Question

The number of dipeptides possible with three different amino acids combined are

Short answer

The number of dipeptides possible is 9.

Step-by-step solution

Identify the Components

There are three different amino acids given. We'll name them as A, B, and C for simplicity.

Define a Dipeptide

A dipeptide consists of two amino acids linked together in a particular order. For example, one dipeptide could be AB, and another might be BA.

Determine Dipeptide Combinations

With three distinct amino acids (A, B, and C), each dipeptide can be formed in such a way that each position in the dipeptide can be filled by any of the three amino acids. Thus, the number of possible combinations is given by 3 choices for the first position and 3 choices for the second position.

Calculate Total Dipeptides

Multiply the number of choices for the first amino acid by the number of choices for the second amino acid. Therefore, the total number of dipeptides is: \[ 3 \times 3 = 9 \]

Key concepts

Dipeptide Combinations

When learning about peptides, a crucial part is understanding the variety of combinations possible, especially when you only have a small set of amino acids to work with. A dipeptide consists of exactly two amino acids connected in a specific sequence.
In our example, we have three amino acids, which we'll call A, B, and C. Each one can potentially pair with any other, including itself, to form a dipeptide. This means the sequence matters: AB is not the same as BA.

Here's how we calculate the number of possible dipeptide combinations:

• For the first position in the dipeptide, you can choose any of the three amino acids: A, B, or C.
• For the second position in the dipeptide, again, you have the same three choices: A, B, or C.

So, with 3 choices for the first position and 3 choices for the second, you multiply the two to find there are \( 3 \times 3 = 9 \) possible dipeptide combinations.
Understanding these combinations helps in comprehending how complex structures are created from simple building blocks.

Amino Acids

Amino acids are the building blocks of peptides and proteins. They are organic compounds made of an amine group, a carboxylic acid group, and a side chain that is unique to each amino acid.
There are 20 standard amino acids, but even a small subset of these, like our three (A, B, and C), can create a surprising diversity of compounds because of how they combine.

Key features of amino acids:

• Structure: Each amino acid has a central carbon atom known as the alpha carbon.
• Side Chain (R Group): This gives an amino acid its unique properties, like polarity or electrical charge.
• Polarity: Some amino acids are hydrophilic (water-loving), while others are hydrophobic (water-fearing).

These features not only define individual amino acids but determine how they interact with each other and with broader chemical structures, influencing how peptides and proteins fold and function in biological processes.

Chemical Bonding

At the heart of peptide formation is chemical bonding, specifically the peptide bond, which is crucial for connecting amino acids together. This bond is formed through a dehydration synthesis reaction.
During this reaction, the amine group of one amino acid bonds to the carboxylic acid group of another, releasing a molecule of water in the process.

Understanding the peptide bond:

• Peptide Bond Formation: This bond is an amide linkage that occurs between the nitrogen atom of the amine group of one amino acid and the carbon atom of the carboxylic group of another.
• Bond Stability: Peptide bonds are quite stable due to their resonance structure, which provides a degree of rigidity and planarity.
• Role in Proteins: These bonds are key in protein structure because they form the backbone of the protein's primary structure.

Appreciating these bonds is critical for understanding how complex molecular structures are built from simple units like amino acids, paving the way for more advanced studies in biochemistry and molecular biology.