Ribosomes and Protein Assembly

Ribosomes and Protein Assembly There are two major types of cells: prokaryotic and eukaryotic cells. Ribosomes are cell organelles that consist of RNA and proteins. They are responsible for assembling the proteins of the cell. Depending on the protein production level of a particular cell, ribosomes may number in the millions. Key Takeaways: Ribosomes Ribosomes are cell organelles that function in protein synthesis. Ribosomes in plant and animals cells are larger than those found in bacteria.Ribosomes are composed of RNA and proteins that form ribosome subunits: a large ribosome subunit and small subunit. These two subunits are produced in the nucleus and unite in the cytoplasm during protein synthesis.Free ribosomes are found suspended in the cytosol, while bound ribosomes are attached to the endoplasmic reticulum.Mitochondria and chloroplasts are capable of producing their own ribosomes. Distinguishing Characteristics Structure of a Ribosome. Interaction of a ribosome with mRNA.   ttsz/iStock/Getty Images Plus Ribosomes are typically composed of two subunits: a large subunit and a small subunit. Eukarotic ribosomes (80S), such as those in plant cells and animal cells, are larger in size than prokaryotic ribosomes (70S), such as those in bacteria. Ribosomal subunits are synthesized in the nucleolus and cross over the nuclear membrane to the cytoplasm through nuclear pores. Both ribosomal subunits join together when the ribosome attaches to messenger RNA (mRNA) during protein synthesis. Ribosomes along with another RNA molecule, transfer RNA (tRNA), help to translate the protein-coding genes in mRNA into proteins. Ribosomes link amino acids together to form polypeptide chains, which are further modified before becoming functional proteins. Location in the Cell Ribosomes can be found attached to the endoplasmic reticulum or free within the cytoplasm.   ttsz/iStock/Getty Images Plus There are two places where ribosomes commonly exist within a eukaryotic cell: suspended in the cytosol and bound to the endoplasmic reticulum. These ribosomes are called free ribosomes and bound ribosomes respectively. In both cases, the ribosomes usually form aggregates called polysomes or polyribosomes during protein synthesis. Polyribosomes are clusters of ribosomes that attach to a mRNA molecule during protein synthesis. This allows for multiple copies of a protein to be synthesized at once from a single mRNA molecule. Free ribosomes usually make proteins that will function in the cytosol (fluid component of the cytoplasm), while bound ribosomes usually make proteins that are exported from the cell or included in the cells membranes. Interestingly enough, free ribosomes and bound ribosomes are interchangeable and the cell can change their numbers according to metabolic needs. Organelles such as mitochondria and chloroplasts in eukaryotic organisms have their own ribosomes. Ribosomes in these organelles are more like ribosomes found in bacteria with regard to size. The subunits comprising ribosomes in mitochondria and chloroplasts are smaller (30S to 50S) than the subunits of ribosomes found throughout the rest of the cell (40S to 60S). Ribosomes and Protein Assembly Ribosomes interact with mRNA to produce proteins in a process called translation.   ttsz/iStock/Getty Images Plus Protein synthesis occurs by the processes of transcription and translation. In transcription, the genetic code contained within DNA is transcribed into an RNA version of the code known as messenger RNA (mRNA). The mRNA transcript is transported from the nucleus to the cytoplasm where it undergoes translation. In translation, a growing amino acid chain, also called a polypeptide chain, is produced. Ribosomes help to translate mRNA by binding to the molecule and linking amino acids together to produce a polypeptide chain. The polypeptide chain eventually becomes a fully functioning protein. Proteins are very important biological polymers in our cells as they are involved in virtually all cell functions. There are some differences between protein synthesis in eukaryotes and prokaryotes. Since eukaryotic ribosomes are larger than those in prokaryotes, they require more protein components. Other differences include different initiator amino acid sequences to start protein synthesis as well as different elongation and termination factors. Eukaryotic Cell Structures This is a diagram of an animal cell. colematt/iStock/Getty Images Plus   Ribosomes are only one type of cell organelle. The following cell structures can also be found in a typical animal eukaryotic cell: Centrioles - help to organize the assembly of microtubules.​Chromosomes - house cellular DNA.​Cilia and Flagella - aid in cellular locomotion.​Cell Membrane - protects the integrity of the interior of the cell.​Endoplasmic Reticulum - synthesizes carbohydrates and lipids.​Golgi Complex - manufactures, stores and ships certain cellular products.​Lysosomes - digest cellular macromolecules.​Mitochondria - provide energy for the cell.​Nucleus - controls cell growth and reproduction.Peroxisomes - detoxify alcohol, form bile acid, and use oxygen to break down fats. Sources Berg, Jeremy M. Eukaryotic Protein Synthesis Differs from Prokaryotic Protein Synthesis Primarily in Translation Initiation. Biochemistry. 5th Edition., U.S. National Library of Medicine, 2002, www.ncbi.nlm.nih.gov/books/NBK22531/#_ncbi_dlg_citbx_NBK22531.Wilson, Daniel N, and Jamie H Doudna Cate. The structure and function of the eukaryotic ribosome. Cold Spring Harbor Perspectives in Biology vol. 4,5 a011536. doi:10.1101/cshperspect.a011536

How to get rid of depression

How to get rid of depression Learn the effective ways how to get rid of depression Very often it becomes harder for us to enjoy our lives and be satisfied with the current state of things and the things around us. The thoughts that that we are not satisfied with this or that come into our heads, bringing the feelings that everything is bad and there is no way to solve problem, if any. That is the state of depression and in such a situation it is very important not to let these feelings evolve and become stronger. Below you can find the ways and means how to get rid of depression and enjoy your life. Sports It has been proved a long time before that physical activity helps to keep mental and psychological condition of human’s body. Very often when you feel bad morally or mentally, it is a good means to improve your state by going in for sports. Doing physical exercises requires concentration and dedication, so you need to improve your thinking to do all this. And as a result you can clear up your head of bad thoughts or some irritation and develop your body at the same time. Sport can become your personal psychologist, who will take care of your wellbeing. Food Yes, this is right, food can help you improve your mental state and bring you joy. But at the same time it is very important to have the right approach to it. If you eat unhealthy food or a big amount of it – it will bring you no good. Though, eating something healthy, useful and, of course, tasteful can help you receive those pleasant feelings to conquer the depression and put it off. This can also help you develop new and right approach to nutrition as the means to support your health and physical shape. And this is an effective way to get rid of depression and to enjoy fine food. Travelling Finding out something new in one’s life is very useful to overcome the depression. And in such a situation why not discover some new places around and enjoy visiting them. Changing of surrounding is very effective for improving your mental condition. Also when travelling, you are able to meet new people or new cultures and by interacting with them, you can easily change your life and bring new positive emotions in it. New connections can make your life more interesting and absorbing. Self-education By learning something new we also get things to become better and to change our mindset. New information or skills can improve our thinking and moral condition. No matter if it is reading new books or studying some new disciplines or undergoing particular academic programs – it is very effective for you to become better and more sophisticated. When we conceive new information, we greatly improve our way of thinking and the ability to treat various things in a right manner. The learning process is a good means to obviate depression and make your life better. Right thinking No matter in what conditions we live, we can always be happy. Everything depends on the way we treat this or that thing. Some people have a lot of things in his or her life, or at least a lot more than others, though still thinking that it is not enough or all this is not so good. But pessimistic attitude will never result in anything good for you. The way how we treat everything around us greatly depends on the way of our thinking, so if you want to live a happy life, you should think in a positive way. Engaging in positive course of conduct will help in dealing your problems and bring you optimistic outcome. The above stated things can direct you in the right way to make your life more interesting and full of bright colors. When comprehending something new we evolve and improve ourselves. We hope that these clues will help you get rid of depressive thoughts once and for all.