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What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature?
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Solution
Cancer
Cancer is a disease caused by an uncontrolled division of the cells and usually their subsequent invasion into other body parts.
Contact inhibition
Contact inhibition is the property exhibited by the normal cells in which they inhibit their growth when they come in contact with other cells.
Cancer cells do not show contact inhibition and continue to divide.
Regulatory mechanisms
The process of cell division in normal cells has certain checkpoints or regulatory mechanisms whereas these regulatory mechanisms are lost in cancerous cells.
Response to death signals
Normal cells respond to death signals and undergo apoptosis while the cancerous cells do not do so.
Metastasis
Metastasis is not exhibited by normal cells while cancerous cells usually exhibit metastasis.
Molecular basis of transformation
Normal cells contain genes called proto-oncogenes which are the inactive genes of oncogenes (cancer-causing genes). Exposure to certain physical, chemical and biological agents drive mutations in those genes transforming them into oncogenes. These agents are collectively called mutagens.
Physical mutagens
Physical mutagens include temperature and radiation. Ultraviolet rays, gamma rays and X-rays induce mutation by breaking the bonds in DNA structure.
For example, UV rays cause thymine dimer formation that disturbs DNA double helix and affects DNA replication.
Chemical mutagens
Chemical mutagens include chemicals like nitrous acid that cause oxidative deamination on A, G and C bases which contain amino groups.
Arcidines and proflavins are very powerful mutages. These can intercalate between DNA bases and interfere with DNA replication.
Base analogues cause mispairing and eventually alter DNA sequences in the subsequent daughter strands produced.
Biological mutagens
Biological mutagens include viruses that enter host cells, induce mutation and replicate using the cell's machinery. Examples include oncoviruses.
Cancer is a disease caused by an uncontrolled division of the cells and usually their subsequent invasion into other body parts.
Contact inhibition
Contact inhibition is the property exhibited by the normal cells in which they inhibit their growth when they come in contact with other cells.
Cancer cells do not show contact inhibition and continue to divide.
Regulatory mechanisms
The process of cell division in normal cells has certain checkpoints or regulatory mechanisms whereas these regulatory mechanisms are lost in cancerous cells.
Response to death signals
Normal cells respond to death signals and undergo apoptosis while the cancerous cells do not do so.
Metastasis
Metastasis is not exhibited by normal cells while cancerous cells usually exhibit metastasis.
Molecular basis of transformation
Normal cells contain genes called proto-oncogenes which are the inactive genes of oncogenes (cancer-causing genes). Exposure to certain physical, chemical and biological agents drive mutations in those genes transforming them into oncogenes. These agents are collectively called mutagens.
Physical mutagens
Physical mutagens include temperature and radiation. Ultraviolet rays, gamma rays and X-rays induce mutation by breaking the bonds in DNA structure.
For example, UV rays cause thymine dimer formation that disturbs DNA double helix and affects DNA replication.
Chemical mutagens
Chemical mutagens include chemicals like nitrous acid that cause oxidative deamination on A, G and C bases which contain amino groups.
Arcidines and proflavins are very powerful mutages. These can intercalate between DNA bases and interfere with DNA replication.
Base analogues cause mispairing and eventually alter DNA sequences in the subsequent daughter strands produced.
Biological mutagens
Biological mutagens include viruses that enter host cells, induce mutation and replicate using the cell's machinery. Examples include oncoviruses.
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