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Macromolecules. Ch 1. Molecules of Life. All cells are composed of 4 main molecules These molecules are called macromolecules . They are composed mainly of atoms of Carbon (C) , Hydrogen (H) and Oxygen (O).

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Ch 1

Molecules of Life

  • All cells are composed of 4 main molecules

  • These molecules are called macromolecules.


  • These atoms are joined to form molecules which are then joined to form macromolecules.

  • These macromolecules are COVALENTly bonded.

    • They share electrons

  • All living organisms are composed of 4 major classes of macromolecules: carbohydrates, lipids, proteins and nucleic acids.

Molecules of Life

  • The primary component of all macromolecules is carbon

  • Carbon has 4 electrons in its outer energy level, and carbon seeks to fill its energy level by sharing its electrons with other atoms. Carbon atoms form long chains that are the backbone of many different kinds of molecules.

  • These long carbon chains are organic compounds

Molecules of Life

  • Carbohydrates are energy sources

  • A carbohydrate is composed of C, H, and O

  • Some carbohydrates like table sugar are simple, small molecules called monomers.

  • Other carbohydrates (starches like potatoes & pasta) exist as chains of many subunits (monomers) that form complex polymers





Molecules of Life

  • The simplest carbohydrate molecules are small sugars or monosaccharides (monomers) that taste sweet. The formula for glucose is C6H12O6

  • Carbohydrates are made by linking individual sugars together to form long chains called polysaccharides (polymers).

  • Polysaccharides are insoluble in water. They can be deposited in specific storage areas in a cell. The cells ability to store energy in the form of polysaccharides lets organisms build energy reserves called glycogen.

Molecules of Life

  • Starch is a polysaccharide composed of glucose subunits (monomers)

  • Amylose is the simplest kind of starch – it is a long unbranched chain. Baking or boiling breaks the long chain into shorter lengths

  • Humans consume a lot of starchy carbohydrates such as the seeds of rice, wheat and corn. It makes up about two-thirds of all calories used by people.

  • Animals store glucose in long branched chains called glycogen.

Molecules of Life

  • Many organisms use polysaccharides as structural molecules such as plants.

  • Plants make cellulose which forms the cell walls of plants. Most animals cannot break the cellulose down so it is undigested. – we call it dietary fiber.

  • Cows and horses have special bacteria that do break the cellulose down.

Molecules of Life

  • Lipids store energy. They are composed of C & H

  • A lipid is not soluble in water, but it is soluble in oil

  • The most important kind of lipid is fat, an energy storage molecule.

  • Fats have more carbon-hydrogen bonds than carbs and can store more energy! But the body cannot process fats as easily as carbs . So the body can metabolize more carbs than fats in a given time and therefore receive more energy from the carbs!

  • The backbone of the structure is a glycerol molecule and the branches are fatty acids

Molecules of Life

  • Saturated fats are usually solid – butter, Crisco

  • Unsaturated fats are usually liquid – cooking oil

  • Steroids – hormones in your body

  • Waxes – earwax or candle wax

Molecules of Life

  • A protein is composed of long chains of subunits called amino acids.

  • There are 20 different kinds of amino acids used by humans. There is an endless variety of possible proteins the body can produce!

  • A typical protein has approximately 100 amino acids linked together in its chain.

Molecules of Life

  • The chemical properties of a protein depend on its structure.

  • The sequence of amino acids in the protein is called its primary structure.

  • Amino acids interact with neighboring amino acids which causes parts of the chain to coil or bend. The coiling and bending determines the protein’s secondary structure.

  • In most proteins, the entire chain folds into a compact mass called its tertiary structure.

  • When 2 or more proteins combine for form clusters, the mix of proteins forms quaternary structures.

Molecules of Life

  • Proteins often play structural roles in organisms.

    • Cartilage and tendons are made of a protein called collagen.

  • Proteins second major role in living organisms is forming enzymes. Enzymes increase the rate at which chemical reactions occur during metabolism.

  • Most chemical reactions necessary for growth, movement and other body activities would not take place without enzymes.

Molecules of Life

  • The fourth major class of macromolecules is called nucleic acids. Nucleic Acids contain genetic info.

  • The two types of nucleic acids are: DNA or Deoxyribonucleic acid and RNA or Ribonucleic acid.

  • The subunits of DNA and RNA are called nucleotides.

  • These nucleotides are grouped into units called genes. Genes encode information concerning how given organisms will grow and develop.

  • RNA is involved in making working copies of genetic information. These RNA copies are used in assembling amino acids to produce certain proteins which produce specific cells.

  • A DNA molecule consists of two interlocking coil-shaped strands that resemble a spiral staircase called a double helix.

  • DNA is stored in a compact form called chromosomes. It encodes the sequence of all the cells proteins

  • RNA have a variety of shapes depending on their function. RNA assembles or builds the proteins from the instructions given by the DNA.


  • What is a macromolecule

  • What is a carbohydrate, what is it made of, examples

  • What is a lipid, what is it made of, examples

  • What is a protein, what is it made of, examples

  • What is a nucleic acid, what is it made of, examples

Macromolecule mini poster

  • Divide your paper into 4 equal parts

  • Find 10examples of each macromolecule (except nucleic acids)

  • Paste into the correct section and explain what each macromolecule does

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