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16 November, 2015 - 15:24
alternative RNA splicing a post-transcriptional gene regulation mechanism in eukaryotes in which multiple protein products are produced by a single gene through alternative splicing combinations of the RNA transcript
codon three consecutive nucleotides in mRNA that specify the addition of a specific amino acid or the release of a polypeptide chain during translation
DNA ligase the enzyme that catalyzes the joining of DNA fragments together
DNA polymerase an enzyme that synthesizes a new strand of DNA complementary to a template strand
deoxyribose a five-carbon sugar molecule with a hydrogen atom rather than a hydroxyl group in the 2' position; the sugar component of DNA nucleotides
double helix the molecular shape of DNA in which two strands of nucleotides wind around each other in a spiral shape
epigenetic describing non-genetic regulatory factors, such as changes in modifications to histone proteins and DNA that control accessibility to genes in chromosomes
exon a sequence present in protein-coding mRNA after completion of pre-mRNA splicing
gene expression processes that control whether a gene is expressed
genetic code the amino acids that correspond to three-nucleotide codons of mRNA
helicase an enzyme that helps to open up the DNA helix during DNA replication by breaking the hydrogen bonds
intron non–protein-coding intervening sequences that are spliced from mRNA during processing
lagging strand during replication of the 3' to 5' strand, the strand that is replicated in short fragments and away from the replication fork
leading strand the strand that is synthesized continuously in the 5' to 3' direction that is synthesized in the direction of the replication fork
mRNA messenger RNA; a form of RNA that carries the nucleotide sequence code for a protein sequence that is translated into a polypeptide sequence
mismatch repair a form of DNA repair in which non-complementary nucleotides are recognized, excised, and replaced with correct nucleotides
mutation a permanent variation in the nucleotide sequence of a genome
nitrogenous base a nitrogen-containing molecule that acts as a base; often referring to one of the purine or pyrimidine components of nucleic acids
nontemplate strand the strand of DNA that is not used to transcribe mRNA; this strand is identical to the mRNA except that T nucleotides in the DNA are replaced by U nucleotides in the mRNA
nucleotide excision repair a form of DNA repair in which the DNA molecule is unwound and separated in the region of the nucleotide damage, the damaged nucleotides are removed and replaced with new nucleotides using the complementary strand, and the DNA strand is resealed and allowed to rejoin its complement
Okazaki fragments the DNA fragments that are synthesized in short stretches on the lagging strand
phosphate group a molecular group consisting of a central phosphorus atom bound to four oxygen atoms
post-transcriptional control of gene expression after the RNA molecule has been created but before it is translated into protein
post-translational control of gene expression after a protein has been created
primer a short stretch of RNA nucleotides that is required to initiate replication and allow DNA polymerase to bind and begin replication
promoter a sequence on DNA to which RNA polymerase and associated factors bind and initiate transcription
RNA polymerase an enzyme that synthesizes an RNA strand from a DNA template strand
rRNA ribosomal RNA; molecules of RNA that combine to form part of the ribosome
replication fork the Y-shaped structure formed during the initiation of replication
semiconservative replication the method used to replicate DNA in which the double-stranded molecule is separated and each strand acts as a template for a new strand to be synthesized, so the resulting DNA molecules are composed of one new strand of nucleotides and one old strand of nucleotides
splicing the process of removing introns and reconnecting exons in a pre-mRNA
start codon the AUG (or, rarely GUG) on an mRNA from which translation begins; always specifies methionine
stop codon one of the three mRNA codons that specifies termination of translation
tRNA transfer RNA; an RNA molecule that contains a specific three-nucleotide anticodon sequence to pair with the mRNA codon and also binds to a specific amino acid
telomerase an enzyme that contains a catalytic part and an inbuilt RNA template; it functions to maintain telomeres at chromosome ends
telomere the DNA at the end of linear chromosomes
template strand the strand of DNA that specifies the complementary mRNA molecule
transcription bubble the region of locally unwound DNA that allows for transcription of mRNA