This is because twilight or mesopelagic zone (extending from 200 meters to 1,000 meters) is the zone that contains the thermocline.
A thermocline or the thermal layer is a layer in an ocean or lake where the temperature changes more rapidly with depth than in the other layers. The thermocline in twilight zone divides the upper mixed layer from the calm deep water below.
Answer:
1. Histone methylation occurs at different amino acids: c. Activates and inactivates
2. A transcriptional binds an enhancer sequence: d. No effect
3. Histone acetyltransferase attach acetyl groups to the N-terminus of histones: a. Activates
4. Histone deacetylases remove acetyl groups from the N-terminus of histones: b. Inactivates
Explanation:
Epigenetics refers to the mechanisms associated with changes in gene expression which do no involve alteration in DNA sequence. Epigenetic marks include DNA methylation and histone modifications (acetylation, methylation, phosphorylation, etc). These mechanisms act together in order to regulate gene expression at specific genomic sites (<em>loci</em>). Histone methylation is an epigenetic mark involved both in transcriptional repression and transcriptional activation. For example, trimethylation of the histone H3 at lysine 4 (H3K4me3) has been associated with transcriptional activation, while dimethylation of histone H3 at lysine 9 (H3K9me2) is often involved in transcriptional repression. Moreover, histone acetylation by histone acetyltransferases (HATs) is an epigenetic mark that is involved in transcriptional activation and chromatin decondensation, while histone deacetylation by deacetylases (HDACs ) is generally associated with gene repression. However, it is important to highlight that there are exceptions to this rule (for example, acetylation of the histone H4 lysine 20 is associated with gene repression). Finally, transcriptional activators are proteins that bind to enhancers in order to recruit coactivator proteins/complexes and thus activate transcription.
False <span>its predator-prey relationship</span>
Answer:
a. Coelom
Explanation:
The coelom is the body cavity contain coelomic fluid. The organisms have a true coelom called the coelomate animals. Coelom gives space and provides protection to the internal organs. The coelom is present between the mesoderm and alimentary canal of the organisms. The invertebrates such as annelids, arthropods, helminths, echinoderms, and vertebrates have a true coelom.
enzyme activity, cell to cell recognition, cell signalling, transporting materials
