AP Biology Campbell Chapter 17

A modified form of guanine nucleotide added onto the nucleotide at the 5' end of a pre-mRNA molecule.

One of a ribosome’s three binding sites for tRNA during translation. The A site holds the tRNA carrying the next amino acid to be added to the polypeptide chain. (A stands for aminoacyl tRNA.)

A type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns.

An organic molecule possessing both carboxyl and amino groups. Amino acids serve as the monomers of polypeptides.

An enzyme that joins each amino acid to the appropriate tRNA.

(an´-ti-ko´-don) A nucleotide triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.

A type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides.

(shap'-er-o'-nin) A protein molecule that assists in the proper folding of other proteins.

(ko´-don) A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.

(1) A taxonomic category above the kingdom level. The three domains are Archaea, Bacteria, and Eukarya. (2) An independently folding part of a protein.

One of a ribosome’s three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosome. (E stands for exit.)

The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles; includes the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, and vacuoles.

A sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed.

A mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.

The process by which DNA directs the synthesis of proteins or, in some cases, just RNAs.

A mutation involving the addition of one or more nucleotide pairs to a gene.

(in´-tron) A noncoding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing; also refers to the region of DNA from which this sequence was transcribed.

A type of RNA, synthesized using a DNA template, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.

A base-pair substitution that results in a codon that codes for a different amino acid.

(myu´-tuh-jen) A chemical or physical agent that interacts with DNA and causes a mutation.

(myu-ta´-shun) A change in the nucleotide sequence of an organism’s DNA, ultimately creating genetic diversity. Mutations also can occur in the DNA or RNA of a virus.

A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.

One of a ribosome’s three binding sites for tRNA during translation. The P site holds the tRNA carrying the growing polypeptide chain. (P stands for peptidyl tRNA.)

A change in a gene at a single nucleotide pair

A sequence of 50 to 250 adenine nucleotides added onto the 3' end of a pre-mRNA molecule.

(pol´-e-ri´-bo-som´) A group of several ribosomes attached to, and translating, the same messenger RNA molecule.

An initial RNA transcript; also called pre-mRNA when transcribed from a protein-coding gene.

A specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.

The emission of electromagnetic waves by all objects warmer than absolute zero.

On an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis.

(ri´-buh-so´-mul) The most abundant type of RNA, which together with proteins makes up ribosomes.

(ri'-buh-som') A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus. See also nucleolus.

(ri´-bo-zim) An RNA molecule that functions as an enzyme, catalyzing reactions during RNA splicing.

An enzyme that links ribonucleotides into a growing RNA chain during transcription.

Modification of RNA transcripts, including splicing out of introns, joining together of exons, and alteration of the 5' and 3' ends.

After synthesis of a eukaryotic primary RNA transcript, the removal of portions (introns) of the transcript that will not be included in the mRNA.

A sequence of about 20 amino acids at or near the leading (amino) end of a polypeptide that targets it to the endoplasmic reticulum or other organelles in a eukaryotic cell.

A protein-RNA complex that recognizes a signal peptide as it emerges from a ribosome and helps direct the ribosome to the endoplasmic reticulum (ER) by binding to a receptor protein on the ER.

(spli´-se-o-som) A large complex made up of proteins and RNA molecules that splices RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons.

A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex.

The DNA strand that provides the pattern, or template, for ordering the sequence of nucleotides in an RNA transcript.

In bacteria, a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detach from the DNA.

The synthesis of RNA using a DNA template.

A regulatory protein that binds to DNA and affects transcription of specific genes.

The completed assembly of transcription factors and RNA polymerase bound to a promoter.

A region of DNA that is transcribed into an RNA molecule.

An RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA.

The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of “language” from nucleotides to amino acids.

A set of three-nucleotide-long words that specify the amino acids for polypeptide chains.

Flexibility in the base-pairing rules in which the nucleotide at the 5' end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3' end) of a codon.