BIO100 Chptr 2 Flashcards
Chemical Basis of Life
bio-
life: biochemistry—branch of science dealing with the chemistry of life forms
di-
two: disaccharide—a molecule composed of two bonded simple sugar units.
glyc-
sweet: glycogen—complex carbohydrate composed of glucose molecules bonded in a particular way.
iso-
equal: isotope—atom that has the same atomic number as another atom but a different atomic weight.
lip-
fat: lipids—group of organic compounds that includes fats.
-lyt
break down: electrolyte—substance that breaks down and releases ions in water.
mono-,
one: monosaccharide—a molecule consisting of a single simple sugar unit.
poly-
many: polyunsaturated—molecule with two or more double bonds between its carbon atoms.
sacchar-
sugar: monosaccharide—a molecule consisting of a single simple sugar unit.
syn-
together: synthesis—process by which chemicals join to form new types of chemicals.
Chemistry
considers the composition of substances and how they change.
a field of life science called biological chemistry, or biochemistry,
Biochemistry has been important not only in helping to explain physiological processes but also in developing ways to detect, diagnose, and treat disease.
Matter
is anything that has weight and takes up space. This includes all the solids, liquids, and gases in our surroundings as well as in our bodies.
The simplest examples of matter with specific chemical properties are the elements
Most elements occur naturally and others are artificially made. Among the elements are such common materials as iron, copper, silver, gold, aluminum, carbon, hydrogen, and oxygen. are termed bulk elements.
atomic number
The atoms of different elements have different numbers of protons. The number of protons in the atoms of a particular element is called its atomic number.
atomic weight
the number of protons plus the number of neutrons in each of an element’s atoms essentially equals the atomic weight of that atom.
isotopes
Atoms that have the same atomic number but different atomic weights are called isotopes (i′so-tōpz) of an element.
molecule
Two or more atoms may combine to form a distinctive type of particle called a molecule.
molecular formula
is shorthand used to depict the numbers and types of atoms in a molecule.
It consists of the symbols of the elements in the molecule with numerical subscripts that indicate how many atoms of each element are present. For example, the molecular formula for water is H2O, which indicates two atoms of hydrogen and one atom of oxygen in each molecule. The molecular formula for the sugar glucose, C6H12O6, indicates six atoms of carbon, twelve atoms of hydrogen, and six atoms of oxygen.
bonds
Atoms combine with other atoms by forming links called bonds. Chemical bonds result from interactions of electrons.
electron shells
The electrons of an atom occupy one or more regions of space called electron shells that encircle the nucleus.
octet rule
The number of electrons in the outermost shell of an atom determines whether it will react with another atom. Atoms react in a way that leaves the outermost shell completely filled with electrons, achieving a more stable structure. This is called the octet rule, because, except for the first shell, eight electrons are required to fill the shells in most of the atoms important in living organisms.
inert
Atoms such as helium, whose outermost electron shells are filled, already have stable structures and are chemically inactive or inert (they cannot form chemical bonds).
ions
Atoms that gain or lose electrons become electrically charged and are called ions (i′onz)
cations
anions
ionic bonds
Positively charged ions are called cations (kat′i-onz), and negatively charged ions are called anions (an′i-onz). Ions with opposite charges attract, forming ionic bonds (i-on′ik bondz).
covalent bond
A chemical bond between atoms that share electrons is called a covalent bond (ko′va-lent bond).
polar
Unlike an ion, a polar molecule has an equal number of protons and electrons, but more of the electrons are at one end of the molecule, making that end slightly negative, while the other end of the molecule is slightly positive. Typically, polar covalent bonds form where hydrogen atoms bond to oxygen or nitrogen atoms.
hydrogen bond
The attraction of the positive hydrogen end of a polar molecule to the negative nitrogen or oxygen end of another polar molecule is called a hydrogen bond.
reactants
Chemical reactions form or break bonds between atoms, ions, or molecules. The starting materials changed by the chemical reaction are called reactants
synthesis
When two or more atoms, ions, or molecules bond to form a more complex structure, as when hydrogen and oxygen atoms bond to form molecules of water, the reaction is called synthesis
products
The atoms, ions, or molecules formed at the reaction’s conclusion are called products.
decomposition
If the bonds of a reactant molecule break to form simpler molecules, atoms, or ions, the reaction is called decomposition
exchange reaction
In a third type of chemical reaction, an exchange reaction (replacement reaction), parts of two different types of molecules trade positions as bonds are broken and new bonds are formed.
reversible reaction
This means the product or products can change back to the reactant or reactants. A reversible reaction is symbolized using a double arrow
Catalysts
Catalysts (kat′ah-listz) are molecules that influence the rates (not the direction) of chemical reactions but are not consumed in the process.
dissociate
When ionically bound substances are placed in water, the ions are attracted to the positive and negative ends of the water molecules and tend to leave each other, or dissociate.
electrolytes
The resulting solution has electrically charged particles (ions), so it conducts an electric current. Substances that release ions in water are, therefore, called electrolytes
acids
Electrolytes that dissociate to release hydrogen ions (H+) in water are called acids
bases
Substances that release ions that combine with hydrogen ions are called bases
pH scale
Each whole number on the pH scale, which extends from 0 to 14, represents a tenfold difference in hydrogen ion concentration. As the hydrogen ion concentration increases, the pH number decreases.
neutral
In pure water, which ionizes only slightly, the hydrogen ion concentration is 0.0000001 g/L, and the pH is 7.0. Water ionizes to release equal numbers of acidic hydrogen ions and basic hydroxide ions, so it is neutral.
solvent
A substance in which other substances dissolve is a solvent.
solute
A substance dissolved in a solvent, such as water, is called a solute.
solution
The combination of a solvent and any solutes dissolved in it is called a solution.
Oxygen
Molecules of oxygen gas (O2) enter the internal environment through the respiratory organs and are carried throughout the body by the blood, especially by red blood cells. In cells, organelles use oxygen to release energy from nutrient molecules. The energy then drives the cell’s metabolic activities. A continuing supply of oxygen is necessary for cell survival and, ultimately, for the survival of the organism.
Carbon Dioxide
Carbon dioxide (CO2) is a simple, carbon-containing inorganic compound. It is a waste product of the release of energy during certain metabolic reactions. As carbon dioxide moves from cells into the interstitial fluid and blood, most of it reacts with water to form a weak acid (carbonic acid, H2CO3). This acid ionizes, releasing hydrogen ions (H+) and bicarbonate ions (HCO3−), which the blood carries to the respiratory organs. There, the chemical reactions reverse, and carbon dioxide gas is produced and is then exhaled.
Carbohydrates
Carbohydrates (kar′bo-hi′drātz) provide much of the energy that cells require. They also supply materials to build certain cell structures and they often are stored as reserve energy supplies.
Carbohydrates are water-soluble molecules that include atoms of carbon, hydrogen, and oxygen.
Organic Substances
Important groups of organic chemicals in cells include carbohydrates, lipids, proteins, and nucleic acids.
Lipids
Lipids (lip′idz) are a group of organic chemicals that are insoluble in water but soluble in organic solvents, such as ether and chloroform. Lipids include a number of compounds, such as fats, phospholipids, and steroids, that have vital functions in cells and are important constituents of cell membranes
Proteins
Proteins (pro′tenz) have a great variety of functions. The human body has more than 200,000 types of proteins. Some are structural materials, energy sources, and chemical messengers (hormones). Other proteins combine with carbohydrates (forming glycoproteins) and function as receptors on cell surfaces, allowing cells to respond to specific types of molecules that bind to them. Antibody proteins recognize and destroy substances foreign to the body, such as certain molecules on the surfaces of infecting bacteria. Proteins such as hemoglobin and myoglobin carry oxygen in the blood and muscles, respectively, and actin and myosin are contractile proteins that provide muscle action.
Triglycerides
Three fatty acid molecules bound to a glycerol molecule
Most common lipid in the body; stored in fat tissue as an energy supply; fat tissue also provides insulation beneath the skin
Phospholipids
Two fatty acid molecules and a phosphate group bound to a glycerol molecule (may also include a nitrogen-containing molecule attached to the phosphate group)
Used as structural components in cell membranes; large amounts are in the liver and parts of the nervous system
Steroids
Four connected rings of carbon atoms
Widely distributed in the body with a variety of functions; includes cholesterol, sex hormones, and certain hormones of the adrenal glands
amino acids
The building blocks of proteins are amino acids
Nucleic acids
Nucleic acids (nu-kle′ik as′idz) carry the instructions, in the form of genes that control a cell’s activities by encoding the amino acid sequences of proteins.
nucleotides
The very large and complex nucleic acids include atoms of carbon, hydrogen, oxygen, nitrogen, and phosphorus, which form building blocks called nucleotides
There are two major types of nucleic acids.
RNA (ribonucleic acid) - Most RNA molecules are single-stranded polynucleotide chains, but they can fold into shapes that enable them to interact with DNA.
DNA (deoxyribonucleic acid) - DNA is a double polynucleotide chain wound into a double helix.
