I.
IntroductionOut of all the organelles thereare two that have fascinated microbiologists for the past hundred years. Thefirst is the mitochondria, nicknamed the “powerhouse of the cell. ” The secondis the chloroplast in plant cells that have functions similar to those of themitochondria. What do these organelles do? What are the similarities and differencesof these organelles? This essay will help you to understand these two fascinatingorganelles. II.
MitochondriaMitochondria are small cytoplasmic organelles. They are five to 10 micrometers long and one to . 5 micrometers wide. They mainfunction is to provide energy for cell activities.
They house the respiratoryenzymes that convert oxygen and the products of fat, carbohydrate, and proteinmetabolism into adenosine triphosphate (ATP) and guanosine triphosphate (GTP),chemicals that have high-energy bonds. They are hollow all except for a foldedline of matter that contains the ribonucleic acid (RNA) or deoxyribonucleicacid (DNA) of the cell. Mitochondrion make use of a process known as oxidationto make fat acids and pyruvate acid into (indirectly) ATP and Pi (inorganicphosphate). The process goes as follows:1) Oxidation of pyruvate acidinto acetyl coenzyme A. 2) Oxidation of fat acids into acetyl coenzyme A. 3)Oxidationof acetyl coenzymes from step one and two into CO2 and NADH2.
4) Oxidationof NADH2 by oxygen forming water. 5) Synthesis of ATP coupled to NADH2 oxidationby process of oxidative phosphorylation. Most of this is self explanatoryexcept for the last step (5). The final step contains a phrase “coupled to.
“This means that the compound (NADH2) must be present and have been oxidizedfor the synthesis of ATP, similar to a catalyst’s presence of some reactions. Althoughthe mitochondrion’s major purpose is to supply the cell with the much neededATP, it has others. Included in this list are nitrogen metabolism, porphyrinsynthesis and steroid hormone synthesis. III.
ChloroplastsChloroplastsare complicated green organelles that occur within the cytoplasm of plant cells. They are the main sites of photosynthesis. Photosynthesis is the change oflight energy, CO2 water into sugar which is used as food. They are disk shapedorganelles and are surrounded by two layers of membrane that enclose the wateryinside or stroma.
Inside the stroma there are green dots called grana (grains)that hold chlorophyll. As with the mitochondrion the Chloroplasts use radiantor solar energy to make a product. In this case hexose. 1) The pigment complexesin the chloroplasts (including but not limited to chlorophyll) collect solarenergy. 2) The light energy gathered in the first step is used to run an electrontransport chain that oxidizes water into 0xygen. NADP is reduced.
3) ATPsynthesis is coupled to the electron transport train. 4) Carbon dioxide isfixed and converted to hexose. This process requires ATP and the reduced NADPcreated in step three and two respectively. IV. ConclusionBoth themitochondria and the chloroplasts have complex purposes in the cell. This firstas the powerhouse that creates energy for cell activities.
The second, chloroplastswhich produce food that is used to power the cell. These procedures are facinatingand more could be learned if time would allow it. Bibliography:CytoplasmicGenes and Organelles. Sager, Ruth. 1972.
London. Genetics and Biogenesisof Chloroplasts and Mitochondria. Bucher, Th. . 1976.
Amsterdan. Mitochondria,Chloroplasts and Bacterial Membranes. Prebble, J N. 1981.
New York. Methodsin Enzymology. Volume 207. Rudy Benardo.
1992. San Diego.Category: Science
