This set of Biochemistry Multiple Choice Questions & Answers focuses on “Oncogenes, Tumor Suppressor Genes and Programmed Cell Death”.
1. Proto-oncogenes can be transformed to oncogenes by all of the following mechanisms except
a) Elimination of their start signals for translation
b) During a viral infection cycle
c) Chromosomal rearrangements
d) Chemically induced mutagenesis
e) Radiation induced mutation
Explanation: Elimination of their start signals cannot promote cancer.
2. Oncogenes do not encode for
a) Trans-membrane protein receptors
b) Growth factors
c) DNA-dependent RNA polymerase
d) Cytoplasmic G-proteins and protein kinases
Explanation: Oncogenes encode for RNA-dependent DNA polymerase.
3. Programmed cell death is termed as
d) Mitotic termination
Explanation: Apoptosis can also be termed as programmed cell death.
4. Which of the following could be coded by a tumor-supressor gene?
a) A protein that helps prevent progression through cell cycle
b) A protein that helps prevent apoptosis
c) A protein that codes for a DNA repair enzyme
d) A protein that forms part of a growth factor signaling pathway
Explanation: A protein that helps prevent progression through cell cycle could be coded by a tumor-supressor gene.
5. How does Ras oncogene contribute to cancers?
a) It codes for an anti-apoptotic protein, produced in abnormally large amounts
b) It codes for a GTPase switch protein, which in its mutated form cannot be switched off
c) It codes for a transcription factor produced abnormally in large amounts
d) A growth factor that is continually active is encoded in its truncated form
Explanation: Ras oncogene codes for a GTPase switch protein, which in its mutated form cannot be switched off.
6. Which property of p53 enables it to prevent the development of cancer?
a) It is a transcription factor that causes protein production which stimulates the cell cycle
b) It prevents replication of cells with damaged DNA
c) It prevents cells from triggering apoptosis
d) It stimulates synthesis of DNA repair enzymes that replace telomere sequence lost during cell division
Explanation: p53 prevents replication of cells with damaged DNA.
7. The characteristic of malignant other than a benign tumor is
a) Undergoes metastasis
b) Develops blood supply
c) Cell divides an unlimited number of times
d) Grows without needing a growth signal
Explanation: Only malignant tumor involves migration of cancerous cells from the site of origin to other areas.
8. The mutation which cannot give rise to an oncogene
a) Addition or deletion of a base producing a nonsense message and an inactive protein product
b) A point mutation changing just one amino acid in protein product
c) A translocation, putting gene under control of strong promoter producing over expression
d) A point mutation producing stop codon, premature termination
Explanation: Addition or deletion of a base producing a nonsense message and an inactive protein product cannot produce an oncogene.
9. Which of the following about Rb tumor suppressor protein is correct?
a) It binds E2F transcription factor and prevents cell from entering S phase until a mitogenic signal is received
b) It is activated when phosphorylated by Cdk
c) It is a transcription factor
d) When a mitogenic signal is received, it binds the transcription factor E2F and thus stimulates the cell to enter S phase
Explanation: Rb protein binds E2F transcription factor and prevents cell from entering S phase until a mitogenic signal is received.
10. Migration of cancerous cells from the site of origin to other part of the body forming secondary tumors is called
Explanation: Metastasis can be defined as migration of cancerous cells from the site of origin to other part of the body forming secondary tumors.
Sanfoundry Global Education & Learning Series – Biochemistry.
To practice all areas of Biochemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.