AP Biology_Chapter 10

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Biologists finally established the role of DNA in heredity through experiments with bacteria and the viruses that infect them. This breakthrough ushered in the field of __________ _________, the study of heredity at the molecular level.
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Terms in this set (52)
Watson and Crick's model predicts that when a double helix replicates, each of the two daughter molecules will have one old strand, which was part of the parental molecule, and one newly created strand. This model of DNA replication is known as the ________________ ________ because half of the parental molecule is maintained (conserved) in each daughter molecule.semiconservative modelThe enzymes that link DNA nucleotides to a growing daughter strand, called ______ ________________, add nucleotides only to the 3' end of the strand, never to the 5' end.DNA polymerasesAnother enzyme, called _____ ________, then links, or ligates, the pieces together into a single DNA strand.DNA ligaseThe two main stages are _____________, the synthesis of RNA under the direction of DNA, and _____________, the synthesis of protein under the direction of RNA.transcription, translationExperiments have verified that the flow of information from gene to protein is based on a _______ ______: The genetic instructions for the amino acid sequence of a polypeptide chain are written in DNA and RNA as a series of nonoverlapping three-base "words" called ______.triplet code, codonsThe RNA nucleotides are linked by the transcription enzyme ___ _______________, symbolized in the figure by the large gray shape.RNA polymeraseThe "start transcribing" signal is a nucleotide sequence called a ___________.promoterFinally, in the third phase, termination, the RNA polymerase reaches a sequence of bases in the DNA template called a ____________.terminatorThe kind of RNA that encodes amino acid sequences is called _________________ because it conveys genetic messages from DNA to the translation machinery of the cell.messenger RNA (mRNA)Most genes of plants and animals, it turns out, include such internal noncoding regions, which are called ________.intronsThe coding regions-the parts of a gene that are expressed-are called _____.exonsThis cutting-and-pasting process is called _________.RNA splicingTo convert the words of nucleic acids (codons) to the amino acid words of proteins, a cell employs a molecular interpreter, a special type of RNA called ___________.transfer RNA (tRNA)A single-stranded loop at one end of the folded molecule contains a special triplet of bases called an __________.anticodonThe final components are the _________, structures in the cytoplasm that position mRNA and tRNA close together and catalyze the synthesis of polypeptides.ribosomesA ribosome consists of two sub-units, each made up of proteins and a kind of RNA called ________.ribosomal RNA (rRNA)A special initiator tRNA binds to the specific codon, called the _____ _______, where translation is to beingo n the mRNA molecule.start codonThis site, called the _ ____, will hold the growing polypeptide.P siteThe other tRNA binding site, called the _ ____, is vacant and ready for the next amino-acid-bearing tRNA.A siteThe anticodon of an incoming tRNA molecule, carrying its amino acid, pairs with the mRNA codon in the A site of the ribosome.Codon recognitionThe polypeptide separates from the tRNA in the P site and attaches by a new peptide bond to the amino acid carried by the tRNA in the A site. The ribosome catalyzes formation of the peptide bond, adding one more amino acid to the growing polypeptide chain.Peptide bond formationThe P site tRNA now leaves the ribosome, and the ribosome translocates (moves) the remaining tRNA in the A site, with the growing polypeptide, to the P site. The codon and anticodon remain hydrogen-bonded, and the mRNA and tRNA move as a unit. this movement brings into the A site the next mRNA codon to be translated, and the process can start again with step 1.TranslocationElongation continues until a ____ ______ reaches the ribosome's A site.stop codonAny change in the nucleotide sequence of DNA is called a _______.mutationSuch a change is called a _____ ________.silent mutationOther substitutions, called _____ ________, do change the amino acid coding.missense mutationsSome substitutions, called ________ _________, change an amino acid codon into a stop codon.nonsense mutationsBecause mRNA is read as a series of nucleotide triplets (codons) during translation, adding or subtracting nucleotides may alter the ________ ______ (triplet grouping) of the message.reading frameThe production of mutations, called __________, can occur in a number of ways.mutagenesisOther mutations are caused by physical or chemical agents, called _________.mutagensIn a sense, a ______ is nothing more than "genes in a box": an infectious particle consisting of a bit nucleic acid wrapped in a protein coat called a _______ and, in some cases, a membrane envelope.virus, capsidThis sort of cycle is called a _______ _______ because it results in the lysis (breaking open) of the host cell and the release of the viruses that were produced within the cell/lytic cycleDuring a ____________ _______, viral DNA replication occurs without destroying the host cell.lysogenic cycleOnce inserted, the phage DNA is referred to as a __________, and most of its genes are inactive.prophageHIV carries molecules of an enzyme called ______ _________, which catalyzes reverse transcription, the synthesis of DNA on an RNA template.reverse transcriptaseThis unusual process, which is opposite the usual DNA -> RNA flow of genetic information, characterizes _______ (retro means "backward").retrovirusesFigure 10.22A illustrates ___________, the uptake of foreign DNA from the surrounding environment.transformationThe transfer of bacterial genes by a phage is called __________.transductionThis physical union of two bacterial cells - of the same of different species - and the DNA transfer between them is called ____________.conjugationThe ability of a donor E. coli cell to carry out conjugation is usually due to a specific piece of DNA called the __ _________ (F for fertility).F factorAlternatively, as Figure 10.23B shows, an F factor can exist as a _______, a small, circular DNA molecule separate from the bacterial chromosome.plasmidPlasmids of one class, called ___ __________, pose serious problems for human medicine.R plasmids