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

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 __________.

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?

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

Proteoglycans in the extracellular matrix of animal tissues

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?

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

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

Adherens junctions

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?

A malignant tumor is more dangerous than a benign tumor because

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

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

Which of the following statements about collagen is FALSE?

A metastasis is

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

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

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?

Both multicellular plants and animals have

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