All questions of Biomolecules for NEET Exam

In humans, arginine is classified as a semiessential or conditionally essential amino acid, depending on the developmental stage and health status of the individual. Preterm infants are unable to synthesize or create arginine internally, making the amino acid nutritionally essential for them.

The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O. group of the amino acid located three or four residues earlier along the protein sequence.

The active form of vitamin D is calcitriol.

Calcitriol, also known as 1,25-dihydroxyvitamin D3, is the active form of vitamin D in the body. It is the biologically active metabolite that is synthesized from calcidiol, also known as 25-hydroxyvitamin D3, which is the storage form of vitamin D.

Explanation:

1. Vitamin D and its forms:
Vitamin D is a fat-soluble vitamin that plays a crucial role in maintaining bone health and calcium homeostasis. It exists in several forms, including vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), which are obtained from dietary sources or synthesized in the skin upon exposure to sunlight.

2. Conversion of vitamin D to its active form:
When vitamin D2 or D3 is ingested or synthesized, it undergoes a series of metabolic conversions in the liver and kidneys to become the active form of vitamin D. The first step involves hydroxylation in the liver, where vitamin D is converted to calcidiol (25-hydroxyvitamin D3) through the action of the enzyme 25-hydroxylase.

3. Activation of calcidiol to calcitriol:
The second and final step in the activation of vitamin D occurs in the kidneys. Calcidiol undergoes further hydroxylation by the enzyme 1-alpha-hydroxylase, resulting in the formation of calcitriol (1,25-dihydroxyvitamin D3). This conversion is tightly regulated by various factors, including parathyroid hormone (PTH), calcium levels, and phosphate levels.

4. Biological functions of calcitriol:
Calcitriol acts as a hormone and binds to the vitamin D receptor (VDR) in target tissues, such as the intestines, bones, and kidneys. It regulates the absorption of calcium and phosphate in the intestines, promotes bone mineralization by increasing calcium and phosphate uptake, and helps maintain normal blood calcium levels. Calcitriol also has non-skeletal functions, including modulation of immune responses and cell growth.

Conclusion:
In conclusion, the active form of vitamin D is calcitriol, which is synthesized from calcidiol through the action of 1-alpha-hydroxylase in the kidneys. Calcitriol plays a crucial role in maintaining calcium homeostasis and bone health, as well as other physiological processes in the body.

Because mRNA is called messanger RNA, which carries the information from DNA to synthesis of protein and other essential products in cell.

DNA TO DNA - replication
DNA TO RNA-transcription
RNA TO PROTEIN-translation

Purine is a type of nitrogenous base found in DNA and RNA molecules. The purine bases are adenine and guanine. Among the given options, the purine derivative is:

c) Guanine

Explanation:

- Purine and pyrimidine are two types of nitrogenous bases found in DNA and RNA molecules.
- Purine bases are larger and have a double-ring structure, while pyrimidine bases are smaller and have a single-ring structure.
- Adenine and guanine are purine bases, while cytosine, thymine, and uracil are pyrimidine bases.
- Therefore, among the given options, the purine derivative is guanine.

The structure of nucleotide and nucleoside units are distinguished primarily by the presence (or lack thereof) of this phosphate group. Deoxyribose in DNA differs from the ribose found in RNA in that it has only a hydrogen atom in the same position that ribose has a hydroxyl (-OH) group.

Lactose intolerance is the inability to break down a type of natural sugar called lactose. Lactose is commonly found in dairy products, such as milk and yogurt. A person becomes lactose intolerant when his or her small intestine stops making enough of the enzyme lactase to digest and break down the lactose.

Hydrolysis of sucrose is inversion because the angle of specific rotation of the plane polarized light changes from positive to negative value due to the presence of optical isomers of mixture of glucose and fructose sugar...

Proteins are polymers of amino acids therefore their hydrolysis gives amino acids

Uracil is not found in DNA , as it Uracil has more base pair affinity to adenine , guanine and cytosine. Instead thymine is present in DNA.

It forms glucose pentaacetate. The acetic anhydride esterifies with all the alcohol groups on the glucose ring.

Yes. option a is correct as enzymes are proteins and contain amino acids and the correct option is only they have optimum activity at body temperature... hope you got it...

Alpha helix in secondary structure.

All sacchrides /carbohydrates form glycosidic bond by eliminating water molecule

Glucose and C2 of fructose, which does not have a free aldehyde or ketone group to undergo oxidation and reduction reactions.
c)Sucrose does not react with Benedict's reagent, which is used to detect the presence of reducing sugars.
d)Sucrose cannot be hydrolyzed by acid or enzyme into its constituent monosaccharides.

Non-reducing sugars do not have an OH group attached to the anomeric carbon so they cannot reduce other compounds. All monosaccharides such as glucose are reducing sugars. A disaccharide can be a reducing sugar or a non-reducing sugar. Maltose and lactose are reducing sugars, while sucrose is a non-reducing sugar.

Because it is in the ratio of 1:2:1

In lysine,the amino group is attached to alpha carbon which makes it Alpha amino acid and it has more amino groups as compared to -COOH groups ,thus basic . so, op A,B.

Explanation:
Purine bases:
Purine bases are nitrogen-containing molecules that are formed by a pyrimidine ring fused to an imidazole ring. The purine bases are guanine and adenine.

Pyrimidine bases:
Pyrimidine bases consist of a single ring structure and include thymine, cytosine, and uracil.

Answer:
Therefore, the correct answer is option A and B, which are guanine and adenine. These bases are found in DNA and RNA and are important for the genetic code. Thymine is a pyrimidine base found only in DNA, while uracil is a pyrimidine base found only in RNA.

Amylopectin and glycogen

Ans - because in this case both are counted in Right Side (glucose in "a" & fructose in "b") but only single in figure fructose always counted in left side & glucose right side.

A peptide bond is formed (-CONH) between the –NH2 group and the –COOH group of any two adjacent amino acids and it leads to the elimination of a water molecule. The resultant product formed is an amide.

It is called invert sugar because the angle of the specific rotation of the plain polarized light changes from a positive to a negative value due to the presence of the optical isomers of the mixture of glucose and fructosesugars.

Yes biuret is a blue solution,when it reacts with protein ,its color become pink - purple. molish test & Benedict both are for carbohydrate where as beilstein is for halides

B)3

Polypeptide is the correct answer.

Explanation:

When more than ten amino acids react, the product formed is called a polypeptide. A polypeptide is a chain of amino acids joined together by peptide bonds. Peptide bonds are formed through a condensation reaction between the carboxyl group of one amino acid and the amino group of another amino acid, resulting in the release of a water molecule.

Key points:
- Polypeptides are formed by the polymerization of amino acids.
- Amino acids are organic compounds that contain an amino group (-NH2) and a carboxyl group (-COOH) attached to a central carbon atom.
- There are 20 different types of amino acids that can be found in proteins, each with a unique side chain or R-group.
- The order and sequence of amino acids in a polypeptide chain determine the structure and function of the protein.
- Polypeptides can vary in length, ranging from just a few amino acids to thousands of amino acids in length.
- Polypeptides can fold into specific three-dimensional structures, such as alpha helices and beta sheets, which are stabilized by various types of interactions between amino acid side chains.
- These folded structures are critical for the proper functioning of proteins and can determine their enzymatic activity, binding specificity, and overall stability.
- Polypeptides can also undergo post-translational modifications, such as phosphorylation or glycosylation, which can further modify their structure and function.
- Polypeptides can interact with other molecules, such as other polypeptides or small molecules, to form larger protein complexes or perform specific biological functions.
- Polypeptides are an essential component of all living organisms and play critical roles in processes such as metabolism, signaling, and immune response.

In conclusion, when more than ten amino acids react, the product formed is called a polypeptide, which is a chain of amino acids joined together by peptide bonds. Polypeptides are the building blocks of proteins and are essential for the structure and function of biological systems.

It shows that glucose exists as n-hexane...i.e. it has straight linear chain...