Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Benzene and polynuclear aromatic hydrocarbons (PAHs) containing more than two benzene rings fused together possess toxic and carcinogenic (cancer-producing) properties.
These compounds are formed during the incomplete combustion of organic substances like tobacco, coal, and petroleum.
When these hydrocarbons enter the human body, they undergo various biochemical reactions and are converted into reactive metabolites.
The reactive metabolites (such as epoxides) bind covalently to , leading to mutations and causing the uncontrolled growth of cells, which results in cancer.
Examples of carcinogenic hydrocarbons include -Benzpyrene, -Dimethylbenzanthracene, -Methylcholanthrene, and -Benzanthracene.
📐Formulae
💡Examples
Problem 1:
Why are polynuclear aromatic hydrocarbons like -Benzpyrene considered harmful to human health?
Solution:
They are considered harmful because they are carcinogenic. In the human body, they are metabolized into reactive intermediates that react with .
Explanation:
These reactive species form covalent bonds with the nitrogenous bases of . This damage to the genetic material interferes with normal cell regulation, leading to the development of malignant tumors.
Problem 2:
Identify the conditions under which carcinogenic polynuclear hydrocarbons are typically formed.
Solution:
Explanation:
When fuels like coal or tobacco do not have enough oxygen to burn completely, the carbon atoms rearrange into stable, fused-ring aromatic structures which are toxic and carcinogenic.