Question Answer
Linked genes Genes located on the same chromosome
Linkage group Genes located together on the same chromosome
Nonrecombinant (parental) gamete Contains only the original combinations of genes present in the parents
Nonrecombinant (parental) progeny Possesses the original combinations of traits possessed by the parents
Recombinant gamete Possesses new combinations of genes
Recombinant progeny Possesses new combinations of traits formed from recombinant gametes
Recombination frequency Proportion of recombinant progeny produced in a cross
Coupling (cis) configuration Arrangement in which two or more wild-type genes are on one chromosome and their mutant alleles are on the homologous chromosome
Repulsion (trans) configuration Arrangement in which a chromosome contains one wild-type allele and one mutant allele; also called repulsion
Genetic map Map of the relative distances between genetic loci, markers, or other chromosome regions determined by rates of recombination; measured in percent recombinant or map units
Physical map Map of physical distances between loci, genetic markers, or other chromosome segments; measured in base pairs
Map unit (m.u.) Unit of measure for distances on a genetic map; 1 map unit equals 1% recombination
CentiMorgan Another name for map unit
Two-point testcross Cross between an individual heterozygous at two loci and an individual homozygous for recessive alleles at those loci
Three-point testcross cross between an individual heterozygous at three loci and an individual homozygous for recessive alleles at those loci
Interference Degree to which one crossover interferes with additional crossovers
Coefficient of coincidence Ratio observed double crossovers to expected double crossovers
Semiconservative replication Replication in which the two nucleotide strands of DNA separate, each serving as a template for the synthesis of a new strand. All DNA replication is semiconservative
Replication origin Sequence of nucleotides where replication is initiated
Theta replication Replication of cicular DNA that is initiated by the unwinding of the two nucleotide strands, producing a replications bubble. Unwinding continues at one or both ends of the bubble, making it progressively larger…….
Theta replication CONTINUED DNA replication on both of the template strands is simultaneous with unwinding until the two replication forks meet.
Replication bubble Segment of a DNA molecules that is unwinding and undergoing replication
Replication fork Point at which double-stranded DNA molecule separates into two single stands that serve as templates for replication
Bidirectional replication Replication at both ends of a replication bubble
DNA polymerase Enzyme that synthesizes DNA
Continuous replication Replication of the leading strand in the same direction as that of unwinding, allowing new nucleotides to be added continuously to the 3' end of the new strand as the template is exposed
Leading strand DNA strand that is replicated continuously
Discontinuous replication Replication of the lagging strand in the direction opposite that of unwinding, which means that DNA must be synthesized in short stretches (Okazaki fragments)
Lagging strand DNA strand that replicated discontinuously
Okazaki fragment Short stretch of newly synthesized DNA. Produced by discontinuous replication on the lagging strand, these fragments are eventually joined together
Ribozyme RNA molecule that can act as a biological catalyst
Ribosomal RNA (rRNA) RNA molecule that is a structural component of the ribosome
Messenger RNA (mRNA) RNA molecule that carries genetic information for the amino acid sequence of a protein
Pre-messenger RNA (pre-mRNA) Eukaryotic RNA molecule that is modified after transcription to become mRNA
Transfer RNA (tRNA) RNA molecule that carries an amino acid to the ribosome and transfers it to a growing polypeptide chain in translation
Template strand The strand of DNA that is used as a template during transcription. The RNA synthesized during transcription is complementary and antiparallel to the template strand.
Nontemplate strand The DNA strand that is complementary to the template strand; not ordinarily used as a template during transcription
Transcription unit Sequence of nucleotides in DNA that encodes a single RNA moleculem along with the sequences necessary for its transcription; normally contains a promoter, an RNA-coding sequence, and a terminator
Promoter DNA sequence to which the transcription apparatus binds so as to initiate transcription; indicates the direction of transcription, which of the two DNA strands is to be read as the template, and the starting point of transcription
Terminator Sequence of DNA nucleotides that causes the termination of transcription
Ribonucleoside triphosphate (rNTP) Substrate of RNA synthesis; consists of ribose, a nitrogenous base, and three phosphates linked to the 5' -carbon atom of the ribose. In transcription, two of the phosphates are cleaved, producing an RNA nucleotide
RNA polymerase Enzyme that synthesizes RNA from a DNA template during transcription
Core enzyme Part of bacterial RNA polymerase that, during transcription, catalyzes the elongation of the RNA molecule by the addition of RNA nucleotide; consists of four subunits: two copies of alpha, a single copy of beta, and a single copy of beta prime
Sigma factor Subunit of bacterial RNA polymerase that allows the RNA polymerase to recognize a promoter and initiate transcription
Holoenzyme Complex of an enzyme and other protein factors necessary for complete function
Consensus sequence Comprises the most commonly encountered nucleotides found at a specific location in DNA or RNA
-10 consensus sequence (Pribnow box) Consensus sequence (TATAAT) found in most bacterial promoters approximately 10 bp upstream of the transcription start site
Colinearity Concept that there is a direct correspondence between the nucleotide sequence of a gene and the coninuous sequence of amino acids in a protein
Exon Coding region of a split gene (a gene that is interrupted by introns). After processing, the exons remain in messenger RNA.
Intron Intervening sequence in a split gene; removed from the RNA after transcription
Codon Sequence of three nucleotides that encodes one amino acid in a protein
5' untranslated region Sequence of nucleotides at the 5' end of mRNA; does not encode the amino acids of a protein
Protein-coding region The part of mRNA consisting of the nucleotides that specify the amino acid sequence of a protein
3' untranslated region Sequence of necleotides at the 3' end of mRNA; does not encode the amino acids of a protein but affects both the stability of the mRNA and its translation
One-gene, One-enzyme hypothesis Idea proposed by Beadle and Tatum that each gene encodes a separate enzyme
One-gene, One-polypeptide hypothesis Modification of the one gene, one enzyme hypothesis; proposes that each gene encodes a separate polypeptide chain
Amino acid Repeating unit of proteins; consists of an amino group, a carboxyle group, a hydrogen atom, and a variable R group
Peptide bond Chemical bond that connects amino acids in a protein
Polypeptide Chain of amino acid linked by peptide bonds; also called a protein
Sense codon Codon that specifies an amino acid in a protein
Degenerate genetic code Refers to the fact that the genetic code contains more information than is needed to specify all 20 common amino acids
Synonymous codons Different codons that specify the same amino acid
Isoaccepting tRNAs Different tRNAs with different anticodons that specify the same amino acid
Wobble Base pairing between codon and anticodon in which there is nonstandard pairing, usually at the third (3') position of the codon; allows more than one codon to pair with the same anticodon
Reading frame Particular way in which a nucleotide squence is read in groups of three nucleotides (codons) in translation. Each reading frame begins with a start codon and ends with a stop codon.
Initiation codon The codon in mRNA that specifies the first amino acid (fMet in bacterial cells; Met in eukaryotic cells) of a protein; most commonly AUG
Stop (termination or nonsense) codon Codon in mRNA that signals the end of translation. The three common stop codons are UAA, UAG, and UGA
Universal genetic code Refers to the fact that particular codons specify the same amino acids in almost all organisms
tRNA charging
Initiation factor (IF-1, IF-2, IF-3) Protein required for the initiation of translation in bacterial cells; 1-enhances the dissociation of the large and small subunits of the ribosome. 2-forms a complex with GTP and the charged initiator tRNA and delivers charged tRNA to initiation complex..
Initiation factor CONTINUED 3-binds to the small subunit of the ribosome and prevents the large subunit from binding during initiation
Aminoacyl (A) site One of the three sites in a ribosome occupied by a tRNA in translation. All charged tRNAs (with the exception of the initiator tRNA) first enter the A site in translaion
Peptidyl (P) site One of the three sites in a ribosome occupied by a tRNA in translation. In the elongation stage of protein synthesis, tRNAs move from the aminoacyl (A) site into the P site
Exit (E) site One of the three sites in a ribosome occupied by a tRNA. In the elongation stage of translation, the tRNA moves from the peptidyl (P) site to the E site from which it then exits the ribosome

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