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Chapter 25: Problem 16

Discuss the main functions of proteins in living systems.

Short Answer

Expert verified
Proteins play numerous crucial roles in living beings. These include enzymatic activity, providing structure, transport of molecules, defense against foreign substances, signaling within and between cells, facilitating movement through muscle contraction, and storing specific molecules.

Step by step solution

01

Enzymatic activity

Proteins function as enzymes, which are catalysts that speed up chemical reactions in the cell. Without enzymes, these reactions would occur too slowly to sustain life. An enzyme protein, for example, might break down a complex sugar molecule into simpler, more easily absorbed sugars.
02

Structural Function

Proteins provide structure to cells and organisms. Keratin is a structural protein found in hair and nails, while collagen is a structural protein found in skin, bones, and ligaments. These proteins give cells and organisms their shape and provide structural integrity.
03

Transport

Proteins in the cell membrane provide a network of transport channels, allowing specific molecules to enter or leave the cell. For instance, hemoglobin, a protein in red blood cells, binds to oxygen in the lungs and carries it to the body’s cells.
04

Defense

Proteins are involved in defense mechanisms in the form of antibodies. Antibodies are proteins that can recognize, bind to, and help destroy foreign invaders like bacteria and viruses.
05

Signaling

Proteins also play a role in cell signaling and communication. For example, hormones are signaling proteins that can bind to receptors on the surface of cells and trigger an internal response.
06

Movement

Proteins are responsible for muscle contraction and movement. The proteins actin and myosin interact in muscle cells to produce contraction, which allows for movement.
07

Storage

Proteins also function in storage of certain molecules. Examples include ferritin, which stores iron in the liver, and casein, the major protein in milk that provides amino acid nutrients.

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Most popular questions from this chapter

How many different tripeptides can be formed by lysine and alanine?

Proteins vary widely in structure, whereas nucleic acids have rather uniform structures. How do you account for this major difference?

Describe the two major mechanisms of organic polymer synthesis.

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Discuss the characteristics of an amide group and its importance in protein structure.
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