What is life? A Guide to Biology: Chapter 2

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Terms in this set (...)

Element
A substance that cannot be broken down chemically into any other substances.
Atom
A particle of matter that cannot be further subdivided without losing its essential properties.
Nucleus
The central and most massive part of an atom usually made of two types of particles, protons and neutrons, which move about the nucleus.
Proton
A positively charged particle in the atomic nucleus, it is identical with the nucleus of the hydrogen atom, which lacks a neutron, and has atomic number 1.
Neutron
An electrically neutral particle in the atomic nucleus.
Mass
The amount of matter in a given sample of a substance.
Electron
A negatively charged particle that moves around the atomic nucleus.
Atomic mass
The mass of an atom - the combined mass of the protons, neutrons and electrons in an atom. (the mass of the electron is so small as to be almost negligible).
Atomic number
The number of protons in the nucleus of an atom of a given element.
Isotope
Variants of atoms that differ in the number of neutrons they possess; isotopes do not vary in charge, because neutrons have no electrical charge, but the atom's mass changes with the loss or addition of a particle in the nucleus
Radioactive
The property of some elements or isotopes of having a nucleus that breaks down spontaneously, releasing tiny, high-speed particles that carry energy
Periodic Table
A tabular display in which all all the known chemical elements are arranged in the order of their atomic number and on the basis of other aspects of their atomic structures
Ion
An atom that carries an electrical charge, positive or negative, because it has either gained or lost an electron or electrons from its normal, stable configuration.
Molecule
A group of atoms held together by covalent bonds.
Bond Energy
The strength of a bond between two atoms, defined as the energy required to break the bond
Covalent Bond
A strong bond formed when two atoms share electrons, the simplest example is the H2 molecule, in which each of the two atoms in the molecule shares its lone electron with the other atom.
Double bond
The sharing of two electrons between two atoms, for example, the most common form of oxygen is the O2 molecule, in which two electrons from each of the two atoms of oxygen are shared.
Ionic Bond
A bond created by the transfer of one or more electrons from one atom to another, the resulting atoms, now called ions, are charged oppositely and so attracted each other to form a compound.
Compound
A substance composed of atoms of different elements of specific ratios, held together by ionic bonds.
Hydrogen Bond
A type of weak chemical bond formed between the slightly positively charged hydrogen atoms of one molecule and the slightly negatively charged atoms of another (often oxygen or nitrogen atoms); hydrogen bonds are important in building multi-atom molecules, such as complex proteins, and are responsible for many of the unique and important features of water.
pH
A logarithmic scale that measures the concentration of hydrogen ions (H+). In a solution, with decreasing values indicating increasing acidity; water, in which the concentration of hydrogen ions (H+) equals the concentration of hydroxyl ions (OH-), is pH = 7, the midpoint of the scale.
Acid
Any fluid with a pH below 7.0, indicting the presence of more H+ ions that OH-ions.
Base
Any fluid with a pH above 7.0, that is, with more OH- ions than H+ ions.
Buffers
A chemical that quickly absorbs excess H+ ions in a solution (preventing it from becoming to acidic) or quickly release H+ ions to counteract increases in OH- concentration.
Carbohydrate
One of the four types of biological macromolecule, containing mostly carbon, hydrogen, and oxygen; carbohydrates are the primary fuel for cellular activity and form much of the cell structure in all life forms.
Monosaccharide
The simplest carbohydrate and the building blocks of more complex carbohydrates; monosaccharides, which cannot be broken down into other monosaccharides, include glucose, fructose, and galactose; also known as simple sugars.
Simple sugar
Monosaccharide carbohydrate, generally containing three to seven carbon atoms, which store energy in their chemical bonds and which biological cells can break down; cannot be broken down into other simple sugars; include glucose, fructose, and galactose
Glycogen
A complex carbohydrate consisting of stored glucose molecules linked to form a large web, which breaks down to release glucose when it is needed for energy.
Polysaccharide
Complex carbohydrates formed by the union of many simple sugars.
Disaccharide
Carbohydrates formed by the union of two simple sugars, such as sucrose (table sugar) and lactose (the sugar found in milk).
Complex Carbohydrate
A carbohydrate that contains multiple simple carbohydrates linked together; types of complex carbohydrates include starch, which is the primary form of energy storage in plants, and glycogen, which is the primary form of short-term energy storage in animals.
Starch
A complex polysaccharide carbohydrate consisting of a large number of monosaccarides linked in a line; in plants, starch is the primary form of energy storage.
Chitin
A complex carbohydrate, indigestible by humans, that forms the rigid outer skeleton of most insects and crustaceans (such as lobsters and crabs).
Cellulose
A complex carbohydrate, indigestible by humans, that serves as the structural material for a huge variety of plant structures. It is the single most prevalent organic compound on earth.
Hydrophobic
Repelled by water, as, for example, non-polar molecules that tend to minimize contact with water.
Hydrophilic
Attracted to water, as, for example, polar molecules that readily form hydrogen bonds with water.
Saturated fat
A fat in which each carbon in the hydrocarbon chain forming the tail region of the fat molecule is bound to two hydrogen atoms; saturated fats are solid t room temperature.
Unsaturated fat
A fat in which at least one carbon in the hydrocarbon chain forming the tail region of the fat molecule is bound to only one hydrogen atom; unsaturated fats are liquid at room temperature .
Trans fat
An unsaturated fat that has been partially hydrogenated (meaning that hydrogen atoms have been added to make the fat more saturated and to improve a food's taste, texture, and shelf-life); the added hydrogen atoms are in a trans orientation, which differs from the cis ("near") orientation of hydrogen atoms in the unsaturated fat.
Sterol
A lipid important in regulating growth and development; the sterols include cholesterol and the steroid hormones testosterone and estrogen, and are all modifications of a basic structure of four interlinked rings of carbon atoms.
Cholesterol
One of the sterols, lipids important in regulating growth and development, cholesterol is an important component of most cell membranes, helping the membrane to maintain its flexibility.
Phospholipids
A lipid that is the major component of the plasma membrane; phospholipids are structurally similar to fats, but contain a phosphorus atom and have two, not three, fatty acid chains.
Wax
A lipid similar in structure to fats but with only one long-chain fatty acid linked to the glycerol head of the molecule; because the fatty acid chain is highly non-polar, waxes are strongly hydrophobic.
Protein
One of four types of biological macromolecules; constructed of unique combinations of 20 amino acids that result in unique structures and chemical behavior, proteins are the chief building blocks of tissues in most organisms.
Amino acid
One of 20 molecules built of an amino group, a carboxyl group, and a unique side chain; proteins are constructed of combinations of amino acids.
Carboxyl Group
A functional group characterized by a carbon atom double-bonded to one oxygen atom and single-bonded to another oxygen atom. Amino acids are made up of an amino group, a carboxyl group, and a side chain
Amino Group
A nitrogen atom bonded to three hydrogen atoms
Peptide bond
A bond in which in which the amino of one amino acid is bonded to the carboxyl group of another; two amino acids so joined form a dipeptide, several amino acids so joined form a polypeptide.
Primary structure
The sequence of amino acids in a polypeptide chain.
Secondary structure
The corkscrew-like twists or folds formed by hydrogen bonds between amino acids in a polypeptide chain.
Tertiary structure
The unique and complex three-dimensional shape formed by multiple twists of the secondary structure of the protein as amino acids come together and form hydrogen bonds or covalent sulfur-sulfur bonds.
Quanternary structure
Two or more polypeptide chains bonded together in a single protein; hemoglobin is an example of a protein molecule with this structure.
Denaturation
The disruption of protein folding, in which secondary and tertiary structure are lost, caused by exposure to extreme conditions in the environment such as heat or extreme pH (that is, a strong acid or a strong base); denaturation causes proteins to lose their function; also the disruption of DNA, also known as DNA melting, in which the bonds liking complementary bases are broken and the two strands separate from each other.
Enzymes
A that protein that initiates and accelerates a chemical reaction in a living organism enzymatic proteins take a part in chemical reactions on the inside and outside surfaces of the plasma membrane.
Active Site
The part of an enzyme to which reactants (or substrates) bind and undergo a chemical reaction
Substrate
The molecule on which an enzyme acts; the active site on the enzyme binds to the substrate, initiating a chemical reaction, for example, the active site on the enzyme lactase binds to the substrate lactose, breaking it down into the two simple sugars glucose and galactose.
Activation Energy
The minimum energy needed to initiate a chemical reaction (regardless of whether the reaction releases or consumes energy
Inhibitors
A chemical within a cell that binds to an enzyme or substrate molecule and in doing so reduces the enzyme's ability to catalyze a reaction
Competitive Inhibitors
A chemical within a cell that binds to the active its of an enzyme, blocking substrate molecules from the site and thereby reducing the enzyme's ability to catalyze a reaction
Noncompetitive Inhibitors
A chemical within a cell that binds to part of an enzyme away form the active site, but alters the enzyme's shape so as to alter the active site, thereby reducing or blocking the enzyme's ability to bind with a substrate
Activator
A chemical within a cell that binds to an enzyme, altering the enzyme's shape or structure in a way that causes the enzyme to catalyze a reaction
Nucleic acids
One of the four types of biological macromolecules, the nucleic acids, DNA and RNA store genetics information in unique sequences of nucleotides.
Nucleotides
A molecule containing a phosphate group, a sugar molecule, and a nitrogen-containing molecule; nucleotides are the individual units that together, in a unique sequence, constitute a nucleic acid.
Deoxyribonucleic acid (DNA)
A nucleic acid, DNA carries information about the production of particular proteins in the sequences of its nucleotides bases.
Ribonucleic acid (RNA)
A nucleic acid, RNA serves as a middleman in the process of converting genetic information in DNA into protein; messenger RNA (mRNA) takes instructions for production of a given protein from DNA to another part of the cell, whereas transfer RNA (tRNA) interprets the mRNA code and directs the construction of the protein from its constituent amino acids.
Base (of DNA)
A fluid with a pH above 7.0, that is, with more OH- ions than H+ ions. One of the nitrogen-containing side-chain molecules attached to a sugar molecule in the sugar-phosphate backbone of DNA and RNA. The four bases in DNA are adenine (A), thymine (T), guanine (G), and cytosine (C); the four bases in RNA are adenine (A), uracil (U), guanine (G), and cytosine (C); the information in a molecule of DNA and RNA is determined by its sequence of bases.
Double helix
The spiraling ladder-like structure of DNA composed of two strands of nucleotides; the bases protruding from each strand like "half-rung" meet in the center and bind to each other (via hydrogen bonds), holding the ladder together.
Fatty Acid
A long hydrocarbon (a chain of carbon-hydrogen molecules); fatty acids form the tail region of triglyceride fat molecules
Glycerol
A small molecule that forms the head region of a triglyceride fat molecule.
Lipid
One of four types of macromolecules, lipids are insoluble in water and greasy to the touch; they are important in energy storage and insulation (fats), membrane formation (phospholipids), and regulating growth and development (sterols).
Macromolecule
A large molecule made up of smaller building blocks or subunits; four types of biological macromolecules are carbohydrates, lipids, proteins, and nucleic acids.
Triglyceride
A fat having three fatty acids linked to the glycerol molecule.
-Water has unusual properties that make it critical to life.
#1 Water's cohesive nature (sticks together)
#2 Water's ability to moderates temperature (large heating capacity)
#3 Floating ice (Low density as a solid)
#4 Versatility of water as a solvent (good at breaking things down)
-pH scale acids 0-6 - Acids are fluids that have a greater proportion of H+ ions to OH- ions.
• H+ ions are very reactive
• Strong acids are corrosive to metals
• Acids break down food in your digestive tract
• Acids are generally sour in taste
• 0 being the strongest (battery acid) to 6 the lowest (coffee)
-pH scale bases 8-14 - bases are fluids that have greater proportion of OH- ions to H+ ions
• OH- ions bind with H+ ions, neutralizing acids
• Strong bases are caustic to your skin
• Bases can be found in many household cleaners
• Bases are generally bitter in taste and soapy
• 14 being the lowest (bleach) to 8 in the middle (blood)
-When water is the solvent, the result is called an aqueous solution
Water (solvent) + Kool-aid crystals (solute) + Delicious beverage (solution)
-The primary elements of life
• Carbon
• Hydrogen
• Oxygen
• Nitrogen
C.H.O.N.
Matter: Elements and Compounds
• Matter is anything that occupies space and has mass.
• Matter is found on the Earth in three physical states:
1. Solid
2. Liquid
3. Gas
Macromolecules are broken down into 4 categories
1. Carbohydrates = (ENERGY) monosaccharides, glucose, fructose, disaccharides, lactose, sucrose, polysaccharides, starch, cellulose.

2. Lipids = Fats, oils, and steroids

3. Proteins = Lactase (an enzyme), hemoglobin

4. Nucleic acids = DNA, and RNA
...
BIOLOGICAL MACROMOLECULE: Carbohydrates, FUNCTION: Dietary energy, storage, plant structure, MONOMER: monosaccharide, EXAMPLES: (energy) monosaccharides, glucose, fructose, disaccharides, lactose, sucrose, polysaccharides, starch, cellulose.

BIOLOGICAL MACROMOLECULE: Lipids, FUNCTION: long term energy storage (for fats); hormones, for steroids, MONOMER: components of fat molecule, EXAMPLES: Fats, oils, and steroids

BIOLOGICAL MACROMOLECULE: Proteins, FUNCTION: Enzymes, structure, storage, contraction, transport, etc., MONOMER: amino acids, EXAMPLES: Lactase (an enzyme), hemoglobin.

BIOLOGICAL MACROMOLECULE: Nucleic acids, FUNCTION: information storage, MONOMER: Nucleotide, EXAMPLES: DNA, and RNA
...
Category: Carbohydrates, Monomer: monosaccharides e.g. glucose, fructose, bond glucose + fructose = sucrose disaccharide, Polymer: Polysaccharides e.g. starch, Examples: sugar, breads, potatoes, pasta, rice, and cellulose.
...
Category: Proteins, Monomer: Amino Acids (20 different types), Polymer: Polypeptides (protein), Examples: Meat, chicken, muscle hemoglobin, and enzymes (Lactase).
...
Category: Lipids, Monomer: Fatty Acids, Polymer: fatty acids, oils, steroids, cholesterol, hormones (triglycerides), Examples: Testosterone, estrogen, phospholipids, and triglycerides.
...
Category: Nucleic acids, Monomer: Nucleotides, Polymer: DNA & RNA, Examples: Genetic material.