Genetics Chapter 8 Vocab

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polypeptide chains

Back 1

a polymer of amino acids linmked together by pepptide bonds

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R-group

Back 2

refers to the side chain connected to the alpha carbon that differs for each amino acid

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peptide bond

Back 3

a polymer of amino acids linked together by peptide bonds

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amino terminus

Back 4

the end of a polypetide chain at which the amino acid bears a free amino group

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carboxyl terminus

Back 5

the end of a polypeptide chain at which the amino acid has a free carboxyl group

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RNA polymerase holoenzyme

Back 6

any of several large protein complexes that inlcudes RNA polymerase aming its constituents

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RNA polymerase I

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used exclusively in producing the transcript that becomes prcessed into ribosomal RNA

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RNA polymerase II

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the workhorse eukaryotic polymerase responsible for transcribing all protein-coding genes as well as the genes for a number of small nuclear RNA's (U1, U2, U3, and so forth) used in RNA processing

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RNA polymerase III

Back 9

used in transcribing all transfer RNA genes as well as the 5S component of ribosomal RNA

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Promoter recognition

Back 10

The first process of of RNA recognizing which strand of DNA should be transcribed in which the RNA polymerase binds to the promoter

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promoter

Back 11

A dna sequence at which RNA polymerase binds and initiates transcription

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consensus sequence

Back 12

a generalized base sequence derived from closely related sequences found in many locations in a genome or in many organisms; each position in the sequence consists of the base found in the majority of sequences in that position

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TATA box

Back 13

the base sequence 5 prime TAT 3 prime in the DNA of a promoter

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Chain initiation

Back 14

The second stage of RNA transcription in which after the initial binding step, the RNA polymerase initiates RNA synthesis at a nearby transcription start site

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Chain Elongation

Back 15

the second stage of RNA transcription in which RNA polymerase moves along the DNA template strand, adding nucleotides to the growing RNA chain.

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Chain terminiation

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the forth and final step of RNA transcription in which the RNA polymerase reaches a transcription termination sequence in the DNA and the polymerase enzyme disassociates from the DNA, and the newly synthesized RNA molycule is released.

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primary transcript

Back 17

the RNA molecule produced from a DNA template

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messenger RNA

Back 18

An RNA molecule transcribed from a DNA sequence and translated into the amino acid sequence of a polypeptide. In eukaryotes, the primary transcript undergoes elaborate processing to become the mRNA

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5' untranslated region

Back 19

the initial part of a mRNA which does not code for protein

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open reading frame (ORF)

Back 20

in the coding strand of DNA or in mRNA, a region containing a series of codonss uninterrupted by stop codons and therefore capable of coding for a polypeptide chain

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3' untranslated region

Back 21

the terminal portion of a messenger RNA, following the stop codon, which does not code for protein

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cap

Back 22

a ccomplex structure at the 5' termini of most eukaryotic mRNA molecules, having a 5'-5' linkage instead of the usual 3'-5' linkage

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poly-A tail

Back 23

the sequence of adeninees added to the 3' end of many eukaryotic mRNA molecules in processing

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introns

Back 24

a noncoding DNA sequence in a gene that is transcribed but is then excised from the primary transcript in froming a mature mRNA molecule; found primarily in eukaryotic cells

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exons

Back 25

the sequences in a gene that are retained in the messenger RNA after the introns are removed from the primary transcript.

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RNA splicing

Back 26

excision of introns and joining of exons.

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RNA splicing

Back 27

excision of introns and joining of exons

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spliceosomes

Back 28

an rna protein particle in the nucleus in which hintrons are removed from RNA transcripts

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snRNPs

Back 29

any of several classes of small ribonucleoprotein particles involved in RNA splicing

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ribozymes

Back 30

an RNA molecule able to catalyze one or more biochemical reactions

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Translation : Messenger rNA

Back 31

component of translation - needed to bring the ribosomal subunits together and to provide the coding sequence of bases that determines the amino acid sequence in the resulting polypeptide chain

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Translation : Ribosomes

Back 32

component of translation - particles on which protein synthesis takes place. They move along an mRNA molecule and align successive transfer RNA molecules; the amino acids are attached one by one to the growing polypeptide chain by means of peptide bonds. Ribosomes consist of two separate RNA-protein partics, which come together in polypeptide synthesis to form a mature ribosome.

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Translation : transfer RNA

Back 33

component of translation - the sequence of amino acids in a polypeptide is determined by the base sequence in the mRNA by means of a set of adapator molecules, the tRNA molecules each which is attached to a particular amino acid. Each set of the mRNA form a codon that binds to a group of 3 adjacent bases in the tRNA, the anticodon, bringing the attached amino acid into line for elngation of the growing polypeptide chain

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Translation : Aminoacyl-tRNA synthetases

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component of translation - Each enzyme in this set of molecules catalyzes the attachment of a particular amino acid to its corresponding tRNA molecule. A tRNA attached to its amino acid is called an aminoacylated tRNA or a charged tRNA

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Translation : initiation, elongation, and termination factors

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polypeptide synthesis can be divided into three stages. Initiation, elongation, and termination. Each stage requires specialized molecules.

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aminoacylated tRNA

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charged tRNA; a tRNA covalentily attached to its amino acid

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initiation (protein synthesis)

Back 37

the process by which mRNA binds with ribosomes and other factors and protein synthesis begins

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start codon

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an mRNA codon, usually AUG, at which polypeptide synthesis begins

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E (exit site)

Back 39

the tRNA-binding site on the ribosome that binds each uncharged tRNA just prior to its release

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elognation phases

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1. Bringing each new aminoacylated tRNA into line
2. Forming the new peptide bond to elongate the polypeptide
3. Moving the ribosome to the next codon along th mRNA

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release phase

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when a stop codon is encountered, the tRNA holding the polypeptide remains in the p site, and a release factor (RF) binds with the ribosome. GTP hydrolysis provides the energy to cleave the polypeptide from the tRNA to wich it is attached, as well as to eject the release factor and dissociate the 80S ribosome from the mRNA

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chaperones

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proteins that aid in the proper folding of polypeptides

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polycistronic mRNA

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An mRNA molecule from which two or more polypeptides are translated; found primarily in prokaryotes

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ribosome-binding site

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the base sequence in a prokaryotic mRNA molecule to which a ribosome can bind to initiate protein synthesis; also called Shine-Dalgarno sequence

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genetic code

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the set of 64 triplets of bases (codons) that correspond to the 20 amino acids in proteins and the signals for the initiation and terminiation of polypeptide synthesis

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reading frame

Back 46

the phase in which successive triplets of nucleotides in mRNA form codons; depending on the reading frame, a particular nucleotide in an mRNA could be in the first, second, or third position of a codon. The reading frame actually used is defined by the AUG codon that is selected for chain initiation

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frameshift mutations

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a mutational event caused by the insertion or deletion of one or more nucleotide pairs in a gene, resulting ina shift in the reading frame of all codons following the mutational site

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redundancy

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the feature of the genetic code in which an amino acid corresponds to more than one codon; also called degeneracy

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wobble

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the acceptable pairing of several possible bases ina an anticodon with the base present in the third position of a codon

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polysome

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a complex of two or more ribosomes associated with an mRNA molecule and actively engaged in polypeptide synthesis; a polyribosome.

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coupling

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the simulataneous execution of transcription and translation

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Domain

Back 52

contiguous region of a polypeptide chain or protein molecule that folds into a characteristic structure relatively independently of other such regions, often contributing unique structural characteristics or binding properties to the molecule as a whole

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5' UTR

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Untranslated region of a messenger RNA; upstream of the protein-coding region

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3' UTR

Back 54

Untranslated region of a messenger RNA; downstream of a protein-coding region

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Aminoacyl site

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The tRNA-binding site on the ribosome which each incoming charfed tRNA is initially bound

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Exon Shuffle model

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The theory that new genes can evolve by the assembly of separate exons from preexistin ggenes, each coding for a discrete functional domain in the new protein.

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chaperonins

Back 57

proteins that shield the very slow and inefficient folding pathways of the most complex proteins