Gene Expression Flashcards
Gene expression refers to the processes that result in the production of ___ ___. Gene expression can be controlled at the levels of ___, ___ (splicing in eukaryotes), ___, ___mRNA stability, and ___ stability.
- functional protein
- transcription
- processing
- translation
- mRNA
- protein
Tissue-specific gene expression is essential for:
multicellular, differentiated organisms.
Transcription factors, as noted previously, are ___ that bind to ___ and affect the ___ of genes located ___ where they bind.
- proteins
- DNA
- transcription
- near
Control of gene expression is also essential for organisms to be able to ___ properly to their ___. For example, E. coli prefers ___ for energy, but must be able to use other sugars, like ___, when they are available.
- respond
- environments
- glucose
- lactose
An ___ is a prokaryotic system for organizing genes all under the ___ transcriptional ___. Genes on the same operon in prokaryotes are all synthesized on the same ___. mRNAs containing multiple gene coding sequences are referred to as ___.
- operon
- same
- control
- mRNA
- polycistronic
The lactose operon consists of ___ linked structural genes that encode enzymes of lactose ___, plus adjacent ___ sites. The three enzymes –_, _, and _–encode ___-______, ___-___ ___ (a transport protein), and ___ ___ (an enzyme of still unknown metabolic function), respectively.
- three
- utilization
- regulatory
- z, y, and a
- beta-galactosidase
- beta-galactose permease
- thioglactoside transacetylase
Transcription of the lac operon commences at a promoter (___) before ___ and transcribes a ___ nucleotide mRNA molecule, ending at a terminator beyond ___.
- lacP
- lacZ
- 5200
- lacA
___ is a synthetic substance used to study ___ ___ expression. ___ has the useful property that it turns ___ when acted on by ___-______, giving a measure of how much the operon has been induced by the amount of blue color produced.
- X-Gal
- lac operon
- X-Gal
- blue
- beta-galactosidase
___ transcriptional regulation of the lac operon is accomplished by a protein known as the ___ ___. It binds the operon’s ___ ___ and ___ transcription.
- Negative
- lac repressor
- operator region
- inhibits
In the absence of ___ ___, the lac repressor ___ ___ to the operator and ___ transcription of the operon. When inducer molecules are present, they bind to the ___ ___ and change its shape and ___ its ability to bind the operator, thus allowing the ___ ___ to bind the promoter and start transcription.
- inducer molecules
- tightly binds
- inhibits
- lac repressor
- reduce
- RNA polymerase
The promoter sequence of the lac operon differs somewhat from the ___ ___ ___ of an E. coli promoter.
-ideal consensus sequence
In the ___ of positive acting elements, the ___ ___ does ___ function well on its own. A protein that acts positively to help activate the lac operon is the ___ (also called ___-___ ___ ___).
- absence
- lac promoter
- not
- CAP (CRP-cAMP receptor protein)
CAP is important because the lac promoter by itself is not a ___ one.
Attenuation is a regulatory mechanism for several E. coli operons involved in ___ ___ ___ .
- strong
- amino acid metabolism
The ___ operon of E. coli (trp operon) acts as a “sensor” for ___ in the cell and controls the expression of genes necessary to make ___. When ___ is abundant in E. coli, the ribosome moves ___ along the trp operon mRNA, making ___.
- tryptophan
- tryptophan
- tryptophan
- tryptophan
- quickly
- protein
Control of the ___ operon is set up so that transcription of the entire operon only occurs when tryptophan is ___ in the cells. When tryptophan is abundant, transcription ___ very ___. The system is set up such that translation of the operon plays a role in the early ___ termination.
- tryptophan
- limiting
- terminates
- early
- transcriptional
The trp operon accomplishes being a “sensor” by a “___” sequence that contains coding for a ___ ___. It includes within it coding for two ___ ___ ___ ___.
- leader
- short polypeptide
- consecutive trptophan amino acids
If tryptophan is in short supply in the cell, the ribosome pauses to wait for ___-___ to come. This pause allows an ___-___ ___ to form in the mRNA. The anti-terminator causes the RNA polymerase to ___ synthesizing the rest of the operon.
- trp-tRNA
- anti-terminator sequence
- continue
If tryptophan is abundant in the cell, the ribosome covers up the ___-___ sequence and a ___ sequence instead forms in the mRNA. The ___ sequence causes the RNA polymerase to ___ synthesizing the operon
- anti-terminator
- terminator
- terminator
- stop
Common DNA-binding structures are found in the diverse set of transcription factors that are known. They include motifs (structural features) for ___-___-___, ___, ___ ___, and ___ ___.
- helix-turn-helix
- homeodomains
- leucine zippers
- zinc fingers
Leucine zipper structures are found in adjacent ___ ___ and contain regions with ___ ___ appearing about every _ amino acids. The leucine ___ with each other to hold the strands together and in doing so allow other portions of the helix to bind ___ properly.
- alpha helices
- leucine residues
- 7
- interact
- DNA
Zinc fingers are structures with ___ residues that hold ___ ___ and create a ___-like structure that can stick into the ___ ___.
- cysteine
- zinc ions
- finger
- DNA helix
Proteins that bind to specific DNA sequences must “___” the sequence of bases inside the helix, usually by inserting a region into the ___ ___ of the DNA and “___” the ___ ___ ___ inside.
- read
- major groove
- checking
- hydrogen bonding molecules
Since different base pairs have unique hydrogen bonding orientations, the proteins that find and bind to ___ ___ ___.
-specific base sequences
In eukaryotic cells, DNA is wrapped up (coiled up) with basic proteins called ___. ___ sequences are strongly conserved from ___ to ___.
- histones
- histones
- yeast
- humans
