Key Terms

3' UTR
3' untranslated region; region just downstream of the protein-coding region in an RNA molecule that is not translated
5' cap
a methylated guanosine triphosphate (GTP) molecule that is attached to the 5' end of a messenger RNA to protect the end from degradation
5' UTR
5' untranslated region; region just upstream of the protein-coding region in an RNA molecule that is not translated
activator
protein that binds to prokaryotic operators to increase transcription
catabolite activator protein (CAP)
protein that complexes with cAMP to bind to the promoter sequences of operons that control sugar processing when glucose is not available
cis-acting element
transcription factor binding sites within the promoter that regulate the transcription of a gene adjacent to it
dicer
enzyme that chops the pre-miRNA into the mature form of the miRNA
DNA methylation
epigenetic modification that leads to gene silencing; commonly found in cancer cells
enhancer
segment of DNA that is upstream, downstream, perhaps thousands of nucleotides away, or on another chromosome that influence the transcription of a specific gene
epigenetic
heritable changes that do not involve changes in the DNA sequence
eukaryotic initiation factor-2 (eIF-2)
protein that binds first to an mRNA to initiate translation
gene expression
processes that control the turning on or turning off of a gene
guanine diphosphate (GDP)
molecule that is left after the energy is used to start translation
guanine triphosphate (GTP)
energy-providing molecule that binds to eIF-2 and is needed for translation
histone acetylation
epigenetic modification that leads to gene silencing; commonly found in cancer cells found in cancer cells
inducible operon
operon that can be activated or repressed depending on cellular needs and the surrounding environment
initiation complex
protein complex containing eIF2-2 that starts translation
lac operon
operon in prokaryotic cells that encodes genes required for processing and intake of lactose
large 60S ribosomal subunit
second, larger ribosomal subunit that binds to the RNA to translate it into protein
microRNA (miRNA)
small RNA molecules (approximately 21 nucleotides in length) that bind to RNA molecules to degrade them
myc
oncogene that causes cancer in many cancer cells
negative regulator
protein that prevents transcription
operator
region of DNA outside of the promoter region that binds activators or repressors that control gene expression in prokaryotic cells
operon
collection of genes involved in a pathway that are transcribed together as a single mRNA in prokaryotic cells
poly-A tail
a series of adenine nucleotides that are attached to the 3' end of an mRNA to protect the end from degradation
positive regulator
protein that increases transcription
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
proteasome
organelle that degrades proteins
repressor
protein that binds to the operator of prokaryotic genes to prevent transcription
RISC
protein complex that binds along with the miRNA to the RNA to degrade it
RNA stability
how long an RNA molecule will remain intact in the cytoplasm
RNA-binding protein (RBP)
protein that binds to the 3' or 5' UTR to increase or decrease the RNA stability
small 40S ribosomal subunit
ribosomal subunit that binds to the RNA to translate it into protein
trans-acting element
transcription factor binding site found outside the promoter or on another chromosome that influences the transcription of a particular gene
transcription factor
protein that binds to the DNA at the promoter or enhancer region and that influences transcription of a gene
transcription factor binding site
sequence of DNA to which a transcription factor binds
transcriptional start site
site at which transcription begins
trp operon
series of genes necessary to synthesize tryptophan in prokaryotic cells
tryptophan
amino acid that can be synthesized by prokaryotic cells when necessary
untranslated region
segment of the RNA molecule that are not translated into protein. These regions lie before (upstream or 5') and after (downstream or 3') the protein-coding region