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 which 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; a process involving adding a methyl group to the DNA molecule
- 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 expression; a process involving adding or removing an acetyl functional group
- inducible operon
- operon that can be activated or repressed depending on cellular needs and the surrounding environment
- initiation complex
- protein complex containing eIF-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 is not translated into protein. These regions lie before (upstream or 5′) and after (downstream or 3′) the protein-coding region