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TCN A&P ch. 4
The chemical basis of life
122
Anatomy
Professional
03/10/2012

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Term
Active site
Definition
In the general theory of enzyme catalysis, the tertiary structure of an enzyme forms a pocket in which the reactants are brought together in the proper orientation for bond formation.
Term
Adenosine Triphosphate
Definition
The main source of energy available to cells to drive energy-requiring reactions that ordinarily would not proceed spontaneously.
Term
Adenosine Diphosphate
Definition
In the process of ATP driving energy-requiring reactions, one of the three phosphate groups of ATP is split off, yielding this and inorganic phosphate (Pi).
Term
Activation energy barrier
Definition
In order to bond to one another, the two reactants must meet each other with sufficient energy to overcome an this required for a bond to form.
Term
Acidosis
Definition
Excess acic in extracellular fluid.
Term
Alkalosis
Definition
Excess base in extracellular fluid.
Term
Adenine
Definition
A base in DNA
Term
Acid
Definition
A substance that decreases the pH of a solution.
Term
Allosteric Phosphoylation
Definition
At another site other than the active site, attachment of a phosphate group [PO4] at a specific site on the protein by another enzyme, kinase.
Term
Amiphipathic
Definition
A molecule that is most stable when its head is in an aqueous environment and its tail in a nonpolar environment.
Term
Amino acids
Definition
Organic compounds that contain at least one carbon atom that is bonded simultaneously to carboxyl group; amino group; hydrogen atom; and a side chain of varying complexity, the structure of which determines its type. The side chain may be polar, nonpolar, acidic, basic, or aromatic.
Term
Anion
Definition
In an ionic bond, the acceptor atom that is negatively charged.
Term
Anabolism
Definition
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.
Term
Allosteric regulation
Definition
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.
Term
Base
Definition
A substance that increases the pH of a solution.
Term
Atomic weight
Definition
The sum of the number of protons and neutrons in its nucleus.
Term
Atoms
Definition
The basic units of all matter.
Term
Buffer
Definition
A system of reactants that acts to minimize changes in pH.
Term
Avogadro's number
Definition
No matter what the compound,one mole contains 6.023*10^23 of molecules.
Term
Atomic number
Definition
The number of protons in the nucleus of atom that establishes the chemical identity of the atom.
Term
Chemical reactions
Definition
Processes that form or break chemical bonds, resulting in the formation of new compounds.
Term
Catabolism
Definition
A series of reactions in which the cell extracts energy from chemical sources in the environment.
Term
Cation
Definition
In an ionic bond, the donor atom that is positively charged.
Term
Chemical bond
Definition
Forms when there is interaction between the orbitals of the outermost energy levels of two atoms.
Term
Catalysts
Definition
Substances that promote reactions by lowering their activation energy barriers without themselves being changed in the reaction.
Term
Cellular respiration
Definition
An oxidation process in which ATP used in cellular activities is rapidly regenerated by the cell's energy metabolism.
Term
Chromosome
Definition
A nuclear structure consisting of a double stand of DNA together with a large number of associated smaller molecules that are involved in regulation of gene expression and chromosomal structure.
Term
Colloid
Definition
A suspension whose particles are so small that intermolecular forces can overcome the force of gravity and keep the particles suspended.
Term
Covalent bond
Definition
The strongest form of atomic bonding in which the bonded partners share one or more electrons to complete their outer energy levels.
Term
Dipole
Definition
Atoms connected by a polar bond.
Term
Dehydration reaction
Definition
A reaction in which the removal of a H+ from one reactant and an OH- from the other simultaneously allows the formation of a molecule of water and a bond between the two reactants, creating disaccharides from monosaccharides.
Term
Cytosine
Definition
A base in DNA
Term
Compound
Definition
Substances composed of molecules of the same type.
Term
Denatured
Definition
When the tertiary structure of enzymes begin to unravel.
Term
Disaccharides
Definition
Formed from monosaccharides by dehydration reaction.
Term
Decomposition reactions
Definition
The opposite of synthesis reactions, taking the form AB A+B
Term
Electrolytes
Definition
Compounds that incorporate ionic bonds are typically separated into their component ions in water solution.
Term
Energy level
Definition
An electron orbital arragned around the nucleus of an atom.
Term
Electron donor
Definition
Those atoms that are far from having a filled outer level can find stability most easily by moving in the direction of emptying their outermost energy levels.
Term
Electron acceptors
Definition
Those atoms with nearly full outer levels tend to acquire electrons to fill their orbitals.
Term
Enzyme
Definition
A protein that acts as the body’s catalysts, permitting it to carry out at body temperature reactions that would require a much higher temperature if conducted without catalysis.
Term
DNA (Deoxyribonucleic acid)
Definition
One type of nucleic acid in which two 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 the formation of reproductive cells in the gonads.
Term
Equivalent (Eq)
Definition
Expressing solute concentrations as a measure of the number of charges per unit volume rather than the number of particles.
Term
Glycogen
Definition
A polysaccharide that has an important role as an energy store within cells.
Term
Gametes
Definition
Reproductive cells.
Term
Exons
Definition
Pieces of RNA that remain after editing that are spliced back together during the posttransciptional processing.
Term
Fatty acids
Definition
Chains of carbons terminating a carboxyl group.
Term
Glyoclipids
Definition
Lipids with covalently bound carbohydrates - The bound carbohydrate chain may be from one to seven or more monosaccharides long.
Term
Equilibrium constant (Keq)
Definition
The characteristic ratio of reactants to product at equilibrium.
Term
Homologous pairs
Definition
Present in all cells except gametes; the members of each pair are of similar size and contain genes that are related, but not necessarily identical.
Term
Introns
Definition
Parts that will be edited and not appear in the final RNA transcript.
Term
Hydrogen bonds
Definition
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.
Term
Guanine
Definition
A base in DNA
Term
Hydration shell
Definition
An ion in solution surrounded by a shell of water molecules oriented with their electrically opposite poles towards the ion.
Term
Inducers
Definition
Remove repressors and prevent their binding to the DNA.
Term
Ionic bond
Definition
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.
Term
Haploid
Definition
A reproductive cell that has twenty-two somatic chromosomes and either an X or a Y chromosome.
Term
Kinase
Definition
An enzyme
Term
Isotope
Definition
Different forms of the same element having the same number of protons but differing in the number of neutrons.
Term
Lysosomes
Definition
Digest condemned proteins within the endocytotic vesicle, making the proteins’ component amino acids available for reuse.
Term
Isozyme
Definition
Enzymes that exist in multiple forms with different enzymatic properties.
Term
Lipids
Definition
The major nonpolar, water-insoluble organic molecules in the body.
Term
Isomer
Definition
Different forms of molecules with the same chemical formula.
Term
Isoform
Definition
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.
Term
Meisosis
Definition
The formation of reproductive cells in the gonads.
Term
Molecules
Definition
Structures that result from attachment of atoms to one another by chemical bonds.
Term
Motifs
Definition
Within the secondary structure of 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.
Term
Monosaccharides
Definition
Molecules that contain six carbons arranged in a six-sided ring (hexoses) or a five-sided ring (pentoses). They are one of the chief starting materials for energy metabolism since they can be oxidized with release of considerable energy.
Term
Molecular weight
Definition
The total of all of the atomic weights of its components expressed in grams.
Term
Mitochondrion
Definition
A cellular organelle.
Term
Messenger RNA (mRNA)
Definition
Carries the information for protein sequences from the nucleus to the protein synthesis machinery in the cytoplasm.
Term
Micelles
Definition
Phospholipid bilayers.
Term
Molarity
Definition
For a solution, the number of grams of solute per liter of water,divided by solute's molecular weight.
Term
Nonpolar bond
Definition
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.
Term
Nucleotides
Definition
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.
Term
Orbitals
Definition
Spaces in which there is a 90 percent probability of finding a particular electron at any particular instant. Each orbital is full when it contains two electrons.
Term
Nucleic acids
Definition
Linear chains of nucleotides strung together in a sequence that carries information (DNA and RNA).
Term
Oxidized
Definition
In redox reactions, one atom donates one or more electrons to another atom. The donor atom becomes this, 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 this happens.
Term
Nucleus
Definition
In the atom, it contains a variable number of protons and neutrons.
Term
Organic
Definition
Compounds that contain carbon and hydrogen.
Term
Neutrons
Definition
Uncharged particles in the nucleus of the atom.
Term
Polysaccharides
Definition
Chains of sugars, such as starch and glycogen.
Term
Phospholipids
Definition
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.
Term
Peptide bonds
Definition
Join proteins in chains of amino acids.
Term
Posttranslational processing
Definition
During the translation of the nucleotide sequence into a corresponding amino acid sequence, sometimes parts of the amino acid sequence are clipped off or two or more polypeptides are attached together to form a functional complex.
Term
Posttranscriptional processing
Definition
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.
Term
Primary sequence
Definition
The first, most elementary level in the structure of proteins. This is simply the order of amino acids in the protein chain.
Term
pH
Definition
Pure water at standard temperature has hydrogen and hydroxyl ion concentrations of 10-7mEq/l each. It is convenient to express the hydrogen ion concentration as a logarithm: log (1/[H+]). This results in a pH scale that runs from 1–14.
Term
Primary transcript
Definition
The working copies of individual sentences that are made in the form of a single strand of complementary messenger RNA (mRNA).
Term
Quaternary structure
Definition
Fully structured proteins that may associate with one another to form functional units (e.g., the enzyme, lactate dehydrogenase).
Term
Pulmonary surfactant
Definition
Secreted by the lungs, interfering with the water-water interactions and reduces surface tension.
Term
Prostaglandins
Definition
Derivatives of arachidonic acid, a twenty-carbon fatty acid.
Term
Radioactive
Definition
Isotopes that are unstable and undergo a decay process in which the atoms reach a stable state by emitting high-energy particles from their nuclei.
Term
Promoter
Definition
Each gene has a sequence at its head end. Transcription of a gene begins when RNA polymerase binds to this site and continues until the polymerase reaches the terminator site. This sequence and terminator sequences simply act to attach and detach the polymerase—they don’t get transcribed.
Term
Products
Definition
In a chemical reaction, elements or compounds that were not present in that form initially.
Term
Receptor
Definition
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 on the target cells.
Term
Protons
Definition
Positively charged particles in the nucleus of an atom.
Term
Redox reaction
Definition
In (oxidation-reduction) reactions, one atom donates one or more electrons to another atom. The donor atom becomes oxidized, and the recipient becomes reduced.
Term
RNA
Definition
One type of nucleic acid, curled into a single spiral helix, comprising linear chains of nucleotides strung together in a sequence that carries information. Uracil (U) appears instead of thymidine.
Term
Secondary structure
Definition
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).
Term
Rough ER
Definition
An endoplasmic reticulum studded with ribosomes and is a visible sign that the cell is actively synthesizing such proteins.
Term
Ribosome
Definition
Protein synthesizing organelles.
Term
RNA polymerase
Definition
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.
Term
Ribosomal RNA (rRNA)
Definition
One of three functional classes of RNA, largely composing the ribosomes.
Term
Repressors
Definition
Proteins that may block the attachment of polymerase to the promoter by attaching to the promoter site.
Term
Solubility coefficient
Definition
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.
Term
Synthetic reactions
Definition
Combine two or more elements or compounds to form a new compound according to the form A + B AB.
Term
Solvent
Definition
A fluid in which other substances (the solutes) can be dissolved.
Term
Substrates
Definition
An enzyme’s reactants.
Term
Stereoisomers
Definition
Variant forms of molecules that differ in the orientation of a key functional group.
Term
Signal sequence
Definition
Causes the ribosome translating the mRNA to attach itself to the endoplasmic reticulum.
Term
Suspension
Definition
Particles with dimensions exceeding that of the typical molecule may be dispersed in water.
Term
Solutes
Definition
Substances that can be dissolved in a solvent.
Term
Thymine
Definition
A base in DNA
Term
Tracylglycerols
Definition
The major form of stored lipid in the body, making up the majority of the fat in adipose cells.
Term
Terminator
Definition
Each gene has a sequence at its tail end. Transcription of a gene begins when RNA polymerase binds to the promoter site and continues until the polymerase reaches this site. The promoter and these sequences simply act to attach and detach the polymerase—they don’t get transcribed.
Term
Transfer RNA (tRNA)
Definition
Responsible for recognizing particular amino acids and adding them to the growing polypeptide chain in the order specified by the mRNA.
Term
Valence
Definition
The number of electrons an element can accept or donate.
Term
Ubiquitin
Definition
A molecule that labels proteins that are to undergo destruction.
Term
Uracil
Definition
In RNA, a nitrogen-containing aromatic base that appears instead of thymidine (DNA).
Term
Valence electron
Definition
An electron in an outer energy level that an element can donate.
Term
Van der Waals forces
Definition
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.
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