1 Chemical Constituents of Cells Organic v. Inorganic Molecules Organic molecules Contain C and H Usually larger than inorganic molecules Dissolve in water and organic liquids Carbohydrates, proteins, lipids, and nucleic acids Inorganic molecules Generally do not contain C Usually smaller than organic molecules Usually dissociate in water, forming ions Water, oxygen, carbon dioxide, and inorganic salts

2 Chemical Constituents of Cells Organic v. Inorganic Molecules

3 Inorganic Substances Water Most abundant compound in living material Universal Solvent Many solutes are dissolved in our body’s water Many ionic compounds (NaCl) dissociate or break apart in water Participates in many chemical reactions (cells and fluid) Dehydration (synthesis) – water is removed from adjacent atoms to form a bond between them. Hydrolysis (degradation) – water is used to break bonds between molecules. Water is an excellent temperature buffer Absorbs and releases heat very slowly Water provides an excellent cooling mechanism It requires a lot of heat to change water from a liquid to a gas. If water does change form and evaporates, it leaves a cool surface behind.

4 Inorganic Substances Water (Cont) Water serves as a lubricant Mucus, joints and internal organs. Two-thirds of the weight of an adult human Major component of all body fluids (about 70%) Medium for most metabolic reactions Important role in transporting chemicals in the body Oxygen (O 2 ) Used by organelles to release energy from nutrients in order to drive cell’s metabolic activities Necessary for survival Gas that is transported in the blood.

5 Inorganic Substances Carbon dioxide (CO 2 ) Waste product released during metabolic reactions Must be removed from the body Inorganic salts Abundant in body fluids Sources of necessary ions (Na +, Cl -, K +, Ca 2+, etc.) Play important roles in metabolism

6 Organic Substances Contains the atoms carbon (and hydrogen) Small molecules (monomers or building blocks) are covalently bonded Together to form large polymers or macromolecules Water is usually involved in the formation and breakage of bonds between monomers. Dehydration synthesis – removal of water to form a covalent bond between monomers; Hydrolysis – using water to break bonds between monomers.

Copyright © 2010 Pearson Education, Inc. + Glucose Fructose Water is released Monomers linked by covalent bond Water is consumed Sucrose (a) Dehydration synthesis Monomers are joined by removal of OH from one monomer and removal of H from the other at the site of bond formation. + (b) Hydrolysis Monomers are released by the addition of a water molecule, adding OH to one monomer and H to the other. (c) Example reactions Dehydration synthesis of sucrose and its breakdown by hydrolysis Monomer 1Monomer 2 Monomer 1Monomer 2 +

8 Organic Substances Four major classes found in the cells include; Carbohydrates Lipids Proteins Nucleic acids

9 Organic Substances Carbohydrates (Sugars) Provide energy to cells Supply materials to build cell structures Water-soluble Contain C, H, and O Ratio of H to O close to 2:1 (C 6 H 12 O 6 ) Monomers (building blocks) Monosaccharides – glucose, fructose, galactose Disaccharides ( 2 monosaccharides covalently bonded together): maltose = glucose + glucose sucrose = glucose + galactose lactose = glucose + frutose Polysaccharides – many glucose molecules covalently bonded together. Glycogen = animal storage carbohydrate; stored in liver and skeletal muscles Cellulose = starch/ plant storage carbohydrate

10 Organic Substances Carbohydrates (Sugars) Function = energy storage/energy source How is the energy that is stored in carbohydrates release? CELLULAR RESPIRATION OVERVIEW oxygen ↓ glucose → H 2 O + CO 2 ↓ energy (ATP)

11 Organic Substances Carbohydrates (a) Some glucose molecules (C 6 H 12 O 6 ) have a straight chain of carbon atoms. C C C C C C H O H O O O HH OH H H H H O H H H H C H O O H H O H O H H HH C O H C C C O C H (b) More commonly, glucose molecules form a ring structure. O (c) This shape symbolizes the ring structure of a glucose molecule. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

12 Organic Substances Carbohydrates O (a) Monosaccharide OO O (b) Disaccharide O O O (c) Polysaccharide Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

13 Organic Substances Lipids Soluble in organic solvents; insoluble in water Types Fats (triglycerides) Used primarily for energy; most common lipid in the body Contain C, H, and O but less O than carbohydrates (C 57 H 110 O 6 ) Building blocks are 1 glycerol and 3 fatty acids per molecule Saturated Have only single bonds between carbons in their fatty acid chains Are solid at room temperature Are animal fats Are nutritionally “BAD” fat Unsaturated Have one or more double bond between the carbons in their fatty acid chains Are liquid at room temperature - oils Are plant fats Are nutritionally “GOOD” fat

14 Organic Substances Lipids Fats (triglycerides) Trans fats Unsaturated fats that have been solidified by artificial means Not produced nor maintained in the body Include margarine The WORST type of fat Function = energy storage/energy source Glycerol portion Fatty acid portions C O OHCC H H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H H C O OHCC H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H H C H C H H C H H C H H C H H C H H C H H H C O OHCC H HH C H H C H H C H H C HH H C

15 Organic Substances Lipids Phospholipids Building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per molecule -Triglyceride with the substitution of a polar phosphate group (PO 4 ) for one fatty acid Hydrophilic and hydrophobic Function = Major component of cell membranes C H C OH CH H Glycerol portion (a) A fat molecule O O Fatty acid H C H H H H C H H N O O O POCH O – Phosphate portion (b) A phospholipid molecule (the unshaded portion may vary) H CH C H H O (c) Schematic representation of a phospholipid molecule Water-insoluble (hydrophobic) “tail” Water-soluble (hydrophilic) “head” Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

16 Organic Substances Lipids Steroids Four connected rings of carbon Widely distributed in the body, various functions Function = Component of cell membrane; Used to synthesize hormones Cholesterol (a) General structure of a steroid C C C H 2 C H 2 CC H (b) Cholesterol C CH H C HC H 2 H 2 CH C H 2 C H 3 HOC CH 3 2 C Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Organic Substances Proteins Amino Acid Structure Amino group R group Carboxyl group Protein building blocks are amino acids Amino acids held together with peptide bonds 17 HN H C H C O OH S C H HH HN H C H C O C C C H H CH CH H CH CH HN H C H C O R (a) General structure of an amino acid. The portion common to all amino acids is within the oval. It includes the amino group (—NH 2 ) and the carboxyl group (—COOH). The "R" group, or the "rest of the molecule,“ is what makes each amino acid unique. (b) Cysteine. Cysteine has an R group that contains sulfur. Phenylalanine. Phenylalanine has a complex R group. Improper metabolism of phenylalanine occurs in the disease phenylketonuria. Types of amino acid 20 different based on R-groups or side chains

Organic Substances Proteins Function of Proteins Structural material Keratin in hair, nails, and skin Transport hemoglobin Chemical Messengers Hormones Neurotransmitters Movements Actin and myosin in muscle Catalysts Enzymes Defense Antibodies Protein building blocks are amino acids Amino acids held together with peptide bond Length of amino acid change may vary; Peptide = aa’s Polypeptide = 100 –thousands of aa’s with a function Protein = 100-thousands of aa’s with a specific function. 18

19 Four Levels of Protein Structure Pleated structure Coiled structure Amino acids N N N N N H H H H H C C C C O O O C C C C C C O C O N N H H C O C C O C H N N H O O C C C C N N N NH H HOC CC O O CC C HOC C C N C NHO CC HOC C N N N NH H HOC O O CC C HOC H R H R H R H R H R H R H R H R H R H H R H H R H R H R HH RR HH RR C H C H (b) Secondary structure—The polypeptide chain of a protein molecule is often either pleated or twisted to form a coil. Dotted lines represent hydrogen bonds. R groups (see fig. 2.17) are indicated in bold. (a) Primary structure—Each oblong shape in this polypeptide chain represents an amino acid molecule. The whole chain represents a portion of a protein molecule. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Organic Substances Proteins Three-dimensional folding HH (c) Tertiary structure— The pleated and coiled polypeptide chain of a protein molecule folds into a unique three- dimensional structure. (d) Quaternary structure—Two or more polypeptide chains may be connected to form a single protein molecule.

20 Protein Denaturation The loss of 3-dimensional conformation (shape) of a protein. The results in loss of function. Reasons for denaturation; Extreme pH values Extreme temperature values Harsh chemicals (disrupt bonding) High salt concentrations

21 Animation: Protein Denaturation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at

22 Organic Substances Nucleic Acids Carry genes Encode amino acid sequences of proteins Building blocks are nucleotides – 3 parts DNA (deoxyribonucleic acid) – double polynucleotide RNA (ribonucleic acid) – single polynucleotide S P B Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

23 Organic Substances Nucleic Acids Carry genes Encode amino acid sequences of proteins Building blocks are nucleotides – 3 parts Pentose sugar (5-C) Nitrogenous base Phosphate group S P B

24 Organic Substances Nucleic Acids DNA (deoxyribonucleic acid) – double polynucleotide Structure: Sugar deoxyribose Base – adenine (A), thymine (T), cytosine (C), guanine (G) Double stranded; strands held together by H-bonds between bases on the opposite strands; A complements T (2 hydrogen bonds) C complements G (3 hydrogen bonds) Function = genetic material DNA directs protein synthesis DNA contains all necessary information needed to sustain and reproduce life

25 Organic Substances Nucleic Acids RNA (ribonucleic acid) – double polynucleotide Structure: Sugar = ribose Base – adenine (A), cytosine (C), guanine (G), uracil (U) (replaces thymine), Function = transport DNA code during protein systhesis DNA directs protein synthesis