Chapter 6 The Chemistry of Life

6.1: Atoms and Their Interactions You are responsible for this material! It is a review of material from Physical Science. Use the 6.1 study guide questions worksheet to review this material.

6.2: Water and Diffusion Polar- molecule with an unequal distribution of charge, has a positive and negative end due to unequal sharing of electrons Attracts ions Attracts other polar molecules Attracts other water molecules

Hydrogen bond- attraction of opposite charges between hydrogen and oxygen in water molecules Gives water the ability to creep up thin tubes- capillary action Gives water surface tension properties

Capillary action

Water resists temperature change Specific heat- the amount of energy required to change one gram of material one degree Celsius Water has a high specific heat Helps maintain steady environment when situations fluctuate Helps maintain homeostasis

Molecular Motion Solids, liquids, and gases all have kinetic energy whether they are in motion or not The molecules that make them up are in constant motion- Brownian motion Temperature is a measure of this motion

Diffusion Diffusion- the movement of particles from an area of higher to lower concentration No energy required Result of Brownian motion

Factors that affect the rate of diffusion: 1. Concentration gradient- difference in concentration of a substance across space greater concentration gradient, faster diffusion 2. temperature- higher temperature means molecules move faster and bump into each other more often

3. pressure- increasing pressure increases particle motion

How long does diffusion continue? Until all areas are equal in concentration Particles continue to move, but there is no overall concentration change This is called dynamic equilibrium

Dynamic Equilibrium

6.3: Life Substances How many electrons does carbon have available for bonding in its outer energy level? Because it can form 4 bonds, it makes a good backbone or skeleton on which to build larger molecules Bonds easily with hydrogen, oxygen, & nitrogen

Types of covalent bonds: Carbon can bond with other carbon atoms & other elements to form: Single- one pair of shared electrons Double- two pairs of shared electrons Triple- three pairs of shared electrons

When carbon atoms bond with each other, they can form: Straight chains Branched chains Rings

Isomers- compounds with the same chemical formula but with different 3-dimensional structures Organic compounds- contain at least one carbon chain

Macromolecules Monomers- fundamental molecular unit Polymer- macromolecules formed by linking the same kind of functional unit

Carbohydrates Carbo- carbon Hydrate- water Macromolecule composed of carbon, hydrogen & oxygen General formula= (CH2O)n

Monosaccharide Monomer of carbohydrates Simple sugar “ose” indicates that a substance is a sugar Examples- glucose, fructose Cells link monosaccharides to form-

Disaccharides Sugar composed of 2 monosaccharides Example- sucrose, lactose

Polysaccharides Polymers composed of many monosaccharides Examples: Starch- long term energy storage in plants, animals can break down starch to obtain glucose

Glycogen- long term energy storage in animals, animals can break down glycogen to obtain glucose

Cellulose- AKA fiber, structural molecule in cell walls of plants and algae, animals cannot break it down

Lipids Functions- Energy storage Insulation Protective covering Major component of cell membranes

Fats Energy storage molecules Mostly carbon and hydrogen General formula= (CH2)n Hydrophobic- Hydro- water, Phobic- fearing Triglyceride- glycerol molecule & 3 fatty acids, monomer of fats

Types of fats: 1. Saturated fats- no double bonds between carbon atoms in carbon chains Solid at room temperature- butter, lard

2. Unsaturated fats- double bonds between carbons in chain Liquid at room temperature- oil

Phospholipids, waxes, and steroids Phospholipids- major components of cell membranes Waxes- hydrophobic coatings composed of fatty acid & alcohol Steroids- cholesterol based, important in digestion & synthesis of male & female hormones

Proteins Composed of carbon, hydrogen, oxygen, nitrogen, (sometimes sulfur) Functions: Structural-hair, nails, horns, hooves Contractile- produce movement, muscle Storage- egg white Defense- antibodies, membrane proteins Transport- hemoglobin Signaling- hormones, membrane proteins Catalysts- enzymes

Amino Acids (AA) Monomer of proteins Peptide bond- covalent bond between AA in protein chain (sometimes called polypeptides) 20 kinds of AA

Structure Determines Function A protein is a chain of AA folded, twisted, & sometimes joined with other AA chains to form complex structures A protein needs a particular shape to do its job

Enzymes Proteins that act as catalysts and change the rate of a chemical reaction Speed reactions in nearly all metabolic processes Affected by: Temperature Ionic conditions- salt pH Hint- if it ends in “ase”, it’s probably an enzyme!

Nucleic Acids- more in coming chapters Macromolecules that contain information for the construction of proteins

Nucleotides Monomer of nucleic acids Structure- Phosphate group 5-carbon sugar Nitrogenous base

DNA- deoxyribonucleic acid Two chains of nucleotides formed into a double helix Genetic code found in every cell

RNA- ribonucleic acid Single chain of nucleotides wrapped around itself Made from DNA and used in making proteins