The Macromolecules of Cells: Carbohydrates Lipids Proteins Nucleic Acid

Organic Molecules * Organic molecules are found in living things (vs. Nonorganic) * Referred to as “macromolecules” -- Carbohydrates -- Lipids -- Proteins -- Nucleic Acids The term “macromolecule” means large molecule.

Organic molecules are made of carbon and can form a huge variety of carbon backbone chains.

Macromolecules (polymers) are formed from smaller building blocks called monomers. Polymer Monomer carbohydrates monosaccharides proteins amino acids nucleic acids nucleotides Lipids “none”

Carbohydrates Carbohydrates (sugars) serve as 1) quick energy and short-term energy storage 2) they play a structural role in plants, bacteria, and insects 3) many end in the suffix “ose” Carbohydrates also play a role in cell-to-cell recognition. Carbohydrates have the atomic grouping H-C-OH, in which the ratio of H to O atoms is close to 2:1.

Monosaccharides Monosaccharides are sugars that are made up of only one sugar. There are only 3 monosaccharides Glucose Fructose Galactose

Monosaccharide -- one sugar carbohydrate Glucose

Disaccharides Disaccharides are made out of two simple sugars (monosaccharides) Sucrose (table sugar) -- glucose + fructose Maltose (malt sugar) -- glucose + glucose Lactose (milk sugar) -- galactose + glucose

A disaccharide is made from linking two monosaccharides together.

Reactions The making or breaking of disaccharides uses a molecule of water Condensation: reaction makes a disaccharide from two monosaccharides and removes a water molecule in the process. Hydrolysis: reaction breaks down a disaccharide by adding a water molecule to satisfy the exposed bonding sites on the two new monosaccharides.

Condensation Reaction Water is removed to allow the two sugars to bond together.

Hydrolysis Reaction Water is added so O- and OH+ can be added to exposed bonding sites. Satisfies bonds

Polysaccharides Larger sugars are made from linking many glucose molecules Starch Glycogen Cellulose Chitin

Examples of Polysaccharides: starch -- (helical structure) energy storage in plants glycogen cellulose -- (unbranched) found in plants for structure. It is not available as an energy source because of structure. Chitin – found in the exoskeleton of insects and crustaceans (highly branched) quick energy for animals Starch and glycogen are the storage forms of glucose in plants and animals, respectively. Cellulose is found in plant cell walls. In cellulose, the glucose chains are joined differently than in glycogen or starch; human digestive enzymes cannot break these linkages in cellulose (thus humans derive no energy from eating cellulose).

Starch Starch is a storage molecule for plants. It is stored in structures called plastids. Starch is high in energy and is stored energy for the plant.

Glycogen Glycogen is a molecule that is used by animals for temporary storage of energy. If not utilized, energy will be stored as fat.

Chitin Chitin is a polysaccharide found in exoskeletons of crustaceans and insects.

Cellulose Polysaccharide found in the cell walls of plants. Strong molecule used for structure and support of the plant cell.

Lipids do not dissolve in water!!! *Lipids serve as long-term energy stores in cells, form membranes, and serve as hormones and insulation. Lipids do not dissolve in water!!! Main reason why lipids are classified together; all other molecules are soluble in water

Structure of Triglycerides Formed from a glycerol molecule and three fatty acid molecules.

Fatty Acid Chains Fatty acids are long chains of carbons with many hydrogens attached. Full of energy since all bonds are potential energy for an organism. Fatty acids may be saturated fatty acids or unsaturated fatty acids. Saturated fatty acids are commonly from animal sources and are solid at room temperature. There are no double covalent bonds between carbons; these molecules are saturated with hydrogen atoms at every position. Saturated fatty acids are associated with increased incidence of cardiovascular disease. Unsaturated fatty acids come from plants sources and are liquid at room temperature. One or more double covalent bonds are found within the carbon chain; these molecules do not have hydrogen atoms at every position along the carbon chain.

Saturated vs. Unsaturated “bad for you” “good for you” Saturated Fats have no double bonds Found in tropical oils and animal fats All carbons are “saturated” with hydrogens. Straight chains Solid at room temp. Unsaturated Fats have varying numbers of double bonds Common in plants All carbons are not fully bonded with hydrogens Chains are bent at double bonds Liquid at room temp.

Some lipids are phospholipids that form cell membranes Some lipids are phospholipids that form cell membranes. These only have two fatty acids chains. Glycerol head is hydrophilic -- loves water Fatty Acid tails are hydrophobic -- hate water

Other lipids are steroids -- no fatty acid chains. Examples: Steroids -- Cholesterol (thickens arteries and is important in cell membrane) Hormones (estrogen and testosterone) Waxes

Proteins Proteins: 1. Serve as structural proteins (cartilage, fingernails, hair, etc.) 2. Act as enzymes to speed reactions 3. Serve as transport carriers 4. Act as antibodies 5. Allow materials to cross membranes

Proteins are polymers of amino acids. Amino acids have an amino group (–NH2) and a carboxyl group (-COOH). The rest of the molecule is the R group for Remainder of the molecule. It is the R group that varies from one amino acid to the next.

Water is removed when joining two amino acids.

Proteins have levels of organization. Primary structure refers to the sequence of amino acids joined by peptide bonds. Secondary structure is any folding or twisting of the chain in space. Tertiary structure comes about when proteins fold into globular shapes. Quaternary structure occurs in proteins that have more than one polypeptide chain twisted together. Extremes in temperature or pH, or chemicals, radiation, and so forth can cause proteins to unfold, thus denaturing them.

Protein Organization Primary Structure (1°) -- linear chain of amino acids. Number and sequence of amino acids varies. Secondary Structure(2°) -- shortening of amino acid chain by coiling or pleating Tertiary Structure (3°) -- further folding of chain to create a more compact structure Quaternary Structure (4°) -- only some proteins have this structure which is two or more chains bonded together.

Nucleic Acids Nucleotides are monomers of nucleic acids. Examples include Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA). Deoxyribonucleic acid (DNA) serves as genetic material for cells. Ribonucleic acid (RNA) carries the information from DNA to the rest of the cell.

DNA is double-stranded, with complementary base pairing.