THE CHEMISTRY OF LIFE

THE CHEMISTRY OF LIFEBiochemistry is the study of organic chemistry, mainly the compounds known as carbohydrates, lipids, proteins, and nucleic acids.

All living things are made up of various chemical compounds.

The Nature of MatterAtoms are the basic building blocks of matter

Elements are substances which are made of only one kind of atom

Compounds are a combination of two or more kinds of atoms in a defined proportion

Structure of Atoms

Structure of AtomsNucleus – made up of protons (+ charge, 1 atomic mass unit) and neutrons (no charge, 1 atomic mass unit) # of protons = # of neutrons

Electrons – orbit the nucleus (- charge, very little mass) determine the chemistry of atoms first energy level contains up to 2 electrons outside levels can hold up to 8 electrons when an electron orbital is full the atom is chemically inactive if orbital in not full the atom “looks” to

gain, lose, or share electrons with other atoms

Structure of Atoms

http://www.classzone.com/cz/books/bio_09/resources/htmls/animated_biology/unit1/bio_ch02_0059_ab_atombond.html (Great Review of atoms and bonding!)

Mass number & Atomic NumberAtomic number is equal to the number of protons

Mass number (atomic mass) is equal to the number of protons plus the number of neutrons

Isotopes Atom of an elements that has a different number of neutrons from that of other atoms of the same element

Radioactive isotopes are unstable and break down at a constant rate over time (some can be used as tracers)

Isotopes of Carbon

Chemical Bonding Ionic bonds – Fig. 2-3 – form when atoms gain or lose electrons, become chemically charged and are attracted to each otherhttp://www.dnatube.com/video/366/Ionic-Bond

Chemical Bonding Covalent bonds – Fig. 2-4 – formed when atoms share one or more pairs of electronshttp://www.dnatube.com/video/1290/Covalent-bond

Chemical Bonding Van der Waals forces – Fig. 2-5 – a slight attraction that develops between the oppositely charged regions of nearby molecules

Properties of WaterH2O – most important inorganic compound; All organisms need H2O to survive. Formed by polar covalent bonds between hydrogen & oxygen

inorganic – contains no carbon/hydrogen

bondsorganic – contains carbon

Properties of WaterPolar Covalent Bonds are formed when partial positive (+) and partial negative (-) charges are formed as a result of unequal sharing of electrons

Properties of WaterPolar Covalent Bonds are formed when partial positive (+) and partial negative (-) charges are formed as a result of unequal sharing of electrons

Properties of Water – Hydrogen BondsHydrogen bonds are weak electrical attractions between the partial negative charge of one molecule and the partial positive charge of a different moleculehttp://www.youtube.com/watch?v=lkl5cbfqFRM

Properties of Water Cohesion is the attraction of molecules of the same substance (Fig. 2-8). Because of cohesion of H2O molecules, H2O is able to store a lot of heat. This ability to store heat protects organisms from damaging changes in temperature

Properties of Water Adhesion is the attraction between molecules of one substance and molecules of another substance; adhesion makes H2O one of the best solvents

http://www.youtube.com/watch?v=EBfGcTAJF4o&NR=1

Solutions & SuspensionsMixtures of two or more elements or compounds that are

physically NOT chemically combined

Solution – mixtures in which the molecules of the substances are evenly distributed between the solvent and the solute

Suspension – mixture of water and nondissolved materials

Acids, Bases, and pHpH is a measurement of the H+ concentration in a solution

Water (H2O) is a neutral molecule (neither acidic or basic) which will dissociate into and equal number of H+ and OH- and is the basis of pH comparison

Acids, Bases, and pHpH is a measurement of the H+ concentration in a solution

The pH scale (Fig. 2-10)

Acids, Bases, and pHpH is a measurement of the H+ concentration in a solution

Acids, Bases, and pHpH is a measurement of the H+ concentration in a solution

•pH of water is 7•Acids have a greater [H+] than [OH-] pH is less than 7•Bases have a greater [OH-] than [H+] pH is greater than 7

•Buffers are weak acids or bases that can react with strong acids or bases to help prevent sharp sudden changes in pH (maintain homeostasis)

Carbon Compounds Carbon compounds contain carbon and usually hydrogen; most occur naturally only in bodies & products of living things

Electron Structure of Carbon

Characteristics of CarbonCarbon can bond with a variety of other elements

Carbon can bond to other carbon molecules (Fig. 2-11)

Carbon can form single, double or triple bonds

Carbon can be bonded into long chains, branches, or rings

MacromoleculesDehydration synthesis – a reaction in which 2 molecules are bonded together by the removal of one H+ and one OH- to form H2O and another compound http://www.youtube.com/watch?v=b7TdWLNhMtM&NR=1

MacromoleculesHydrolysis – a reaction in which a complex molecule is broken apart into simpler molecules by the addition of H2O

CarbohydratesOrganic compounds of C, H, & O; ratio of H to O is always 2:1

CarbohydratesOrganic compounds of C, H, & O; ratio of H to O is always 2:1

Function of Carbohydrates

Energy storage (Fig. 2-13) starch is stored form of sugar in plants glycogen is stored form of sugar in animals

Support cellulose is found in

plant cell walls chitin forms the

exoskeletons of

insects &arthropods

LipidsOrganic compounds made up of C, H, & O, but much less O than

carbs.Structure of Lipids – Fats are made up of 1 glycerol and three fatty acids (Fig. 2-14)

LipidsOrganic compounds made up of C, H, & O, but much less O than

carbs.Structure of Lipids – Phospholipids are the major

component of cell membranes (Fig. 7-12)

LipidsOrganic compounds made up of C, H, & O, but much less O than

carbs.Lipids also serve as:

insulationenergy storageprotection – organs; waxy cuticle on the surface

of leaves

Lipids are non-polar – will not dissolve in water

Nucleic AcidsDNA, RNA – compounds that contain phosphorus (P) and

nitrogen (N) in addition to C, H, & OStructure of DNA – double helix – Fig. 12-7Function of DNA – hereditary material, base pairs

act as a code that determines what proteinswill be made

Nucleic AcidsDNA, RNA – compounds that contain phosphorus (P) and

nitrogen (N) in addition to C, H, & O

Structure of RNA – Fig. 12-12 – single chain of nucleic acids that are involved in protein synthesis

Proteins Compounds that contain N as well as C, H, & O, some also

contain sulfur (S) and very small amounts of phosphorus (P)

StructureFig. 2-17

Proteins Compounds that contain N as well as C, H, & O, some also

contain sulfur (S) and very small amounts of phosphorus (P)

FunctionStructural – cartilage, bone, muscle

Hormones – chemical messengers (ex. – insulin)

Antibodies – prevent disease

Enzymes – speed up reactions

Transport proteins are found in cell membranes

Chemical Reactions & EnzymesChemical reactions involve the breaking of bonds in reactants and the formation of new bonds in products

Reactants – elements or compounds that enter into a reaction

Products – elements or compounds that are produced by a reaction

Chemical Reactions & EnzymesEnergy in Reactions is either released or absorbed (Fig. 2-19)

Energy releasing reaction – the energy stored in the reactants is greater than the energy stored in the products (usually occurs spontaneously)

Energy absorbing reaction – the energy stored in the products is greater than the energy stored in the reactants (requires energy to initiate)

Activation energy – energy required to initiate a reaction

Chemical Reactions & Enzymes

Chemical Reactions & Enzymes

http://www.classzone.com/cz/books/bio_09/resources/htmls/animated_biology/unit1/bio_ch02_0052_ab_exoendo.html

This link is a great review of difference between exothermic and enothermic reactions

Chemical Reactions & EnzymesEnzymes are protein catalysts that are necessary for most of the chemical reactions that occur in living cells

Catalyst – substance that brings about a reaction without being changed itself; can be re-used

Enzymes – lower the activation energy, energy needed to break bonds, therefore reactions can occur quickly and at normal body temps. (Fig. 2-20)

Chemical Reactions & Enzymes

Enzyme Actions – Fig. 2-21Substrate – substance that enzyme acts uponEnzymes are specific for their substrates

Active site – the region on the surface of an enzyme where substrate molecules attachhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

Chemical Reactions & EnzymesRegulation of Enzyme Activity

Only small amounts of enzymes are needed because each molecule is re-used

Temperature – most enzymes work best at normal body temperatures

pH – different enzymes work best at different ranges of pH

Concentration of substrate & enzyme determines reaction rate as long as both are freely accessible to each other (up to a certain point)