CHAPTER 13 Test Your Knowledge
Driving Question 1
What is the structure of tissues and organs, and how can organs be repaired or replaced?
By answering the questions below and studying Infographics 13.1, 13.2, 13.3, and 13.5, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
Which of the following statements applies to tissues?
a. Only one cell type is present.
b. Multiple cell types are present.
c. Each tissue has a specific function.
d. Cells within a tissue cooperate.
e. all of the above
f. b, c, and d
The brain and spinal cord are made up of nervous tissue. This tissue includes neurons–cells that fire electrical impulses that communicate information–as well as glial cells. Some glial cells enable the electrical impulse to travel faster in a neuron. How are the roles of neurons and glial cells consistent with a functional tissue?
You shed skin cells every day. How are those cells replaced?
a. by mitotic division and specialization of embryonic stem cells
b. by differentiation of neighboring neurons into skin cells
c. by differentiation of red blood cells that leave the circulation and migrate into deeper layers of the skin
d. by mitotic division and differentiation of tissue stem cells
e. all of the above
USE IT
What are the pros and cons of receiving an organ transplant versus growing a replacement organ from one’s own cells?
Why does a recipient of a liver transplant have a high risk of bacterial infections?
a. because the liver plays a critical role in the immune response
b. because donor livers are often contaminated with disease-causing bacteria
c. because transplant recipients have to take drugs that suppress their immune system
d. because the surgery poses a high risk for introducing bacteria into the recipient
e. because the immune system may reject the liver
From the information provided in Question 2, would it be sufficient to just replace the neurons in someone who suffered nervous tissue damage? Why or why not?
Why is engineering a bladder more challenging than engineering skin?
Driving Question 2
What are the properties of specialized cells in tissues, and how do stem cells differentiate into these specialized cells?
By answering the questions below and studying Infographic 13.4, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
Relative to one of your liver cells, one of your skin cells
a. has the same genome (that is, the same genetic material).
b. has the same function.
c. has a different pattern of gene expression.
d. a and c
e. b and c
A muscle cell does not have keratin--the protein that gives skin its elasticity and “waterproofing.” Why would muscle cells not have keratin?
Is the genome of stem cells larger than that of specialized cells?
a. yes, because they need the genes found in every cell type, whereas specialized cells need only a subset of all the genes
b. yes, because they express more genes than do specialized cells
c. no, because all cells in a person have the identical set of genes in their genome
d. no; they have a smaller genome, because stem cells are equivalent to gametes (which are haploid) in that they can potentially create an entire individual
e. no; they have a smaller genome because stem cells express only a subset of genes
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USE IT
Different cells have different functions. Muscle cells contract because of the sliding action of actin and myosin proteins in muscle cells; a protein called retinal is important for the function of the light-detecting photoreceptor cells in the retina of the eye; helper T cells of the immune system have a protein on their surface called CD4 that participates in the immune response. From this information, complete the following table.
A woman has had a heart attack, and her heart muscle is damaged. What genes would a possible replacement cell have to express in order to begin to take over the function of cardiac muscle? For each gene, explain briefly why its expression would be important in this situation.
Driving Question 3
How do stem cells contribute to regenerative medicine, and how can we obtain or produce stem cells for this purpose?
By answering the questions below and studying Infographics 13.3, 13.5, 13.6, 13.7, and 13.8, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
Compare and contrast embryonic stem cells and somatic (that is, adult) stem cells in regard to at least two features.
An adult stem cell from bone marrow is most useful in treating
a. a heart attack.
b. a large burn on the upper thigh.
c. a disorder affecting the development of white blood cells.
d. a degenerative eye disease affecting the retina.
e. a degenerative nervous system disease such as Alzheimer disease.
USE IT
List and then describe some of the successes and challenges associated with using adult stem cells for stem cell therapy in comparison with embryonic stem cells.
MINI CASE
History was made in 2008 when a 30-year-old woman whose airway was severely damaged from tuberculosis was treated with an engineered trachea that was a perfect match. A trachea consists of a cartilage tube, chondrocytes (cells that help maintain the cartilage by producing proteins that make up cartilage), and an epithelial lining. Physicians used the following components in order to accomplish the procedure: an intact donor trachea (from a woman who had died from cardiac complications); the patient’s own bone marrow stem cells; and the patient’s own airway epithelial cells.
The engineered trachea was surgically implanted in the patient. She did not take any drugs to suppress her immune system, and after 3 months, she had normal airway function, no evidence of rejection of the engineered trachea, and a much improved quality of life.
From the information provided, describe the steps that the physicians must have followed in order to accomplish this successful procedure.
SOURCE: Macchiarini, P., et al. (2008) Clinical transplantation of a tissue-engineered airway. The Lancet 372:2023–2030.
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INTERPRETING DATA
Specific proteins expressed by specific cell types can be used as markers to both identify and isolate specific cell types from a population of cells. The table at the right provides a list of markers specifically associated with different cell types.
(i) A scientist has isolated a population of cells that express telomerase.
a. Can these cells differentiate into neurons? What marker would you look for to determine if they had differentiated into neurons?
b. Can these cells differentiate into white blood cells? What marker would you look for to determine if they had differentiated into white blood cells?
(ii) Experiments in mice have shown that hematopoietic stem cells can be coaxed out of the bone marrow and into the circulation and then differentiate into cardiac muscle in mice that have experienced a heart attack. What markers must the scientists have followed to confirm this result?
(iii) In the Mini Case of the engineered trachea (Question 16), what marker was most likely on the bone marrow stem cells isolated from the patient? What marker would the scientists have looked for to confirm that the cells were differentiating into cartilage cells?
BRING IT HOME
Your roommate’s best (dog) friend recently died. This beloved pet had been with your roommate since she was in the second grade, and she is very upset about the loss. She has stated that she is going to try and have her pet cloned. You have heard about cloning, and that many pets have been cloned. But you have also heard that cloning is controversial. You decide to do some research. What can you find out about the differences between reproductive and therapeutic cloning? Do you think that reproductive cloning should be allowed? Does your opinion differ for pets vs. humans?