Biology 1225 Chapter Notes - Chapter 2: Starch, Carboxylic Acid, Energy Carrier
5 Jun 2018
School
Department
Course
Professor
2: Molecules of Life
Monday, May 21, 2018
12:57 PM
Exam purposes
• Focus on atomic structure and bonding as they relate to water
• Know the general characteristics of lipids, carbs, proteins and nucleic acids
• Understand why water is essential to life (it is a polar molecule and this polar property makes
water a good solvent)
• DO NOT FOCUS ON STRUCTURAL DETAILS OF MOLECULES
2.1--Fear of Frying
• People ingest much more fat than needed
• Types of fat matter more than quantity of fat
"This is your chemistry. It makes you far more than the sum of your body's molecules"
Message: Small differences in our molecules when being put together can have big effects on the
organism
2.2--Start with Atoms
• Protons: Positively Charged subatomic particle that occurs in the nucleus of atoms
• Neutron: Uncharged subatomic particle in the atomic nucleus
• Charge: Electrical property; opposite charges attract, and like charges repel
• Atomic number: Number of protons in the atomic nucleus; determines the element. All atoms
have protons
• Element: A pure substance that consists only of atoms with the same number of protons
• Isotopes: Forms an element that differ in the number of neutrons their atoms carry
• Maas Number: The total number of protons and nuetrons in the atomic nucleus of an isotope
• Radioisotope: Isotope with an unstable isotope that breaks up spontaneously
• Radioactive Decay: The process by which atoms of a radioisotope emit energy and subatomic
particles when their nucleus spontaneously breaks up
• Tracer: A substance that can be traced via its detectable component
Why Electrons Matter?
• An electron gains energy by absorbing the precise amount needed to boost it to the next energy
level. It also loses energy by emitting the exact difference between 2 energy levels
• The farther an electron is from the nucleus, the greater its energy (PG 26)
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• Shell Model: Model of electron distribution in an atom
• Free Radical: Atom with an unpaired electron
• Ion: Atom or molecule that carries a net charge
Message:
• Atoms consist of electrons moving around a nucleus of protons and neutrons
• The number of protons determines the element. Isotopes are a form of an element that have a
different number of neutrons
• Unstable nuclei of radioisotopes emit radiation as they spontaneously break down. They decay
at a predictable rate to form predictable products
• An atoms electrons are the basis of its chemical behavior. When an atoms outermost shell is not
full of electrons, it has a vacancy and is chemically active
• Atoms that get rid of vacancies by gaining or losing electrons become Ions (charged)
2.3--From Atoms to Molecules
• Chemical bond: An attractive force that arises between 2 atoms when their electrons interact.
Links atoms to molecules.
• Compound: Molecule that has atoms of more than one element
• Covalent Bond: Type of chemical bond in which 2 atoms share a pair of electrons
• Ionic Bond: Type of chemical bond in which a strong mutual attraction links ions of opposite
charge
• Polarity: Any separation of charge into distinct positive and negative regions
Message:
• A chemical bond forms between atoms when their electrons interact. Depending on the atoms,
the bond may be ionic or covalent
• An ionic bond is a strong mutual attraction between ions of opposite charge
• Atoms share a pair of electrons in a covalent bond. When the atoms share electrons unequally,
the bond is polar
2.4--Hydrogen Bonds and Water
o Water has unique properties that arise from 2 polar covalent bonds
o Each hydrogen atom in water molecule + Charge. The oxygen atom has a slight - charge
o Hydrogen bonds are not chemical bonds but they stabilize characteristic structures of bio
molecules like DNA and proteins
o Water is an excellent solvent
• Solvent: Liquid in which other substances dissolve
• Hydrophilic: Describes a substance that easily dissolves in water
find more resources at oneclass.com
find more resources at oneclass.com
