Chapter 8 Review Flashcards
From the sequencing of the human genome, we believe that there are approximately 21,000 protein-coding genes in the genome, of which 1500–3000 are transcription factors. If every gene has a tissue-specific and signal-dependent transcription pattern, how can such a small number of transcriptional regulatory proteins generate a much larger set of transcriptional patterns?
Transcription regulators are generally used in combinations, thereby increasing the possible regulatory repertoire of gene expression with a limited number of proteins.
Many transcriptional regulators function together to decide the expression level of a particular gene. This describes the concept of
combinatorial control.
MicroRNAs block the expression of a specific gene product by binding to the ___________ and inhibiting ___________.
mRNA; translation
Gene transcription patterns can also be transmitted across generations through positive _________loops that can involve a transcription regulator activating its own transcription in addition to other genes. These mechanisms all allow for cell __________, a property involving the maintenance of gene expression patterns important for cell identity.
feedback, memory
MicroRNAs are non-coding RNA that are incorporated into a protein complex called _____, which searches the _____ in the cytoplasm for sequence complementary to that of the miRNA. When such a molecule is found, it is then targeted for _______.
RISC, mRNA, destruction
_______________ control determines which completed mRNAs in the cell nucleus exported to the cytoplasm.
mRNA transport and localization
Which of the following is the main point of control for regulating gene expression levels?
transcription
The transmission of information important for gene regulation from parent to daughter cell, without altering the actual nucleotide sequence, is called __________ inheritance. This type of inheritance is seen with the inheritance of the covalent modifications on ____________ proteins bound to DNA these modifications are important for reestablishing the pattern of chromatin structure found on the parent chromosome.
epigenetic, histone
A housekeeping gene is a gene whose cellular function is
important for processes found in all cell types.
_______________ control determines which mRNAs in the cytoplasm are transcribed by ribosomes.
mRNA degradation
_______________ control activates, inactivates, or compartmentalizes specific protein molecules after they have been made.
protein degradation control and proactivity
Cells have a defense mechanism for destroying “foreign” double-stranded RNAs, many of which are produced by viruses. It makes use of ________ RNAs that are produced from the foreign RNAs in a process called RNAi
siRNAs
_______________ control determines how the primary RNA transcripts is spliced or otherwise processed.
RNA processing
1
activator protein
Protein-DNA interactions are among the tightest and most specific Molecular Interactions known in biology. True or False?
True
miRNAs, tRNAs, and rRNAs all _____________.
do not code for proteins.
The figure below depicts which of the following mechanisms that cells use to maintain their identity through cell divisions?
positive feedback
Cell differentiation is achieved by changes in ______.
Gene expression
If lactose and glucose are both available to a bacterial cell, which carbon source(s) will be used?
glucose
_____ is a complex process by which cells selectively direct the synthesis of the many thousands of proteins and RNAs encoded in their genome.
Gene expression
Transplanting the nucleus of an epithelial cell into an egg cell lacking genetic information leads to the formation of
a normally developing embryo.
The genes of a bacterial ___________ are transcribed into a single mRNA. Many bacterial promoters contain a region known as an _____________, to which a specific transcription regulator binds.
operon, operator
In principle, gene expression can be controlled at any of the steps between a gene and its ultimate functional product. For the majority of genes, however, the __________ is the most important point of control. Because this control point can ensure that no unnecessary intermediates are synthesized.
transcription
Inhibiting the transcription of genes that are not currently needed help keep unnecessary intermediates from being synthesized.
2
mediator
_______________ control selectively destabilizes certain mRNA molecules in the cytoplasm.
translational
Another way to inherit chromatin structure involves DNA __________, the covalent modification that occurs on cytosine bases that typically turns off the transcription of a gene.
methylation
_______________ control determines when and how often a given gene is transcribed.
transcriptional
All organism’s ____________ encodes all of the RNA and protein molecules that are needed to make its cell. Nearly all the cells of a multicellular organism contain the same ___________.
DNA; genome
4
RNA Polymerase
RNAi is triggered by the presence of foreign __________ molecules, which are digested by the ________ enzyme into shorter fragments approximately 23 nucleotide pairs in length.
double-stranded RNA, DICER
3
general transcription factors
How are most eukaryotic transcription regulators able to affect transcription when their binding sites are far from the promoter?
by looping out the intervening DNA between their binding site and the promoter
