Archive for category Biology
What is Molecular Biology
Posted by in Biology on July 7, 2011
Molecular biology is the science of study of biology at the molecular level.
William Astbury in Nature described molecular biology as:
“… not so much a technique as an approach, an approach from the viewpoint of the so-called basic sciences with the leading idea of searching below the large-scale manifestations of classical biology for the corresponding molecular plan. It is concerned particularly with the forms of biological molecules and ….. is predominantly three-dimensional and structural – which does not mean, however, that it is merely a refinement of morphology – it must at the same time inquire into genesis and function” (W.T. Astbury, Nature 190, 1124. 1961)
Molecular biology has allowed us to uncover the mysteries of the human body, viruses, bacteria and all other life. As such, it has allowed the progress of medicine to advance to such a degree so that we may begin to cure the previously incurable, and to eventually find cures for every disease that afflicts human kind.
Molecular biology depends not only on biology but also chemistry, genetics, and biochemistry. The understanding of the interactions between DNA, RNA, proteins and lipids is vital in understanding how cells work and how diseases affect these interactions. Researchers and scientists are slowly piecing together these interactions and how each biological molecule functions. By understanding this, scientists can then examine disease conditions, and see if the function of any of the molecules has changed. If a molecule or interaction is affected by disease, scientists can then create therapies which target these alterations and repair them.
In conclusion, molecular biology is a vital field in our advancement of medicine and technology. By understanding how biological molecules interact and function, we will be able to not only gain an appreciation of the workings inside the cell, but also it will allow us detect and to fix any problems that arise during disease states.
By Joey_Manny
Structure and Function of Cell Nucleus, ER, Ribosomes and Golgi Apparatus
Posted by in Biology on July 7, 2011
Endoplasmic reticulum
Endoplasmic reticulum structure
Endoplasmic reticulum (ER) is a type of organelle inside a cell. ER is a network of fluid-filled tubes. There are two types of ER, rough and smooth. A cell may have both or only one, depending on its function.
• Rough ER is joined to the nuclear membrane. Its external surface is studded with ribosomes (organelles involved with protein formation).
• Smooth ER is continuous with rough ER but has no ribosomes.
Endoplasmic reticulum functions Rough ER
• Manufactures the building blocks of cell membranes (phospholipids and cholesterol).
• Helps make and transport proteins.
• The external face provides a site for chemical reactions.
Protein synthesis and transport
1 Ribosomes on the rough ER wall manufacture protein strands.
2 Within the lumen, the protein strands fold into distinctive shapes unique to their chemical structure, identifying them as specific proteins.
3 Sugars may be added to proteins to form glycoproteins.
4 Completed proteins are encased in membranous vesicles (tiny membrane sacs), which pinch off the ER and travel to other sites in the cell.
Smooth ER Enzymes (biological catalysts) embedded in its membrane walls are involved with chemical reactions concerning:
• the making of cholesterol;
• the making of sex hormones (steroids, hormones made from cholesterol);
• processing fats;
• the detoxification of poisons; and
• muscle cell contraction.
Ribosomes Location and structure
Ribosomes are organelles found inside a human cell. They are also found in all other plant and animal cells. Ribosomes are used to decode DNA (deoxyribonucleic acid) into proteins.
They are tiny, round granules.
Ribosomes are located on the rough endoplasmic reticulum (giving it the “rough” appearance). They are also found individually throughout the cytoplasm.
Close to the nucleus
Ribosomes are most obvious on the rough ER, where most of the cell’s proteins are manufactured. Ribosomes read mRNA (messenger ribonucleic acid) molecules, a type of nucleic acid copied from the cell’s DNA, that are carried from the nucleus through the ER lumen. Read the rest of this entry »