Chapter 2 Molecules of Life. The Atom Fundamental unit of matter Nucleus Protons : Positive charge; mass of 1 Neutrons : No charge; mass of 1 Electrons Spin around the nucleus in orbitals (shells) Negative charge; No mass
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Molecules of Life
Volumes of space that surround the
Electrons move in orbitals
Electron shells and electron orbitals
The 1st shell in any atom can hold 2 electrons
The 2nd shell in any atom can hold 8 electrons
The 3rd shell in any atom can hold 8 electrons
Shell # of electrons each shell can hold
First shell 2
Second shell 8
Third shell 8
P + N
Why is it necessary to understand how electron orbitals work? This isn’t a Chemistry class, right??
Electrons and the energy they posses (their energy state) determine the chemical behavior of atoms thus, the losing, gaining or sharing of electrons is the BASIS FOR CHEMICAL REACTIONS IN WHICH CHEMICAL BONDS FORM (chemical bonds include hydrogen bonding, ionic bonding and covalent bonding).
If electrons couldn’t lose or gain other electrons, or share with other electrons, chemical bonds would NOT form!
a substance that cannot be reduced into a simpler component substance through a chemical process
Number of protons in the nucleus
Number of protons and neutrons in the nucleus
N = Atomic Mass - P
Can an element ever have a variable number of neutrons?
Atomic ## protons # protons # protons
6 6 6
Atomic Mass# P + # N#P + # N # P + # N
6 + 6 = 12
6 + 7 = 13
6 + 8 = 14
The isotope is specific for a protein unique to kidney cells.
Remember, electrons are the basis for chemical reactions!!
So… if 99Tc has a different number of neutrons in its nucleus, the stability of the electrons in the other shell of that 99Tc atom are changed.
There are 43 isotopes of Technitium!
It just so happens that the particular stability of 99Tc seeks to form a chemical bond with this unique kidney protein.
Example: Table salt
Sodium atom has 1 lone electron in its outer orbital (Ax)
Chloride atom has 7 electrons in its outer orbital (Ax)
Sodium ION that has given up an electron from its outer shell
Chloride ION that has accepted an electron from Sodium and has included it in its outer shell
Both the sodium ion and the chloride ion are electrically attracted because of the opposite charges incurred by the altered electron orbitals.
This electrical attraction results in the formation of an elaborate matrix resulting in a crystal of table salt.
Non-Polar Covalent Bond: Methane (CH4)
Non-Polar Covalent Bond: Methane (CH4)
Polar Covalent Bonding: H2O
Solute = Salt
Solvent = Water
Since water is polar, it is attracted to other polar molecules. Cohesion occurs when the other polar molecule is water.
Created by cohesion and due to the strong hydrogen bonding between the polar water molecules.
Five Principle FunctionalGroups
View animation on Polymer formationhttp://science.nhmccd.edu/biol/dehydrat/dehydrat.html
Liquid at room temperature Low melting point
The C C bond in unsaturated fats creates a negative charge that causes the fat molecules to repel each other rather than stick together (as they do in long chain saturated fats).
Margarine has been found to be contaminated with aluminum. Al is a causative agent in AD
Because the fatty acid chains that come off the glycerol backbone differ. Each different fatty acid has a different melting point.
Basic structure of a triglyceride
Basic structure of a phospholipid
amino group (-NH2)
carboxyl group (-COOH)
an “R” group
Polar Ionizable (Acidic)
Polar Ionizable (Basic)
Amino acid sequence of the protein
Four levels of protein structure:
All levels of protein structure are ultimately determined by amino acid sequence!!
Initial folding of the polypeptide chain caused by formation of hydrogen bonds
Can result in sheets (Beta sheets) or coils (alpha helices) of polypeptides
Because some AAs are polar and some are nonpolar, a polypeptide folds in solution: nonpolar regions are forced together (forced by the polar groups and their attraction to water resulting in the polar groups repulsion of nonpolar amino acids)
Secondary Structure of a Protein
The polar nature of the environment
When the polar nature of the environment changes (↑ temp or ↓ pH), hydrogen bonding may be altered which may then cause unfolding of the protein, or denaturation.
Each nucleotide serves as a letter and each nucleicacid has different nucleotides (letters)
Normal Lactose Metabolism
LactoseGlucose + Galactose
Covalent bond (both polar and non-polar types)
2.Isotopes have a different measure of stability when compared to their ‘parent’ element on the periodic table. True or False
3. You can determine the number of neutrons present in an atom by subtracting the number of protons from the ____.
4. When preparing a solution, you accidentally add too much of an acidic component. This creates an excess of _____. The desired pH is 8; the pH you measure is 6. You decide that it shouldn’t make too much of a difference, you’re only 2 units off. What is wrong with this logic?
H+, or Hydrogen ions
A difference of 2 units on the pH scale correlates to a 100 fold more acidic solution. Therefore, your solution has 100 times more Hydrogen ions then the desired solution concentration.