Chapter 17 Flashcards
One gene-one polypeptide hypothesis
Premise that a gene is a segment of DNA that codes for one polypeptide
Transcription
The synthesis of RNA under the direction of DNA; the synthesis of RNA on a DNA template
Messenger RNA (mRNA)
A type of RNA, synthesized from DNA, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein
Translation
The actual synthesis of a polypeptide, which occurs under the direction of mRNA
Ribosomes
Sites of translation that are complex particles that facilitate the orderly linking of amino acids into polypeptide chains
organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which make up two subunits
RNA processing
Modification of RNA before it leaves the nucleus, a process unique to eukaryotes
Primary transcript
An initial RNA transcript; also called pre-mRNA when transcribed from a protein-coding gene
Triplet code
A set of three-nucleotide-long words that specify the amino acids for polypeptide chains
Template strand
The DNA strand that provides the template for ordering the sequence of nucleotides in an RNA transcript
Codons
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code
Reading frame
The way a cell’s mRNA-translating machinery groups the mRNA nucleotides into codons
RNA polymerase
An enzyme that links together the growing chain of ribonucleotides during transcription
Promoter
A specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing RNA
Terminator
In prokaryotes, a special sequence of nucleotides in DNA that marks the end of a gene. It signals RNA polymerase to release the newly made RNA molecule, which then departs from the gene
Transcription unit
A region of a DNA molecule that is transcribed into an RNA molecule
Transcription factors
A regulatory protein that binds to DNA and stimulates transcription of specific genes
Transcription initiation complex
The completed assembly of transcription factors and RNA polymerase bound to the promoter
TATA box
A promoter DNA sequence crucial in forming the transcription initiation complex