clinical significance
This Gram-positive coccus, known for causing strep throat, scarlet fever, and necrotizing fasciitis, was the source of the CRISPR-Cas9 system that revolutionized gene editing.
What is Streptococcus pyogenes?
During mRNA processing, this modification adds a 7-methylguanosine structure to the 5′ end, protecting the transcript and aiding in ribosome recognition.
What is GTP capping (or 5′ cap addition)?
These large phagocytic cells patrol tissues, engulf pathogens, and release cytokines — earning their name from the Greek for “big eaters.”
What are macrophages?
These bacterial enzymes act as molecular scissors, cutting DNA at specific palindromic sequences and forming the basis of recombinant DNA technology.
What are restriction enzymes?
This adaptor molecule carries amino acids to the ribosome, matching its anticodon with the mRNA codon during translation.
What is tRNA (transfer RNA)?
These double-ring nitrogenous bases — adenine and guanine — can accumulate as uric acid when degraded, leading to gout if not properly excreted.
What are purines?
This post-transcriptional modification adds a tail of repeating adenine nucleotides to the 3′ end of mRNA, enhancing stability and export from the nucleus.
What is polyadenylation?
These immune cells display fragments of digested pathogens on their surface to activate T cells, serving as the immune system’s “show and tell” specialists.
What are antigen-presenting cells (APCs)?
These viruses infect bacteria, injecting their genetic material and sometimes leaving behind “plaques” of dead cells on a bacterial lawn.
What are bacteriophages?
This enzyme charges each tRNA with its correct amino acid using ATP, ensuring the fidelity of translation.
What is aminoacyl-tRNA synthetase?
A mutation in this short cytosolic motif of the LDL receptor — containing the amino acid sequence NPXY — prevents proper internalization of LDL particles, leading to familial hypercholesterolemia.
What is the NPXY internalization signal?
Formed during mRNA splicing, this looped structure results when the branch point adenine attacks the 5′ splice site, creating a transient intron intermediate.
What is the lariat intermediate?
This group of cell-surface proteins presents peptide antigens to T cells and determines tissue compatibility in organ transplants.
What is the major histocompatibility complex (MHC)?
In this viral life cycle, a bacteriophage integrates its DNA into the host genome and remains dormant until triggered to enter the lytic phase.
What is the lysogenic cycle?
Because of flexibility at the third position of the codon–anticodon pairing, this phenomenon allows one tRNA to recognize multiple codons.
What is the wobble base (or wobble hypothesis)?
This carbohydrate tag added in the Golgi directs soluble enzymes to lysosomes by binding specific receptors that recognize it.
What is mannose-6-phosphate?
This general transcription factor in eukaryotes unwinds DNA at the transcription start site and phosphorylates RNA polymerase II’s CTD to begin elongation.
What is transcription factor IIH (TFIIH)?
These conserved microbial structures, such as lipopolysaccharides or flagellin, are recognized by innate immune receptors like Toll-like receptors to trigger an immune response.
What are pathogen-associated molecular patterns (PAMPs)?
Some phage genomes exhibit this structural feature, where linear DNA molecules have different starting points but contain the same sequence information overall.
What is a circularly permuted genome?
These proteins help assemble the ribosome–mRNA–tRNA complex at the start codon, setting the stage for translation to begin.
What are initiation factors?
Deficiency of this Golgi enzyme, which normally adds phosphate groups to N-acetylglucosamine residues on lysosomal enzymes, causes I-Cell disease by preventing mannose-6-phosphate tagging.
What is N-acetylglucosamine phosphotransferase?
These RNA–protein complexes, found in the spliceosome, recognize intron–exon boundaries and catalyze the removal of introns from pre-mRNA.
What are small nuclear ribonucleoproteins (snRNPs)?
These lymphocytes produce antibodies and can act as antigen-presenting cells; once activated, they differentiate into plasma cells that secrete immunoglobulins.
What are B cells?
This RNA-guided endonuclease from bacterial CRISPR systems cuts foreign DNA at precise locations, forming the foundation of modern genome editing.
What is Cas9?
This bacterial toxin inhibits protein synthesis by inactivating eukaryotic elongation factor 2 through ADP-ribosylation, leading to cell death and the characteristic sore throat of its namesake disease.
What is diphtheria toxin?