Biology Custom Essay

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Cellular respiration and photosynthesis coexist as paired metabolic processes. Photosynthesis uses light energy to convert carbon dioxide into glucose, a simple sugar, in two steps, the light dependent and light independent reactions. Oxygen is produced as a by-product during photosynthesis. This reaction stores energy in the chemical bonds of glucose. Sugar and other carbohydrates are used as fuel sources by cells. During the process of aerobic cellular respiration, glucose is broken down using oxygen. This reaction releases energy, which is used to create ATP molecules, the energy carrier molecule of cells. The process also releases carbon dioxide as a byproduct. Part 1: Download and fill out this table to compare and contrast photosynthesis and aerobic cellular respiration. You will submit the completed table for Part 1. Photosynthesis Aerobic Cellular Respiration Full balanced equation Reactants Products Is this reaction endergonic or exergonic? State which one it is. Energy source used Cell organelles involved in the reaction Role of ATP in the reaction Part 2: After completing the table you will have a basic understanding of these two complementary metabolic processes. Using what you have learned, and additional reference information, answer the following questions. What is the name given to the types of organisms that can use photosynthesis to produce glucose? In addition, provide THREE specific examples. What is the name given to the types of organisms that exclusively use aerobic cellular respiration to break down glucose to produce ATP for energy? In addition, provide THREE specific examples. If oxygen is lacking, how might cells meet their energy needs through fermentation? Explain and give some examples of cells that can do this. Both photosynthesis and aerobic cellular respiration are examples of complex metabolic pathways, consisting of many linked chemical reactions that require enzymes to function. Briefly, explain two (ONLY TWO) attributes of enzymes in catalyzing chemical reactions and in metabolic pathways. Be sure to list and cite in APA, all references used to prepare both parts of this IP assignment ———————–COURSE MATERIAL————————– (this information may help in developing the answers) Presentation: The Building Blocks of Biology Part II This topic covers the basics of organic molecules; their differences from other molecules and variety within their group. Additionally, you will learn the role that organic molecules play in living things. The chemistry of living things involves a variety of very large and complex molecules. Organic chemistry has carbon atoms as its focal point. Carbon atoms can connect to form a variety of long chains or rings that form a vast array of molecules. The structure of these molecules will determine its specific function and changes in the structure of a molecule will cause it to function abnormally. This is commonly referred to as disease. The most common organic molecules found in living things are: carbohydrates, lipids, proteins, and nucleic acids. Understanding basic biology requires a fundamental understanding of the structure of living organizations and how they manage to exert or produce energy for maintaining life. These fundamentals include three main constructs: cell structure and function, enzymes, and the biochemical pathways that determine the routes of energy within and among living organisms. The biological science community has come a long way since the initial separation of the cell into cytoplasm and nucleus. We now know that eukaryotic and prokaryotic cells contain a number of organelles with specific functions in the maintenance and structure of the cells. In the most basic sense, the cell is the common unit of life. It functions as an individual living organism and also as a part of many-celled beings, working in concert to support them. Osmosis, diffusion, and active transport allow cells to function in their environments with a minimum amount of complexity. Enzymes are protein catalysts that can speed up chemical reactions with relatively little change in temperature. Their structure resembles that of a particular substrate molecule and when this molecule and the enzyme meet at the activation site their complex reacts to form an end product. Enzymes are sensitive to environmental conditions like temperature and pH because they are of a protein nature. The number and kinds of enzymes are controlled by genetic information in the particular cell. Enzymes can be influenced by coenzymes inhibitors or other enzymes that compete with them. Changing the environmental conditions of a cell will cause its enzymatic make up to shift as well. So just where does the cell get the energy it needs to stay alive? We will discover how cells take in, convert and transport energy to sustain life in both animals and plants. All cells need to take in energy to survive. As all living things are but a collection of cells, they need energy. Energy is consumed, used and produces a byproduct. Plants, for example, rely on photosynthesis to survive. Chlorophyll traps sunlight to produce adenosine triphosphate (ATP) and a source of hydrogen. They release oxygen as a byproduct. In a complex series of events, a simple carbohydrate is formed. That carbohydrate can be used in reactions to create energy or raw materials. Organisms use the process of respiration to convert foods into ATP and waste materials. Oxygen allows organisms to employ the Kreb’s Cycle and electron-transport system. Another molecular interconversion system is glycolysis. Glycolysis relies on sugar molecules to create energy and food. Article: What are cells? Introduction One of the most basic units of life is the cell. During the study of cells, you will learn more about their components, their purpose, and the different types of cells that exist. What is a cell? A cell is defined as the basic unit of life that is present in all living things. Although cells differ in their shapes, sizes, and primary functions, each cell works together to keep an organism alive and functioning (Starr, 2006). Even though humans start out as a single cell, that cell grows to millions of other cells that make it possible for people to perform all of the bodily functions necessary to sustain life (Starr, 2006). Common Parts of the Cell These cells, although responsible for different functions, all begin with three common components: the plasma membrane, the nucleus or nucleoid, and cytoplasm. The plasma membrane is the outer layer of the cell that is responsible for keeping the cell together and only allowing in the nutrients and other substances that the cell needs. To put it in terms of a simple analogy, Starr (2006) compares the plasma membrane to the structure of a house: It keeps all of the components inside of it safe and only lets what is invited inside the house through doors or windows. The nucleus or nucleoid is the next common component of all cells. It contains the DNA found in the cell and serves not only to protect the DNA from unwanted reactions with other parts of the cell but to control access to the DNA as well. In a prokaryotic cell, the nucleoid region is present, but in a eukaryotic cell, the nucleus is found (Starr, 2006). The cytoplasm is the last common component of all cells. It encompasses everything else in the cell around the nucleus and between the plasma membrane. It is made up of a semifluid matrix and ribosome (Starr, 2006). Types of Cells Although there are many different cells in living things, all of the cells fall into one of two categories: prokaryotic and eukaryotic. Prokaryotic cells are the simplest and smallest types of cells found and are considered to be single celled. There are two subcategories of this type of cell: bacteria and archea. Prokaryotic cells are distinctive because they lack a nucleus to house the DNA material. Instead, they have a nucleoid region where the DNA material is concentrated. Some prokaryotic cells, such as certain types of bacteria, also have a cell wall that surrounds the plasma membrane that serves as structural support for the cell (Starr, 2006). Eukaryotic cells are the second type of cell that may be found in living organisms. These cells are much larger in both size and number than their prokaryotic counterparts. Within this type of cell, the subcategories of protists, fungi, plants, and animal cells can be found. Eukaryotic cells also contain the nucleus to store the DNA that prokaryotic cells lack. In addition, unlike the prokaryotic cells, eukaryotic cells have a cytoskeleton and other organelles such as the nucleus that allow the cell to compartmentalize the materials coming in and out of the cells. The cytoskeleton serves as an additional support structure for the cell and aides in protection and organization as well (Starr, 2006). Functions of Cells Depending upon the type of cell, there are various functions that can be performed by cells. For example, some cells are responsible for metabolism while others aide in responses to stimuli. No matter what the function is, cells are an integral part of living; without them, an organism would not be able to sustain life (Starr, 2006). Reference Starr, C. (2006). Basic concepts in biology (6th ed.). Belmont, CA: Brooks/Cole. Questions and Answers Question #1 What functions does the plasma membrane serve? The plasma membrane serves four functions: (1) to isolate the cell cytoplasm from the external environment, (2) to regulate the exchange of substances between the cytoplasm and the external environment, (3) to communicate with other cells, and (4) to identify the cell as a particular type in a particular species. Question #2 How do prokaryotic and eukaryotic cells differ? Prokaryotic and eukaryotic cells both possess a plasma membrane surrounding the cytoplasm. Prokaryotic cells are smaller and simpler than eukaryotic cells. Eukaryotic cells possess several membranous organelles in the cytoplasm, and a membrane-bound nucleus. Question #3 What physical and metabolic constraints limit cell size? Cells are limited in size because they must exchange materials with their surroundings by diffusion. Because diffusion is relatively slow, the interior of the cell must never be too far from the plasma membrane, and the plasma membrane must have a large surface area through which materials can diffuse relative to the volume of its cytoplasm. Both of these constraints limit the size of cells. Question #4 Describe the structure and function of enzymes. How is enzyme activity regulated? Enzyme function is intimately related to enzyme structure. Enzymes are proteins with complex three-dimensional shapes that bind to specific substrates. Enzymes possess the characteristics of inorganic catalysts; however, enzymes are very specific, usually promoting a single reaction involving one or two specific molecules, whereas an inorganic catalyst can usually speed up many different reactions. Enzyme activity is regulated in three ways: A cell may regulate how much of an enzyme it contains; a cell may synthesize an enzyme in an inactive form and activate it only when necessary; a cell can temporarily activate or inhibit enzymes through feedback inhibition. Question #5 How do the laws of thermodynamics pertain to cellular activity? Although all living organisms, including cells, seem to increase in complexity, order, and amount of concentrated energy over time, the second law of thermodynamics is not violated because Earth, itself, is not an isolated system but is receiving an enormous amount of concentrated energy from the sun, which is the ultimate source of energy for most life-forms and cells. Question #6 What is photosynthesis? Photosynthesis captures the energy of sunlight to convert inorganic molecules of carbon dioxide and water into high-energy organic molecules such as glucose. In plants, photosynthesis takes place in the chloroplasts, in two major steps: (1) the light-dependent and (2) the light-independent reactions. Light-dependent reactions occur in the thylakoids. Light excites electrons in chlorophyll molecules and transfer the energetic electrons to electron transport systems. Light-independent reactions occur in a cycle of chemical reactions called the Calvin-Benson or C3 cycle. The C3 cycle has three major parts: (1) carbon fixation; (2) synthesis of glyceraldehyde-3-phosphate (G3P); and (3) the regeneration of ribulose bisphosphate (RuBP), a carbon dioxide capturing sugar. Question #7 Why does aerobic respiration yield more energy than anaerobic respiration? In aerobic respiration, glycolysis splits glucose into two pyruvates, yielding 2 adenosine triphosphate (ATP which is the most common energy-carrier molecule in cells) and 2 NADH (an energized electron carrier), which eventually yield an additional 2 ATP each from chemiosmosis. The two pyruvates are converted into 2-carbon acetyl groups, and in the process 2 NADH are created, which result in the production of 3 ATP each though chemiosmosis. Each acetyl group enters the Krebs cycle, which generates an ATP, 3 NADH (3 ATP each), and 1 FADH2 (2 ATP each). In short, one molecule of glucose yields a total of 36 ATP. In anaerobic respiration, only two ATP are produced as glucose is broken down into two pyruvates as a result of glycolysis. Pyruvate is then converted into either lactic acid or ethanol, depending on the type of fermentation in which the organism engages. Resource Links Apple discussions ( Troubleshooting PowerPoint Appleinsider ( Excel for Mac, 2008 Ars technical ( First Look: Microsoft Office for Mac 2008. Cell Biology ( This group of web pages provides basic information about cell biology topics. Most of these topics focus on structure/function correlations. Click on Cell Biology. Cell Structures and Functions ( This site provides links relating to cell structures and functions. In the search box type “Cellular Biology” > Search > Cellular Biology > Structures/Functions. Cellular Respiration ( An explanation with visual support of cellular respiration. Center for the Study of Early Events in Photosynth ( Provided by Arizona State University this site contains multiple resources and texts on photosynthesis. Enzymes ( This page is a descriptive text, with links, on enzymes. Click on Beginning Biochemistry > Introduction to Enzymes. Eukaryotes ( To date, about 60 lineages of eukaryotes have been identified (Patterson 1999). The relationships among these are not clear. In the tree provided the authors identify some of the more familiar lineages, including those groups which contain the most diverse multicellular eukaryotes (plants, animals and fungi). The remaining lineages are grouped together on a separate page for practical purposes. On an accessory page, the authors also provide an overview of the major lineages of eukaryotes. Glycolysis and the Kreb’s Cycle ( There is good information on these topics and this directory allows users to get to those sources. In the search box type “Glycolysis” > Go > Glycolysis and the Krebs Cycle. Harvard School of Public Health The Nutrition Source. ( Harvard School of Public Health The Nutrition Source. Introduction to Photosynthesis ( This introduction to photosynthesis has appeared in condensed form in the magazine “The World Mac World ( Explanation of Excel for 2008 on Mac. MacFixIt ( Forum on Microsoft products problems with Mac computers. Mactopia ( Gude for PowerPoint on Mac. Mactopia ( Comprehensive help for Microsoft Office on Mac users. Microsoft help and support ( Using Applescript with Excel for macx. Microsoft help and support ( Trouble shooting formatting issues for Excell for Mac. Microsoft help and support ( Troubleshooting word docs in Mac. Microsoft help and support ( Curing font problems in Word with Mac. Microsoft Knowledge Base Article ( Troubleshooting opening files in Mac using Microsoft products. Microsoft Office Online ( Help with clipart not showing on Mac. Prokaryotes vs. Eukaryotes ( This page provides prokaryotes and eukaryotes links. In the search box type “Cellular Biology” > Search > Cellular Biology > Prokaryotes vs. Eukaryotes. The Three Laws of Thermodynamics ( Concise explanations of the laws of thermodynamics are presented on this page.

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