Chapter 5 The Molecules of Life

Water Water – makes up 70% of a cell’s weight Most intracellular reactions occur in the aqueous environment

Water Properties: Inorganic Molecule – nonliving and does not contain C Ex. H2O Polar compound – one that has a more positive charge on one side, and a more negative charge on the other Makes a great solvent; dissolves ions and other polar molecules easily Dissolve

Hydrogen Bonds – weak attraction between a molecule with a negative charge (ex oxygen) and a hydrogen atom Cohesion – tendency of the molecules of a substance to stick together Adhesion – attractive force between unlike substances Capillary action – ability to spread through narrow pores or tubes against gravity Water is less dense at lower temperatures

Draw on your papers

Carbon Compounds Organic Compounds – contain C and living Exceptions: graphite, diamonds, CO2 Carbon exhibits bonding power of 4 C Most often bonds with hydrogen, oxygen, nitrogen, or to itself and forms chains Hydrocarbon – long chains composed of hydrogen and carbon

Draw the example in your notes

Functional group – group of atoms within a molecule that interact with other molecules in a predictable way Ex. See table

Ex: a sugar molecule in starch Monomer - A single, repeated molecule unit Ex: a sugar molecule in starch Polymer – complex molecules consisting of repeated monomers Macromolecules – large polymers (starch) Condensation Reaction (dehydration synthesis) – process of bonding two monomers together by the removal of a H2O Hydrolysis – process of breaking apart a complex molecule by the addition of a water molecule

The Four Biological Molecules 1. Carbohydrates – organic compound made up of sugar molecules The most abundant of all biological molecules Contain C, H, and O

Carbohydrates Monosaccharide (simple sugars) – one monomer of sugar Cannot be hydrolyzed into a smaller unit, C6H12O6 Ex: Glucose, Fructose, Galactose Isomers – Compounds that have the same exact molecular formula but differ in structure and function

Monosaccharide ISOMERS

Carbohydrates Disaccharide – two monosaccharides joined together by a condensation reaction forming a double sugar, C12H22O11 Ex: Sucrose, Maltose, Lactose Polysaccharides – complex carbohydrates made up of many joined monosaccharides Ex: Cellulose – plants structure Starch – plants store food Glycogen – animals store food

Lipids 2. Lipids - Fatty hydrocarbon compounds also composed of C,H,O Fats – lipid molecule that have 3 fatty acid tails attached to a glycerol molecule Saturated – all single bonds therefore carbon is bonded to the maximum number of atoms Unsaturated – double bonds appear therefore carbon is attached to fewer atoms

Fats Triglyceride

Saturated vs. Unsaturated

Lipids Steroids – lipid molecule in which the carbon skeleton forms four fused rings Ex: hormones, cholesterol, plant poisons

Draw a Phospholipid (makes up the cell membrane)

Proteins 3. Proteins – a polymer constructed from a set of just 20 kind monomers called amino acids Most diverse group of the large biological molecules Ex. Hair, fur, nails

Proteins Amino Acids – building blocks of proteins, 20 Structure of an amino acid Carbon atom Hydrogen atom Carboxyl group Amino group R group

Proteins Peptide bonds – bond that links two amino acids together Ex: Dipeptide – 2 amino acids joined together Polypeptide – proteins of three or more amino acids Proteins bend and fold to achieve the correct shape so that they can function Denaturation – loss of normal shape of protein Heat, pH, other environmental factors

Proteins Enzymes – Class of proteins which act as catalysts by speeding up specific metabolic reactions by lowering the activation energy Activation Energy – energy needed for a reaction to occur Substrate – substance acted upon by enzyme Active Site – particular region on an enzyme where a substrate binds

Nucleic Acids 4. Nucleic Acids – complex organic molecules made up of monomers of nucleotides Ex: DNA – Deoxyribonucleic Acid RNA – Ribonucleic Acid

Nucleic Acids Nucleotides – Small organic compound comprised of: 1. Phosphate group 2. 5-C sugar (pentose) – ribose or deoxyribose 3. nitrogen base – adenine, guanine, cytosine, thymine

Organic Molecules Flipchart

Organic Compounds Video Watch the video and answer the questions.