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Chapter 17
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Transcription
The synthesis of RNA under the direction of DNA
mRNA
It carries a genetic message from the DNA to the
protein-synthesizing machinery of the cell
Translation
The actual synthesis of a polypeptide, which
occurs under the direction of mRNA
RNA Processing
Modification of RNA before it leaves the nucleus
Primary Transcript
The initial RNA transcript from any gene
Triplet Code
The genetic instructions for a polypeptide chain
are written in the DNA as a series of nonoverlapping, three-nucleotide words
Template Strand
It provides the template for ordering the
sequence of nucleotides in an RNA transcript
Codons
The mRNA base triplets
Reading Frame
The way a cell’s mRNA-translating machinery
groups the mRNA nucleotides into codons
Promoter
The DNA sequence where RNA polymerase attaches
and initiates transcription
Terminator
The sequence that signals the end of
transcription
Transcription Unit
The stretch of DNA that is transcribed into an
RNA molecule
Transcription factors
A collection of proteins that 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 the promoter
TATA Box
A crucial promoter DNA sequence
Poly-A Tail
A promoter DNA sequence crucial in forming the
transcription initiation complex
RNA Splicing
The removal of a large portion of the RNA molecule
that is initially synthesized
Introns
The noncoding segments of nucleic acid that lie
between coding regions
Exons
A coding region of a eukaryotic gene
Spliceosome
Several different snRNPs joined with additional
proteins to form a larger assembly
Ribozymes
RNA molecules that function as enzymes
Alternative RNA Splicing
Different mRNA molecules are produced from the
same primary transcript
Domains
A modular architecture consisting of discrete
structural and functional regions
tRNA
The interpreter of the series of codons along an
mRNA molecule
Anticodon
A specialized base triplet at one end of a tRNA molecule
that recognizes a particular codon on an mRNA molecule
rRNA
The ribosomal subunits are constructed
of proteins and RNA molecules
A Site
It holds the tRNA carrying the next amino acid
to be added to the chain
E Site
Discharged tRNAs leave the ribosome from this
exit site
Point Mutations
Chemical changes in just one base pair of a gene
Base-pair substitutions
The replacement of one nucleotide and its
partner with another pair of nucleotides
Missense Mutations
A base-pair substitution in which the new codon
makes sense in that it still codes for an amino acid
Nonsense Mutations
A mutation that changes an amino acid codon to
one of the three stop codons
Mutagen
A number of physical and chemical agents that
interact with DNA in ways that cause mutations
Frameshift Mutation
A mutation that occurs whenever the number of
nucleotides inserted or deleted is not a multiple of three
P Site
A site that holds the tRNA carrying the growing
polypeptide chain
Author
lysabaclig
ID
42036
Card Set
Chapter 17
Description
Molecular Cell Biology
Updated
2010-10-14T01:05:41Z
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