Amino Acid Chain: Types, Functions, Essential & Non-Essential Amino Acids

Edited By Team Careers360 | Updated on Jul 02, 2025 05:14 PM IST

Amino acid chains play important roles in our bodies. It is responsible for the decomposition of food, the repair of body tissues, and the growth of the body. It is the body's building block and also plays a role in maintaining its pH level, and stores nitrogen in the body. Asparagine and glutamine are amino acid derivatives found in the body and play a role in retaining nitrogen in the body.

This Story also Contains

Amino Acid Chains
Types Of Amino Acids
Essential Amino Acids
Non-Essential Amino Acids
Amino Acid Functions

Amino Acid Chain: Types, Functions, Essential & Non-Essential Amino Acids

Amino Acid Chains

Amino Acid Chains consist of (NH2) and carboxylic acids (-COOH- ) and organic side chains. Twenty different types of amino acids are used for the construction of proteins. Proteins can contain one or more chains of amino acids called polypeptides. The amino acid chain sequence causes the polypeptide to fold into a biologically active form.

It decomposes food, repairs body tissues, and makes the body grow. It is the body's building block and also plays a role in maintaining its pH level, and stores nitrogen in the body. Asparagine and glutamine are amino acid derivatives found in the body and play a role in retaining nitrogen in the body.

Types Of Amino Acids

Amino acids are classified into four types according to the position of their functional groups-

Alpha amino acids
Beta amino acids
Gamma amino acids
Delta amino acids

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1. Alpha amino acids

Alpha amino acids are amino acids with an amine group attached to the alpha carbon atom. The general formula for alpha amino acids is H2NCHRCOOH, where R is an organic side chain.

Glycerine is an example of alpha amino acids.

2. Beta Amino Acids

Beta amino acids are amino acids in which the amine group is attached to the beta carbon atom of the carboxylic acid group. The general formula for beta amino acids is H2NCH2CH2COOH, where R is an organic side chain.

Lysine and arginine are examples of beta amino acids.

3. Gamma Amino Acids

Gamma amino acids are amino acids in which the amine group is attached to the gamma carbon atom of the carboxylic acid group. The general formula for the γ amino acid is C4H9NO2. 2-aminoisobutyric acid and aminobutyric acid are examples of gamma amino acids.

4. Delta Amino Acids

Delta amino acids are amino acids in which the amine group is attached to the delta carbon atom of the carboxylic acid group. The general formula for delta amino acids is C5H12NO2+.

The amino acids are divided into two types based on the position of the amine group in the Fischer projection-

L-Amino Acids
D-Amino Acids

L-Amino Acids

When plotted in a Fischer projection, L-amino acids have the amine group on the left, the carboxylic acid group on top, and the carbon chain on the bottom.

These are left-handed. That is, it rotates linearly polarized light clockwise. These have been replaced by the R notation, which the cell uses to synthesize proteins.

D-Amino Acids

When plotted in a Fischer projection, D-amino acids have the amine group on the right, the carboxylic acid group on top, and the carbon chain on the bottom.

These are dextrorotatory. That is, it rotates linearly polarized light counterclockwise. They have been replaced by the S notation and are found in bacterial cell walls.

We can classify amino acids into two types based on their production in the body-

Essential Amino Acids
Non-Essential Amino Acids

Essential Amino Acids

Essential amino acids are amino acids that are not synthesized by the body and are obtained from food.

Helps build and repair body muscle tissue.
9 out of 20 amino acids are considered essential amino acids.
It plays a vital role in transmission of the information to the brain.

Non-Essential Amino Acids

Non-essential Amino Acids are amino acids that are synthesized by the body and are not required in the diet.

They plays an important role in removing toxins, synthesizing WBC and RBC, and promoting brain function.
11 out of 20 amino acids are considered non-essential amino acids.
Examples of essential amino acids are arginine, aspartic acid, glutamic acid, glycine, and tyrosine.

Amino Acid Functions

Amino Acid helps remove toxins from the body.
Helps protein synthesis and growth hormone.
Helps produce glucose.
Helps regulate sleep cycles.
A deficiency of the amino acid can cause insomnia, depression, anorexia, edema, headaches, and anemia.

Frequently Asked Questions (FAQs)

1. What are Amino acid chains?

2. What are the types of Amino acid chains?

Amino acids are classified into four types according to the position of their functional groups-

Alpha amino acids
Beta amino acids
Gamma amino acids
Delta amino acids

3. Write about the Amino Acid Functions?

The functions of Amino Acid are-

Amino Acid helps remove toxins from the body.
Helps protein synthesis and growth hormone.
Helps produce glucose.
Helps regulate sleep cycles.
A deficiency of the amino acid can cause insomnia, depression, anorexia, oedema, headaches, and anaemia.

4. What are the Non-Essential Amino Acids?

Non-essential Amino Acids are amino acids that are synthesized by the body and are not required in the diet.

They plays an important role in removing toxins, synthesizing WBC and RBC, and promoting brain function.
11 out of 20 amino acids are considered non-essential amino acids.
Examples of essential amino acids are arginine, aspartic acid, glutamic acid, glycine, and tyrosine.

5. What are the Essential Amino Acids?

Essential amino acids are amino acids that are not synthesized by the body and are obtained from food.

Helps build and repair body muscle tissue.
9 out of 20 amino acids are considered essential amino acids.
They play a vital role in the transmission of the information to the brain.

6. What is a peptide bond, and how is it formed?

A peptide bond is a covalent bond formed between the carboxyl group of one amino acid and the amino group of another amino acid. It is created through a condensation reaction, where a water molecule is released as the bond forms, linking amino acids together to create peptides and proteins.

7. How do amino acids contribute to protein structure?

Amino acids contribute to protein structure through their sequence (primary structure), which determines how the protein folds into secondary structures (like alpha helices and beta sheets), tertiary structure (overall 3D shape), and quaternary structure (multiple protein subunit arrangements).

8. What is a polypeptide?

A polypeptide is a chain of amino acids linked by peptide bonds. It can range from a few amino acids to hundreds or thousands. Proteins are made up of one or more polypeptide chains folded into specific three-dimensional structures.

9. How do mutations in the genetic code affect amino acid sequences?

Mutations in the genetic code can lead to changes in the amino acid sequence of proteins. Point mutations might change a single amino acid, while insertions or deletions can shift the entire reading frame. These changes can alter protein structure and function, potentially leading to diseases or evolutionary adaptations.

10. How does the body break down proteins into amino acids?

The body breaks down proteins through a process called protein digestion. This occurs in the stomach and small intestine using enzymes like pepsin, trypsin, and chymotrypsin, which hydrolyze peptide bonds, breaking proteins into smaller peptides and individual amino acids for absorption.

11. What are amino acids and why are they important?

Amino acids are organic compounds that serve as the building blocks of proteins. They are crucial for life because they form the structure of proteins, which perform numerous essential functions in our bodies, including catalyzing biochemical reactions, providing structural support, and transporting molecules.

12. How do the properties of amino acid side chains affect protein function?

The properties of amino acid side chains (e.g., hydrophobic, hydrophilic, acidic, basic) determine how proteins fold, interact with other molecules, and function. For example, hydrophobic side chains often form the core of proteins, while hydrophilic ones are usually on the surface, interacting with water.

13. What is the role of amino acids in neurotransmitter synthesis?

Several amino acids serve as precursors for neurotransmitters. For example, tryptophan is used to synthesize serotonin, tyrosine is used to make dopamine and norepinephrine, and glutamate itself acts as a neurotransmitter. This highlights the importance of amino acids in brain function and mood regulation.

14. How do amino acids contribute to the body's pH balance?

Amino acids play a role in maintaining the body's pH balance through their amphoteric nature. They can act as buffers by accepting or donating protons depending on the surrounding pH, helping to minimize changes in blood and cellular pH levels.

15. What is the significance of the amino acid sequence in proteins?

The amino acid sequence, also known as the primary structure of a protein, is crucial because it determines how the protein will fold into its three-dimensional shape. This shape, in turn, dictates the protein's function, including its ability to interact with other molecules, catalyze reactions, or provide structural support.

16. Can you name the 9 essential amino acids?

The 9 essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These must be obtained through diet as the human body cannot synthesize them.

17. What is a branched-chain amino acid (BCAA), and why is it important?

Branched-chain amino acids (BCAAs) are essential amino acids with a branched side chain, including leucine, isoleucine, and valine. They are important for muscle protein synthesis, energy production during exercise, and glucose homeostasis. BCAAs are often used as supplements by athletes to support muscle growth and recovery.

18. What is the concept of limiting amino acids in nutrition?

The concept of limiting amino acids refers to the essential amino acid present in the lowest quantity relative to the body's needs. This amino acid limits the body's ability to use other amino acids for protein synthesis. In many plant-based diets, lysine or methionine are often limiting amino acids, which is why combining different plant protein sources is recommended for a complete amino acid profile.

19. How do amino acids contribute to muscle growth and repair?

Amino acids, especially branched-chain amino acids (BCAAs), are essential for muscle growth and repair. They serve as building blocks for new muscle tissue and can stimulate muscle protein synthesis. After exercise, increased amino acid availability helps repair damaged muscle fibers and promote muscle growth, which is why protein intake is important for athletes and bodybuilders.

20. How do amino acid imbalances affect health?

Amino acid imbalances can lead to various health issues. Deficiencies in essential amino acids can impair protein synthesis, affecting growth, immune function, and overall health. Excesses of certain amino acids can be toxic, interfering with the absorption of other amino acids or causing metabolic disturbances. Some genetic disorders, like phenylketonuria, result from the inability to properly metabolize specific amino acids.

21. What is the difference between essential and non-essential amino acids?

Essential amino acids cannot be synthesized by the human body and must be obtained through diet. Non-essential amino acids can be produced by the body from other compounds. There are 9 essential amino acids and 11 non-essential amino acids in humans.

22. What is the relationship between amino acids and hormones?

Many hormones are peptides or proteins composed of amino acids, such as insulin, growth hormone, and oxytocin. Additionally, some amino acids serve as precursors for non-peptide hormones. For example, tyrosine is used to synthesize thyroid hormones and catecholamines like adrenaline.

23. How do amino acids contribute to the body's immune response?

Amino acids play crucial roles in the immune system. They are necessary for the synthesis of antibodies and other immune proteins. Some amino acids, like arginine and glutamine, are particularly important for immune cell function and proliferation. Additionally, amino acids are involved in the production of inflammatory mediators and antioxidants that protect against oxidative stress.

24. How do amino acids contribute to the taste of food?

Certain amino acids contribute significantly to the taste of food. For example, glutamate is responsible for the savory "umami" taste, while aspartate and glutamate can enhance overall flavor. Sweet-tasting amino acids include glycine and alanine, while bitter tastes are often associated with tryptophan, tyrosine, and phenylalanine.

25. What is the role of amino acids in collagen synthesis?

Amino acids are crucial for collagen synthesis, with glycine, proline, and hydroxyproline being particularly important. Collagen, the most abundant protein in the human body, provides structural support to various tissues including skin, bones, and blood vessels. The unique amino acid composition of collagen, with glycine at every third position, contributes to its triple-helix structure.

26. How many different types of amino acids are commonly found in proteins?

There are 20 different types of standard amino acids commonly found in proteins. These amino acids combine in various sequences to form the vast array of proteins needed for life processes.

27. What is the general structure of an amino acid?

The general structure of an amino acid consists of a central carbon atom (alpha carbon) bonded to four groups: an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom (H), and a unique side chain (R group) that determines the specific properties of each amino acid.

28. What is a zwitterion, and how does it relate to amino acids?

A zwitterion is a molecule with both positive and negative electrical charges. At physiological pH, amino acids exist as zwitterions, with the amino group protonated (-NH3+) and the carboxyl group deprotonated (-COO-). This property contributes to the amphoteric nature of amino acids.

29. What is the isoelectric point of an amino acid?

The isoelectric point is the pH at which an amino acid carries no net electrical charge. At this point, the amino acid exists predominantly as a zwitterion. The isoelectric point is unique for each amino acid and depends on its side chain properties.

30. What is the significance of post-translational modifications of amino acids in proteins?

Post-translational modifications (PTMs) of amino acids in proteins can significantly alter their function, localization, or interactions. Common PTMs include phosphorylation, glycosylation, and ubiquitination. These modifications allow for rapid and reversible changes in protein activity, enabling cells to respond quickly to various stimuli.

31. What is the significance of amino acid catabolism in glucose homeostasis?

Amino acid catabolism plays a role in glucose homeostasis, particularly during fasting or low-carbohydrate conditions. Through gluconeogenesis, certain amino acids can be converted to glucose, helping to maintain blood sugar levels. This process is especially important in prolonged fasting, where protein breakdown provides amino acids for glucose production.

32. How do amino acids contribute to the body's energy production?

Amino acids can be used for energy production when carbohydrates are not available. Through a process called deamination, the amino group is removed, and the remaining carbon skeleton can enter the citric acid cycle for ATP production. This process is particularly important during prolonged fasting or intense exercise.

33. What is the role of amino acids in the synthesis of non-protein molecules?

Amino acids serve as precursors for various non-protein molecules in the body. For example, tryptophan is used to synthesize the hormone melatonin, tyrosine is used to make thyroid hormones, and glycine is a component of heme in hemoglobin. This demonstrates the diverse roles of amino acids beyond protein structure.

34. How do amino acids participate in cell signaling?

Some amino acids act as signaling molecules themselves or as precursors to signaling molecules. For instance, glutamate and glycine act as neurotransmitters, while nitric oxide, derived from arginine, is an important signaling molecule in the cardiovascular system. Additionally, the phosphorylation of specific amino acids in proteins is a key mechanism in many cell signaling pathways.

35. What is the role of amino acids in the urea cycle?

The urea cycle is a series of biochemical reactions that convert toxic ammonia, produced from amino acid breakdown, into urea for excretion. Key amino acids involved in this cycle include ornithine, citrulline, and arginine. The urea cycle is crucial for nitrogen balance and detoxification in the body.

36. How do amino acids contribute to the production of neurotransmitters?

Several amino acids serve as precursors or are directly involved in neurotransmitter production. For example, tryptophan is converted to serotonin, tyrosine to dopamine and norepinephrine, and glutamate itself acts as an excitatory neurotransmitter. The availability of these amino acids can influence mood, cognition, and various neurological functions.

37. What is the significance of amino acid transporters in cellular function?

Amino acid transporters are proteins that facilitate the movement of amino acids across cell membranes. They are crucial for nutrient uptake, cellular metabolism, and signaling. Different transporters have varying specificities for different amino acids, allowing cells to regulate their amino acid composition and respond to nutritional and metabolic demands.

38. How do amino acids contribute to the body's antioxidant defenses?

Some amino acids play important roles in the body's antioxidant defenses. For instance, cysteine is a key component of glutathione, one of the body's most important antioxidants. Taurine and methionine also have antioxidant properties. These amino acids help protect cells from oxidative stress and damage caused by free radicals.

39. What is the relationship between amino acids and gene expression?

Amino acids can influence gene expression through various mechanisms. They can act as signaling molecules, triggering pathways that affect transcription factors. For example, leucine can activate mTOR signaling, which influences protein synthesis and cell growth. Additionally, the availability of certain amino acids can affect the expression of genes involved in their own metabolism and transport.

40. How do amino acids contribute to wound healing?

Amino acids are crucial for wound healing. They are necessary for the synthesis of new proteins required for tissue repair, such as collagen and elastin. Arginine and glutamine are particularly important, as they support immune function and cell proliferation. Adequate protein intake, providing all essential amino acids, is vital for efficient wound healing.

41. What is the role of amino acids in the synthesis of creatine?

Creatine, an important compound for energy metabolism in muscles, is synthesized from three amino acids: glycine, arginine, and methionine. The synthesis occurs primarily in the liver and kidneys. Creatine plays a crucial role in rapidly regenerating ATP in muscle cells during high-intensity, short-duration activities.

42. How do amino acids contribute to the body's acid-base balance?

Amino acids contribute to acid-base balance through their amphoteric nature and their metabolism. The catabolism of sulfur-containing amino acids (cysteine and methionine) produces sulfuric acid, contributing to acid load. Conversely, the metabolism of other amino acids can produce bicarbonate, which is alkaline. The kidneys use amino acids in various ways to regulate pH, including glutamine metabolism for ammonia production.

43. What is the significance of amino acid racemization in aging and disease?

Amino acid racemization is the conversion of L-amino acids to their D-isomers. This process occurs slowly over time and is associated with aging and certain diseases. Racemization can affect protein structure and function, potentially contributing to age-related changes in tissues like the lens of the eye and cartilage. It's also used in archeology for dating organic materials.

44. How do amino acids contribute to the formation of advanced glycation end-products (AGEs)?

Amino acids in proteins can react with sugars in a process called glycation, forming advanced glycation end-products (AGEs). This non-enzymatic reaction is associated with aging and various diseases, including diabetes complications. The lysine and arginine residues in proteins are particularly susceptible to glycation, which can alter protein structure and function.

45. What is the role of amino acids in the synthesis of porphyrins?

Amino acids play a crucial role in the synthesis of porphyrins, which are essential components of molecules like hemoglobin and chlorophyll. Glycine and succinyl-CoA (derived from amino acid metabolism) are the starting materials for porphyrin synthesis. The process involves a series of enzymatic reactions in the mitochondria and cytoplasm.

46. How do amino acids contribute to the body's osmotic balance?

Free amino acids in cells contribute to the intracellular osmotic pressure. Some amino acids, like taurine, play specific roles in osmoregulation. In the kidneys, amino acids are involved in the countercurrent multiplication system that concentrates urine. The reabsorption and secretion of amino acids in the kidneys also influence osmotic balance and blood pressure regulation.

47. How do amino acids contribute to the formation of biological pigments?

Several amino acids are precursors for biological pigments. For example, tyrosine is the starting point for melanin synthesis, the pigment responsible for skin, hair, and eye color. Tryptophan is a precursor for the synthesis of serotonin and melatonin, which can influence skin pigmentation. Understanding these pathways is important in studying disorders of pigmentation.

48. What is the role of amino acids in protein folding and stability?

The sequence and properties of amino acids determine how a protein folds into its three-dimensional structure. Hydrophobic amino acids often form the core of globular proteins, while hydrophilic ones are usually on the surface. Certain amino acids, like proline, can induce turns in the protein structure. Disulfide bonds between cysteine residues can stabilize protein structure. Understanding these relationships is crucial in protein engineering and studying protein-related diseases.

49. How do amino acids contribute to the body's nitrogen balance?

Amino acids are the primary source of nitrogen in the body. Nitrogen balance refers to the state where nitrogen intake equals nitrogen excretion. Positive nitrogen balance (more intake than excretion) is associated with growth and tissue repair, while negative balance can indicate malnutrition or disease. The body's ability to efficiently use dietary amino acids and recycle amino acids from protein breakdown is crucial for maintaining nitrogen balance.

50. What is the significance of amino acid supplementation in clinical nutrition?

Amino acid supplementation is important in various clinical scenarios. In conditions like severe burns, trauma, or certain digestive disorders, specific amino acids may be supplemented to support healing and maintain muscle mass. Branched-chain amino acids