Question 1

DNA damage may result in all of the following EXCEPT
A)Increased activation of ATM.
B)Increased activation of Chk1/Chk2.
C)Increased levels of p53 protein.
D)DNA double strand breaks.
E)Ubiquitylation of p53.

Accepted Answer

DNA damage typically results in increased activation of ATM (a protein kinase that responds to DNA damage), increased activation of Chk1/Chk2 (checkpoint kinases that also respond to DNA damage), increased levels of p53 protein (a tumor suppressor protein that plays a key role in response to DNA damage), and can cause DNA double strand breaks. However, ubiquitylation of p53, which is a process that tags p53 for degradation, is not a direct result of DNA damage. Instead, DNA damage usually leads to stabilization and activation of p53, not its ubiquitylation and degradation.

Question 2

The process of formation of new blood vessels is called
A)Leukemogenesis.
B)Hematopoiesis.
C)Vasculogenesis.
D)Thrombopoiesis.
E)Angiogenesis.

Accepted Answer

Angiogenesis is the process of formation of new blood vessels. It is a key process in both normal development and also in the growth and spread of cancer.

Question 3

Which of the following results in an increase in the levels of p53 protein?
A)Oncogenic signaling
B)UV radiation
C)Ionizing radiation
D)Hypoxia
E)All of the above

Accepted Answer

All of the above (oncogenic signaling, UV radiation, ionizing radiation, and hypoxia) can result in an increase in the levels of p53 protein. p53 is a tumor suppressor protein that is activated by stress signals such as DNA damage, hypoxia, and oncogenic signaling. Its activation leads to an increase in its levels, which in turn triggers various cellular responses such as cell cycle arrest, DNA repair, or apoptosis, depending on the nature and severity of the stress signal. Therefore, different stress signals can activate p53 and result in an increase in its levels.

Question 4

Increased expression of MDM2 may result in
A)Increased expression of p53.
B)Apoptosis.
C)Cell cycle arrest.
D)Degradation of p53.
E)Senescence.

Accepted Answer

MDM2 is a negative regulator of p53 and promotes its degradation. Increased expression of MDM2 would result in increased degradation of p53, leading to decreased cell cycle arrest, apoptosis, and senescence.

Question 5

An irreversible arrest in the cell cycle resulting in a viable but nongrowing state is known as
A)The arrest point.
B)Senescence.
C)Quiescence.
D)Inactivation.
E)Involution.

Accepted Answer

Senescence is an irreversible arrest in the cell cycle resulting in a viable but nongrowing state. The other options are not accurate descriptions of senescence.

Question 6

The cell's latent suicide program,resulting in rapid cell death,is called
A)Apoptosis.
B)Necrosis.
C)Eradication.
D)Ischemia.
E)Caspase.

Accepted Answer

Apoptosis is the programmed cell death process that occurs in response to various stimuli, such as cell damage or stress. This process is regulated by specific genes and involves the activation of enzymes called caspases, which break down the cell's components and result in rapid cell death. Necrosis, on the other hand, is an uncontrolled form of cell death that occurs as a result of injury or infection. Eradication and ischemia are not related to programmed cell death. Caspase is an enzyme that plays a role in apoptosis but is not the name of the cell death program itself.

Question 7

p53 signaling may result in all of the following EXCEPT
A)Apoptosis.
B)Senescence.
C)Angiogenesis.
D)DNA repair.
E)Cytostatic response.

Accepted Answer

p53 signaling inhibits angiogenesis rather than promoting it.

Question 8

Which of the following proteins may INHIBIT apoptosis?
A)Bcl-2
B)Caspase-9
C)Lamin
D)Apaf-1
E)Noxa

Accepted Answer

Bcl-2 is a well-known anti-apoptotic protein that can inhibit the intrinsic pathway of apoptosis by blocking the release of cytochrome c from the mitochondria and preventing the activation of caspases.

Question 9

Which of the following scenarios will NOT result in an increase in apoptotic activity?
A)Overexpression of Noxa
B)Inhibition of Bcl-2 signaling
C)Phosphorylation of Bim
D)Activation of caspase-9
E)Flux in cellular calcium levels

Accepted Answer

Phosphorylation of Bim often leads to its inactivation or degradation, which would not increase apoptotic activity but rather decrease it, as Bim is a pro-apoptotic BH3-only protein that promotes apoptosis when active.

Question 10

Which of the following types of p53 mutations would be MOST beneficial to a tumor cell?
A)Splice site change.
B)Premature stop codon.
C)Silent mutation.
D)Frameshift.
E)Missense mutation.

Accepted Answer

A missense mutation alters one amino acid in the p53 protein, which may affect its function but not necessarily completely eliminate it. This can lead to the production of a mutant protein with a gain-of-function activity that promotes cell proliferation and survival, while retaining some of the wild-type p53 tumor suppressor activity. This is known as a dominant-negative effect and is thought to be important in the development and progression of many tumors. Thus, a missense mutation would be most beneficial to a tumor cell.

Question 11

Which of the following is NOT true of p53?
A)Most tumor-associated p53 mutations are the result of nonsense codons.
B)p53 is mutated in over 30-50% of all cancers.
C)Normal p53 functions as a "tumor suppressor."
D)Mice lacking p53 are viable.
E)Exposure to UV radiation results in increased expression of p53.

Accepted Answer

Most tumor-associated p53 mutations are missense mutations or deletions/insertions. Nonsense codons may result in truncated, nonfunctional p53 protein, but they are not the most common mutation type.

Question 12

Apoptotic cell death can be induced by
A)p53 signaling.
B)Signaling from surface cell death receptors.
C)Extracellular stresses.
D)A,B,and C.
E)None of the above.

Accepted Answer

Apoptotic cell death can be induced by multiple factors, including p53 signaling, signaling from surface cell death receptors, and extracellular stresses. Therefore, choice D (A,B,and C) is the best answer. Choice E (None of the above) is incorrect because apoptotic cell death can be induced by the factors listed in choices A, B, and C.

Question 13

Release of cytochrome c from the mitochondrial membrane is stimulated by A)Bcl-2 and Bcl-X_L. B)Bax and Bad. C)Bcl-W and Mcl-1. D)Caspase-9. E)None of the above.

Accepted Answer

Bax and Bad are pro-apoptotic members of the Bcl-2 family that promote the release of cytochrome c from the mitochondria, initiating the apoptotic cascade.

Question 14

The p14^ARF protein may be activated in response to all of the following EXCEPT A)Ras signaling. B)Increased levels of E1A. C)Decreased activity of E2F transcription factors. D)C-Myc signaling. E)None of the above.

Accepted Answer

The question asks for the exception, so we need to find the answer that does not activate the p14^ARF protein. Options A, B, and D are all known to activate p14^ARF protein, whereas option C suggests decreased activity of E2F transcription factors. Therefore, option C is the exception and does not activate the p14^ARF protein.

Question 15

Which of the following proteins has a BH4 domain?
A)Bax
B)Bid
C)Puma
D)Bcl-2
E)Hrk

Accepted Answer

The BH4 domain is a characteristic domain of some proteins that are part of the Bcl-2 family, which are involved in the regulation of apoptosis. Among the options given, Bcl-2 is the correct answer because it is known to contain the BH4 domain, which is crucial for its anti-apoptotic function.

Question 16

Which of the following types of alterations would NOT promote tumorigenesis?
A)Overexpression of MDM2
B)Overexpression of Bak
C)Overexpression of Bcl-2
D)Defective Chk2 kinase signaling
E)Increased activation of PI3K

Accepted Answer

Overexpression of Bak, a pro-apoptotic protein, would not promote tumorigenesis. In fact, it would likely have the opposite effect by inducing apoptosis in cancer cells. The other options listed are alterations that have been associated with promoting tumorigenesis.

Quiz 9: P53 and Apoptosis: Master Guardian and Executioner

DNA damage may result in all of the following EXCEPT

The process of formation of new blood vessels is called

Which of the following results in an increase in the levels of p53 protein?

Increased expression of MDM2 may result in

An irreversible arrest in the cell cycle resulting in a viable but nongrowing state is known as

The cell's latent suicide program,resulting in rapid cell death,is called

p53 signaling may result in all of the following EXCEPT

Which of the following proteins may INHIBIT apoptosis?

Which of the following scenarios will NOT result in an increase in apoptotic activity?

Which of the following types of p53 mutations would be MOST beneficial to a tumor cell?

Which of the following is NOT true of p53?

Apoptotic cell death can be induced by

Release of cytochrome c from the mitochondrial membrane is stimulated by

The p14ARF protein may be activated in response to all of the following EXCEPT

Which of the following proteins has a BH4 domain?

Which of the following types of alterations would NOT promote tumorigenesis?

The p14^ARF protein may be activated in response to all of the following EXCEPT