Transcription and Translation Flashcards
gene
a sequence of DNA that codes for a specific polypeptide or RNA molecule
translation
the second step of gene expression during which a polypeptide chain is produced from an mRNA molecule
mutation
a change in the nucleotide sequence of a segment of DNA that codes for a gene product
gene expression
the process by which gene products are synthesized by a cell
reading frame
the correct grouping of codons in mRNA that produces the intended polypeptide sequence; determined by the start codon and can be shifted by the addition or deletion of nucleotides in DNA
ribosomes
cellular structures that bind to mRNA and provide the location for the assembly of the corresponding polypeptide chain
mutagen
a physical or chemical agent such as X rays, ultraviolet radiation, and carcinogens (e.g.:benzene), that causes mutations in DNA
genetic code
specific sequences of nucleotide bases in mRNA, arranged in codons that correspond to each of the 20 different amino acids
messenger RNA (mRNA)
a type of RNA that carries genetic information from the nucleus to the cytosol
base-pair substitution
the replacing of one base pair with another in DNA
template strand
one of the two strands of DNA that provides the instructions for building a polypeptide chain; also called the anti-sense strand or non-coding strand
messenger RNA (mRNA)
a type of RNA that carries genetic information from the nucleus to the cytosol
ribosomal RNA (rRNA)
a type of RNA found in ribosomes that catalyzes the formation of peptide bonds between amino acids during the process of translation
point mutation
a change in just one nucleotide in the coding strand of DNA
coding strand
the sequence of DNA analogous to the mRNA produced from the template strand; also called the sense strand
transfer RNA (tRNA)
a type of RNA that carries amino acids to the ribosome during the process of translation
missense mutation
a mutation in DNA that results in the replacement of one amino acid by another
degeneracy/redundancy
the property of the genetic code that allows for a single amino acid to be coded for by multiple codons; the code is unambiguous such that any particular codon will never code for different amino acids
polyribosome
several ribosomes simultaneously translating the same mRNA
nonsense mutation
a mutation in DNA that results in the early termination of translation
anticodon
a sequence of nucleotides in tRNA complementary to a codon in mRNA
poly-A tail
a sequence of 100 to 300 adenine nucleotides added to the 3’ end of pre-mRNA to assist in the export of mRNA from the nucleus
start codon
a sequence of nucleotides in mRNA (AUG) that provides the code for the first amino acid (Methionine) during translation
frameshift mutation
a mutation that alters the reading frame of the mRNA molecule
RNA polymerase
an enzyme that catalyzes the synthesis of RNA using DNA as a template
stop codon
a sequence of nucleotides in mRNA (UAA, UAG, or UGA), which signals the termination of translation
silent mutation
a mutation in DNA that does not alter the amino acid sequence of the polypeptide chain
promoter
a nucleotide sequence found in the template strand of DNA that includes the site where transcription by RNA polymerase will begin
spliceosome
an RNA-protein complex that cuts out introns and joins together exons during pre-mRNA processing
TATA box
a sequence of nucleotides found in the promoter region of eukaryotic genes that is recognized by transcription factors
terminator
a sequence of nucleotides in DNA that signals the end of transcription
exons
nucleotide sequences in eukaryotic genes that code for amino acids
transcription factors
in eukaryotic organisms, proteins that facilitate the binding of RNA polymerase to the promoter sequence
codon
a sequence of three nucleotides in mRNA that codes for a particular amino acid
alternative splicing
variation in the splicing of exons for a given mRNA that produces two or more different polypeptide sequences from the same gene
transcription
the first step of gene expression during which a complementary mRNA molecule is produced from the DNA template strand
pre-mRNA
in eukaryotic organisms, the product of transcription before any RNA processing has occurred; also called the primary transcript
5′ cap
a chemically-modified guanosine triphosphate that is added to the 5’ end of pre-mRNA to facilitate binding by ribosomes and to provide protection from enzymes that break down RNA
RNA splicing
introns are removed from pre-mRNA and exons are joined together during this process
small nuclear ribonucleoprotein particles (snRNP)
RNA-protein molecules that bind to other proteins to form a spliceosome
introns
non-coding nucleotide sequences in eukaryotic genes that are removed during RNA processing
aminoacyl t-RNA synthetases
enzymes that catalyze the addition of an amino acid to a corresponding tRNA molecule
RNA processing
in eurkaryotic organisms pre-mRNA is modified before it leaves the nucleus: introns are removed, exons are spliced together, and a 5’ cap and poly-A-tail are added
