Cell Walls and Plasma Membranes - Essay Example

Experiment Labeling   cilia Questions For each structure identified, do you think its location affects its ability to function? Why or why not?  (Hint: those buried deep in the cell probably do different things than those closer to the cell membrane)  Yes, for most of the structures identified, location does affect their ability to function. Cell wall and plasma membrane are primary examples because they protect the contents of the cell from the external environment as well as harmful foreign bodies. A nucleus is the brain of a cell and so it tends to be located in the center of an animal cell. Similarly, the nucleoid region in the bacteria also tends to be located towards the center. In plant cells, however, it is located on the side due to the presence of the central vacuole. The endoplasmic reticulum and golgi apparatus are located closer to the plasma membrane due to their functions of self-destruction, releasing toxic substances to the outside environment and collecting waste products. Certain structures like the mitochondria, vacuole, contractile vacuole, chloroplast and ribosomes are dispersed in the cell as they are related to the overall cell productivity and function. The flagella and cilia in the bacteria help in locomotion. 2. Draw a labeled diagram of a small section of the plasma membrane and briefly describe its structure and function.  The foundation in the structure of the plasma membrane is the phospholipid bilayer forming a barrier between two aqueous compartments on the two sides of the cell: inside and outside. There are specific functions for proteins embedded in the interior of the phospholipid bilayer. They carry out various functions such as selective transport of molecules and cell to cell identification. Thus, the main function of the plasma membrane is to control the active and passive movement of various substances into and out of the cell. 3. Describe the differences between animal and plant cells.  The main difference between animal and plant cells is the presence of a cell wall in plant cells which has a rigid, rectangular-shaped structure.  A cell wall is composed of cellulose, hemicellulose, lignin, enzymes and structural proteins. Animal cells do not have cell wall; therefore, they are usually roughly spherical-shaped.  Another major difference is that plant cells have chlorophyll which is a light-absorbing pigment required for photosynthesis. Chlorophyll is responsible for giving the plants a green color and is found in chloroplasts.   Plants cells have a single large, central vacuole, whereas animal cells may have various smaller vacuoles. The central vacuole is used to store water, ions and sometimes, toxins. Animal cells are composed of centrioles, cilia, lysosomes and peroxisomes. 4. Which of the following structures are present in both prokaryotic and eukaryotic cells?  Plasma membrane, Golgi apparatus, DNA, lysosomes and peroxisomes, cytoplasm Every living organism is made up of two type of cells: prokaryotic or eukaryotic. Prokaryotic are single-cellular, whereas eukaryotic are multicellular.  Both prokaryotic and eukaryotic cells contain plasma membrane which is a protective layer of membrane separating the contents of the cell from the external environment. However, golgi apparatus, lysosomes and peroxisomes are only found in eukaryotic cells due to the fact that there are no membranous structures within the prokaryotic cells except the plasma membrane.   DNA is present in both the type of cells. Cytoplasm is found in eukaryotes, as well as prokaryotes, and is the foundation of the cells.  5. Where is genetic material found in plant cells?  The genetic material is found in the nucleus of the plant cells.    6. Mitochondria are the only organelles that contain their own DNA (circular) and have a double membrane. Why do you think this might be so?  (Hint 1: Where else do we see circular DNA?)  (Hint 2: What do you know about the relative age of eukaryotic cells?)  Mitochondria are known as the “power plant of the cell” because they are responsible for synthesizing most of the energy supply for the cell. This energy is in the form of adenosine triphosphate (ATP). Mitochondria are also responsible for producing cholesterol and heme and in the self-destruction mechanism of the cell. Mitochondria have circular DNA which replicates similar to bacteria by a reproductive process called fission, they can make their own proteins. Moreover, as the structure always relate to the function, the presence of double membrane, i.e. a smooth outermost membrane and an inner membrane which has many folds known as cristae. The cristae increase the surface area; thereby they enhance productivity of cellular respiration. 7. How is the structure of the plant’s cellulose-based cell wall related to its function?   Plant cells are known to be rigid structures with a defined shape which is due to the cell wall. The structure of the cell wall pertains to its various functions. A primary function is providing strength and protection, the rigid but flexible cell wall easily provides that by preventing harmful foreign bodies from entering. The cell wall is semi-permeable meaning that homeostasis is maintained in the cell. Cell wall also maintains turgor pressure by preventing it from bursting or shrinking by regulating cell volume. 8. Defects in structures of the cell can lead to many diseases. Pick one structure of a eukaryotic cell and develop a hypothesis as to what you think the implications would be if that structure did not function properly. Lysosomes are eukaryotic organelles that contain a collection of enzymes responsible for the breakdown of polymers from carbohydrates to proteins, lipids and nucleic acids. They do so by functioning as the digestive system of the cell, breaking down foreign substances and digesting useless products in the cell. If lysosomes are to malfunction, it means that there is no outlet for the waste products of the cells as well as undigested polymers. This can lead to the death of the cell affecting bodily functions at the organ level.   9. Using books, articles, the internet, etc. conduct research to determine if your hypothesis was correct.  According to Simon, Dickey, and Reece (2012), malfunction of the lysosome can lead to various diseases such as Tay-Sachs which occurs when the enzyme responsible for the breakdown of phospholipids is absent impairing biological processes in the brain. Therefore, the hypothesis that malfunction of lysosomes leads to the death of the cell and impairment at the organ level is correct. Work Cited Simon, Eric J., Jean L. Dickey, Jane B. Reece. Campbell Essential Biology. 5th ed. New York: Benjamin Cummings, 2012. Print.  Read More