ATI TEAS GUIDE TO SCIENCE | UNDERSTANDING MACROMOLECULES

ATI TEAS SCIENCE REVIEW – MACROMOLECULES

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QUIZ QUESTIONS LISTED AT END OF REVIEW

Questions related to the macromolecules will test your familiarity of the four types of molecules. As the applicant, you will need to demonstrate understanding of how proteins, carbohydrates, lipids, and nucleic acids function. Let’s get started in understanding how macromolecules are important on the ATI TEAS.

Macromolecules are very large molecules. Most are formed when organic molecules, also known as monomers, combine with covalent bonds during dehydration reactions to form biological polymers. Most of the macromolecules are groups of the same monomer or similar monomers linked together over and over.

There are four types of macromolecules

• Proteins
• Carbohydrates
• Lipids
• Nucleic acids

These macromolecules are the food groups needed by the body and can be broken down by hydrolysis (chemical breakdown of a compound due to reaction with water) during digestion for use by the body’s cells.

UNDERSTANDING PROTEINS

Proteins are long chains of amino acid monomers. The long chains are called polypeptides and they sometimes fold over to form three-dimensional shapes. Different shapes have different functions.

Of the 20 primary amino acids, only 11 of these can be produced by the body itself. The remaining 9 must be obtained through the diet. These 9 amino acids are known as essential amino acids. They can be found in protein sources such as meat, eggs fish, and some plant sources.

NINE ESSENTIAL AMINO ACIDS

• Histidine
• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Threonine
• Tryptophan
• Valine

Enzymes are a vital class of proteins that catalyze chemical reactions. Without enzymes, life would not exist. They are essential for biosynthesis and perform many functions in the digestive system. There are two categories of enzymes: catabolic enzymes, which break down their substrate, and anabolic enzymes, which use their substrate to build more complex molecules.

Hormones are another class of proteins with which you should be familiar. Hormones are signaling molecules produced by glands in endocrine system. They are transported by the circulatory system to organs throughout the body to regulate physiology and behavior.

FUNCTION OF PROTEINS

Proteins have many vital functions within the body, such as:

• Proteins catalyze chemical reactions
• Proteins synthesize and repair DNA
• Proteins provide structural support
• Proteins transport materials across the cell
• Proteins respond to stimuli
• Proteins send and receive chemical signals

UNDERSTANDING CARBOHYDRATES

Carbohydrates molecules form with a ratio of carbon to hydrogen to oxygen 1:2:1. They can be classified into three subtypes:

• Monosaccharide is a simple sugar, with only 3-7 carbon atoms. Glucose, fructose, and galactose are common monosaccharides.
• Disaccharide forms when two monosaccharides bond. Sucrose, lactose, and maltose are common disaccharides.
• Polysaccharide is a long chain of monosaccharides. Glycogen, cellulose, starch, and chitin are common polysaccharides.

FUNCTION OF CARBOHYDRATES

Carbohydrates are the body’s source of quick fuel because they break down faster in the body than proteins and fats. Carbohydrates covert to sugar, or glucose, which is a ready source of fuel. Simple carbohydrates, such as cane sugar, break down fastest when consumed. Complex carbohydrates, such as grains and starchy vegetables, breaks down more slowly than simple carbohydrates and turn into sugar less quickly in the bloodstream.

Fiber is a component found in carbohydrates that cannot be digested by the body. Because it does not break down into glucose, fiber adds bulk to the diet and improves the process of transporting foods through the digestive system. Adequate fiber intake can also be helpful for controlling blood sugar levels.

While some carbohydrates perform energy storage functions, other carbohydrates perform structural functions. The polysaccharide cellulose performs an important function in plant cells. The rigid cell wall is made up of cellulose. Another polysaccharide, chitin, performs an important function in arthropods: it forms an exoskeleton to protect their internal organs. Other carbohydrates, such as glycoproteins, have recognition functions.

UNDERSTANDING LIPIDS

Lipids are macromolecules that contain hydrocarbons. They are highly reduced forms of carbon and when they are metabolized, lipids are oxidized to release large amounts of energy.

Some lipids examples include

• Fats
• Oils
• Waxes
• Sterols
• Fat-soluble vitamins
• Monoglycerides
• Diglycerides
• Triglycerides
• Phospholipids

FUNCTION OF LIPIDS

Lipids are efficient source of fuel for the body; once digested, they break down into fatty acids and glycerol. Fats take longer to digest than either protein or carbohydrates, so they provide the body with sustained energy. Saturated fats are derived mainly from animal sources and tend to raise cholesterol and increase the risk of heart attack and stroke. Unsaturated fats are derived from certain vegetables, fish, and nuts. These fats can lower cholesterol levels, particularly monosaturated fats, such as those found in avocado and olive oil.

Lipids also have signaling functions and act as a major structural component of cell membranes.

UNDERSTANDING NUCLEIC ACIDS

Nucleic acids include deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

DNA is a polymer made from a long string of repeating units called nucleotides. Nearly all DNA molecules consist of two biopolymer strands that are coiled around each other to form a double helix shape. As you probably know, DNA stores biological information and is the hereditary material in all living organisms.

RNA is also a chain of nucleotides, but it usually forms a single strand folded onto itself, rather than a double-strand like DNA. RNA is mostly involved in protein synthesis. A type of RNA known as messenger RNA carries copies of the genetic information to ribosomes, where catalytic ribosomal RNA molecules and transfer RNA molecules coordinate to make a functional protein.

FUNCTION OF NUCLEIC ACIDS

Nucleic acids carry out several cellular processes. They are especially involved in the regulation and expression of genes.