Deck 19: Cell Death and Cell Renewal

Question 1

Humans possess about _______ different cell types.

A) 100
B) 200
C) 500
D) 1,000

Answer 1

B

Question 2

In adult organisms, cell death must be balanced by cell

A) elongation.
B) differentiation.
C) renewal.
D) migration.

Answer 2

C

Question 3

Most cells in adult animals are in the _______ stage of the cell cycle.

A) G₀
B) G₁
C) G₂
D) S

Answer 3

A

Question 4

Fibroblasts are stimulated to exit G₀ and proliferate by _______ growth factor.

A) fibroblast
B) platelet-derived
C) epithelial
D) stem cell

Question 5

Which of the following adult cell types is arrested in G₀?

A) Fibroblasts
B) Endothelial cells
C) Liver cells
D) All of the above

Question 6

VEGF is secreted by

A) cells deprived of oxygen.
B) injured endothelial cells.
C) injured smooth muscle cells.
D) platelets.

Question 7

Which of the following is not a key property of stem cells in tissues?

A) Dividing to produce one daughter cell that remains a stem cell
B) Dividing to produce one cell that then differentiates
C) Exhibiting self-renewal
D) Dividing within each tissue to maintain a set number of cells

Question 8

A hematopoietic stem cell may give rise to which of the following differentiated cells?

A) Erythrocytes
B) Macrophages
C) Granulocytes
D) All of the above

Question 9

Which of the following signaling pathways is not important to stem cell physiology?

A) Wnt
B) Notch
C) TGF-β
D) Bax

Question 10

Hematopoietic stem cells can give rise to

A) erythrocytes.
B) erythrocytes and lymphocytes.
C) all blood cells and macrophages.
D) all blood cells, macrophages, and skin cells.

Question 11

Intestinal stem cells may give rise to all of the following terminally differentiated cell types in the intestinal epithelium except _______ cells.

A) absorptive epithelial
B) goblet
C) transit-amplifying
D) enteroendocrine

Question 12

Intestinal epithelial stem cells are located _______ the crypt.

A) at the top of
B) at the bottom of
C) at the sides of
D) throughout

Question 13

When stem cells of the intestinal epithelium and epidermis divide, they give rise to two different cells: one stem cell and one _______ cell.

A) goblet
B) crypt
C) G₀
D) transit-amplifying

Question 14

The stem cells of skeletal muscle are called

A) myoblasts.
B) myocytes.
C) satellite cells.
D) myo-stem cells.

Question 15

Mammalian embryonic stem cells are cultured from cells taken from

A) the four-cell embryo.
B) the inner cell mass.
C) trophoblast cells.
D) amnion cells.

Question 16

Of the offspring that result from the reproductive cloning of mammals by somatic nuclear transfer, _______% are viable.

A) 1-2
B) 10
C) 15-20
D) 25

Question 17

In 2006, Takahashi and Yamanaka demonstrated that somatic cells can be reprogrammed or converted into induced pluripotent stem cells. Subsequent studies in _______ showed that these cells, like embryonic stem cells, are capable of differentiating into virtually all cells.

A) mice
B) rats
C) chimpanzees
D) humans

Question 18

Early experiments by Takahashi and Yamanaka showed that a set of four genes introduced by retroviral expression are capable of transforming somatic cells into induced pluripotent stem cells. The four proteins encoded by these genes were all

A) G-protein coupled receptors.
B) transcription factors.
C) tyrosine kinases.
D) calcium-binding proteins.

Question 19

Which of the following transcription factors has the potential to act as an oncogene, resulting in a high risk of cancer?

A) Oct4
B) Sox2
C) Klf4
D) c-Myc

Question 20

Which of the following are the three core transcription factors that can reprogram adult somatic cells into induced pluripotent cells?

A) Sox2, Oct4, and Nanog
B) Sox2, Oct4, and Hedgehog
C) Oct4, c-Myc, and Klf4
D) Sox2, c-Myc, and Nanog

Question 21

The reprogramming of somatic cells into other types of differentiated cells (other than induced pluripotent stem cells) is referred to as

A) transduction.
B) transfection.
C) transdifferentiation.
D) translocation.

Question 22

Using approaches similar to those of Takahashi and Yamanaka, scientists have now reprogrammed adult fibroblasts to become

A) heart muscle cells.
B) platelets.
C) red blood cells.
D) adipocytes.

Question 23

The distinct series of changes that characterizes programmed cell death is called

A) necrosis.
B) apoptosis.
C) sepsis.
D) execution.

Question 24

During development, 50% of neurons die; those that survive are those that

A) generated axons.
B) received epithelial growth factor.
C) made correct connections with their target cells.
D) did not receive an extracellular cell death signal.

Question 25

Which of the following events is not part of apoptosis?

A) Fragmenting of chromosomal DNA
B) Fragmenting of the nucleus
C) Fragmenting of the cell
D) Lysis of cell fragments and release of their contents

Question 26

Cells that die as the result of acute injury undergo

A) lysis.
B) sepsis.
C) apoptosis.
D) execution.

Question 27

Apoptotic cells produce "eat me" signals, which include _______ of cell surface _______.

A) loss; carbohydrates
B) loss; phosphatidylserines
C) gain; phosphatidylserines
D) gain; phosphatidylethanolamines

Question 28

The gene ced-3 of C. elegans codes for a proteolytic enzyme that is a

A) serine protease.
B) chymotrypsin.
C) ubiquitin-targeted protease.
D) caspase.

Question 29

Ced-9 functions directly to

A) inhibit Ced-3.
B) inhibit Ced-4.
C) stimulate Ced-3.
D) stimulate Ced-4.

Question 30

An apoptosome is a complex containing multiple subunits of

A) Apaf-1.
B) Apaf-1 and caspase-9.
C) Apaf-1 and caspase-3.
D) Apaf-1, caspase-9, and cytochrome c.

Question 31

Effector caspases cleave

A) nuclear lamins.
B) cytoskeletal proteins.
C) DNase inhibitor.
D) All of the above

Question 32

Members of the Bcl-2 family of proteins are

A) all caspases.
B) either antiapoptotic or proapoptotic.
C) all antiapoptotic.
D) all proapoptotic.

Question 33

Bax and Bak act by

A) interacting with Apaf-1 to initiate a proapoptotic signal.
B) interacting with Ced-9 to initiate a proapoptotic signal.
C) oligomerizing in the mitochondrial outer membrane, forming pores that release cytochrome c.
D) oligomerizing with Apaf-1 to block an apoptotic signal.

Question 34

Many stimuli that trigger cell death release the molecule _______ from the intermembrane space of mitochondria so they can bind to Apaf-1.

A) cytochrome c
B) citric acid
C) ubiquinone
D) ATP synthase

Question 35

The key protein involved in "deciding" whether a cell with DNA damage should delay its cell cycle or undergo apoptosis is

A) Akt.
B) pRB.
C) p53.
D) p15.

Question 36

A major pathway that signals cell survival and inhibits cell death is the _______ pathway.

A) PI 3-kinase/Akt
B) Hedgehog
C) TNF
D) Wnt

Question 37

Which of the following is not phosphorylated by Akt?

A) PI 3-kinase
B) p53
C) FOXO
D) Bad

Question 38

Following injury or exercise, _______ cells become activated and repair damaged skeletal muscle.

Question 39

Mouse embryonic stem cells were first cultured from _______.

Question 40

With the birth of _______, Wilmut and colleagues became the first scientists to produce a successfully cloned mammal by somatic cell nuclear transfer.

Question 41

Genes for regulation and execution of programmed cell death, or _______, were originally discovered in C. elegans.

Question 42

In addition to cytochrome c, other proapoptotic factors are released from _______.

Question 43

The two proapoptotic proteins that enable the release of cytochrome c from the mitochondria are _______ and _______.

Question 44

If the gene _______ is mutated in C. elegans so that it does not function, no cells will die during development.

Question 45

Cell death in cancer cells can be caused by the cytokine _______.

Question 46

Most differentiated cell types do not themselves proliferate, but they can be replaced by the proliferation of stem cells.

Question 47

Liver cell injury induces proliferation of liver stem cells.

Question 48

Injured muscle cells regenerate by division of muscle fibers to form myoblasts that proliferate and fuse to form new muscle fibers.

Question 49

Satellite cells are located beneath the basal lamina of muscle fibers.

Question 50

Each of the three cell types in the adult intestinal epithelium is derived from a different stem cell.

Question 51

Goblet cells and enteroendocrine cells have the same stem cells as absorptive epithelial cells.

Question 52

The clinical application of adult stem cells is limited by difficulties in isolating and culturing the appropriate stem cell populations.

Question 53

It is relatively easy to isolate and propagate embryonic stem cells.

Question 54

If reintroduced into early embryos, embryonic stem cells can give rise to cells in all tissues of a mouse.

Question 55

Reproductive cloning of humans raises ethical concerns.

Question 56

Programmed cell death plays an important role in development.

Question 57

Most tissues maintain a balance between cell proliferation and cell death.

Question 58

As a causal factor in the development of tumors, the inability of cancer cells to undergo apoptosis is as significant as their uncontrolled proliferation.

Question 59

A mutant bcl-2 gene can be an oncogene.

Question 60

In normal, nonapoptotic cells, antiapoptotic members of the Bcl-2 protein family bind to proapoptotic members and inhibit their activity.

Question 61

Provide three examples of adult human cells that are typically in G₀ but can proliferate when stimulated.

Question 62

Provide three examples of normal human cells that, in their fully differentiated form, can no longer proliferate but can be replaced by means of stem cell proliferation and differentiation.

Question 63

When two-thirds of the liver of a rat is cut away, what happens to the remaining cells?

Question 64

Define a stem cell.

Question 65

What do skeletal muscle stem cells do when activated?

Question 66

Why are skin, hair, intestinal epithelia, and blood cells particularly problematic areas after radiation exposure or chemotherapy for cancer?

Question 67

What is the advantage of using skin grafts derived from the patient's own stem cells, as opposed to cells derived from a donor?

Question 68

Which human disease could potentially be cured with stem cell transplantation therapy?

Question 69

How do embryonic stem cells differ from adult stem cells?

Question 70

How can the toxic effect of high-level chemotherapy on the hematopoietic system be repaired?

Question 71

How can embryonic stem cells be directed to differentiate along specific pathways?

Question 72

What mammalian species was the first to be cloned from an adult nucleus transplanted into an oocyte cytoplasm?

Question 73

What is the difference between reproductive and therapeutic cloning?

Question 74

What observation in C. elegans suggested that cell death occurs as a specific developmental fate?

Question 75

In multicellular organisms, why is apoptosis not problematic, whereas cell death after acute injury is?

Question 76

What is the difference between an initiator caspase and an effector caspase?

Question 77

Why are cells with damaged genomes dangerous and often destroyed?

Question 78

What determines whether DNA damage to a given cell will result in cell cycle delay or apoptosis?

Question 79

How does tumor necrosis factor (TNF) trigger apoptosis?

Question 80

Name two types of cells, other than cancer cells, that are killed by tumor necrosis factor (TNF).