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Kelp is eaten by sea otters. Kelp is a large, brown plant that grows in the sea and is used in some foods and medicines
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Uranus
Uranus' axis is tilted, so it rotates from top to bottom.
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Explanation:
To understand how gene expression is regulated, we must first understand how a gene codes for a functional protein in a cell. The process occurs in both prokaryotic and eukaryotic cells, just in slightly different manners.
Prokaryotic organisms are single-celled organisms that lack a cell nucleus, and their DNA therefore floats freely in the cell cytoplasm. To synthesize a protein, the processes of transcription and translation occur almost simultaneously. When the resulting protein is no longer needed, transcription stops. As a result, the primary method to control what type of protein and how much of each protein is expressed in a prokaryotic cell is the regulation of DNA transcription. All of the subsequent steps occur automatically. When more protein is required, more transcription occurs. Therefore, in prokaryotic cells, the control of gene expression is mostly at the transcriptional level.
Eukaryotic cells, in contrast, have intracellular organelles that add to their complexity. In eukaryotic cells, the DNA is contained inside the cell’s nucleus and there it is transcribed into RNA. The newly synthesized RNA is then transported out of the nucleus into the cytoplasm, where ribosomes translate the RNA into protein. The processes of transcription and translation are physically separated by the nuclear membrane; transcription occurs only within the nucleus, and translation occurs only outside the nucleus in the cytoplasm. The regulation of gene expression can occur at all stages of the process (Figure 1). Regulation may occur when the DNA is uncoiled and loosened from nucleosomes to bind transcription factors (epigenetic level), when the RNA is transcribed (transcriptional level), when the RNA is processed and exported to the cytoplasm after it is transcribed (post-transcriptional level), when the RNA is translated into protein (translational level), or after the protein has been made (post-translational level).
Translation is a complex process that translated the genetic information from the language of DNA in the language of RNA. The first step in this process is the binding of the initiator tRNA (that is bound to the aminoacid methionine) to the small ribosomal unit. Then, the small ribosomal unit joins the mRNA; it is the part of the ribosome mainly responsible for translating. After that, the initiator tRNA binds to the start codon. This reaction frees some initiation factors that make large ribosomal units bind to the small one. Hence, <span>the large ribosomal subunit completes the initiation complex afterwards. The role of the large ribosomal unit is mainly to make the peptidic bonds between the aminoacids in the new protein. After that, </span><span>amino acids are paired with anticodons, gradually forming a long chain</span>; this chain is called a polypeptide and is the skeleton of the protein that is created. Finally, this process stops when one of the three possible stop codons are reached.
