Chapter 17 Flashcards
Transcription
The synthesis of RNA using template DNA
Translation
Synthesis of polypeptide using the information in the mRNA.
Primary transcript
An initial RNA transcript from any gene
Triplet code
information system that uses a series of 3 nucleotides to specify a sequence of amino acids for a polypeptide
Template strand
The DNA strand that provides the template for the order of polypeptides
Codons
3 nucleotide sequence of polynucleotide that specifies an amino acid or termination signal
Coding strand
Non-template DNA strand that the same sequence as mRNA
Reading frame
On mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis
RNA polymerase
An enzyme that links ribonucleotides into growing RNA chain during transcription
Promotor
Specific nucleotide sequence in DNA of a gene that binds RNA polymerase, so it can transcribe in the right place
Terminator
Sequence of DNA that marks the end of a gene and signals RNA polymerase to release it
Transcription unit
Region of DNA that is transcribed into an RNA molecule
Startpoint
The nucleotide position on the promotor where RNA polymerase begins synthesis of RNA
Transcription factors
protein that binds to DNA & affect transcription of genes
Transcription initiation complex
The completed assembly of transcription factors and RNA polymerase on promoter
TATA Box
Dna sequence in eukaryotic promoters crucial in forming the transcription complex
RNA processing
Modification of pre-mRNA, by removing introns, joining exons, & alteration of 5’ & 3’ ends
5’ cap
Modified form of guanine nucleotide added to 5’ end of pre-mRNA (GTP)
Poly-A tail
Sequence of adenine nucleotides added onto the 3’ end of a pre mRNA
RNA splicing
Removal of introns in the mRNA and joining exons
Introns
Noncoding intervening sequence within a pre-mRNA that’s removed from transcript
Exons
Sequence within primary mRNA that remains after processing
Spliceosome
Large complex made up of proteins and RNA that splices that splices RNA
Ribozymes
Rna molecule that acts as an enzyme
Transfer RNA
RNA molecule that functions in translation by applying specific amino acid to polypeptide chain in ribosome
Anticodon
A nucleotide triplet at an end of tRNA that base pairs with a codon on mRNA
Aminoacyl-tRNA synthase
An enzyme that joins each amino acid to appropriate tRNA
Charged tRNA
tRNA covalently bonded to an amino acid
Wobble
Flexibility in base-pairing where the nucleotide at the 5’ end of a tRNA anticodon can hydrogen bond with more than one kind of base in third position (3’ end) of codon
Ribosomal RNA
RNA molecule combined with proteins, to make ribosomes
Translation initiation complex
Union of mRNA, initiator tRNA, and ribosomal subunit followed by attachment of a large ribosomal subunit
N-terminus
Methionine
C-terminus
Carboxyl end
Codon recognition
Anticodon of incoming charged tRNA base pairs with complementary codon
Peptide bond formation
An rRNA molecule of large subunit forms peptide bond between carboxyl end of polypeptide and new amino acid in A site
Translocation
The ribosome translocated tRNA in A site to P site. tRNA in P site moves to E site where it’s released from ribosome
Release factor
Proteins shaped like charged tRNA
Signal peptide
Sequence of 20 amino acids at or near N-terminus that targets ribosome to ER
Signal recognition particle
Protein RNA complex that recognize a signal peptide as it emerges from a ribosome, and it helps direct the ribosome to ER by binding to receptor protein on ER
Polyribosome
Group of several ribosomes attaches to, and translating, the same mRNA
Point mutation
Change in single nucleotide pair of gene
Nucleotide pair substitution
Type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced
Silent mutation
A new nucleotide pair substitution that has no observable effects on phenotype
Missense production
A nucleotide pair substitution that results in a codon that codes for different amino acid
Nonsense mutation
A mutation that changes an amino acid codon to one of the 3 stop codons
Insertions
A mutation involving the addition of one or more nucleotide pairs to a gene
Deletion
A subtraction of one or more nucleotide pairs to a gene
Frameshift mutation
Occurring when nucleotides are inserted or deleted from a gene in non multiples of 3
Mutagens
Chemical or physical agent that interacts with DNA and can cause a mutation
