Tag Info

New answers tagged

1

The two distinct types you have mentioned in your question (determinate/indeterminate cleavage) are actually called autonomous specification and conditional specification, respectively. In the case of the former one, if we were to remove a blastomere, it would still produce the previously determined type of cells, while in the case of conditional ...


2

Transcription interference can also be a good mechanism to provide such switches. Transcription interference occurs between genes in close adjacency to each other. This is basically, as the term suggest, that the neighbouring genes can interfere with each others transcription (by overlapping promoters blocking transcription initiation, collision of ...


4

Positive feedbacks can be one alternative. Positive feedbacks exhibit bistability and can therefore adopt one of the two stable states depending on the initial condition. A famous example of a positive feedback switch would be that between cI and Cro in λ-phage, which repress each other. Positive feedbacks also display hysteresis: if the state of the system ...


2

The gene expression profile may change at different time points between the two groups; you should decide what you actually want to measure. If you want to see if the diseased group is different from the control then you should compare them at every time point. For most situations you would need to compare just their steady state behaviour. Imagine a ...


0

lacID is an example of a dominant-negative allele (or mutation) so the phenotype is visible in m/+ (the bacterial merodiploids are the prokaryotic version of heterozygotes), and therefore, by definition, dominant, however the phenotype (in this case constitutive expression of the lac operon) is the same as the loss-of-function phenotype (a complete ...


2

Concerning the difference between dominant vs. recessive mutations, in general, recessive, or loss-of-function mutations, are much more frequent than dominant, or gain-of-function, mutations, because there are many different ways to "break" or inactivate a protein. For example, not every amino acid site has the potential to mutate to a residue with dominant ...


8

Yes, these sequences exist and they are called "silencers" (surprising, right?). There are different mechanisms by which this silencing of genes can happen. In the "classical" way the silencer is bound by a transcription factor which either passively suppress the gene by hindering the binding of specific transcription factors or by actively preventing the ...


0

I found a great article that might help. To summarize the contents of the article, there are two classes of CAP dependent promoters/genes, and the distance of the CAP bindings site in these classes are different. Also the actions in which CAP is involved are different in the two classes of promoters. In the first class it does not overlap with the promoter ...


1

In a side-by-side comparison of 3 viral proteins (2 from paramyxoviridae, 1 from caliciviridae) each with both a "maximizing" and "matched" codon bias, we found the "maximized" version produced more protein the "matched" version in each instance. Protein levels were quantified via Western and flow, cell lines tested were 293T, HEp2 (HeLa contaminate), and ...


3

The lac repressor act as a tetramere molecule and requires all 4 of the subunit to be able to bind DNA to act on the operon and repress β-galactosidase expression. The "all 4" is the key here, if any of the 4 subunits is unable to bind DNA then the whole complex cannot attach to the operon. The lacId mutation produces a repressor subunit that cannot attach ...


2

MicroRNA (miRNA) are gene-regulatory RNAs that are loaded onto the RNA-induced silencing complex (RISC) and interact with partially-complementary targets on mRNA to suppress protein expression. The miRNA is originally double-stranded and composed of strands about 21 nucleotides long; on loading onto RISC, one strand is degraded and the other, the "guide" ...


3

21joanna12, look into snRNPs. These are parts of the splicosomal apparatus and some of them (the U1 and U2, U11 and U12 snRNPs) are also the guideposts that bind near the splice junctions at the end of introns. These help guide the splicing apparatus to the splice sites. There are also proteins that bind RNA and interact with the splicing apparatus to ...


2

Addition to the previous answer. How to express channelrhodopsins in neurons? Other than the method involving direct viral injection, as described in the previous answer, these proteins can be expressed in specific cells by making transgenics (by using promoters that will express the downstream gene in only specific cells). How does it work? When ...


3

Short answer Optogenetics can be used to make cells responsive to light. One striking use of this technology is to restore vision in the blind by making the surviving neurons in the retina light-sensitive. This can be done by transfecting the retina with genetically engineered viruses that induce the expression of bacterial channelrhodopsin proteins in ...


8

I can think of at least 3 reasons in addition to the one you gave: 1: As mentioned in the comments, RNA splicing takes place on most messenger RNA encoding proteins in eukaryotes. Sections of the mRNA may be spliced out, therefore multiple mRNAs with different codon sequence can encode the same gene. 2: Translation is a stateful process, since it depends ...


4

In RNA sequencing, the RNA is fragmented, DNA is synthesized complementary to the RNA fragments, which is followed by a complementary strand synthesis. Fragmentation can be done after the cDNA synthesis too. This DNA is then amplified to form a cluster that is sequenced. Most Next-Gen sequencing approaches sequence a short segment of the DNA (it has ...


4

This phenomenon of being insensitive to certain fluctuations is called robustness. The fluctuations can be of two kinds for an input-output device such as a gene that is activated by a signal: Fluctuations in the signal Fluctuations in the intrinsic parameters Signal fluctuations can be temporal but parameter fluctuations are not (parameters are supposed ...



Top 50 recent answers are included