1.03: How Proteins Work

Scientists are finding that cytochrome p450 enzymes are

essential to all living organisms on earth. These similarites point to connections between all living things.

This nerve cell could not carry out its function without the

proteins embedded in its cell membrane.

DNA contains the instructions for

building molecules calledproteins. Recall that the sequence of nitrogenous bases in DNA determines the sequence of amino acids in a protein. That sequence of amino acids, in turn, determines the shape and function of that protein

Genetic variation among people leads to

differences in the proteins they produce.

Cystic fibrosis is a disorder that will be expressed in individuals that have

double recessive alleles for a certain gene. A child with two recessive alleles for cystic fibrosis can't make an important cell membrane protein. As a result, sticky mucus builds up in many internal organs. The missing protein creates many medical problems, but with treatment, more than 50 percent of people with cystic fibrosis can expect to live to be approximately 30 years old.

Here are some additional roles proteins play in your body:

- The protein hemoglobin carries oxygen to all your body's cells. - Antibody proteins protect you from foreign invaders such as viruses. - Enzymes help you digest food. - Proteins help make sure cell division works properly. - Proteins even regulate the production of other proteins.

Some proteins that carry out functions essential to life are common to all organisms.

Cytochrome p450 is the name applied to a whole class of proteins that not only recognize and break down chemicals such as medications, but also help build other important chemicals in the body such as hormones. Scientists have discovered cytochrome p450 enzymes in every group of organisms on earth, from bacteria to protozoa, plants to fungi, to all mammals. Its appearance in such a diverse number of organisms indicates that it carries out many important life processes.

Proteins play many roles in nerve cells.

Every action you perform relies on signals from your nervous system, which tells your muscles how to react in a given situation. Signal transmission and muscular motion are two processes that rely on proteins. Nerve signals come in the form of electrical impulses that travel along the length of a nerve cell membrane. That electrical impulse is produced when various ions enter into or rush out of the cell membrane through proteins called ion channel membrane proteins. Without the proper proteins, your nervous system could not function, your muscles could not contract, and, in effect, life could not exist.

A protein's shape affects its function.

Proteins are complex 3-D structures. The shape of a protein molecule determines many aspects of its function. The amino acid chains that make up proteins fold and twist around themselves to make the 3-D structures required for activity. Sometimes, the shapes that proteins take on are so complicated that their assembly requires the assistance of other proteins called chaperones.The quaternary structure of a protein involves several proteins working together to perform a specific function.

Proteins make up important structures.

Proteins are not only involved in important cell processes, but they also provide structural support to many of your cells and their products. What do your hair and fingernails have in common with a peacock's feathers and a rhino's horn? Each structure is made of the protein keratin. You may remember learning about the keratin in a tortoise's shell. Keratin is also an important structural protein in birds, reptiles, and mammals. Keratin and the protein collagen give strength and support to your skin, as well.

Proteins help keep you healthy.

Proteins are so important to your body that it is impossible to say one function is more important than the next. It is impossible for biologists to imagine life without proteins, and their correct assembly from DNA is important.Understanding the process of assembling proteins from the genetic code is crucial to understanding modern medicine, agriculture, and biology.

Proteins play many important roles in the body.

Proteins perform much of the work of the cell, from providing support and strength, to assisting in communication, to responding to the environment. Proteins keep you healthy by digesting food, carrying oxygen to cells, breaking down medications and other chemicals, and, as antibodies, recognizing and destroying potentially harmful organisms such as bacteria. Scientists today are studying many aspects of protein structure and function to gain a better understanding of how these molecules contribute to human health.

Proteins perform many functions in a cell.

Proteins repair cell structures, help move other molecules into and out of cells, and as enzymes, catalyze many important chemical reactions.Proteins also carry oxygen throughout the body, cause muscles to contract, and help the body respond to changes in the environment. They provide structure and support to cells.

Proteins play many roles in the body.

The human body has a system for identifying and breaking down unfamiliar chemicals, like drugs. A class of proteins in your body—cytochrome p450 enzymes—plays an important role in this system. Cytochrome p450 recognizes drugs and other chemicals in the body and deal with them appropriately. Cytochrome p450 is just one of thousands of proteins that your body makes to perform countless functions. Proteins are complex molecules with intricate 3-D structures. The shape and structure of a protein molecule influences its activity by determining how that protein will chemically and physically interact with other molecules. You don't have to remember the specifics of cytochrome p450, or even its name. It is an example of the importance of proteins in cells.

Proteins play a wide variety of roles in your body

Their proper assembly and function are critical to your health.

If you've ever had a fever, you might have taken medicine to lower it. A few hours later, the fever may have started to come back.Why did this happen?

Your body metabolized the medicine you took, meaning it broke down the medicine and eliminated it.

Genes may exist in variant forms called

alleles. The human genome—or complete set of genes—is made up of about 25,000 genes.Variation in those genes accounts for not only differences in people's appearance, but also in characteristics such as susceptibility to disease.

Which type of protein plays an important role in transmitting signals in the nervous system?

ion channel membrane proteins

Proteins are

molecules made from the instructions in DNA that do the work of the cell.

protein

one of the four major classes of large organic molecules, made of amino acids

What are the proteins in the connective tissues of the foot examples of?

structural proteins

Cystic fibrosis is a genetic disorder that creates excessive mucus in human organs. What is a person with this disorder missing?

the gene that codes for an important cell membrane protein

A change in your DNA, and

ultimately the proteins made by cells, can have a significant impact on human life.