Struktur dan Fungsi Protein | Biomolekul #4

Summary

This video explains the structure and types of proteins, starting with amino acids, the building blocks of proteins. It covers the chemical composition of amino acids, their different types, and how they form proteins through peptide bonds. The video also explores protein folding and denaturation, as well as the four structural levels of proteins, from primary to quaternary. Additionally, it distinguishes between globular and fibrous proteins, providing examples such as enzymes, hemoglobin, collagen, and keratin. The video aims to provide a clear understanding of protein biology and its vital role in the body.

Takeaways

• 😀 Proteins are large, complex molecules made up of smaller subunits called amino acids.
• 😀 Amino acids are simple molecules with a central carbon atom, bonded to hydrogen, amino group, carboxyl group, and a variable side chain.
• 😀 There are hundreds of amino acids, but only 20 of them are proteinogenic and form proteins in humans and higher animals.
• 😀 Amino acids differ in their side chains, which can be hydrophobic, hydrophilic, acidic, or basic.
• 😀 The average size of an amino acid is 110 Dalton, and a protein typically consists of 90 to 1350 amino acids.
• 😀 Amino acids are connected by peptide bonds, forming polypeptide chains that fold into a three-dimensional structure.
• 😀 The folding of proteins is influenced by the environment, and changes in temperature, pH, or chemicals can cause denaturation, where proteins lose their function.
• 😀 Renaturation is the process by which proteins regain their folded shape when environmental conditions are restored.
• 😀 Proteins have different levels of structural complexity: primary, secondary, tertiary, and quaternary.
• 😀 There are two main types of proteins: globular proteins (e.g., enzymes, insulin, hemoglobin) and fibrous proteins (e.g., collagen, keratin).

Q & A

What are amino acids, and how are they structured?

Amino acids are simple molecules composed of a central carbon atom bonded to a hydrogen atom, an amine group, a carboxyl group, and a variable side chain. The side chain can vary in structure, giving each amino acid distinct properties.

How do amino acids behave in water?

When amino acids are in water, they become zwitterions, meaning they carry both a positive and a negative charge due to the ionization of the amine and carboxyl groups.

What is the difference between proteinogenic and non-proteinogenic amino acids?

Proteinogenic amino acids are those that are incorporated into proteins, and there are 20 such amino acids in humans and animals. Non-proteinogenic amino acids do not participate in protein synthesis.

How do the side chains of amino acids influence their properties?

The side chains of amino acids determine their chemical properties, such as whether they are hydrophobic (repel water), hydrophilic (attract water), acidic, or basic. These properties affect protein folding and function.

How are proteins formed from amino acids?

Proteins are formed by linking amino acids through peptide bonds. The sequence of amino acids forms a polypeptide chain, which then folds into a specific three-dimensional structure.

What is the typical size of a protein in terms of amino acids?

A typical protein consists of 90 to 1350 amino acids, based on studies of average amino acid and protein sizes.

What happens to protein structure if environmental conditions change?

Changes in environmental conditions like temperature, pH, or the presence of chemicals can cause proteins to denature, meaning they unfold and lose their functional shape. However, under favorable conditions, they can renature and regain their functional structure.

What are the four levels of protein structure?

The four levels of protein structure are: 1) Primary structure - the linear sequence of amino acids. 2) Secondary structure - local folding patterns such as alpha helices and beta-pleated sheets. 3) Tertiary structure - the three-dimensional shape of a single protein molecule. 4) Quaternary structure - the arrangement of multiple protein subunits to form a larger complex.

What is the difference between globular and fibrous proteins?

Globular proteins are spherical, complex, and often function as enzymes, hormones, or antibodies. Fibrous proteins are elongated, insoluble in water, and serve structural roles, such as collagen and keratin.

How does the environment affect protein folding?

The environment influences protein folding by determining whether hydrophobic amino acids are buried inside the structure or exposed on the outside, as well as how the protein interacts with water. Changes in temperature or pH can disrupt these interactions and cause denaturation.