11/6/2012 Bio Lab W 8
Cell Structure and Function
Prokaryotic cells do not contain a nucleus. Eukaryotic cells do contain a nucleus. Organisms are eukaryotic except Bacteria and Achaea. Organelles are small membranous bodies, each with a specific structure and function. Prokaryotes do have cytoplasm, which is the material bounded by a plasma membrane and cell wall. This contains ribosomes, small granules that coordinate the synthesis of proteins. Prokaryotes also have a nucleoid which is the inner interior of the cell where the DNA is organized and stored but not enclosed by the membrane.
Prokaryotic cells lack membrane-bounded organelles as well as a nucleus. Their DNA is in a nucleoid region. The prokaryotic cell consists of a fimbriae, flagellum, ribosome, nucleoid, plasma membrane, cell wall, and capsule. The fimbriae is hair-like bristles that allow adhesion to the surfaces. The flagellum is rotating filament present in some bacteria that pushes the cell forward. Ribosomes are the site of protein synthesis. The nucleoid is the location of the bacterial chromosome. The plasma membrane is the main entrance and exit of molecules thru the cell. The cell wall covers, protects, supports and shapes the cell. The capsule has a gel-like coating outside cell wall.
The animal cell and plant cell structures are structurally different. There are many organelles are membranous, such as the nucleolus, endoplasmic reticulum, Golgi apparatus, vacuoles and vesicles, lysosomes, peroxisome, mitochondrion, and chloroplast. The unique structures between the two: plant cells- large central vacuole, cell wall, chloroplast; animal cell- small vacuoles, and centrioles.
In the animal cell, they have many structures and functions: plasma membrane defines the cell boundaries and regulates molecule passage in and out the membrane. The nucleus stores genetic information such as DNA. The nucleolus is the ribosomal subunit formation in the cell. Protein synthesis occurs in the ribosomes. The endoplasmic reticulum modifies proteins and other substances distributed by the vesicle. Rough ER is the folding, modification and transportation of proteins. Smooth ER is lipid synthesis in some cells. The golgi apparatus packages and distributes proteins and lipids throughout the cell. The vesicle is a storage place for the cells. Lysosomes are the intracellular digestion of the cell. The mitochondrion goes through the cellular respiration process. Centrioles are the formation of basal bodies in the animal cell. The cytoskeleton shapes the cell and movement of its parts.
In the plant cell, the cell wall, central vacuole, and chloroplasts all are main points that you can see in the difference between the two cells. The plant cell consists of the nucleous, nucleolus, centrosome, rough ER, smooth ER, golgi body, large vacuole, cell wall, mitochondria, microtubules, plasma membrane, and the granum.
Diffusion is the movement of molecules from a higher to a lower concentration until equilibrium is achieved and the molecules are distributed equally. At that point, the molecules may still be moving back and forth, but there is no net movement in any one direction. Diffusion is a general phenomenon in the environment. The speed of diffusion is dependent on such factors as the temperature, the size of the molecule, and the type of medium. In chapter 4.3, in figure 4.6 is the process of diffusion and the diffusion is apparent when dye molecules have equally dispersed.
Some molecules can be diffused across a plasma membrane and some cannot. In general, small, noncharged molecules can cross a membrane by simple diffusion, but large molecules cannot diffuse across a membrane.
Hypertonic solutions vs. hypotonic solutions: hypotonic solution is where the cell fills with water and bursts. This is from high water to low water. Hypertonic solution is from low to high and the exact opposite. There is a step where the two become equal. In a hypertonic solution, the large vacuole of plant cells exerts turgor pressure, and the chloroplasts are seen pushing against the cell wall. Ina hypertonic solution, the central vacuole loses water, and the cytoplasm, including the chloroplasts, have plasmolysis the cell wall.
The pH scale ranges from 0-14. From 0-6 is an acid and from 8-14 is a base. 7 is neutral pH. A buffer is a system of chemicals that takes up excess hydrogen ions or hydroxide ions as appropriate. This is important to maintain for humans because our blood must have at least 7.4 pH level or we can become ill. All living things have to maintain a certain pH level for themselves.
Mader, Sylvia S. "Inquiry into Life Lab ." Mader, Sylvia S. Inquiry into Life Lab . Learning Solutions, 2012. 41-53. Lab Manual.