Abstract
In the last century with the invention of phase contrast microscopy by the Nobel Prize winner Frits Zernike, nucleoli were among the most con-spicuous structures. The nucleolus was first de-scribed between 1835 and 1839, but it had to go through another century before it was discovered to be related with a specific chromosomal locus, which marked it as a cytogenetic entity.1
At the end of the 18th century, Montgomery was the first to publish the monumental monograph, which included color figures of nuclei and nucleo-li.1
Based on the Montgomery work, further studies where conducted to analyze the function of the nucleolus in the next century. In fact himself has studied nucleoli in the oocytes of over 175 differ-ent species and had approached at three re-markable conclusions that still hold true today: 1) In one cell there can be more than one nucleolus;
2) Cells with higher growth are presented with more and larger size;
3) The last conclusion was, the size of the cells interfere with the size of nucleolus.2
After the 1960 numerous discovers made a huge impact in the modern science, one of these is the study on the rRNA which lead to the conclusion that the nucleolus is the site of ribosomal RNA synthesis and nascent ribosome assembly.1
In the early 70s it was observed that the ribonu-cleoprotein precursors to ribosomes contain two classes of protein. The difference between these proteins was thought to be that one class could be recognized as ribosomal proteins,
[4] – Frank Schluenzen et al, Structure of Functionally Active Small Ribosomal Subunit at 3.3A Resolution
Ribosomes in any type of organism are all the same, but we distinguish between two
3) As a ribosome moves along the mRNA, the genetic message is translated into a protein with a specific amino acid sequence.
Ribonucleic acid (RNA): It is a single nucleic acid supported by adenine, guanine, cytosine and uracil supported by ribose sugars. mRNA, rRNA and tRNA.
In M phase (Mitosis), the DNA and proteins in each chromosome form highly compacted structures
Translation is a task that makes ribosomes synthesize proteins utilizing mRNA transcript made during transcription. In the begining of this task mRNA attaches it self to a ribosome so that it can be reveal a codon (three nucleotides).
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.
This paper explores the history and some interesting facts about DNA. The last couple centuries have seen an exponential growth in our knowledge of DNA. The history of the DNA can be traced back to multiple devoted scientist. This article attempts to summarize, and review the basic history of DNA while providing some fascinating information about it.
In the early 1950s, the race to find the structure of DNA was in full swing. The search was being conducted at three different colleges. At the California Institute of Technology, Linus Pauling,
18) Looking into your microscope, you spot an unusual cell. Instead of the typical rounded cell shape, the cell has a very narrow middle separating two bulging ends. It sort of looks like the number 8! Then you realize that this cell is
The origins of DNA were first discovered during 1857 by Gregor Mendel the "Father of Genetics”, whom was performing an experiment of genetics with pea plants, and would provide a basic foundation towards DNA and Genetics. Friedrich Miescher and Richard Altmann in 1869 were also part of the first people to discover DNA. While testing some sperm of a salmon, they discover a strange substance that they would name as "nuclein", which is known as DNA. This new form of "nuclein" (DNA) would be found to only exist in chromosomes. Frederick Griffith, a researcher, found the basis on DNA, from a molecule inheritance experiment involving mice and two types of pneumonia. His findings were that, when virulent disease is heated up (to kill) and is
Cytogenic analysis – Microscopic examination of lymphocytes to look for structural changes or changes in number of chromosomes.
The purpose of this experiment was to determine the effects of tonicity on a cell membrane using red blood cells, potato strips and three unknown solutions (A, B, C). First three slides were prepared containing RBC’s and unknown solutions A, B and C. A control slide was prepared only using RBC’s. After observing each slide under the microscope it was determined that unknown solution A was hypertonic because the RBC appeared to have shrunk. The RBC in unknown solution B appeared to be swollen, therefor, the tonicity of unknown solution B was hypotonic. Unknown solution C showed no change to the RBC shape, it was suggested that unknown solution C was isotonic. To confirm the tonicity
Q1: What does the comparison of the supernatant fraction between the experimental and control samples prove, regarding the normal cellular location of the CRUSOE1? [2 marks]
In contrast, eukaryotic cells are more complex than prokaryotes as their transcriptions process are utilize by three different types of RNA polymerase. These polymerases differ in number and type of subunits they contain and also the class of RNA they subscribe. RNA polymerase I, which located in the nucleolus, transcribe ribosomal RNA (rRNA), RNA polymerase II, which located in the nucleoplasm, transcribe messenger RNA (mRNA) and RNA polymerase III, which also located in the nucleoplasm, transcribe both ribosomal and transfer RNA (tRNA). All eukaryotic RNA polymerases are homologous to one another and to prokaryotic RNA