Metabolic ProcessesWhat does that mean??

The cell is a highly organized assembly of atoms and molecules programmed by genetic instructions to carry out chemical reactions that define “life”.

Living organisms are characterized by a balance of anabolism and catabolism. Together, they are called metabolism.

Metabolic Processes:

Chemistry of LifeMonday, March 1st

Miss Tee

Chemical Fundamentals

Chemical Fundamentals

The AtomMass number: # protons, neutrons

Atomic number: # of protons

Isotope: atom of an element with same

atomic number but different mass number

IsotopesNucleus of some isotopes spontaneously decays

We call these radioisotopes and they are radioactive

Radioactivity results in:1. Formation of new element2. Release of subatomic particles3. Radiation

Isotopes

Half-lifeEvery radioisotope has a characteristic property:

half-life

What is a half-life?The time it takes for ½ atoms in a sample to decay

What application does this have for us today?Radioisotopes emit radiation as they decay can be

detectedRadioactive tracers are used to follow chemicals

through reactions as they occur in the body BIG medical research industry

Chemical BondingOrbital

Volume of space where electrons are most likely to be found

Can accommodate no more than 2 electronsWhen 2 electrons pair up and occupy an orbital =

more stable

IonCation, anion (loss, gain of e-)

Ionic bondForce of attraction between anion and cationNaCl

Ionic Bonding

Covalent BondingAtoms share electrons in outer shell, creating full

shells for both

Diamond is a good example

Molecular ShapeOverall shape contributes to molecule behaviour

When atoms react to form covalent bonds, their valence electrons undergo “hybridization” Change in orientation of the valence electrons Since electrons are all –vely charged, the pairs will repel

each other and will move as far apart as possible Molecular shapes include:

Tetrahedral Pyramidal Angular Linear

WaterH2O’s polar covalent bonds and asymmetrical

shape create a highly polar moleculeAllows it to form chemical bonds with other

molecules and ionsBonds BETWEEN molecules are called

“intermolecular bonds”

Intermolecular bonds weaker than intramolecular bonds

3 types:1. London Forces2. Dipole-dipole forces3. Hydrogen bonds

London ForcesWeakest, exist between all atoms and molecules

Formed by temporary unequal distribution of electrons as they move randomly about the nucleus

Transient “electron cloud” will attract positive nucleus of neighbour atom

London Forces

Dipole-dipole ForcesHold polar molecules together

Partially positive side of a molecule attracts the partially negative side of another molecule

Hydrogen BondsEspecially strong dipole-dipole forces

Form only between electropositive H of one molecule and an electronegative N, O, or F atom of neighbour polar molecule

Hydrogen Bonds

Van der Waals forcesLondon forces, dipole-dipole forces and hydrogen

bonds are collectively referred to as “Van der Waals forces”Electrostatic charges between adjacent atoms

Water as a SolventSmall non-polar molecules (O2, CO2) cannot form

hydrogen bonds with water only slightly solubleThat is why we need hemoglobin

Large non-polar molecules (fats, oils) also do not form hydrogen bonds “hydrophobic” (opposite is…?)

Unique Properties of WaterWater clings

CohesionAdhesion

Water absorbs a lot of heatHigh specific heat capacityHigh specific heat of vaporization

Solid water is less dense than liquid water

Unique Properties of Water1. Homework:

Make a table listing the 5 unique properties of water with: A definition for each property The effect of that property An example of that property in everyday

human or animal life

2. Prepare your unit glossary

Acids, Bases and BuffersAt 25°C, 2 H2O molecules/ 550 million react with

each other

1 H2O donates an H+ to the other H2O molecule OH-, H3O+

This is called “autoionization”

Acids, Bases and BuffersWhat is an acid? Base?

An acid is a proton donor; a base is a proton accepter

What do you know about pH and the human body? Internal environment of multicellular organisms is

very sensitive to pH levelsMost cellular processes operate best at pH 7.0- 7.4Living cells use “buffers” (proton

accepting/donating system) to resist significant changes in pH

Acids, Bases and BuffersThe most important buffer to the human body is

carbonic acid (H2CO3) and bicarbonate (HCO3-)

buffer system

BuffersAcidosis and alkalosis can be serious medical

conditions, potentially fatal

Internal buffers can donate H+ ions when they are required (if a patient is alkalotic) and can remove H+ ions when there are too many in a solution (if a patient is acidotic).

They are reversible reactions.