In a protein molecule various amino acids are linked together by

Options

A. `beta`-glycosidic bond
B. peptide bond
C. dative bond
D. `alpha`-glycosidic bond

Explanation

To answer the question "In a protein molecule, various amino acids are linked together by," we will go through the following steps:

### Step 1: Understand the Structure of Amino Acids
Amino acids are the building blocks of proteins. Each amino acid contains two functional groups: an amino group (-NH2) and a carboxyl group (-COOH).

**Hint:** Remember the basic structure of an amino acid, which includes an amine and a carboxylic acid.

### Step 2: Linking Amino Acids Together
When two amino acids come together, a chemical reaction occurs between the carboxyl group of one amino acid and the amino group of another. This reaction results in the formation of a covalent bond.

**Hint:** Focus on the functional groups involved in the reaction when amino acids link together.

### Step 3: Formation of Water
During the linkage of two amino acids, a molecule of water (H2O) is removed. This process is known as a condensation reaction or dehydration synthesis.

**Hint:** Consider what happens to the components of the amino acids during the bonding process.

### Step 4: Identify the Type of Bond Formed
The bond formed between the two amino acids is called a peptide bond. This bond is specifically an amide bond, which is formed between the carbon atom of the carboxyl group of one amino acid and the nitrogen atom of the amino group of another.

**Hint:** Recall the name of the bond formed specifically between amino acids in proteins.

### Step 5: Conclusion
Thus, in a protein molecule, various amino acids are linked together by peptide bonds.

**Final Answer:** The correct option is **peptide bond**.

### Summary of Steps:
1. Understand the structure of amino acids.
2. Learn how amino acids link together.
3. Recognize the formation of water during the reaction.
4. Identify the bond formed as a peptide bond.
5. Conclude with the answer.