A & P - College Network - Chapter 4

Front 1

Acid

Back 1

A substance that decreases the pH of a solution.

Front 2

Acidosis

Back 2

Excess acid in extracellular fluid.

Front 3

Activation Energy Barrier

Back 3

In order to bond to one another, the two reactants must meet each other with sufficient energy to overcome an activation energy barrier required for a bond to form.

Front 4

Active Site

Back 4

In the general theory of enzyme catalysis, the tertiary structure of an enzyme forms a pocket in which the reactants are brought in the proper orientation for bond formation.

Front 5

Adenine

Back 5

A base in DNA.

Front 6

Adenosine Diphosphate

Back 6

In the process of ATP driving energy-requiring reactions, one of three phosphate groups of ATP is split off, yielding adenosine diphosphate (ADP) and inorganic phosphate (Pi).

Front 7

Adenosine Triphosphate

Back 7

The main source of energy available to cells to drive energy-requiring reactions and ordinarily would not proceed spontaneously.

Front 8

Alkalosis

Back 8

Excess base in extracellular fluid.

Front 9

Allosteric Phosphorylation

Back 9

At another site other than the active site, the attachment of a phosphate group [PO4] at a specific site on the protein by another enzyme, kinase.

Front 10

Allosteric Regulation

Back 10

Allosteric means "at another site" than the active site. A major principle of enzyme regulation within cells is that the activity of an enzyme can be regulated--increased or decreased, depending on the particular enzyme and binding site--by phosphorylation (attachment of a phosphate group [PO4] at a specific allosteric site on the protein by another enzyme called a kinase). Likewise, some key enzymatic reactions are regulated by allosteric inhibition of the product of the reaction acting on the enzyme.

Front 11

Amino Acids

Back 11

Organic compounds that contain a least one carbon atom that is bonded simultaneously to carboxyl group; amino group; hydrogen atom; and a side chain of varying of complexity, the structure which determines the type of amino acid. The side chain may be polar, nonpolar, acidic, base, or aromatic.

Front 12

Amphiphathic

Back 12

A molecule that is most stable when its head is in an aqueous environment and its tail is a nonpolar environment.

Front 13

Anabolism

Back 13

Energy captured in catabolic processes is used to assemble simple molecules from food into the proteins, nucleic acids, lipids, and other macromolecules needed for cellular growth and maintenance.

Front 14

Anion

Back 14

In an ionic bond, the acceptor atom that is negatively charged.

Front 15

Atomic Number

Back 15

The number of protons in the nucleus of atom that establishes the chemical identity of the at atom.

Front 16

Atomic Weight

Back 16

The sum of the numbers of protons and neutrons in the nucleus.

Front 17

Atoms

Back 17

The basic units of all matter.

Front 18

Avogadro's Number

Back 18

No matter what the compund, one mole contains on Avogadro's number (6.023 x 10 to 23rd) of molecules.

Front 19

Base

Back 19

A substance that increases the pH of a solution.

Front 20

Buffer

Back 20

A system of reactants that acts to minimize changes in pH.

Front 21

Catabolism

Back 21

A series of reactions in which the cell extracts energy from chemical sources in the environment. The term catabolism also includes reactions that convert complex molecules from the food into simple ones that can be used to construct new molecules needed by the cell.

Front 22

Catalysts

Back 22

Substances that promote reactions by lowering their activation energy barriers without themselves being changed in the reaction.

Front 23

Cation

Back 23

In an ionic bond, the donor atom is positively charged.

Front 24

Cellular Respiration

Back 24

An oxidation process in which ATP used in cellular activities is rapidly regenerated by the cell's energy metabolism.

Front 25

Chemical Bond

Back 25

Forms when there is interaction between the orbitals of the outermost energy levels of two atoms.

Front 26

Chemical Reactions

Back 26

Processes that form or break chemical bonds, resulting in the formation of new compounds.

Front 27

Chromosome

Back 27

A nucleus structure consisting of a double strand of DNA together with a large number of associated smaller molecules that are involved in regulation of gene expression and chromosomal structure.

Front 28

Colloid

Back 28

A suspension whose particles are so small that intermolecular forces can overcome that force of gravity and keep the particle suspended.

Front 29

Compounds

Back 29

Substances composed of two or more elements.

Front 30

Covalent Bonds

Back 30

The strongest form of atomic bonding in which the bonded partners share one or more electrons to complete their outer energy levels.

Front 31

Cytosine

Back 31

A base in DNA.

Front 32

Decomposition Reactions

Back 32

The opposite of synthesis reactions, taking the form AB -> A + B.

Front 33

Dehydration Reaction

Back 33

A reaction in which the removal of a H+ from one reactant and OH- from the other simultaneously allows the formation of a molecule of water and a bond between the two reactants, creating disaccharides from monosaccharides.

Front 34

Denatured

Back 34

When the tertiary structure of enzymes begins to unravel.

Front 35

Dipole

Back 35

Atoms connected by a polar bond.

Front 36

Disaccharides

Back 36

Formed from monosaccharides by a dehydration reaction.

Front 37

DNA

Back 37

Deoxyribonucleic acid. One type of nucleic acid in which tow polynucleotide strands are twined into a double helix. It is the form in which information about the primary sequences of proteins is passed to daughter cells in cell division during growth and development and in formation of reproductive cells in the gonads.

Front 38

Electrolytes

Back 38

Compounds that incorporate ionic bonds are typically separated into their component ions in water solution.

Front 39

Electron Acceptors

Back 39

Those atoms with nearly full outer levels tend to acquire electrons to fill their orbitals.

Front 40

Electron Donors

Back 40

Those atoms that are from having a filled outer level can find stability most easily by moving in the direction of emptying their outermost energy levels.

Front 41

Energy Level

Back 41

An electron orbital arranged around the nucleus of an atom.

Front 42

Enzyme

Back 42

A protein that acts as the body's catalysts, permitting it to carry out a body temperature reactions that would require a much higher temperature if conducted without catalysis.

Front 43

Equilibrium

Back 43

When the relative concentrations of reactants and product will have changed such that the reverse reaction goes as rapidly as the forward reaction.

Front 44

Equilibrium Constant (Keq)

Back 44

The characteristic ratio of reactants to product at equilibrium.

Front 45

Equivalent (Eq)

Back 45

Expressing solute concentrations as a measure of the number of charges per unit of volume rather than the number of particles.

Front 46

Exons

Back 46

The pieces of RNA that remain after editing that are spliced back together during posttranscriptional processing.

Front 47

Fatty Acids

Back 47

Chains of carbons terminating in a carboxyl group.

Front 48

Gametes

Back 48

Reproductive Cells

Front 49

Glycogen

Back 49

A polysaccharide that has an important role as an energy store within cells.

Front 50

Glycolipids

Back 50

Lipids with covalently bound carbohydrates--the bound carbohydrate chain may be from one to seven or more monosaccharides long.

Front 51

Guanine

Back 51

A base in DNA.

Front 52

Haploid

Back 52

A reproductive cell that has twenty-two somatic chromosomes and either an X or Y chromosome.

Front 53

Homologous Pairs

Back 53

Present in all cells except gametes; the members of each pair are similar in size and contain genes that are related, but not necessarily identical.

Front 54

Hydration Shell

Back 54

An ionic solution surrounded by a shell of water molecules oriented with their electrically opposite poles towards the ion.

Front 55

Hydrogen Bonds

Back 55

The result of the fact that hydrogen-nitrogen and hydrogen-oxygen bonds are polar covalent bonds. A hydrogen so bonded has a small positive charge because the electron it is sharing spends most of its time with the oxygen or nitrogen.

Front 56

Inducers

Back 56

Remove repressors and prevent their binding to the DNA.

Front 57

Introns

Back 57

Parts that will be edited and not appear in the final RNA transcript.

Front 58

Ionic Bond

Back 58

Formed when an element that readily gives up electrons reacts with an element that readily accepts them. The result is that one or more electrons are transferred from the donor to the acceptor.

Front 59

Isoform

Back 59

Enzymes that exist in multiple forms with different enzymatic properties, and are the products of separate genes. Tissues may express one specific isoform or may generate a mixture of isoforms.

Front 60

Isomer

Back 60

Different forms of molecules with the same chemical formula.

Front 61

Isotope

Back 61

Different forms of the same element having the same number of protons but differing in the number of neutrons.

Front 62

Isozyme

Back 62

Enzymes that exist in multiple forms with different enzymatic properties

Front 63

Kinase

Back 63

An enzyme.

Front 64

Lipids

Back 64

The major nonpolar, water-insoluble organic molecules in the body.

Front 65

Lysosomes

Back 65

Digest condemned proteins within the endocytotic vesicle, making the proteins' component of amino acids available for reuse.

Front 66

Meiosis

Back 66

The formation of reproductive cells in the gonads.

Front 67

Micelles

Back 67

Phospholipid bilayers.

Front 68

Mitochondrion

Back 68

A cellular organelle.

Front 69

Molarity

Back 69

For a solution, the number of grams of a solute per liter (l) of water, divided by the solute's molecular weight.

Front 70

Molecular Weight

Back 70

The total of all of the atomic weights of its components expressed in grams.

Front 71

Molecules

Back 71

Structures that result from attachment of atoms to one another by chemical bonds.

Front 72

Monosaccharides

Back 72

Molecules that contain six carbons arranged in a six-sided ring (hexoses) or a five-side (pentoses). Monosaccharides are one of the chief starting materials for energy metabolism since they can be oxidized with release of considerable energy.

Front 73

Motifs

Back 73

Within the secondary structure proteins, established by folding, coiling, or pleating the chain at particular regions of the primary sequence to form characteristic simple shapes. These effects are primarily due to the formation of hydrogen bonds and van der Waals interactions between different parts of the primary structure.

Front 74

mRNA

Back 74

Messenger RNA. Carries the information for protein sequences from the nucleus to the protein synthesis machinery in the cytoplasm.

Front 75

Neutrons

Back 75

Uncharged particles in the nucleus of the atom.

Front 76

Nonpolar Bond

Back 76

A covalent bond resulting from bonded atoms with equally strong electron donors and acceptors: each shared electron spends about the same amount of time with each of the two bonded atoms.

Front 77

Nucleic Acids

Back 77

Linear chains of nucleotides strung together in a sequence that carries information (DNA and RNA).

Front 78

Nucleotides

Back 78

Molecules consisting of a five-carbon sugar (which is deoxyribose in DNA and ribose in RNA), a phosphate group, and a nitrogen-containing aromatic base.

Front 79

Nucleus

Back 79

In the atom, it contains a variable number of protons and neutrons.

Front 80

Orbitals

Back 80

Spaces in which there is 90% probability of finding a particular electron at any particular instant. Each orbital is full when it contains 2 electrons.

Front 81

Organic

Back 81

Compounds that contain carbon and hydrogen.

Front 82

Oxidized

Back 82

In redox reactions, one atom donates one or more electrons to another atom. The donor atom becomes oxidized, and the recipient becomes reduced. Such reactions are important in the energy metabolism of cells because, in many cases, the chemical energy potential of foodstuffs is due to their ability to release energy when they are oxidized.

Front 83

Peptide Bonds

Back 83

Join proteins in chains of amino acids. Formation of a peptide bond is a dehydration reaction.

Front 84

pH

Back 84

Pure water at standard temperature has hydrogen and hydroxyl ion concentrations of 10 to -7 mEq/l each. It is convenient to express hydrogen ion concentration as a logarithm: log (1/[H+]}. This results in a pH scale that runs from 1 - 14.

Front 85

Phospholipids

Back 85

Major components of the plasma membrane surrounding cells and of other membranes within the cellular interior. They are the result of replacing one of the fatty acids of a triacylglycerol with a phosphate group bound to a polar molecule.

Front 86

Polysaccharides

Back 86

Chains of sugars, such as a starch and glycogen.

Front 87

Posttranscriptional Processing

Back 87

In the first step of gene expression, the two-stranded DNA is unwound at the appropriate spot and a complementary strand of mRNA is assembled using one of the strands as a template. This process is catalyzed by an enzyme called RNA polymerase. Next, the primary transcript must be edited, for it contains parts, called introns, that will not appear in the final transcript. The pieces of RNA that remain after editing, called exons, are spliced back together.

Front 88

Posttranscriptional Processing

Back 88

During the translation of the nucleotide sequence into a corresponding amino acid sequence, sometimes part of the amino acid sequence are clipped off or two or more polypetides are attached together to form a functional complex.

Front 89

Primary Sequence

Back 89

The firs, most elementary level in the structure of proteins. This is simply the order of amino acids in the protein chain.

Front 90

Primary Transcript

Back 90

The working copies of individual sentences that are made in the form of a single strand of complementary messenger RNA (mRNA).

Front 91

Products

Back 91

In a chemical reaction, elements or compounds that were not present in that form initially.

Front 92

Promotor

Back 92

Each gene has a promotor sequence at its head end. Transcription of a gene begins when RNA polymerase binds to the promotor side and continues until the polymerase reaches the terminator site. The promotor and terminator sequences simply act to attach and detach the polymerase--they don't get transcribed.

Front 93

Prostaglandins

Back 93

Derivatives of a arachidonic acid, a twenty-carbon fatty acid.

Front 94

Protons

Back 94

Positively charged particles in the nucleus of the atom.

Front 95

Pulmonary Surfactant

Back 95

Secreted by the lungs, interfering with the water-water interactions and reduces surface tension.

Front 96

Quarternary Structure

Back 96

Fully structured proteins that may associate with one another to form functional units (e.g., the enzyme high-energy particles from their nuclei.

Front 97

Receptor

Back 97

At the molecular level, this term applies to molecules that recognize signal molecules of specific types and assist in bringing about the signal's effect of the target cells.

Front 98

Redox Reaction

Back 98

In redox (oxidation-reduction) reactions, one atom donates one or more electrons to another atom. The donor atom becomes oxidized, and the recipient becomes reduced.

Front 99

Repressors

Back 99

Proteins that may block the attachment of polymerase to the promotor by attaching to the promotor site.

Front 100

Ribosomal RNA (mRNA)

Back 100

One of three functional classes of RNA, largely composing the ribosomes.

Front 101

Ribosome

Back 101

Protein synthesizing organelles.

Front 102

RNA

Back 102

One type of nucleic acid, curled into a single spiral helix, comprising linear chains of nucleotides strung together in a sequence that carries information. In RNA, uracil (U) appears instead of thymidine.

Front 103

RNA polymerase

Back 103

An enzyme that catalyzes the process in the first step of gene expression: the two-stranded DNA is unwound at the appropriate spot and a complementary strand of mRNA is assembled using one of the strands as a template.

Front 104

Rough ER

Back 104

An endoplasmic reticulum studded with ribosomes and is a visible sign that the cell is actively synthesizing such proteins.

Front 105

Secondary Structure

Back 105

In the structure of proteins, this level is established by folding, coiling, or pleating the chain at particular regions of the primary sequence to form characteristic simple shapes (motifs).

Front 106

Signal Sequence

Back 106

Causes the ribosome translating the mRNA to attach itself to the endoplasmic reticulum.

Front 107

Solubility Coefficient

Back 107

A measure of the maximum amount of that substance that can be held in solution by a given solute under standard conditions of temperature and pressure.

Front 108

Solutes

Back 108

Substances that can be dissolved in a solvent.

Front 109

Solvent

Back 109

A fluid in which other substances (the solutes) can be dissolved.

Front 110

Stereoisomers

Back 110

Variant forms of molecules that differ in the orientation of a key functional group.

Front 111

Substrates

Back 111

An enzyme's reactants.

Front 112

Suspension

Back 112

Particles with dimensions exceeding that of the typical molecule may be dispersed in water.

Front 113

Synthetic Reactions

Back 113

Combine two or more elements or compounds to form a new compound according to the from A + B = AB.

Front 114

Terminator

Back 114

Each gene has a terminator sequence at its tail end. Transcription of a gene begins when RNA polymerase binds to the promotor site and continues until the polymerase reaches the terminator site. The promotor and terminator sequences simply act to attach and detach the polymerase--they don't get transcribed.

Front 115

Thymine

Back 115

A base in DNA.

Front 116

Transfer RNA (tRNA)

Back 116

Responsible for recognizing particular amino acids and adding them to the growing polypeptide chain in the order specified by the mRNA.

Front 117

Triacylglycerols

Back 117

The major form of a stereo lipid in the body, making up the majority of the fat in adipose cells.

Front 118

Ubiquitin

Back 118

A molecule that labels proteins that are to undergo destruction.

Front 119

Uracil

Back 119

in RNA, a nitrogen-containing aromatic base that appears instead of thymidine (DNA).

Front 120

Valence

Back 120

The number of electrons an element can accept or donate.

Front 121

Valence Electron

Back 121

An electron in an outer energy level that an element can donate.

Front 122

van der Waals Forces

Back 122

Attractive forces that develop between molecules or between different parts of the same large molecule as a result of the fact that the distribution of electrons in each molecule varies over time.