Chapter 3: Molecules of Life

An Overview of the Wide-Ranging Functions of Proteins:

*Enzymes:* - Globular proteins that play a key role in many reactions *Keratin (Structural Proteins):* - Forms hair, nails, feathers, and parts of horns. *Collagen (Structural Proteins):* - This is in bones, tendons, and cartilage. *Contractile Proteins:* - Present in muscles are proteins such as actin and myosin. *Transport Proteins:* - Red blood cells, contained of the protein hemoglobin, transports oxygen through the body. *Defensive Proteins:* - White blood cells destroy foreign cells and make antibodies to attack the invaders.

Four General Levels of Protein Structure: (Note: all are ultimately determined by the sequence of amino acids.)

*Primary Structure:* - The sequence of amino acids of a polypeptide chain, linked together by peptide bonds, a great diversity is possible. *Secondary Structure:* - Hydrogen bonds between parts of the polypeptides can stabilize them, can be in coils called alpha-helices, and sheets, beta-pleated sheets. *Tertiary Structure:* - Due to some of the amino acids' nonpolarity, the polypeptide chain folds up in water (very polar), which lends its 3D shape or tertiary structure, determined by where the nonpolar amino acids occur. *Quaternary Structure:* - When a protein is composed of more than one polypeptide chain, four subunits make up this in hemoglobin, where it is held up by interactions/hydrogen bonds.

Organic molecules can be found in foods, such as popcorn. For instance, they include:

- Lipids (includes fats, trans fats, saturated fats, and cholesterol) - Proteins - Nucleic acids (not found in popcorn) - Carbohydrates (include sugars)

Macromolecules are large molecules. The four "building blocks of cells or the brick and mortar" that makes up the body of a cell are:

- Proteins - Nucleic acids - Carbohydrates - Lipids

Ribonucleic acid (RNA):

A class of nucleic acids characterized by the presence of the sugar ribose and the pyrimidine uracil; includes mRNA, tRNA, rRNA, and siRNA.

Dehydration Synthesis: - Joins monomers into polymers. (The dehydration is based on the removal, or taking away, of a molecule of water.)

A covalent bond is formed between two subunits in which a hydroxyl group (OH) is removed from one subunit and a hydrogen (H) is removed from the other. In other words, a chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule.

Unsaturated fats: (Fats whose double bonds are fewer than the maximum number of hydrogen atoms.)

A fat that is liquid at room temperature and found in vegetable oils, nuts, and seeds.

Saturated fats: (Fats whose fatty acid chains are the maximum number of hydrogen atoms.)

A fat that is solid at room temperature and found in animal fats, lards, and dairy products.

Polymers (made up of monomers) are:

A large molecule formed by long chains of similar molecules (monomers).

Phospholipid:

A lipid that contains phosphorus and that is a structural component in cell membranes. It is important because it forms boundary layers in cells called membranes.

Proteins (complex macromolecules) are important biological macromolecules within the bodies of all organisms. Define proteins:

A long chain of amino acids linked end to end by peptide bonds. Because the 20 amino acids that occur in proteins have side groups with very different chemical properties, the function and shape of a protein is critically affected by its particular sequence of amino acids.

A fatty acid is:

A long chain of carbon and hydrogen atoms.

Lipids:

A loosely defined group of water-insoluble, yet oil-soluble molecules. They include oils, such as olive oil, corn oil, coconut oil, and waxes, like beeswax and earwax.

Nucleic Acids: (Serves as the genetic information storage devices of cells.)

A nucleotide polymer (a long chain of nucleotides). (The main types are DNA, double-stranded and RNA, usually single-stranded.)

Enzymes: (They facilitate the positioning of molecules so that the correct chemical bonds are stressed and broken.)

A protein capable of speeding up specific chemical reactions by lowering the energy required to activate or start the reaction that remains unaltered in the process.

Monosaccharides:

A simple sugar, whose molecules are one subunit.

Disaccharide: (Occurs when two _______________ link together through a dehydration reaction.)

A simple, compound sugar, formed by two monoaccharide molecules linked together. (For example, sucrose or table sugar is a disaccharide formed by linking a molecule of glucose to a molecule of fructose.)

Nucleotide:

A single unit of a nucleic acid (composed of a phosphate, a 5-carbon sugar, either ribose or deoxyribose and a purine or a pyrimidine).

Polysaccharides:

A sugar polymer. (A carbohydrate composed of many monosaccharide sugar subunits linked together in a long chain.)

Hydrolysis is when: - Breaks polymers into monomers

A water molecule comes in, then hydrogen becomes attached to one subunit and hydroxyl to another, then the covalent bond is broken. The breaking up of a polymer in this way is name name of this process.

Carbohydrates:

An organic compound consisting of a chain or ring of carbon atoms to which hydrogen and oxygen atoms are attached in a ration of ~1:2:1. A compound of carbon, hydrogen, and oxygen having the generalized formula (CH2O)n where n is the # of carbon atoms.

Carbohydrates and their Functions: (Note: On page 59, revise?)

Cellulose- cell wall plant Ribose - RNA Starch - plant storage Glycogen - animal storage Deoxyribose - DNA Lactose - glucose and galactose Fructose - fruit storage Sucrose - table sugar

Hydrogenated fats:

Fats that are industrially added with hydrogens, to make them solid at room temperature, and found in peanut butter, as ways to extend the shelf life of products.

Why can humans digest starch but not cellulose?

Humans have enzymes that can hydrolyze the alpha glycosidic linkages of starch, but not the beta glycosidic linkages of cellulose. In other words, humans lack enzymes necessary to break down cellulose., though have the ones required for starch.

Plants and animals store energy in polysaccharides formed from glucose, which differs in plants in animals.

In animals, energy is stored in glycogen, a highly insoluble macromolecule formed of glucose polysaccharides that are very long, and unlike starch, highly branched.

Only two base pairs are possible in DNA, which means:

In every DNA double helix, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C) due to properly forming hydrogen bonds.

Prion:

Infectious proteinaceous particles.

The simplest carbohydrates are:

Monosaccharides or simple sugars

Other types of lipids include:

Phospholipids and cholesterol, which play key roles in the membranes, which encase all cells in the human body.

Polypeptides:

Polymers of amino acids.

The difference between RNA and DNA is that:

RNA molecules contain the sugar ribose, in which the 2' carbon is bonded to a hydroxyl group (-OG). - In DNA, this is replaced with a hydrogen atom. DNA contains thymine nucleotide. - RNA contains uracil nucleotide instead. The structure of RNA is a long, single strand of nucleotides. - DNA consists of a double helix of two polynucleotide chains wound around each other. DNA stores genetic information. - RNA molecules regulate how DNA is used.

Monomers (what macromolecules are made up of these smaller bits):

Simple molecules that can join together to form polymers. (For an illustration, imagine each cart in Infinity Train as a monomer, and the train is a polymer.)

For example, if the sequence of one chain is ATTGCAT, the sequence of its helix partner must be: (Hint 1: "AT, Adventure Time") (Hint 2: "GC, GameCube")

TAACGTA.

The glucose polysaccharide that plants use to store energy is called starch.

That is why potatoes are referred to as starchy food.

Deoxyribonucleic Acid (DNA):

The basic storage vehicle or central plan of heredity information. It is stored as sequence of nucleotides in a linear nucleotide polymer. Two of the polymers wind around each other like the outside and inside rails of a circular staircase.

Peptide Bond:

The covalent bond formed between amino acids.

The 3D (three-dimensional) shape of a protein determines its function. For example, in enzymes, globular proteins that help chemical reactions occur in the cell, when folded correctly...

The enzyme surface has a groove or depression that exactly fits a certain molecules. For example, it may induce sugar to undergo a chemical reaction, breaking a covalent bond, making it easier to share electrons and form covalent bonds.

Plants and animals also use glucose chains as building materials, linking the subunits together in different orientations not recognized by most enzymes...

These structural polysaccharides are chitin in animals and cellulose in plants.

Nucleic acids can encode information because they contain more than one kind of nucleotide. There are five different nucleotides found in nucleic acids. They are:

Two larger ones that contain the nitrogenous bases adenine and guanine, and... Three smaller ones that contain the nitrogenous bases cytosine, thymine, and uracil.

Protein Denaturation: (An example of this is cooking an egg.)

When proteins are subject to heat, acid or other conditions that disturb their stability, and alter/break their hydrogen bonds... The protein uncoils, loses its shape, and loses its function.

One of the most important proteins are enzymes:

Which have the key role in cells of helping to carry out particular chemical reactions.

The four different kinds of macromolecules (proteins, nucleic acids, carbohydrates, and lipids) are:

built from different monomers.

Other proteins act as:

chemical messengers within the brain and throughout the body.

Cartilage, bones, and tendons all contain a structural protein called:

collagen.

The process of tearing down a molecule such as the proteins or fats we consume is basically like the opposite of:

dehydration synthesis because instead of removing a water molecule, one is added.

Fat molecules are lipids composed of two kinds of subunits:

fatty acids and glycerol.

Keratin, another structural protein, forms:

hair, the horns of a rhinoceros, and feathers.

Because of the primary structure of a protein (its sequence of amino acids) determines how the protein folds into its functional shape, a change in the identity of even *one* amino acid can:

have profound effects on the protein's shape and ability to function.

In the formation of a nucleic acid, the individual sugars with their attached nitrogenous bases are linked through dehydration reactions in a line by the phosphate groups in very long:

polynucleotide chains (a bunch of connected nucleotides).

Cholesterol is a type of lipid called a:

steroid. It also plays a key role in biological membranes, helping them stay flexible. (Rubber, waxes, and light-absorbing pigments are other important biological lipids).

Amino acids are:

the smallest units of proteins that have a simple basic structure, a central carbon atom attached to an amino group (-NH2), a carboxyl group, (-COOH), a hydrogen atom (H), and a functional group, designated "R".

In some cases of hydrogenated fats, it creates trans fats, a type of:

unsaturated fat linked to heart disease.