Glossary of AU Biology 110 Chapter 16

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A short sequence of DNA that facilitates the binding of RNA polymerase to enable the transcription of downstream genes.
The process by which messenger RNA is made from a DNA template.
RNA polymerase II
One of three RNA polymerase enzymes that catalyze the synthesis of RNA from ribonucleotides in eukaryotes, using a DNA template.
DNA (deoxyribonucleic acid)
A double-stranded, double-helix molecule of deoxyribonucleotides that contains the genetic information of a cell. Each nucleotide contains the sugar deoxyribose, a phosphate group, and one of four possible nitrogenous bases: adenine, guanine, cytosine, or thymine.
RNA (ribonucleic acid)
A usually single-stranded polymer consisting of a string of ribonucleotides. It may be a structural component of ribosomes (rRNA), a transporter of amino acids (tRNA), or a translator of the message of the DNA code (mRNA).
initiation phase
The first stage of transcription, in which RNA polymerase and other proteins bind to the promoter, forcing the DNA double helix in the transcription region to separate into two single strands.
template strand
The strand of DNA that is read by RNA polymerase and used as a pattern to synthesize the new RNA chain. Which strand of the separated DNA becomes the template strand is based on the orientation of the regulatory sequences in the DNA.
nontemplate strand
The strand of DNA that is not transcribed by RNA polymerase. Which strand of the separated DNA becomes the nontemplate strand is based on the orientation of the regulatory sequences in the DNA.
elongation phase
The second stage of transcription, in which the RNA polymerase molecule begins to travel in one direction along the template strand, catalyzing the addition of complementary ribonucleotides and thus elongating the RNA chain.
A nucleotide that contains ribose as its sugar and occurs as a constituent of RNA.
The characteristic of strands of DNA or RNA that run in opposite directions: One strand runs in the 5' to 3' direction; the other is oriented 3' to 5'.
termination phase
The third and final stage of transcription, in which transcription termination signals at the end of the gene direct the RNA polymerase to end transcription.
transcription termination signal
A stretch of DNA sequence that codes for a stretch of RNA that leads to formation of a hairpin in the RNA. The hairpin disrupts the transcription complex and ends transcription.
messenger RNA (mRNA)
An RNA molecule that carries encoded information, transcribed from DNA, for the synthesis of one or more proteins.
The process by which proteins and peptides are synthesized from messenger RNA molecules.
A complex of specialized ribosomal RNA (rRNA) and proteins that mediates protein synthesis from messenger RNA strands, facilitating placement of transfer RNA, and catalyzing formation of the peptide bonds between amino acids.
ribosomal RNA (rRNA)
A class of specialized RNA molecules that forms part of the structure of a ribosome.
transfer RNA (tRNA)
A class of specialized RNA molecules responsible for matching amino acids to messenger RNA codons during translation. They have a cloverleaf shape, with the amino acid binding site at one end and an anticodon at another site.
aminoacyl tRNA
A tRNA molecule that is covalently linked to an amino acid.
The first stage of translation, which begins when a section of rRNA in the small subunit of the ribosome binds to a complementary sequence on the mRNA.
5' cap
A structure consisting of the molecule 7-methylguanylate and three phosphate groups.
start codon
The messenger RNA sequence AUG, which induces the beginning of protein synthesis and codes for the amino acid methionine.
Three bases of a transfer RNA molecule that bind to a messenger RNA codon with a complementary sequence.
The second stage of translation, during which polypeptide chains lengthen to build the protein.
P site
The site in a ribosome where peptide bonds are formed between amino acids.
A site
The site in a ribosome at which an aminoacyl transfer RNA pairs with a messenger RNA codon, in preparation for adding its amino acid to the growing peptide chain.
E site
The site in a ribosome into which an empty transfer RNA is shunted after addition of its amino acid to the growing peptide chain.
A process that occurs during elongation when the ribosome moves down the mRNA in the 5' to 3' direction. It moves the empty tRNA into the E site; moves the tRNA containing the growing polypeptide into the P site; and opens the A site to expose a new mRNA codon.
The last stage of translation, during which three stop codons signal the end of protein synthesis.
stop codon
One of three messenger RNA triplets (UAG, UGA, or UAA) that cause termination of protein synthesis.
release factor
A protein that fits tightly into the A site during translation because its size, shape, and electrical charge are extremely similar to a tRNA.

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