Question

Write the sequence of all possible tetrapeptides composed of the following amino acids. a. two phenylalanines and two glycines b. two phenylalanines, glycine, and alanine

Short answer

a. Possible tetrapeptides with two phenylalanines and two glycines: 1. FFGG 2. FGFG 3. FGGF 4. GFFG 5. GFGF 6. GGFF b. Possible tetrapeptides with two phenylalanines, one glycine, and one alanine: 1. FFGA 2. FGAf 3. FAGF 4. FGAF 5. FAfg 6. GFAF 7. GAFF 8. GfAF 9. AGFF 10. AFGF 11. AGfF 12. GgAF

Step-by-step solution

Identify the amino acids

We are given two phenylalanines (F) and two glycines (G) to form tetrapeptides.

Calculate the number of possible arrangements

Since we have two each of phenylalanines and glycines, there are 4!/(2!2!) possible arrangements.

List all possible arrangements

Now we will list all the possible tetrapeptides: 1. FFGG 2. FGFG 3. FGGF 4. GFFG 5. GFGF 6. GGFF b. Two phenylalanines, one glycine, and one alanine

Identify the amino acids

We are given two phenylalanines (F), one glycine (G), and one alanine (A) to form tetrapeptides.

Calculate the number of possible arrangements

Since we have two phenylalanines, one glycine, and one alanine, there are 4!/(2!) possible arrangements.

List all possible arrangements

Now we will list all the possible tetrapeptides: 1. FFGA 2. FGFa 3. FAGF 4. FGAF 5. FAfg 6. GFAF 7. GAFF 8. GFaf 9. AGFF 10. AFGF 11. AGfF 12. GgAF

Key concepts

Amino Acids

Amino acids are organic molecules that form the building blocks of proteins. They are essential for various biological processes in living organisms. Amino acids typically consist of a central carbon atom, an amino group \((-NH_2)\), a carboxylic acid group \((-COOH)\), a hydrogen atom, and a distinct side chain represented as \(R\). The side chain is what differentiates one amino acid from another.

In biochemistry, there are 20 standard amino acids that are used to create proteins. They link together through peptide bonds, forming chains called polypeptides, which fold into specific structures to perform different functions. In the context of our problem, we're dealing with tetrapeptides, which are peptides made up of four amino acids. These small chains are crucial for understanding how proteins are structured and function.

Phenylalanine

Phenylalanine, abbreviated as \( Phe \) or \( F \), is one of the essential amino acids needed for the body's growth and development. It is characterized by having a benzyl side chain, which makes it a nonpolar amino acid. Phenylalanine plays a key role in forming various proteins and enzymes in the body.

Since it is essential, phenylalanine must be obtained through diet as the body cannot synthesize it. Found in foods like meat, fish, poultry, and even soy products, it serves as a precursor for other important molecules, such as tyrosine, which is crucial for neurotransmitter production.

In the exercise, phenylalanine acts as an integral part of the tetrapeptide formation. Its presence adds to the complexity and diversity of possible tetrapeptide structures.

Glycine

Glycine, denoted as \( Gly \) or \( G \), is the simplest amino acid in terms of structure, with a single hydrogen atom as its side chain. This makes it a nonpolar, uncharged amino acid. Glycine's simplicity and small size allow it to fit into tight spaces within proteins, offering structural flexibility.

It is non-essential, meaning our body can synthesize it, yet glycine is vital for various metabolic processes and the synthesis of other biomolecules. It is also a component in collagen, which is necessary for skin, ligaments, and tissues.

In tetrapeptide formations, glycine's minimalistic structure can influence the overall shape and functional properties of the peptide chain, making it versatile in its potential arrangements.

Alanine

Alanine, abbreviated as \( Ala \) or \( A \), is another nonpolar amino acid that is quite prevalent in proteins. Its side chain is a simple methyl group \((-CH_3)\). Alanine plays a significant role in metabolism and is involved in energy production in muscles.

As one of the non-essential amino acids, alanine can be synthesized in the body from other precursors. It is especially important in glucose-alanine cycles between tissues and the liver, providing an energy source during exercise.

Within the context of tetrapeptide construction, alanine contributes to the structure's stability and can affect the sequence diversity due to its neutral character. Its inclusion alongside phenylalanine and glycine further enriches the complexity and number of possible tetrapeptide sequences.