03+Cell+Physiology

Cell Physiology Chapters Three and Six __//**Content Summary **//__ //Within the unit of cell physiology, cell structure and genetic control along with interaction between cells and the extracellular environment are explored.// //The first major concept within these chapters is diffusion. Diffusion is the inadvertent movement of particles to areas of high density, to areas of a lower population. The movement will always result in the same outcome, the area will reach an equilibrium. The equilibrium is when the area has all the matter spread out about it evenly. The cell membrane is easily accessed by diffusion. Small non-polar molecules are readily allowed through the membrane to create equilibrium inside and out. Note that the only particles that are allowed through are the small non-polar particles though, because larger particles and polar particles are not as easily diffused. This is the same way that your lungs absorb gasses. Now with that being said about the larger and polar compounds, that does not mean that they cannot enter the cell at all. These particles must enter the cell a little differently, and jump through a few more hoops to do so. Charged particles must have an ion channel or a transporter to move in and out of the cell. Membranes often contain channels, but they are sometimes gated shut which does not allow anything to pass through. The gates are opened when a specific molecule bonds to a portion of the protein. The rate of diffusion depends on a few separate factors, the magnitude of its concentration gradient, permeability of the membrane, temperature, and the surface area of the membrane. The bigger the difference in the concentration gradient, the faster the rate of the diffusion travels through the membrane. The polarity and size have a large impact on the permeability aspect of the membrane. The temperature also plays a role in the speed at which things can diffuse through the membrane. When the surface area is warmer the particles move at a great velocity, therefore speeding up the process. And the last factor we discussed is the surface area. The greater the surface area the more places the molecule has to choose from to enter, increasing the availability and the speed of the diffusion once again.// Source (Physiology Book)

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//Another major topic discussed throughout these chapters was RNA synthesis. Transcription begins when a RNA polymerase binds to a DNA start sequence. During transcription, only 1 strand of DNA holds the gene and thus it is the only one that is copied. By pairing this with its complimentary base pairs mRNA is formed. The transcription is not complete until the RNA polymerase reaches a stop sequence in the DNA strand. The process of transcription produces 4 different types of RNA. First is the pre-mRNA, which is eventually modified in the nucleus to become mRNA. Next is the mRNA, which holds the synthesis of a specific protein. After mRNA come the tRNA which basically is the instructions on how to read the mRNA. And lastly is the rRNA is the RNA that forms a part of the ribosomes. Before the mRNA is produced there are exons and introns left over from the DNA that must be dealt with. The introns are shed off and the exons fuse together to form the new mRNA strand. The splicing of the original strand allows the product, the mRNA, to be able to make multiple different kinds of proteins. This in turn allows the body’s genes to produce multiple proteins.// Source (Physiology Book)

//Finally, we have cell signaling which is the way cells can communicate back and forth to each other. In a popular method of signaling, a chemical is released to transfer information. In order to reply to the chemical signal the cell must have the correct receptor protein, otherwise it cannot receive the signal at all. In other signaling methods, such as paracrine signaling, cells release molecules that diffuse to nearby cells. The next type of cell signaling is synaptic. This is where one neuron relays messages to another cell using synapses. And lastly we have the endocrine signaling, which is where chemical regulators move through the blood to distant parts of the body to deliver their messages.// Source (Physiology Book)

__**//Application //**__ //Chapter three goes into depth on how DNA is structured and how it functions. One disease that is linked to a mutation in the DNA strand is Down syndrome. My best friend has a cousin that is diagnosed with this disease. Down syndrome is caused by cell division that results in an extra 21st chromosome. The most common form of this disease is called Trisomy 21. This condition is where an individual has 47 chromosomes in each cell instead of 46. Therefore, being able to learn more information about how our body creates these genetic codes has helped me to be able to picture how this disease occurs.// [|Source]

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__**//Essential Questions //**__ //Cells are considered the basic structure and function of the human body because they are just that. They are the building block to every part of our body. Each tissue, organ, and vessel are all made up of many cells put together. They are the beginning to everything and they control a lot of what goes on in our bodies.//

//The differences between passive and active transport are fairly simple, and the biggest one is that active transport requires the use of ATP. Passive transport uses channels, diffusion, and carriers to easily cross over permeable membranes. Active transport on the other hand requires the use of ATP, an outside energy source which it relies on to enter the cell. Cells mainly need to get things in and out of the membrane to survive. They have a great need to get the waste out, as well as bring the signals and other goods in.//

//Cells communicate through cell signaling. There are a few different types which include synaptic, paracrine, chemical, and endocrine signaling. Each of these is uniquely different as I explained above, but all of them are equally effective.//