Chapter 6

The Chemistry of Life

6.1: Atoms and Their Interactions

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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 electronsDouble- two pairs of shared electronsTriple- three pairs of shared electrons

When carbon atoms bond with each other, they can form:

Straight chainsBranched chainsRings

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 unitPolymer- macromolecules formed by

linking the same kind of functional unit

Carbohydrates

Carbo- carbonHydrate- waterMacromolecule composed of carbon,

hydrogen & oxygen

General formula= (CH2O)n

Monosaccharide

Monomer of carbohydratesSimple sugar“ose” indicates that a substance is a sugarExamples- glucose, fructose

Cells link monosaccharides

to form-

Disaccharides

Sugar composed of 2 monosaccharidesExample- 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 storageInsulationProtective coveringMajor 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 proteinsPeptide 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 group5-carbon sugarNitrogenous base

DNA- deoxyribonucleic acid

Two chains of nucleotides

formed into a double helixGenetic code found in

every cell

RNA- ribonucleic acid

Single chain of nucleotides wrapped around itself

Made from DNA and used in making proteins