1. Levels of Structural Organization
-Organism – made up of the organ systems
-Organ system – consists of 2 or more different organs that work closely together
-Organ – consists of 2 or more different types of tissues
-Tissue – consists of 2 or more similar types cells
-Cellular – cells are made of many different types of molecules
-Organelle – machinery of the cell
Macromolecular – large “super” molecules
-Molecular – atoms are combined to form molecules
-Atomic – atoms make up all matter

2. Levels of Structural Organization

3. Matter The “stuff” of the universe Anything that takes up space
States of matter
Solid has definite shape and volume
Molecules have enough energy to vibrate
Liquid has definite volume, changeable shape
Molecules can move over around each other
Gas has changeable shape and volume
Molecules have enough energy to escape each other
-Plasma -electrons separated from atoms

4. Composition of Matter The Chemical Elements Elements
unique substances that cannot be broken down by ordinary chemical means
Atoms -building blocks for each element
-smallest part of element that still has properties of that element
The Chemical Elements
Organized on the Periodic table
atomic symbols of elements arranged by atomic number (number of protons)
Atomic number of each element
number of protons in its nucleus

5. -Atomic Mass-
- number of protons and neutrons in an atom
Only 24 elements have a role in our body
98.5% of body weight consists of
O, C, H, N, Ca, P

7. Atomic Structure (Bohr or Planetary Model)
Nucleus, the center of atom which contains:
protons
positive charge, mass (weight) of 1 atomic mass unit (amu)
determines atomic number
neutrons
neutral (no) charge, mass of 1 amu
Electron shells that surround the nucleus and contain:
Electrons
-negative charge, mass of 0 amu (1/2000 of proton’s mass)
valence electrons are in the outermost shell
furthest from the nucleus
interact with other atoms

8. All atoms have:
an equal number of protons and electrons
-therefore unreacted atoms are neutral (have no net charge)
-an atomic mass = total mass of protons + neutrons
-Isotope
-an atom of a particular element that has a different number of neutrons
-therefore a different atomic mass

9. Planetary Model of an Atom

10. Electron Shells
-The electron shell closest to the nucleus can hold up to 2 electrons
additional electrons are located in shells outside of the first shell
-All other electron shells outside of the first shell can hold up to 8 electrons
octet rule
an electron shell is full when there are:
2 electrons in the first shell
8 electrons in 2nd, 3rd, 4th,… shell
-an atom will undergo a reaction in order to ensure that it has a full outer shell

11. -If the valence shell of an atom is not completely FULL, then that atom is UNSTABLE
valance electrons of unstable atoms interact with valance electrons of other unstable atoms to create chemical bonds
allows both atoms to become stable
- The valence shells ( and their electrons) are the parts of atoms which will encounter other atoms
-Hence, reactions will occur or not as a result of the contents of the valence shell

12. Planetary Models of Atoms
p+ represents protons, no represents neutrons

13. Chemical Bonds
The interaction between 2 atoms may result in the formation of a chemical bond whereby 2 atoms are chemically linked to one another
Atoms bond with one another to become stable
an atom is stable when the valence shell is completely full (satisfying the “octet rule”)
Groups of atoms that are associated with each other through bonds are called molecules
i.e.chemicals that are LARGER and structurally more CoMpLeX than individual atoms

14. Chemically Inert (Non-reactive) Elements
Inert elements have their valence shell fully occupied by electrons
Incapable of bonding with other atoms

15. Chemically Reactive Elements
Reactive elements do not have their outermost energy level fully occupied by electrons

16. Types of Chemical Bonds
Ionic
Covalent
Hydrogen

17. Molecules Molecules two or more atoms bonded together
carbon dioxide (CO2), Glucose (C6H12O6), water (H2O), sodium chloride (NaCl)…
Structural formula
shows arrangement of atoms in a molecule
used to show how the anatomy of a molecule dictates its physiology
Molecular formula
itemizes each element present (and its quantity) in a molecule

18. - In a molecular formula, subscripts are used to show the number of atoms that are present in a molecule
- a subscript immediately follows the atom it is associated with
- the number 1 is never used, so subscripts start with the number 2
e.g. H2O the number 2 indicates that 2 atoms of hydrogen are present. Note that the number 1 is not used to indicate the number of Oxygens present
Coefficients are used to indicate the number of molecules
- coefficients are written in front of the molecular number
e.g. 2H2O means that there 2 water molecules and therefore 4 hydrogens and 2 oxygens are present

19. Molecular and Structural Formula

20. Biologically Important Molecules
Water
most abundant molecule in the human body
Monosaccharides
basic (smallest) unit of carbohydrates (sugars)
Amino acids
basic (smallest) unit of proteins
Fatty acids
basic (smallest) unit of lipids (fats, oils, waxes)
Nucleotides
basic (smallest) unit of nucleic acids

22. Formation of an Ionic Bond
Ionic bonds form between atoms after the transfer of one or more electrons from one atom to another atom in a process called ionization
-results in the creation of 2 ions
Ions
atoms that have an unequal numbers of protons and electrons
also known as electrolytes
-therefore charged atoms

23. Ionization
transfer of electrons from one atom to another

24. Anions and Cations Anion atom gained one or more electrons
more electrons than protons = net negative charge
Cation
atom lost one or more electrons
more protons than electrons = net positive charge

25. Anions and Cations
The anion and the cation are held together by the ATTRACTION between a positively charged substance and a negatively charged substance
2 substances that have the same charge REPELL one another
Atoms bound by ionic bonds form crystals (salts)
NaCl (sodium chloride)

26. Sodium Chloride Salt Crystal
Ionic bonds cannot exist in water
the bond breaks (dissociates) (water pulls it apart)
the components of the molecule exist in their ionic form (anion and cation) as seen in the body
NaCl → Na+ and Cl-

27. Covalent Bonds -Formed by sharing valence electrons between 2 atoms
Types of covalent bonds include:
polar and nonpolar covalent bonds
single covalent bond
double covalent bond

28. Single Covalent Bond Each atom shares one electron with another atom
Hence pair of shared electrons

29. Single Covalent Bond

30. Double Covalent Bond Each atom shares two electron with another atom
stronger than a single covalent bond
2 pairs of electron being shared

31. Polar Covalent Bonds
Polar bonds occur between an electronegative atom (O or N) and an atom that is neither O nor N
- electronegative means that it pulls electrons towards itself
the nucleus of an electronegative atom has a stronger “pull” on the shared electrons, pulling the shared electron(s) closer to it
this causes the electronegative atom to become partially negative while the other atom in the covalent bond becomes partially positive
similar to a battery
Therefore most electrons are around the electronegative atom

32. Nonpolar Covalent Bonds
Nonpolar bonds occur between two atoms neither of which are O or N (therefore between atoms that are not electronegative)
the shared electrons are pulled equally between the nuclei of the 2 atoms
both atoms remain neutral
the nonpolar covalent bond is neutral

33. Nonpolar vs. Polar Covalent Bonds
electrons shared equally
electrons shared unequally

34. Nonpolar and Polar Covalent Molecules
Polar molecules are ones that contain moderate amounts of O and/or N
charged molecules
Nonpolar molecules are ones that contain very little or no O and/or N
uncharged (neutral) molecules

36. Functional Groups of Organic Molecules
Small parts of larger molecules
groups of covalently bonded atoms arranged in a very specific manner
determine the chemical properties of molecules

37. Hydrogen Bonds
Electrical attraction between a polar covalently bound H (has a partial positive charge) and a covalently bound electronegative atom (O/N) (has a partial negative charge)
-Too weak to bind atoms together
serve as intramolecular (within molecule) bonds
aids in the stabilization of very large molecules
observed in proteins and nucleic acids
-serve as intermolecular (between molecules) bonds
holds 2 or more molecules in close proximity to one another
observed in between water molecules

38. Hydrogen Bonds in Water (intermolecular)

39. Water The most abundant molecule of the human body
70% of body mass (weight) is attributed to water
The ONLY type of molecules that exist in the human body are molecules held together by covalent bonds
Polar molecules
Nonpolar molecules
salts dissociate in water (therefore ionic compounds are not considered to be molecules)

40. Polarity and Water
-All biochemical reactions that take place in the body occur in a water-based environment
All substances within the body are either nonpolar (uncharged/neutral) or polar (charged)
Nonpolar molecules include those containing a high number of nonpolar covalent bonds
lipids (fats, oils, and waxes)
Polar chemicals include every other substance:
molecules containing polar covalent bonds
ions (cations and anions)

41. Polarity and Water
Polar substances mix easily with other polar substances, but do not mix with nonpolar substances (REMEMBER THIS)
Nonpolar substances mix easily with other nonpolar substances, but do not mix with polar substances (REMEMBER THIS)
“like dissolves like”
-The majority of the chemicals found in the body are polar, however lipids are molecules essential for proper functioning of the body
-the body must have ways to associate these nonpolar molecules in a polar dominated environment

42. Polarity (Water vs Lipids)
All polar chemicals mix with water and are considered to be hydrophilic (water loving)
polar chemicals that mix with water will not mix with lipids and are considered to be lipophobic (lipid fearing)
All nonpolar chemicals mix with lipids and are considered to be lipophilic (lipid loving)
Nonpolar chemicals that associate with lipids will not mix with water and are considered to be hydrophobic (water fearing)
Polar = hydrophilic = lipophobic
Non-polar = hydrophobic = lipophilic

43. Properties of Water Solvency ability to dissolve matter
because water is the most abundant compound in the body it is the universal solvent
provides an environment for all metabolic reactions
provides a means for the transport of substances from one location in the body to another
- most substances dissolve in water

44. Water as a Solvent
water molecules form hydration spheres around polar substances
note orientation of water molecules: negative side faces Na+, positive side faces Cl-

45. Properties of Water Adhesion
attraction between two different substances
-molecules of water “stick” to other types of molecules
Cohesion
attraction between one substance and itself
molecules of water stick to themselves
due to hydrogen bonds
High heat capacity(means that it takes a long time to heat up and/or cool down)
prevents rapid increases or decreases in body temperature (water takes along time to heat-up or cool down)

46. Acid/Base Concentration (pH)
pH is the measurement on a scale ranging from 0 to 14 of H+ concentration in a solution
H+ is the ionized form of a hydrogen atom
the only electron has been removed, leaving a single proton
H+ = hydrogen ion = proton
pH = -log[H+]
[H+] = molar concentration of H+ in a solution
the greater the [H+] the lower the pH, the lower the [H+] the higher the pH

47. Acidic solutions have higher [H+]
a lower pH
Alkaline (basic) solutions have lower [H+]
a higher pH

48. pH Scale
Acidic: pH 0 – 6.99
Basic: pH 7.01 – 14
Neutral: pH 7.00

49. - called proton acceptors
Acids and Bases
Acids are molecules that are capable of increasing the number of H+ in a solution
called proton donors
decrease the pH of a solution
Bases are molecules that are capable of decreasing the number of H+ in a solution are
- called proton acceptors
increase the pH of a solution

50. Buffers
Substances that are capable of resisting large changes in the pH of a solution
-allow pH to remain relatively constant
buffers in the body allow the body pH to remain at 7.4 (slightly basic)