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Chapter 2

BIOL 1500 Chapter Notes - Chapter 2: Ribose, Surgical Suture, Ionic Bonding


Department
Biology
Course Code
BIOL 1500
Professor
Tanya Da Sylva
Chapter
2

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Chapter 2: Chemistry &
Macromolecules
Learning Objectives:
Describe the importance of chemical elements to living organisms and relate major
principles of chemistry to the study of biology
oDescribe the structure of an atom and be able to sketch a representative structure
when given key information about an element.
oCompare and contrast between ionic, hydrogen, and covalent bonds.
oDescribe chemical reactions in terms of atomic structure and bonding
oList and define the life-supporting properties of water and relate them to the
structure of water.
oExplain the pH scale and the formation of acid and base solutions.
Define monomer and polymer. Describe the role of dehydration synthesis and hydrolysis
in forming or braking down polymers.
Identify the four major macromolecules that make up living organisms and explain the
importance of their function.
oCorrectly match monomers and polymers.
oDiscuss the roles of carbohydrates within cells
oCompare and contrast different categories of lipids and their structures
oDiscuss the importance of shape in the functioning of a protein
oCompare and contrast the structure of DNA and RNA

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Textbook notes:
2.1 Atoms Make Up All Matter
Matter is any material that takes up space, such as organisms, rocks, the oceans, and
gases in the atmosphere
Energy, on the other hand, is the ability to do work.
Heat, light, and chemical bonds are all forms of energy
A. Elements Are Fundamental Types of Matter
-A chemical element is a pure substance that cannot be broken down by chemical
means into other substances. Examples include pure oxygen (O), carbon (C),
nitrogen (N), and hydrogen (H).
-19th century Russian chemist Dmitry Mendeleyev invented the periodic table, the
chart that we still use today. The chart is “periodic” because the chemical
properties of the elements repeat in each column of the table.
-Only about 25 elements are essential to life. Of these, the bulk elements are
required in the largest amounts because they make up the vast majority of every
living cell.
-Minerals are essential elements other than C, H, O, and N. Some minerals,
including sodium (Na), magnesium (Mg), phosphorus (P), potassium (K), and
calcium (Ca), are bulk elements, totalling about 3.5% of the human body by
weight. The remaining minerals, such as iron (Fe) and iodine (I), are trace
elements, meaning they are required in tiny amounts.
B. Atoms Are Particles of Elements
-An atom is the smallest possible “piece” of an element that retains the
characteristics of the element. Atoms are composed of 3 types of particles.
Protons, which carry a positive charge, and neutrons, which are uncharged,
together form a central nucleus. Negatively charged electrons surround the
nucleus. An electron is vanishingly small compared with a proton or a neutron.
-Thus, most of an atom’s mass is concentrated in the nucleus, while the electron
cloud occupies virtually all of its volume.
-Each element has a unique atomic number, the number of protons in the nucleus.

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-When the number of protons equals the number of electrons, the atom is
electrically neutral; that is, it has no net charge. An ion is an atom (or group of
atoms) that has gained or lost electrons and therefore has a net negative or
positive charge.
C. The Number of Neutrons May Vary
-An atom’s mass number is the total number of protons and neutrons in its nucleus.
Because neutrons and protons have the same mass, subtracting the atomic
number from the mass number therefore yields the number of neutrons in an atom.
-All atoms of an element have the same atomic number but not necessarily the
same number of neutrons. An isotope is any of these different forms of a single
element.
-An elements atomic mass (also called atomic weight) is the average mass of all
isotopes.
-Many of the known isotopes are unstable and radioactive, which means they emit
energy as rays or particles when they break down into more stable forms. Every
radioactive isotope has a characteristic half-life, which is the time it takes for half
of the atoms in a sample to emit radiation, or “decay” to a different, more stable
form.
-Radioactive isotopes have a variety of uses in medicine and science. For example,
radiation can be used to kill microorganisms on medical equipment and on food
surfaces. Likewise, directing radiation at a tumor kills cancer cells. In addition, a
physician might give a patient a radioactive tracer, and then track how the isotope
moves in the body to search for tumors or examine a physiological process. (This
is the basis of a PET scan.) Archaeologists and paleontologists use the known
half-lives of radioactive isotopes to determine the ages of artifacts and fossils.
2.2 Chemical Bonds Link Atoms
A molecule is 2 or more chemically joined atoms.
A compound is a molecule composed of 2 or more different elements.
For example, methane is written CH4, which denotes one carbon atom attached to 4
hydrogen atoms. Table salt’s formula is NaCl, that of water is H2O, and that of the gas
carbon dioxide is CO2.
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