Principles of Biology I - Chapter 2: The Chemistry of Life
While the maximum number of electrons required to fill the outermost shell of an atom varies depending on the size of the atom, almost all of the smaller atoms (atomic numbers 2-20) are considered stable, and thus nonreactive, when they contain ___________ electron(s) in the outermost shell.
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polar bond
A ______________ is a type of chemical bond where a pair of electrons is unequally shared between two atoms. As a result, one end of the molecule has a slightly negative charge and the other a slightly positive charge.
hydrogen bond
A weak bond called a _________________ results from an attraction between a slightly positive region in a molecule and a slightly negative region in the same or a different molecule.
ionic
A(n) _____________ bond forms when one atom gives up one or more electrons to another atom.
covalent
A(n) _______________ bond involves the sharing of electron pairs between atoms, also known as a molecular bond.
Solubility
Amount of solute that will dissolve per volume of solvent.
non-polar bond
Atoms involved in a ______________ equally share electrons; there is no charge separation to the molecule.
ions
Atoms or molecules with a net electric charge due to the loss or gain of one or more electrons are _______________.
Why are all living organisms based on molecules that contain carbon?
Because carbon atoms can form bonds with up to four other atoms.
How do buffers minimize change in the pH of biological systems?
By donating H+ ions when there is a shortage OR by absorbing H+ ions when there is an excess
What are the four classes of large organic molecules important to life on Earth?
Carbohydrates / proteins / lipids / nucleic acids
rearranged
During a chemical reaction, atoms are ____________.
Oxygen, Carbon, Hydrogen, Nitrogen
Four elements that make up 96.3% of living cells.
An acid is a compound that donates _____________ to a solution.
H+
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How many neutrons are in a typical oxygen atom?
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How many protons are in a typical oxygen atom?
molecule
If two or more atoms are bonded together, they form a(n) _____________.
Heterogeneous
Not uniform in composition.
The higher the pH number, the higher the concentration of ___________ in a solution.
OH-
What properties of water molecules have important implications to life?
The ability to dissolve polar substances / The ability of ice to float in water / High surface tension
protons
The atomic number corresponds to the number of _____________ in a specific element.
What causes the surface tension of water to form?
The cohesion of water molecules to each other
What is the most complete explanation of what the pH scale measures.
The concentration of hydrogen ions in an aqueous solution
atomic weight.
The number of protons plus neutrons in an atom, represented as an average of all naturally occurring forms of the element, is known as _______________.
What might happen if a protein has a change in one amino acid?
The protein can no longer function properly / The amino acid chain folds incorrectly / The protein has a new shape.
chemistry
The scientific study of matter is called _____________.
To a large extent, a protein's function is dependent upon its shape. What determines a protein's shape?
The sequence of amino acids
atom
The smallest unit of matter that retains all of the physical properties of that type of matter is a(n) ______________.
Homogeneous
Uniform in composition.
What is responsible for the unusual chemical properties of water?
Water molecules can form an extensive network of hydrogen bonds with one another
Oxygen
What is the most common element in your body?
single bond
When one pair of electrons is shared between two atoms, a ________________ is formed.
double bond
When two pairs of electrons are shared between two atoms, a ______________ is formed.
reactant / product
Within a plant, water (H2O) and carbon dioxide (CO2) can be combined (using the energy of sunlight) to produce glucose (C6H12O6) and oxygen (O2). If you were to write out this chemical reaction, water and carbon dioxide are each an example of a(n) ____________ while glucose and oxygen are each an example of a(n) ______________.
Matter
___________ is anything that occupies space and/or has any substance.
Calcium
_______________ is one of the seven elements that make up a small fraction, approximately 3.7%, of living cells.
Trace elements
________________ also called micronutrients, are any chemical element required by living organisms in minuscule amounts, but cells require them to survive.
Zinc
________________ is one of the fourteen trace elements and is a component of certain digestive enzymes and other proteins.
Atomic number
________________ is the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
A polypeptide is ____________.
a long chain of amino acids (aka protein)
The term for a solution with a low pH number, such as lemon juice or vinegar, is ____________.
acidic
Enzymes speed up chemical reactions by lowering the _______________, which allows the reaction to proceed much more quickly.
activation energy
The specific location within an enzyme molecule where the substrate binds is called the ______________.
active site
What are the monomers of proteins?
amino acids
A protein consists of many __________ joined together by __________ bonds.
amino acids / peptide
The term for a solution with a high pH number, such as ammonia or bleach, is _____________.
basic
A substance that accepts H+ when they are in excess and donates H+ when their concentration drops is called a(n) ___________.
buffer
Organic compounds are distinguished by molecules that contain ___________ bonded to other elements.
carbon
A(n) _______________ inhibitor binds to the active site of the enzyme.
competitive
The building of a large organic molecule from small sub-units involves multiple _____________.
dehydration synthesis reactions
H2SO4, sulfuric acid, contains three different types of atoms: hydrogen (H), sulfur (S), and oxygen (O). Each of these atoms represents a different _____________. Since the three types are combined in a fixed ratio, this means that H2SO4 is a(n) ______________.
element / compound
Lactose takes years to break down on its own. But if exposed to the protein lactase, the reaction proceeds very quickly, while lactase itself remains unchanged. Lactase is an example of a(n) ______________.
enzyme
What represents a simple sugar (also called a monosaccharide)?
glucose
The 2+ in Cu2+ tells us that this atom _____________.
has two more protons than electrons
The breaking of a large organic molecule into smaller, individual sub-units involves multiple ___________.
hydrolysis reactions
All lipids are ________.
hydrophobic ("water-fearing") meaning they do not mix with water
A(n) _______________ is a molecule that can bind to an enzyme and prevent the enzyme from working.
inhibitor
Two molecules that have the same atoms arranged differently are called _____________.
isomers
In an atom, the number of neutrons determines most specifically the _____________.
isotope
The term for a solution that has an equal concentration of H+ and OH- is ____________.
neutral
A(n) __________________ inhibitor binds elsewhere on the enzyme other than the active site.
noncompetitive
_________ bonds hold the atoms together within a molecule of water, and __________ bonds act between molecules of water to hold them together.
polar covalent / hydrogen
During digestion, __________ are broken down into __________ through __________ reactions.
proteins / amino acids / hydrolysis
The atomic weight corresponds to the number of ______________ in a specific element.
protons and neutrons
What would have the highest concentration of C−H bonds?
saturated fat
Food processors are phasing out the use of which types of fats, because research has shown them to be particularly unhealthy?
saturated fats and trans fats
During an enzymatic reaction, a molecule of ___________ binds to the enzyme and is broken down into one or more molecules of ______________, which are released.
substrate / product
