Carbohydrates, lipids, and proteins IB Topic 3.2 Pages 56-61

Introduction Living things are composed of an array of molecules We need to classify them  Certain qualities The more common biochemically important molecules are: Molecule (polymer)Subcomponents (monomer) CarbohydratesMonosaccharides LipidsGlycerol & fatty acids Proteins (polypeptides)Amino acids Nucleic acidsNucleotides

Common biochemicals & their structure Classified as organic or inorganic All organic molecules contain the element carbon However, not all carbon-containing molecules are organic  Example = carbon dioxide (not organic)  Carbohydrates, lipids, proteins ARE organic

Some of the most important categories … CategorySubcategoryExample molecule CarbohydratesMonosaccharidesGlucose, galactose, fructose DisaccharidesMaltose, lactose, sucrose PolysaccharidesStarch, glycogen, cellulose ProteinsXEnzymes, antibodies LipidsXTriglycerides, phospholipids Nucleic AcidsXDNA, RNA

You should learn to recognize the structures of common molecules BUT you do not need to draw them (yea!)  Wait till organic chemistry … Open your book to page 57 Look at figures 3.2, 3.3, 3.4, and 3.5 Answer question 4

Carbohydrates Different “sizes”  Monosaccharides, disaccharides, polysaccharides All serve many functions in living organisms  Short term energy  Because they carbohydrates are soluble Contain only three elements: C, H, O  Hydrogen and oxygen in a 2:1 ratio

Monosaccharide – simple sugar Relatively small; taste sweet and soluble in water Examples:  Glucose: made by green leaves using light energy, our bodies transport it in our blood, respiration (chemical fuel), building block for larger molecules  Galactose  Fructose (found in fruits – makes them sweet)

Disaccharides Made of 2 monosaccharide molecules Examples:  Sucrose (glucose + fructose)  Maltose (glucose + glucose)  Lactose (galactose + glucose)

Polysaccharides Built from many monosaccharide molecules connected by glycosidic links Examples  Starch (polymer of glucose)  Glycogen (polymer of glucose) Stores glucose in liver and muscles  Cellulose (polymer of glucose) Component of cell walls

Lipids Lipids occur in living things as animal fats, plant oils, phospholipids of cell membranes, and steroids Contain C, O, and H (like carbs), but proportion of oxygen is much less Insoluble in water; hydrophobic  Long term energy storage  Can be dissolved in organic solvents (alcohol)

Lipids Fats and oils are compounds called triglycerides  Formed when water is removed between fatty acids and glycerol Long hydrocarbon tails

The Role of Lipids Energy storage  Lipids store about twice as much chemical energy as carbohydrates If you eat more food than you burn, your body will store much of the excess as fat in adipose tissue

Other important roles of lipids 1. Energy storage  Less oxygen atoms/more concentrated source 2. Metabolic water source 3. Thermal insulation and buoyancy 4. Water proofing of hair and feathers 5. Electrical insulation  Myelin sheath

Homework Due Tuesday #4-7 page 61

Bell Ringer: Take out your homework (#4-7 page 61) Take out your PowerPoint questions from yesterday Homework for tonight: amino acids worksheet (will be passed out at the end of class) & bring your book the rest of the week. Topic 3.1 and 3.2 quiz Thursday

Answers to #4-7 page 61 4) a. glucose + fructose  sucrose + water 4) b. condensation reaction 5) a. glycerol + 3 fatty acids  triglyceride + 3 water 5) b. condensation enzyme 5) c. product 5) d. three (b/c three condensation reactions occurred)

Answers to #4-7 page 61 6) a. amino acids 6) b. glycerol and fatty acids 6) c. nucleotides 7) a. nucleotides 7) b. amino acids 7) c. glucose (a monosaccharide)

Amino Acids, peptides, and proteins Contain nitrogen, sulphur, hydrogen, carbon and oxygen  Amino group: NH2 Carboxyl group: COOH Amino acids  peptides and proteins  Polypeptide and protein are used interchangeably Once the chain is constructed, it takes a specific shape – shape matters with proteins  Shape  function

Amino acids Proteins are made from 20 amino acids Also attached is an R group  Differ  different chemical characteristics

Most macromolecules are polymers Carbohydrates, lipids, and proteins are chainlike molecules called polymers  Polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds  Monomers

Condensation and hydrolysis Many organisms rely on food to gain the building block molecules When animals eat, food is digested (or hydrolyzed) into the building blocks  Going from polymers to monomers These building blocks are transported to body cells and bonded together to form larger molecules

What happens when you eat? Foods are chemically digested in your alimentary canal Hydrolyzing enzymes are required Each reaction is called a hydrolysis and requires a molecule of water as a reactant Think about the word hydrolysis:  Hydro = water  Lyse = split

Examples of hydrolysis Hydrolysis of a disaccharide in two … Hydrolysis of a triglyceride lipid to … Hydrolysis of a polypeptide to …

Condensation reactions Are the reverse of hydrolysis Condensation reactions occur to re-form larger biochemical molecules Water molecules are products rather than reactants Also requires a different type of enzyme

Condensation Reaction (or Dehydration Synthesis) The process of connecting monomers to create a polymer  This process requires energy and is aided by enzymes  Removes water molecules  One monomer provides a hydroxyl group and the other provides a hydrogen

Wrap Up All organic molecules contain the element _________ Carbohydrates exist as _______, _______, & _______ The smallest carbohydrates are ___________ The subcomponents of other biochemically important organic molecules are:  _____________, which make up proteins  _____________, which make up lipids (fats and oils)  _____________, which make up nucleic acids (DNA and RNA) Subcomponents are bonded together by ___________ Larger molecules are split by ____________ Although carbohydrates and lipids are used for energy storage …