Chapter Nine: the flow of information from DNA to RNA to Protein Flashcards
pairing of ___ is key to transfer information from DNA to RNA to protein
complementary bases
___ of DNA, RNA, and proteins help guide mechanisms of gene expression
polarity (directionality)
the flow of genetic information from DNA via RNA to protein
gene expression
triplet codons of nucleotides represent individual ___
amino acids
a gene’s nucleotide sequence is ___ with the amino acid sequence of the encoded peptide
colinear
each nucleotide is part of only ___
one codon
studies of ___ showed that codons consist of three nucleotides
frameshift mutations
the beginning of a gene establishes a ___ that contains a start and stop codon with multiples of 3 in between
reading frame
change grouping of nucleotides as a result of an insertion or deletion
frameshift mutations
combinations of ___ mutations restore the reading frame
3+ or 3-
template strand of DNA is ___ to mRNA
complementary
RNA-like strand of DNA has the same ___ and ___ as mRNA
polarity and sequence
5’ to 3’ in the mRNA corresponds to the ___ terminus in the polypeptide
N to C
single nucleotide substitutions, conform to the genetic code
missense mutations
genetic code is almost ___
universal
DNA sequences that provide the signal to RNA polymerase for starting transcription
promoters
RNA polymerase adds nucleotides in the ___ direction
5’ - 3’
DNA sequences that provide the signal to RNA polymerase for stopping transcription
terminators
steps of transcription
- RNA polymerase binds to promoter sequence
- sigma factor binds to RNA polymerase to form a holoenzyme
- region of DNA is unwound to form open promoter complex
- phosphodiester bonds form between the first two ribonucleotides
- sigma factor separates from RNA polymerase
- core RNA polymerase loses affinity for promoter, moves in 3’ to 5’ direction on the template strand of DNA
- within transcription bubble, NTPs are added to 3’ end of nascent mRNA
- transcription stops when a termination sequence is reached
eukaryotic genes have ___ that are required for efficient transcription
enhancers
the single strand RNA that results from transcription
primary transcript
in prokaryotes, the primary transcript is ___
the mRNA
in eukaryotes, the primary transcript is ___
processed to make mRNA
3 post-transcriptional modifications in eukaryotes
- 5’ methylated cap added
- 3’ poly-A-tail added
- introns removed by RNA splicing
expressed regions, sequences found in a gene’s DNA and mature mRNA
exons
intervening regions, sequences found in DNA but not in RNA
introns
___ cut out introns
enzymes
exons can be ___ after splicing
shuffled
three short sequences in the primary transcript that determine where splicing occurs
splice donor
branch site
splice acceptor
two ___ remove an intron
sequential cuts