Operons
This is the collective name for a group of bacterial genes with related functions that are controlled by a single master switch.
What is an operon?
Unlike bacteria, eukaryotic cells require these specific proteins to recognize the promoter and recruit RNA polymerase.
What are transcription factors?
This term refers to the loosely packed, accessible form of DNA that is actively being transcribed.
What is euchromatin?
This mechanism allows a single gene to produce multiple distinct proteins by joining different combinations of exons.
What is alternative RNA splicing?
This enzyme is responsible for "unzipping" the DNA double helix and building an RNA transcript.
What is RNA polymerase?
In a repressible system like the trp operon, this type of molecule binds to the repressor to activate it when levels of the end product are high.
What is a corepressor?
This conserved DNA sequence, located within the promoter, is the primary site for the initiation of transcription in eukaryotes.
What is the TATA box?
These "beads on a string" are the fundamental units of chromatin, consisting of DNA wrapped around histone proteins.
What are nucleosomes?
These small, non-coding RNA molecules can bind to mRNA to block translation or trigger its degradation.
What are microRNAs (miRNAs)?
This is the term for the entire set of genetic information belonging to an organism.
What is a genome?
This specific DNA segment serves as the "on/off" switch of the operon where a repressor protein binds to physically block RNA polymerase.
What is the operator?
These distal DNA sequences act as binding sites for activators and can influence a gene's expression from thousands of base pairs away.
What are enhancers?
DAILY DOUBLE! Adding this specific chemical group to histones reduces their positive charge, causing the DNA to loosen and turn a gene "ON."
What is an acetyl group (Acetylation)?
This small molecule is used as a "death tag" to mark proteins for rapid destruction.
What is ubiquitin?
In the central dogma, this is the name of the process that converts mRNA into a sequence of amino acids.
What is translation?
This type of operon, such as the lac operon, is typically "OFF" and transcription must be activated by a specific inducer molecule.
What is an inducible operon?
DAILY DOUBLE! This process is why a skin cell and a heart cell look different despite having identical genomes.
What is differential gene expression?
This highly condensed form of DNA is transcriptionally silent and inaccessible to RNA polymerase.
What is heterochromatin?
This organelle acts as the cell's "garbage disposal" by breaking down tagged proteins.
What is a proteasome?
While eukaryotic DNA is full of non-coding regions, these organisms have highly compact genomes that are mostly functional genes.
What are prokaryotes?
If a mutation prevents a repressor from ever binding to the operator in an inducible system, the resulting transcription would be...
What is constant?
For eukaryotic transcription to occur, these four elements must be present.
2. Transcription Factors
3. Enhancer region
4. Activator Proteins
Human DNA is linear and wrapped around histones, whereas prokaryotic DNA can be described as this.
What is "naked" and circular?
If a protein's levels are low despite high levels of its mRNA, one plausible explanation could be this.
What is translational interference (or rapid proteolysis)?
DAILY DOUBLE! This percentage represents the amount of the human genome that actually consists of functional, coding genes.
What is less than 3%?