Structure and Function of Nucleolus

[2] – The structure of the nuclear pore complex, The Annual Review of Biochemistry 2011, Hoelz A, Debler EW, Blobel G

When are the nucleoli visible? What are assembled here? Nucleoli are visible in a nondividing nucleus and in cells active in protein synthesis. Within the nucleoli, proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes.

Since DNA has the instructions for making protein we usually wonder how is it able to make ribosomes if DNA is stored within the nucleus. This is when a handy tool comes in called transcription and copies the DNA into mRNA so it can be reached outside of the cell.

Nucleus (A20): The structure that the genetic material is stored in. In the center of the cell.

The nucleolus is one of the most important organelles. This organelle is a eukaryotic cell. The nucleolus is not like most of the other organelles. Most other organelles have a static structure but the nucleolus does not. The structural components are chains of RNA and DNA. It contains granular and fibrillar components.

5.Nissl bodies are in the soma of the nucleus and are made up ofrough ER.

C. A chromatid is a chromosome that has been replicated but has not yet separated from its sister chromatid.

Nearly all animal cells have a nucleus, with the only exception being the red blood cell. The nucleus has two major functions, which are housing the DNA and controlling the cell’s activities. In the centre of the nucleus is the nucleolus. This doesn’t have a membrane, but holds itself together. In the nucleolus, ribosomes are created through the mixture of RNA and proteins. These proteins are originally found in the cytoplasm, outside the nucleus, but they travel through the pores in the nuclear envelope, through the chromatin and into the nucleolus. The structure of the nucleolus allows easy

The nucleus is enclosed in a nuclear membrane which has pores to allow RNA and proteins. The nucleus functions the activity in a plant cell and stores the plant’s DNA. (Plant Cell Anatomy, n.d.)

The nucleus is crucial to the function of the cell because it holds instructions on building proteins and that is vital for the function of every part in the cell, but not only that the nucleus uses sends particular information out so that it can be made into protein. The reason that the nucleus has to send out the information out is because the DNA never leaves the nucleus ... say that the cell needs a particular protein for a certain reason, the nucleus will transcrip that information using a molecule called mRNA, and that mRNA will leave the nucleus and will be translated in the cytoplasm by the ribosomes.

The nucleus in eukaryotic cells contains the DNA in linear chromosomes and is bounded by a nuclear membrane, but since

Nucleus- “the brain” or control center of the cell. The Nucleus, a membrane-bound structure of a cell, plays two crucial roles in controlling the cell. The nucleus carries the cell's genetic information that determines if the organism will develop, for instance, into a tree or a human; and it directs most cell activities including growth, metabolism, and reproduction by controlling protein synthesis. The presence of a nucleus distinguishes the more complex eukaryotic cells of plants and animals from the simpler prokaryotic cells of bacteria and cyanobacteria that lack a nucleus. The nucleus is the most predominate structure in the cell. It is typically round and occupies 10% of the cells total volume. The nucleus is wrapped in a

Transcription is where DNA is transcribed into RNA which then can be pass to the ribosome’s to act as a template for protein synthesis. Before transcription can begin DNA must unwind and the two halves of the molecule much come apart so exposing the base sequence. This process begins when a region of a two DNA strands is unzipped by enzyme called RNA polymerase attaches to the DNA molecule at the imitation site.

The process of DNA replication plays a crucial role in providing genetic continuity from one generation to the next. Knowledge of the structure of DNA began with the discovery of nucleic acids in 1869. In 1952, an accurate model of the DNA molecule was presented, thanks to the work of Rosalind Franklin, James Watson, and Francis Crick. To reproduce, a cell must copy and transmit its genetic information (DNA) to all of its progeny. To do so, DNA replicates following the process of semi-conservative replication. Two strands of DNA are obtained from one, having produced two daughter molecules that are identical to one another and to the parent molecule. This essay reviews the three stages

Another cellular feature shared by both Archaea and Bacteria is size and arrangement of ribosomes. Their ribosomes are much smaller in comparison to eukaryotes. The function of their ribosomes is similar to the ones in eukaryotes; for translating mRNA codons to sequence of amino acids for the synthesis of proteins. Both have 70S Ribosomes composed of 30S and 50S sub units that are joined to make a 70S unit. They contain “three ribonucleic acid molecules” consisting of “16S, 23S AND 5S”. On the other hand, the “primary structure of Archaea r-RNA and r-Proteins” is much similar to the ones in eukaryotes and less similar to that of bacteria. Additionally, the Archaea ribosome is much firm compared to mesophilic bacteria’s ribosomes, this is particularly beneficial in terms of their adaptation to extreme environmental conditions. (Archaeal Ribosomes, Paola Londei, university of Rome, “Sapienza”