why rRNA synthesis took place in nucleolus ,not in cytoplasm?rRnas also present in cytoplasm?
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RNA is short hand for Ribonucleic Acid. RNA has a similar structural appearance to DNA (Deoxyribonucleic Acid). You can read about the chemical structure at the site referenced below.\n\nRNA crops up in several different cell locales from the nucleus to the ribosomes and appears to serve in a variety of cell roles. The basic function most often noted is that of a messenger or transfer template upon which proteins are built. The information for this construction comes from the DNA which unzips long enough for these RNA templates to be formed.\n\nThe less noted ribosomal RNA may well be more important in that the ribosomes are protein factories.  And protein manufacturing is kind of where it is at.  It just that text book writers have to draw the line somewhere on how much information about how many cell types is going to be discussed.  If we are talking the brain cells for instance there is some evidence to suggest RNA might well play a part in memory formation.  \n\nThis is seriously cooked down discussion of a key chemical player in cellular dance of life. If you take up where your book left off I suggest a visit to your local library. The subject area you want is biochemistry or molecular biology.  For the latest info your next step would be to hit the stacks in your local university library to review the science journals.  Citation index is big help here.
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I have no idea about the second part of your question, and I'm not entirely sure if it's true, but I'll tell you what RNA is.\n\nRNA is essentially a copy of DNA that can travel out of the nucleus and to other parts of the cell. RNA is used as instructions. DNA can't leave the cell or it'll be destroyed by enzymes looking for viruses.\n\nMessenger RNA (or mRNA) is the one that goes from the nucleus to the ribosomes (where proteins are made) with instructions for which specific protein is to be made. Transfer RNA (tRNA) brings the appropriate amino acids (pieces of protein) to the Ribosomes so that the desired proteins can be made.\n\nthere are many other types of RNA, such as ribosomal RNA, but I know much less about those.\nhope this helps!
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DNA replication occurs during the "S" phase (or Synthesis phase) of the cell cycle.\n\nGood luck.
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During prophase. But it actually doesn't happen in all organisms. Yeast for example has a nuclear duplication and division without ever breaking down the nuclear membrane.
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Fermentation is anaerobic respiration. It takes place in the cytoplasm as the first step of aerobic respiration. The rest of aerobic respiration, with the addition of oxygen, takes place in the mitochondria and over their membranes. Neither of these events take place in the cell membrane, which would allow either the products or reactants to escape the cell.
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Those organells have their own genome, and it replication is not involved in the chromosome crossing over and other variation mechanisms on cell splitting. During the cell splitting they just stay a few on each side and thats how each new cell has chloroplasts
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Mature human RBC have no nucleus.\n\nMuscle cells have several, as a result of cells fusing together.
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Chromosomes - the gene carriers - are found in the nucleus of cells...and within the nucleus is the nucleoli where DNA is found.  Chromosomes do not "control" the process of mitosis - mitosis just occurs.  It is the procsses of dividing a cell.
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at the ribosomes in the cytoplasm. And they re not creating, just transferring the information from DNA. And they re absolutely not transported inside of endopl.ret. Ribosomes are connected to the rough end.ret. The RNA is not transported inside.messenger RNA is i cytoplasm rewritten o translation RNA which is connected to ribosomes and according the triplets of bases in RNA are connected AMA and lined together to make a peptide and then protein.
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Organelles\nMain article: Organelle \nThe human body contains many different organs, such as the heart, lung, and kidney, with each organ performing a different function. Cells also have a set of "little organs," called organelles, that are adapted and/or specialized for carrying out one or more vital functions. Membrane-bound organelles are found only in eukaryotes.\n\nCell nucleus (a cell's information center)  \nThe cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes, and is the place where almost all DNA replication and RNA synthesis occur. The nucleus is spheroid in shape and separated from the cytoplasm by a double membrane called the nuclear envelope. The nuclear envelope isolates and protects a cell's DNA from various molecules that could accidentally damage its structure or interfere with its processing. During processing, DNA is transcribed, or copied into a special RNA, called mRNA. This mRNA is then transported out of the nucleus, where it is translated into a specific protein molecule. In prokaryotes, DNA processing takes place in the cytoplasm. \nRibosomes (the protein production machine)  \nRibosomes are found in both prokaryotes and eukaryotes. The ribosome is a large complex composed of many molecules, including RNAs and proteins, and is responsible for processing the genetic instructions carried by an mRNA. The process of converting an mRNA's genetic code into the exact sequence of amino acids that make up a protein is called translation. Protein synthesis is extremely important to all cells, and therefore a large number of ribosomes — sometimes hundreds or even thousands — can be found throughout a cell. \nMitochondria and Chloroplasts (the power generators)  \nMitochondria are self-replicating organelles that occur in various numbers, shapes, and sizes in the cytoplasm of all eukaryotic cells. As mitochondria contain their own genome that is separate and distinct from the nuclear genome of a cell, they play a critical role in generating energy in the eukaryotic cell, a process involving a number of complex metabolic pathways. Chloroplasts are larger than mitochondria, and convert solar energy into a chemical energy ("food") via photosynthesis. Like mitochondria, chloroplasts have their own genome. Chloroplasts are found only in photosynthetic eukaryotes, like plants and algae. There is a number of plant organelles that are modified chloroplasts; they are broadly called plastids, and are often involved in storage. \nEndoplasmic reticulum and Golgi apparatus (macromolecule managers)  \nThe endoplasmic reticulum (ER) is the transport network for molecules targeted for certain modifications and specific destinations, as compared to molecules that will float freely in the cytoplasm. The ER has two forms: the rough ER, which has ribosomes on its surface, and the smooth ER, which lacks them. Translation of the mRNA for those proteins that will either stay in the ER or be exported from the cell occurs at the ribosomes attached to the rough ER. The smooth ER is important in lipid synthesis, detoxification and as a calcium reservoir. The Golgi apparatus, sometimes called a Golgi body or Golgi complex is the central delivery system for the cell and is a site for protein processing, packaging, and transport. Both organelles consist largely of heavily-folded membranes. \nLysosomes and Peroxisomes (the cellular digestive system)  \nLysosomes and peroxisomes are often referred to as the garbage disposal system of a cell. Both organelles are somewhat spherical, bound by a single membrane, and rich in digestive enzymes, naturally-occurring proteins that speed up biochemical processes. For example, lysosomes can contain more than three dozen enzymes for degrading proteins, nucleic acids, and certain sugars called polysaccharides. Here we can see the importance behind compartmentalization of the eukaryotic cell. The cell could not
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The ER is needed in eukarytoic cells because they generally metabolize through cellular respiration or photosynthesis which require larger molecules to be transported to specific organelles (chloroplast and mitochondria) but prokaryots often use anaerobic methods such as fermentation and other glycolysis based which can be done in the cytosol (cytoplasm) and do not require transportion to specific oraganelles (which defeats the need for the endoplasmic reticulum)
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interphase: the nucleolus is visible, cell engaged in metabollic activity, ceirtainly a pair of centrioles.
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Protein synthesis is not the simplest process, but I will try to keep this answer as simple as possible.  Here I present a highly simplified reduction of the process of protein synthesis.\n\nmRNA made in the nucleus of a cell is transported to the cytoplasm of a cell.  When mRNA is in the cytoplasm the ribosome assembles around it.  The ribosome is composed of two subunits, a small ribosomal subunit and a large ribosomal subunit.  Each of the subunits is composed of rRNA and proteins.  The two ribosomal subunits will bind to the ribosome binding site (rbs) of the mRNA.  The rbs is located prior to the open reading frame of the ribosome. When the ribosome binds to the mRNA the ribosome begins to move down the mRNA.  \n\nDuring this time tRNA is binding to the mRNA as well.  tRNA simply carries the amino acid that will compose the protein to the mRNA so that the amino acids of the protein can become bound to one another.  \n\nSo as the ribosome moves down the mRNA it will encounter tRNA.  However, the tRNA's amino acids will not be bound together until the ribosome reads a mRNA sequeunce that indicates an open reading frame is present. An open reading frame is the sequence of mRNA that is translated into protein sequence.  So once an open readin frame is indicated to be present the ribosome moves down the mRNA until it reaches the start codon.  Protein synthesis begins at hte start codon.  At the start codon the tRNA specifying methionine is present.  Methionine will be the first amino acid in any protein because the methionine codon is also the start codon.  So the methionine tRNA will move into the A site.  At this site the ribosome will ensure that the correct tRNA is bound to mRNA.  If the correct tRNA is bound then the ribosome A site moves onto the next codon and the tRNA just found to be correct will move into the P-site, in this case the methionine tRNA will move into the P-site.  The tRNA that just moved into the A-site will now be checked to see if it is the correct tRNA.  When the tRNA is found to be correct then the amino acid on the tRNA in the p-site will form a peptide bond with the amino acid on the tRNA from the a-site. The amino acid chain is connected to the tRNA in the a-site as the amino acid that was connected to the p-site tRNA becomes disconnected as it forms a peptide bond with the a-site tRNA's amino acid. Then the ribosome moves down the mRNA again.  The tRNA from the p-site moves to the e-site and it is allowed to exit the ribosome.  The p-site and a-site perform the same function as before and the peptide chain will get longer until the ribosome reaches a stop codon.  Once the ribosome reaches a stop codon the peptide chain will no longer increase in size.  The ribosome will then move until it finds another start codon or until the mRNA sequence indicates that it should dissociate.
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The answer is B\n\nA. Transcription always occurs in the nucleus (in eukaryotes) because transcription uses an RNA polymerase to copy the DNA which is inside the nucleus. Translation is done in the endoplasmic reticulum by ribosomes which read the mRNA (the product of transcription) to produce proteins.\n\nB. Both Transcription and Translation require complementary pairing, thats the whole point.\n\nC. Transcription involves polymerizing nucleotides and translation polymerizes amino acids\n\nD. Translation occurs in ribosomes, transcription from above occurs in the nucleus.\n\nE. Transcription involves RNA polymerase, and translation does not :)
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Messenger RNA (mRNA)\nMessenger RNA is RNA that carries information from DNA to the ribosome sites of protein synthesis in the cell. Once mRNA has been transcribed from DNA, it is exported from the nucleus into the cytoplasm (in eukaryotes mRNA is "processed" before being exported), where it is bound to ribosomes and translated into protein. After a certain amount of time the message degrades into its component nucleotides, usually with the assistance of RNases.\n\nTransfer RNA (tRNA)\nTransfer RNA is a small RNA chain of about 74-93 nucleotides that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. It has sites for amino-acid attachment and an anticodon region for codon recognition that binds to a specific sequence on the messenger RNA chain through hydrogen bonding. It is a type of non-coding RNA.\n\nRibosomal RNA (rRNA)\nRibosomal RNA (rRNA) is a component of the ribosomes, the protein synthetic factories in the cell. Eukaryotic ribosomes contain four different rRNA molecules: 18S, 5.8S, 28S, and 5S rRNA. Three of the rRNA molecules are synthesized in the nucleolus, and one is synthesized elsewhere. rRNA molecules are extremely abundant. They make up at least 80% of the RNA molecules found in a typical eukaryotic cell.
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You're going to have to be more specific.\n\nThere's mRNA, tRNA, and rRNA if you're answering questions from a biology textbook and are too lazy to learn the answer yourself.\n\nmRNA = messenger RNA\ntRNA = transcriptional RNA\nrRNA = ribosomal RNA\n\nThere's also miRNA and siRNA, which are genetic regulator molecules and could thus be considered not "true" RNA, but they're clearly labeled RNA.
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CYTOPLASM... i wish i could live in some cytoplasm, that would be so much fun!