-soluble molecules to pass from cell to cell.
B)interact with the intermediate filaments inside the cell.
C)are formed from claudins and occludins.
D)are found in cells in connective tissues.

Question 10

Which of the following is NOT an example of a connective tissue?

A)bone
B)the layer of photoreceptors in the eye
C)the jellylike interior of an eye
D)cartilage

Question 11

Adherens junctions

A)can be used to bend epithelial sheets into tubes.
B)are most often found at the basal surface of cells.
C)are found only in adult tissues.
D)involve fibronectin and integrin interactions.

Question 12

Which type of junction involves a connection to the actin cytoskeleton?

A)adherens junctions
B)desmosomes
C)tight junctions
D)gap junctions

Question 13

A major distinction between the connective tissues in an animal and other main tissue types such as epithelium, nervous tissue, or muscle is the

A)ability of connective-tissue cells such as fibroblasts to change shape.
B)amount of extracellular matrix in connective tissues.
C)ability of connective tissues to withstand mechanical stresses.
D)numerous connections that connective-tissue cells make with each other.

Question 14

Both multicellular plants and animals have

A)cells capable of locomotion.
B)cells with cell walls.
C)a cytoskeleton composed of actin filaments, microtubules, and intermediate filaments.
D)tissues composed of multiple different cell types.

Question 15

Which of the following statements about integrins is FALSE?

A)Integrins use adaptor proteins to interact with the microtubule cytoskeleton.
B)Integrins can switch to an activated state by binding to an extracellular matrix molecule.
C)Integrins can switch to an activated state by binding to an intracellular protein.
D)An activated integrin molecule takes on an extended conformation.

Question 16

At desmosomes, cadherin molecules are connected to

A)actin filaments.
B)intermediate filaments.
C)microtubules.
D)gap junctions.

Question 17

Which of the following statements about collagen is FALSE?

A)Collagen synthase organizes the mature collagen molecules into ordered collagen fibrils.
B)Collagen is synthesized as procollagen and secreted to the outside of the cell in a secretory vesicle.
C)The terminal procollagen domains are cleaved by a protease in the extracellular space.
D)Cells can break down a collagen matrix using matrix proteases.

Question 18

Which of the following statements about plant cell walls is TRUE?

A)The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall.
B)The molecular components of the cell wall are the same in all plant tissues.
C)Because plant cell walls are rigid, they are not deposited until the cell has stopped growing.
D)The cellulose found in cell walls is produced as a precursor molecule in the cell and delivered to the extracellular space by exocytosis.

Question 19

Which of the following molecules is NOT found in plants?

A)cellulose
B)lignin
C)collagen
D)pectin

Question 20

Hemidesmosomes are important for

A)tubulation of epithelial sheets.
B)linkages to glycosaminoglycans.
C)forming the basal lamina.
D)attaching epithelial cells to the extracellular matrix.

Question 21

Which of the following statements about cancer is FALSE?

A)Viruses cause some cancers.
B)Tobacco use is responsible for more than 20% of all cancer deaths.
C)A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell.
D)Chemical carcinogens cause cancer by changing the nucleotide sequence of DNA.

Question 22

When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by a stock of

A)proliferating precursor cells.
B)cells more apically located than the terminally differentiated cells.
C)Wnt proteins.
D)induced pluripotent cells.

Question 23

An adult hemopoietic stem cell found in the bone marrow

A)will occasionally produce epidermal cells when necessary.
B)can produce only red blood cells.
C)can undergo self-renewing divisions for the lifetime of a healthy animal.
D)will express all the same transcription factors as those found in an unfertilized egg.

Question 24

A malignant tumor is more dangerous than a benign tumor because

A)its cells are proliferating faster.
B)it causes neighboring cells to mutate.
C)its cells attack and phagocytose neighboring normal tissue cells.
D)its cells invade other tissues.

Question 25

Which of the following statements about tumor suppressor genes is FALSE?

A)Gene amplification of a tumor suppressor gene is less dangerous than gene amplification of a proto-oncogene.
B)Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells.
C)Inactivation of tumor suppressor genes leads to enhanced cell survival and proliferation.
D)Individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two functional copies of a tumor suppressor gene.

Question 26

APC is a tumor suppressor and acts in the Wnt signaling pathway to prevent the TCF complex from turning on Wnt-responsive genes.Mice that lack the gene encoding TCF4 do not have the ability to maintain the pool of proliferating gut stem cells needed to renew the gut lining.What do you predict will happen in mice that lack the APC gene?

A)Like the mice lacking TCF4, they will not be able to renew the gut lining.
B)They will have inappropriate proliferation of gut stem cells.
C)Mice lacking the APC gene will have a hyperactive Wnt receptor even though there is no Wnt signal.
D)Mice lacking the APC gene will be like normal healthy mice, since APC is a tumor suppressor and thus not needed unless there is a tumor present.

Question 27

Ras is a GTP-binding protein that is often defective in cancer cells.A common mutation found in cancer cells causes Ras to behave as though it were bound to GTP all the time, which will cause cells to divide inappropriately.From this description, the normal Ras gene is a/an

A)tumor suppressor.
B)oncogene.
C)proto-oncogene.
D)gain-of-function mutation.

Question 28

Which of the following statements about organoids is FALSE?

A)Organoids can be produced from ES and iPS cells.
B)Organoids can only be made for organs that are made up of a single type of differentiated cell.
C)Organoids are self-assembling.
D)Organoids can form multilayered structures.

Question 29

Match each protein with the correct label in Figure 20-1. Figure 20-1

-integrin

Question 30

Cells that are terminally differentiated

A)will undergo apoptosis within a few days.
B)can no longer undergo cell division.
C)are unable to move.
D)no longer produce RNAs.

Question 31

Cadherins

A)are used to transfer proteins from one cell to another.
B)mediate cell-cell attachments through homophilic interactions.
C)are abundant in the plant cell wall.
D)bind to collagen fibrils.

Question 32

A metastasis is

A)a secondary tumor in a different part of the body that arises from a cell from the primary tumor.
B)a cell that is dividing in defiance of normal constraints.
C)a part of the primary tumor that has invaded the surrounding tissue.
D)the portion of the cancerous tumor that displays genetic instability.

Question 33

Which type of junction contributes the most to the polarization of epithelial cells?

A)adherens junctions
B)desmosomes
C)tight junctions
D)gap junctions

Question 34

Mouse embryonic stem (ES) cells

A)can only be grown in the laboratory.
B)can give rise to all tissues and cell types in the body except germ cells.
C)can be made in the lab from human iPS cells.
D)come from the inner cell mass of early embryos.

Question 35

Induced pluripotent stem (iPS) cells

A)can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues.
B)require a supply of donor egg cells, as is the case for embryonic stem cells.
C)can differentiate into a greater variety of adult tissues than embryonic stem cells.
D)have been used to create human clones.

Question 36

Plasmodesmata

A)permit small molecules to pass from one cell to another.
B)are found only in animal cells.
C)are closed by the neurotransmitter dopamine.
D)provide tensile strength.

Question 37

A pluripotent cell

A)can only be produced in the laboratory.
B)can give rise to all the tissues and cell types in the body.
C)can only give rise to stem cells.
D)is considered to be terminally differentiated.

Question 38

The artificial introduction of three key __________ into an adult cell can convert the adult cell into a cell with the properties of ES cells.

A)chromosomes
B)viruses
C)hormones
D)transcription factors

Question 39

Which of the following genetic changes cannot convert a proto-oncogene into an oncogene?

A)A mutation that introduces a stop codon immediately after the codon for the initiator methionine.
B)A mutation within the coding sequence that makes the protein hyperactive.
C)An amplification of the number of copies of the proto-oncogene, causing overproduction of the normal protein.
D)A mutation in the promoter of the proto-oncogene, causing the normal protein to be transcribed and translated at an abnormally high level.

Question 40

The plasmodesmata in plants are functionally most similar to which animal cell junction?

A)tight junction
B)adherens junction
C)gap junction
D)desmosome

Question 41

Match each protein with the correct label in Figure 20-1. Figure 20-1

-fibronectin

Question 42

Match each protein with the correct label in Figure 20-1. Figure 20-1

-actin

Question 43

Drugs that block the function of oncogenic proteins hold great promise in the fight against cancer.Should cancer researchers also be attempting to design drugs that will interfere with the products of tumor suppressor genes? Explain.

Question 44

People who inherit one copy of the Rb (retinoblastoma) gene that is normal and one copy that is mutated-that is, people who are heterozygous for Rb-have a greatly increased risk of cancer.
Given this information, do you agree or disagree with the following statement? Explain your answer.
The Rb mutation must have a dominant effect, which means that it must result in an increase in Rb function.Thus, Rb in its mutant form must be an oncogene.

Question 45

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below.Not all words or phrases will be used; each word or phrase can be used only once.
apical crypt organic
basal extracellular single-layered
blood vessel hyaluronan stratified
bone marrow neuronal villus
The location of stem cells in various tissues varies.In the lining of the small intestine, the different types of intestinal cells are arranged in a continuous __________ epithelium.The epithelium is arranged such that the cells that are in the underlying connective tissue are in the region called the __________, and is where the stem cell population resides.In contrast, the epidermis is a/an __________ epithelium, with stem cells in the __________ layer.Blood contains man circulating cell types which originate from a stem cell population found in the __________.

Question 46

Cancer is a disease of enhanced proliferation and cell survival.DNA repair mechanisms are normally important for cell survival.When a cell senses DNA damage, the cell cycle is inhibited until the damage is fixed.Given the importance of DNA repair mechanisms, how can their failure lead to the production of cancer cells with a competitive advantage over normal cells?

Question 47

Your friend is a pioneer in ES cell research.In her research, she uses an ES cell line that originated from an inbred strain of laboratory mice called FG426.She has just figured out methods that allow her to grow an entire liver from an ES cell and has successfully grown 10 livers.She demonstrates that the newly grown livers are functional by successfully transplanting one of the new livers into a FG426 laboratory mouse.
You are particularly excited about this, because you have a sick pet mouse called Squeaky.You are very attached to Squeaky, as you found him when you were out camping in New Hampshire.Unfortunately, Squeaky has developed liver disease and will not live much longer without a liver transplant.After you see your friend on TV talking about her new method for growing mouse livers, you immediately grab your cell phone to ask her whether Squeaky could have one of the newly grown livers.Just as you are about to dial your friend, you remember something you learned in cell biology and realize that instead, you should ask your friend about possibly creating mouse iPS cells for Squeaky's benefit.
A.Why do you think that one of the newly grown livers may not work in Squeaky?
B.Explain how the use of iPS cells could solve this problem.

Question 48

Match each name below with the best depiction of the type of epithelial sheet shown in Figure 20-2.Each name and each picture will only be used once. (A)


(B)


(C)


(D)

Figure 20-2

-squamous __________

Question 49

Figure 20-17 shows a sequence of mutations that might underlie the development of colorectal cancer.Explain why the loss of p53 is advantageous to cancerous cells.
Figure 20-17

Question 50

Match each name below with the best depiction of the type of epithelial sheet shown in Figure 20-2.Each name and each picture will only be used once. (A)


(B)


(C)


(D)

Figure 20-2

-columnar __________

Question 51

Match each name below with the best depiction of the type of epithelial sheet shown in Figure 20-2.Each name and each picture will only be used once. (A)


(B)


(C)


(D)

Figure 20-2

-cuboidal __________

Question 52

Match each protein with the correct label in Figure 20-1. Figure 20-1

-collagen

Question 53

Match each name below with the best depiction of the type of epithelial sheet shown in Figure 20-2.Each name and each picture will only be used once. (A)


(B)


(C)


(D)

Figure 20-2

-stratified __________

Question 54

A stem cell divides into two daughter cells.One of the daughter cells goes on to become a terminally differentiated cell.What is the typical fate of the other daughter cell?

Question 55

Rb is a tumor suppressor gene; its normal function is to help restrain cell division.Loss of both copies of Rb is a causative factor in some kinds of cancer.You propose to treat these cancers by injecting the patients with a viral vector that carries a copy of the Rb gene and has the ability to infect all the cells of the body, thereby artificially driving expression of Rb in all the cells, including the cancer cells.But your colleague replies, "No! You'll kill the patient, because you will halt cell division throughout the body."
A.Why would halting cell division throughout the body kill a full-grown adult?
B.Is your colleague right in thinking that forced expression of Rb in every cell will halt all cell division?

Question 56

A certain mutation in the receptor for epidermal growth factor (EGF) causes the mutated receptor protein to send a positive signal along the associated intracellular signaling pathway even when the EGF ligand is not bound to it.This signal leads to abnormal cell proliferation in the absence of growth factor.On the basis of this information, would you class the gene for the EGF receptor as a tumor suppressor gene or a potential oncogene? Explain your answer.

Question 57

Ras is a GTP-binding protein that is often defective in cancer cells.A signal from a growth factor through a receptor tyrosine kinase often stimulates normal cells to divide.When the receptor tyrosine kinase binds the growth factor, Ras is stimulated to bind GTP.Ras in turn activates proteins that promote cell proliferation.A common mutation in cancerous cells causes Ras to behave as though it were bound to GTP all the time.
A.Why is this mutation advantageous to cancerous cells?
B.Your friend decides that the signaling pathway involving the Ras protein is a good target for drug design, because the Ras protein is often defective in cancer cells.Your friend designs a drug that will turn off the receptor tyrosine kinase by preventing it from dimerizing.Do you think that this drug will affect cells that have a defective Ras protein that acts as if it were always bound to GTP? Why or why not?