Biology 101 Exam 1 UNC |149 Questions and Answers
Molecules - -A molecule is a group of atoms held together by chemical bonds that store
potential energy.
A molecule is formed by 2 to several dozens of atoms
Some molecules have large amounts of potential energy (PF) in their chemical bonds, they
serve as "Energy Molecules" that provide kinetic energy for all cell activities when their
chemical bonds are broken.
-Adenosine Triphosphate (ATP) - -Is a universal energy molecule found in almost all living
organisms
-Macromolecule - -A macromolecule is formed by hundreds or thousands of atoms
-Chemical bonding's: Ionic Bonds - -Formed by atoms being attracted to each other due to
opposite electrical charges.
• A cation (positive charge) and an anion (negative charge) are usually involved in ionic
bonds.
(e.g. Na++ Cl-→ NaCl).
-Chemical Bonding's: Covalent bonds - -Formed by the sharing of electrons between 2
atoms (e.g. H2O).
• Atoms that form covalent bonds not only gain extra potential energy, they become more
stable because of more electrons on outer orbits.
• Strongest type of chemical bonding in biological molecules
• Allowing cells to build larger molecules and macromolecules.
*Very strong bond; very difficult to break but once broken it releases lots of energy.
-Electronegativity - -The attraction of an atom for shared
electrons.
If the atoms in a molecule have SIMILAR electronegativity, the electrons remain equally
stored between 2 nuclei and the covalent bond is said to be NON-POLAR.
If one element is more electronegative, it pulls the shared electrons closer to itself,
creating POLAR covalent bond.
-Chemical Bonding's: Hydrogen Bonds - -Weakest chemical bond; but very important bc it
plays a key role in forming internal shaping and folding of larger molecules.; can break and
be remade again.
• Hydrogen atoms contain only 1 proton and 1 electron, as a result when it is sharing its
electron with another atom, it has a partial
positive charge (i.e. H+).
, • H+ tends to be attracted to the partial negative charge of oxygen (O-) and nitrogen (N-),
forming hydrogen bonds.
-Important properties of water (H2O): High polarity - -Partial electrical charges of oxygen
and
hydrogen atoms in water molecules cause polarity, allowing water to interact with ions and
other polar molecules.
-Important properties of water (H2O): Heat Storage - -Hydrogen bonds formed between
water
molecules can absorb heat when they break (release heat when they are formed),
minimizing temperature changes in
living organisms.
-Important properties of water (H2O): High Heat of Vaporization - -It takes a lot of energy
to break many hydrogen bonds in water before evaporation is possible.
-Important properties of water (H2O): Low density of Ice - -In cold temperature, hydrogen
bonds
in water spread farther apart, forming ice crystal which is less dense than liquid water, and
as a result ice can float on water.
This prevents freezing of lakes.
-Important properties of water (H2O): Cohesion - -Hydrogen bonds hold water molecules
together, which allows water to be transported upward in the vascular system of plants.
-Water as a Powerful Solvent - -Ions and polar molecules are
attracted to the partial charges of water molecules, allowing these molecules to be
dissolved in water and from new chemical
behavior.
-Water Organizes Nonpolar Molecules - -Molecules that are nonpolar (i.e. fat or oil) "does
not dissolve) are not water-soluble, as a result will be crowded together and from their
own interaction.
-Water ionizes - -When covalent bonds of a water molecule break Spontaneously, it
dissociates into H+ and OH- a process called ionization. H+(hydrogen ion) contributes to
the acidity of a solution, while OH-(hydroxide ion) contributes to the alkalinity (basic) of a
solution.
-Acid - -Is a compound that adds H+ to a solution, by donating H+ ion.
-Base - -Is a compound that reduces H+ in a solution, by accepting H+ ion.
-pH - -[pH is a measurement of the concentration of H+ in a solution. The pH scale is from
0 to 14 where pH 7 is neutral, below 7 is acid, and
Molecules - -A molecule is a group of atoms held together by chemical bonds that store
potential energy.
A molecule is formed by 2 to several dozens of atoms
Some molecules have large amounts of potential energy (PF) in their chemical bonds, they
serve as "Energy Molecules" that provide kinetic energy for all cell activities when their
chemical bonds are broken.
-Adenosine Triphosphate (ATP) - -Is a universal energy molecule found in almost all living
organisms
-Macromolecule - -A macromolecule is formed by hundreds or thousands of atoms
-Chemical bonding's: Ionic Bonds - -Formed by atoms being attracted to each other due to
opposite electrical charges.
• A cation (positive charge) and an anion (negative charge) are usually involved in ionic
bonds.
(e.g. Na++ Cl-→ NaCl).
-Chemical Bonding's: Covalent bonds - -Formed by the sharing of electrons between 2
atoms (e.g. H2O).
• Atoms that form covalent bonds not only gain extra potential energy, they become more
stable because of more electrons on outer orbits.
• Strongest type of chemical bonding in biological molecules
• Allowing cells to build larger molecules and macromolecules.
*Very strong bond; very difficult to break but once broken it releases lots of energy.
-Electronegativity - -The attraction of an atom for shared
electrons.
If the atoms in a molecule have SIMILAR electronegativity, the electrons remain equally
stored between 2 nuclei and the covalent bond is said to be NON-POLAR.
If one element is more electronegative, it pulls the shared electrons closer to itself,
creating POLAR covalent bond.
-Chemical Bonding's: Hydrogen Bonds - -Weakest chemical bond; but very important bc it
plays a key role in forming internal shaping and folding of larger molecules.; can break and
be remade again.
• Hydrogen atoms contain only 1 proton and 1 electron, as a result when it is sharing its
electron with another atom, it has a partial
positive charge (i.e. H+).
, • H+ tends to be attracted to the partial negative charge of oxygen (O-) and nitrogen (N-),
forming hydrogen bonds.
-Important properties of water (H2O): High polarity - -Partial electrical charges of oxygen
and
hydrogen atoms in water molecules cause polarity, allowing water to interact with ions and
other polar molecules.
-Important properties of water (H2O): Heat Storage - -Hydrogen bonds formed between
water
molecules can absorb heat when they break (release heat when they are formed),
minimizing temperature changes in
living organisms.
-Important properties of water (H2O): High Heat of Vaporization - -It takes a lot of energy
to break many hydrogen bonds in water before evaporation is possible.
-Important properties of water (H2O): Low density of Ice - -In cold temperature, hydrogen
bonds
in water spread farther apart, forming ice crystal which is less dense than liquid water, and
as a result ice can float on water.
This prevents freezing of lakes.
-Important properties of water (H2O): Cohesion - -Hydrogen bonds hold water molecules
together, which allows water to be transported upward in the vascular system of plants.
-Water as a Powerful Solvent - -Ions and polar molecules are
attracted to the partial charges of water molecules, allowing these molecules to be
dissolved in water and from new chemical
behavior.
-Water Organizes Nonpolar Molecules - -Molecules that are nonpolar (i.e. fat or oil) "does
not dissolve) are not water-soluble, as a result will be crowded together and from their
own interaction.
-Water ionizes - -When covalent bonds of a water molecule break Spontaneously, it
dissociates into H+ and OH- a process called ionization. H+(hydrogen ion) contributes to
the acidity of a solution, while OH-(hydroxide ion) contributes to the alkalinity (basic) of a
solution.
-Acid - -Is a compound that adds H+ to a solution, by donating H+ ion.
-Base - -Is a compound that reduces H+ in a solution, by accepting H+ ion.
-pH - -[pH is a measurement of the concentration of H+ in a solution. The pH scale is from
0 to 14 where pH 7 is neutral, below 7 is acid, and
