In which of the following is nitrogen not present?
Fats
Understanding Nitrogen in Biological Molecules
The question asks us to identify which of the given options does not contain the element nitrogen. Nitrogen is a crucial element found in many organic molecules essential for life, but it is not present in all classes of biological compounds.
Analyzing Each Option
Let's look at the chemical composition of each option provided:
- Proteins: Proteins are complex molecules made up of smaller units called amino acids. Amino acids have a central carbon atom bonded to an amino group ($\text{NH}_2$), a carboxyl group ($\text{COOH}$), a hydrogen atom, and a side chain (R group). The amino group ($\text{NH}_2$) contains nitrogen. Therefore, proteins always contain nitrogen.
- Fats: Fats, also known as lipids, are primarily composed of glycerol and fatty acids. These molecules are mainly made up of carbon (C), hydrogen (H), and oxygen (O) atoms. The basic structure of fats (triglycerides) does not include nitrogen. While some complex lipids might be associated with other molecules, the core fat structure is nitrogen-free.
- Vitamin B-6: Vitamin B-6 is a water-soluble vitamin that includes several related compounds like pyridoxine, pyridoxal, and pyridoxamine. The chemical structure of Vitamin B-6 contains a pyridine ring, which is a six-membered ring containing one nitrogen atom. Therefore, Vitamin B-6 contains nitrogen.
Comparison of Nitrogen Content
We can summarize the presence of nitrogen in these substances in a table:
| Substance | Contains Nitrogen? | Reason |
|---|---|---|
| Proteins | Yes | Composed of amino acids, which contain an amino ($\text{NH}_2$) group. |
| Fats | No | Primarily composed of carbon, hydrogen, and oxygen in fatty acids and glycerol structure. |
| Vitamin B-6 | Yes | Contains a nitrogen atom in its pyridine ring structure. |
Based on this analysis, fats are the only option among the choices that do not contain nitrogen as a fundamental part of their chemical structure.
Revision Table: Essential Biological Molecules
Here's a quick look at the main classes of biological molecules and key elements they contain:
| Class of Molecule | Primary Elements | Nitrogen Present? |
|---|---|---|
| Carbohydrates (Sugars, Starches) | C, H, O | Generally No (unless modified, e.g., amino sugars) |
| Lipids (Fats, Oils, Steroids) | C, H, O | Generally No (unless complex lipids with other groups) |
| Proteins | C, H, O, N, S (sometimes) | Always Yes |
| Nucleic Acids (DNA, RNA) | C, H, O, N, P | Always Yes (in nucleotide bases) |
Additional Information: Nitrogen's Role in Biology
Nitrogen is a vital element for life and is a key component of many important biological molecules. Besides proteins and Vitamin B-6, nitrogen is found in:
- Nucleic Acids: The building blocks of DNA and RNA, called nucleotides, contain nitrogenous bases (Adenine, Guanine, Cytosine, Thymine, Uracil).
- Some Vitamins: Besides Vitamin B-6, other B vitamins like Riboflavin (B-2), Niacin (B-3), Folic Acid (B-9), and Cobalamin (B-12) also contain nitrogen.
- Neurotransmitters: Many neurotransmitters, such as serotonin and dopamine, contain nitrogen.
- Hormones: Some hormones, like peptide hormones, are proteins or derived from amino acids and thus contain nitrogen.
- Urea: A nitrogen-containing compound produced in the liver and excreted by the kidneys as a waste product of protein metabolism.
Understanding which molecules contain nitrogen is fundamental in biochemistry and nutrition.
Important Questions from Zoology
Which of the following is not a rich source of protein?
Animal with backbone is :
If you take on a tour of children in the northern part of this state and ask them to select the correct statements about elephant herd. What will be their likely reply?
(a) An elephant herd has mainly females and baby elephants upto 14 - 15 years old.
(b) An elephant herd comprises members of a particular family.
(c) An elephant herd may accommodate any number of female elephants and young ones.
(d) The oldest female is the leader of the herd.
Pashmina is a fine type of wool which were first woven in which state of India?
Which of the following is a type of protecting tissue in an animal body?
