Cell types

1. Cell types # 45. Distinguish between function of various body cells based on cell specialization. SC.F.1.4.2 SC.H.2.4.1 B. Thomas

2. Lab Set up Osmosis Lab Before we get into lab specialization we need to set up a seven day lab. Set up your lab and complete through Day 1 We will take our observations at the end of our lecture today.

3. Cell Specialization � it all �stems� from a stem cell All mature cell comes from a stem cell called mesenchym. During the growth of individual, mesenchym will differentiate into various type of cells due to their specializations At the beginning of the development of an embryo from zygote the cells have all the same structure. As the new organism forms, cells change their structure in order to perform their functions with maximum productivity. This is specialization. However it comes with a price: the cell can not perform other functions except the one it has modified in order to due best

4. Trivia Question What is the largest known single cell? An ostrich egg!!! A look at eggs a single cell� An unfertilized cell does only have one cell The cell is a small whitish disk at the top of the yolk It can be seen and can be separated from the egg. When the egg is fertilized the cell begins to divide and multiply The yolk serves as nourishment for the developing embryo.

5. A closer look at cell specializationThe Egg after fertilization. . .http://www.teachersdomain.org/resources/tdc02/sci/life/stru/different/index.html

6. Cell Specialization Why is it an advantage to have different cells specialized to carry out particular functions? Answer provided by Provided by Michael Tri H. Do, HHMI predoctoral fellow at Harvard University. One way to understand the advantage of cell specialization is to think of people in society. Consider all the professions required to keep everything running: farmers to provide food, doctors to preserve health, engineers to maintain infrastructure, ad infinitum. Each job requires unique, sophisticated skills that are acquired over several years and are kept up by persistent effort. It would be impossible to train each person for every profession. To provide those things that we depend on each day, people have shaped themselves to play roles in the larger social context. Organisms are just as complex as societies. Thus, cells must be shaped to perform specific functions in the context of the organism. Take a creature's need to sense its external environment. In primates like us, the predominant sensory system is vision. If you look at the retina, which is to the eye roughly what film is to a camera, you will see a bewildering diversity of cell types. These have unique and often exquisite shapes. For example, each photoreceptor cell is slender and long, and encases a stack of membranous discs. Embedded in these discs are pigment molecules that change shape when struck by light. This change in shape triggers a chain of events that sends electrical signals to the brain. These signals are the raw material of visual perception. Stacking the discs up increases the chance that light traveling through the photoreceptor cell will hit a pigment molecule. Due to this design, these photoreceptor cells work extremely well. In fact, you can sense just a handful of photons falling on your retina (Contrast this with the billions of photons that may hit your retina at a given moment on a sunny day). Now, if there was no cellular specialization, every cell in your body would be the same. Consequently, every cell would have these stacks of membranous discs. You can see how that would be a waste of space and energy for, say, a cell that lines your stomach. In the stomach there is no light to be sensed, and even if there was, the light would be meaningless without the neuronal circuits that effect a light-sensitive response like constricting your pupils or causing you to turn off a lamp. Instead, the stomach cell must use its every resource to extract nutrients from food. And even this is a complex task. Some cells in your stomach are specialized to secrete mucus that protects your stomach wall from the extremely acidic stomach contents. Other cells maintain the high levels of acid, secrete digestive enzymes, and snatch free nutrients out of the slurry to deposit them in the bloodstream. Just how many different cell types are there? No one knows. Even in the retina, which is only about two hundred microns thick, new types are being discovered. In fact, specialization appears to be so fundamental to biology that we can use it to predict what these new cells might do. Space and energy are at such a premium that there is little room for organelles and protein complements that are not necessary for the cell's function. Every organism begins as a single cell; at first glance, a rather unimpressive ball of protoplasm. But in the course of dividing, it somehow forms discrete cell types in all the right places. How do daughter cells know what they should become? With a few known exceptions, every cell in your body has the same DNA and thus has the potential to be any other cell. But somehow, only certain segments of DNA are used. And how do the proteins encoded by DNA shape cells into forms that inspire names such as "starburst," "goblet," and "fountain"? Understanding how cells interact in time and space to create an organism is the vast, booming field of Developmental BiologyAnswer provided by Provided by Michael Tri H. Do, HHMI predoctoral fellow at Harvard University. One way to understand the advantage of cell specialization is to think of people in society. Consider all the professions required to keep everything running: farmers to provide food, doctors to preserve health, engineers to maintain infrastructure, ad infinitum. Each job requires unique, sophisticated skills that are acquired over several years and are kept up by persistent effort. It would be impossible to train each person for every profession. To provide those things that we depend on each day, people have shaped themselves to play roles in the larger social context. Organisms are just as complex as societies. Thus, cells must be shaped to perform specific functions in the context of the organism. Take a creature's need to sense its external environment. In primates like us, the predominant sensory system is vision. If you look at the retina, which is to the eye roughly what film is to a camera, you will see a bewildering diversity of cell types. These have unique and often exquisite shapes. For example, each photoreceptor cell is slender and long, and encases a stack of membranous discs. Embedded in these discs are pigment molecules that change shape when struck by light. This change in shape triggers a chain of events that sends electrical signals to the brain. These signals are the raw material of visual perception. Stacking the discs up increases the chance that light traveling through the photoreceptor cell will hit a pigment molecule. Due to this design, these photoreceptor cells work extremely well. In fact, you can sense just a handful of photons falling on your retina (Contrast this with the billions of photons that may hit your retina at a given moment on a sunny day). Now, if there was no cellular specialization, every cell in your body would be the same. Consequently, every cell would have these stacks of membranous discs. You can see how that would be a waste of space and energy for, say, a cell that lines your stomach. In the stomach there is no light to be sensed, and even if there was, the light would be meaningless without the neuronal circuits that effect a light-sensitive response like constricting your pupils or causing you to turn off a lamp. Instead, the stomach cell must use its every resource to extract nutrients from food. And even this is a complex task. Some cells in your stomach are specialized to secrete mucus that protects your stomach wall from the extremely acidic stomach contents. Other cells maintain the high levels of acid, secrete digestive enzymes, and snatch free nutrients out of the slurry to deposit them in the bloodstream. Just how many different cell types are there? No one knows. Even in the retina, which is only about two hundred microns thick, new types are being discovered. In fact, specialization appears to be so fundamental to biology that we can use it to predict what these new cells might do. Space and energy are at such a premium that there is little room for organelles and protein complements that are not necessary for the cell's function. Every organism begins as a single cell; at first glance, a rather unimpressive ball of protoplasm. But in the course of dividing, it somehow forms discrete cell types in all the right places. How do daughter cells know what they should become? With a few known exceptions, every cell in your body has the same DNA and thus has the potential to be any other cell. But somehow, only certain segments of DNA are used. And how do the proteins encoded by DNA shape cells into forms that inspire names such as "starburst," "goblet," and "fountain"? Understanding how cells interact in time and space to create an organism is the vast, booming field of Developmental Biology

7. A closer look at cell specializationNeurons What is a neuron? A neuron is a nerve cell. The brain is made up of approximately 100 billion neurons. Neurons are similar to other cells in the body in some ways such as: surrounded by a membrane. have a nucleus that contains genes. contain cytoplasm, mitochondria and other "organelles". neurons differ from other cells in the body in some ways such as: Neurons have specialized projections called dendrites and axons. Dendrites bring information to the cell body and axons take information away from the cell body. Neurons communicate with each other through an electrochemical process. Neurons form specialized connections called "synapses" and produce special chemicals called "neurotransmitters" that are released at the synapse