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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 |
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