Chapter 17 Flashcards
Gene Expression
The process by which DNA directs protein synthesis
Two stages of Gene expression
transcription and translation
Transcription
The synthesis of RNA using information in DNA
messenger RNA (mRNA)
What is produced in transcription. Will be used in translation to help create proteins
Translation
the synthesis of a polypeptide, using information in the mRNA
Ribosomes
the sites of translation
In prokaryotes, translation of mRNA can begin…
before transcription has finished
In eukaryotic cells, the nuclear envelope…
separates transcription from translation
Primary transcript
the initial RNA transcript from any gene prior too processing
What is the central dogma of gene expression
DNA -> RNA -> Protein
triplet code
a series of non overlapping, three-nucleotide words
template strand
One of the two DNA strands that provides a template for ordering the sequence of complementary nucleotides in an RNA transcript
Codons
The mRNA base triplets that code for specific amino acids. Read in the 5’ -> 3’ direction
Codons must be read in the correct __________ in oder for the specified polypeptide to be produced
reading frame
RNA polymerase
What catalyzes RNA synthesis. Pries the DNA strands apart and joins together the RNA nucleotides
Promoter
The DNA sequence where RNA polymerase attaches
Terminator
the sequence signaling the end of transcription
transcription unit
The stretch of DNA that is transcribed
Three stages of transcription
1) Initiation
2) Elongation
3) Termination
Transcription factors
mediate the binding of RNA polymerase and the initiation of transcription
Transcription initiation complex
The completed assembly of transcription factors and RNA polymerase II bound to a promoter
TATA box
A promoter that is crucial in forming the initiation complex in eukaryotes
Activators
boost a gene’s transcription
repressors
decrease a gene’s transcription
5’ cap
on the 5’ end that is a modified guanine and protects the transcript from being broken down
ploy-A tail
on the 3’ end and ends the transcript
introns
noncoding regions in RNA
exons
part of the RNA that is eventually expressed, usually translated into amino acid sequences
RNA splicing
removing introns and joins exons, creating an mRNA molecule with a continuous coding sequence
transfer RNA (tRNA)
transfers amino acids to the growing polypeptide in a ribosome
anticodon
Contained in the tRNA and has base-pairs that are complementary to the mRNA
aminoacyl-tRNA synthetase
the enzyme that matches the tRNA and an amino acid together in the first step of translation
Wobble
Flexible pairing at the third base of a codon. Allows some tRNAs to bind to more than one codon
ribosomal RNA (rRNA)
One of the subunits of ribosomes along with proteins
P site
the site that holds the tRNA that carries the growing polypeptide chain
A site
The site that holds the tRNA that carries the next amino acid to be added to the chain
E site
The site that is the exit site, where discharged tRNAs leave the ribosome
