Question

The protein found in the ECM of animals that provides strength and resistance to tearing when stretched is a. elastin. b. cellulose. c. collagen. d. laminin. e. fibronectin.

Short answer

The correct answer is (c) Collagen.

Step-by-step solution

Understanding the question and individual proteins

The question asks to identify the protein that provides strenth and resistance when it is stretched. The proteins from the choices are Elastin, Cellulose, Collagen, Laminin and Fibronectin.

Eliminating incorrect options

Elastin is a protein that allows organs in the body to stretch and then snap back to their original shape. Cellulose can be eliminated as it is a complex carbohydrate not a protein and is not found in animals but in plants. Laminin is involved in the structure of basement membranes, while Fibronectin is involved with cell adhesion, growth, migration, and differentiation.

Identifying the correct protein

The protein in ECM of animals providing strength and resistance to tearing when stretched is Collagen. It is the most abundant protein and gives structure to skin, bones, tendons, fibrous cartilage, connective tissue, and teeth.

Key concepts

Collagen

Collagen is a fundamental component of the extracellular matrix (ECM) in animals and plays a critical role in maintaining the structure and integrity of various tissues. It's the most abundant protein in animals and serves as a key structural protein. It provides tensile strength, meaning resistance to being pulled apart.
Collagen consists of long fibrous proteins that make up one-third of the total protein content in mammals. This protein is responsible for the strength and firmness of skin, tendons, ligaments, and bones. Additionally, collagen aids in tissue repair and cell regeneration. Without collagen, our body tissues would lack stability and cohesion, making them prone to damage and weakness.

Animal Proteins

Animal proteins are the proteins sourced from animals and are crucial for various biological processes. Among these proteins, collagen stands out due to its vital functional significance.
Animal proteins include:

• Collagen: Provides strength and structural support to connective tissues.
• Elastin: Found in tissues requiring elasticity such as skin and arteries.
• Keratin: Found in hair, nails, and the outer layer of skin, offering protection and rigidity.
• Myoglobin and Hemoglobin: Essential for oxygen transport and storage within muscles and blood, respectively.

These proteins are not only vital for maintaining structure and function in animals but also play roles in human health and nutrition, serving as essential sources of amino acids.

Protein Structure

Proteins are composed of chains of amino acids that fold into specific structures to perform their functions effectively. The structure of collagen, as an example, reflects its role as a structural protein. It is made up of three polypeptide chains wound together in a triple helix, which gives it remarkable strength.
Protein structures are organized in several levels:

• Primary Structure: The sequence of amino acids in a protein chain.
• Secondary Structure: Includes α-helices and β-sheets formed by hydrogen bonding.
• Tertiary Structure: The shape of a single polypeptide chain as it folds into a 3D structure.
• Quaternary Structure: The arrangement of multiple polypeptide chains coming together to form a functional protein, such as collagen.

This specific organization allows collagen to fulfill its role in providing tensile strength and stability to tissues. Structural disruptions at any level can lead to impaired protein function, affecting the tissues they support.

Tissue Strength

Tissue strength is pivotal for the body's ability to withstand physical forces and maintain its structure. Proteins like collagen are central to this characteristic, providing tissues with the necessary stiffness and resilience.
Several components contribute to tissue strength:

• Collagen Fibers: These are densely packed in tissues like tendons and ligaments, providing immense tensile strength.
• Extracellular Matrix: Composed of numerous proteins and molecules, it not only supports cell adhesion but also confers elasticity and firmness to tissues.
• Cross-linking: Chemical bonds between collagen fibers increase the rigidity and load-bearing capacity of tissues.

Overall, the structural integrity of tissues ensures they can withstand various mechanical stresses, supporting the body's movements and functions effectively. Without proper structural proteins and organization, tissues would fail under pressure and be prone to injuries.