Kim Woods: BIO assignment 3
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bio_130_module_3_overview.rtfModule 3 Overview
Learning Objectives
Upon completion of this module, you should be able to:
4A
Explain the role of oxygen in aerobic respiration.
4B
Describe the reactants and products of glycolysis, the Krebs cycle, and the electron-transport system.
4C
List the sources of energy used by chemosynthetic and photosynthetic organisms.
4D
Compare the biochemical pathways utilized and the energy yield of aerobic cellular respiration.
4E
Describe two variations of anaerobic respiration.
4F
Identify subunits from fats and proteins that are metabolized by aerobic respiration.
4G
Describe how energy is derived from fats and proteins.
4H
Differentiate between autotrophs and heterotrophs.
4I
Describe the reactants and products of the light-dependent and light-independent reactions of photosynthesis.
4J
Examine the role of glyceraldehyde-3-phosphate in plant metabolism.
4K
Determine the role of pigments in photosynthesis.
Module 3 Reading Assignment
Enger, E. D., Ross, F. C., & Bailey, D. B. (2012). Concepts in biology (14th ed.). New York: McGraw-Hill. Chapters 6 and 7.
Biochemical Pathways
Organisms are broken down into two groups when it comes to how they obtain energy. Autotrophs are considered to be self-feeding. They are able to use raw materials to yield energy. In other words, autotrophs can create their own food for energy. However, they do rely on outside sources, like the sun, for their energy sources. Heterotrophs need to feed off of other things such as carbohydrates, proteins, and fats to produce energy. Unlike autotrophs, heterotrophs are consumers rather than manufacturers.
Autotrophs are made up of two subclasses: phototrophs and chemoautotrophs. Phototrophs use light as their source of energy and are largely plants. Chemoautotrophs use inorganic chemical reactions for their energy sources and are fungi and bacteria. Heterotrophs are broken down into four groups: herbivores, carnivores, omnivores, and saprobes. Herbivores consume plants for their energy, carnivores consume animals, omnivores consume both plants and other animals, and saprobes break down dead plants and animals.
Aerobic and anaerobic respiration are both brought underway solely by glucose. Aerobic respiration takes place when oxygen is present and carbon dioxide is produced as a result. Anaerobic respiration takes place in the absence of oxygen, and lactate and ethanol is produced as a result. Lactate is produced in cases of animal’s muscles and ethanol is produced in cases of organisms. Another difference between the two is the amount of energy that is able to be produced. Aerobic respirations produce more energy because the glucose molecules are able to be completely broken down. Anaerobic respiration is not able to completely break down the glucose because of the lack of oxygen.
Glycolysis uses anaerobic respiration during the process of breaking down carbohydrates, glucose, and sugars. This results in ATP, or adenosine triphosphate as well as pyruvic acid. This process takes place within the cytoplasm.
The Krebs cycle is made up of a sequence of chemical reactions that use aerobic respiration. This cycle is important to all living things that use oxygen to survive as a part of cellular respiration. In this case, glucose is broken down into carbon dioxide, and is later used as ATP. Please watch the video titled, Citric Acid Cycle .
The electron-transport system is used by phototrophs and chemotrophs to make their energy. These organisms use sunlight to produce the ATP that they will later use when they need energy.
Carbohydrates are one of the easiest foods to break down into energy, but sugars and proteins are also used to provide energy. Carbohydrates, fats, and proteins are all broken down into types of sugar before they are able to be used for energy. Sugars or fats actually produce twice as much in regards to energy as carbs or proteins, but carbs are the easiest to break down.
Fats are first stored as triglycerides, which are made up of three saturated fatty acids. As energy is needed, the triglycerides are broken down two carbons at a time, when then turn into sugars. The sugars are then further broken down in the Krebs cycle to produce the energy needed. Sugars are the only foods that can be broken down into energy without the help of oxygen.
Proteins are not one of the top sources the body used for energy, but the body will break down proteins for energy if it needs to. Proteins are composed of amino acids and do not change as they are digested—just multiplied. Before the body can use the proteins as energy, the body must first break down the amino acids into sugars. This process is called deamination. Deamination takes place in the liver where it is turned into urea. Basically, the amino acids are broken down in the liver, and then the liver expels the waste into the blood stream where it is then filtered out of the body by the kidneys. When these amino acids are broken down and the waste has been disposed of, all that is left is keto acid. The keto acid can then be formed into sugar.
Pigments play a large role in photosynthesis. Photosynthetic pigments are derived from different light components based on their specific wavelength. The pigments can capture energy from the correlating pigment in a wavelength. The pigments within a wavelength are as follows: carotene is an orange pigment, xanthophyll is a yellow pigment, chlorophyll a is blue/green pigment, chlorophyll b has a yellow/green pigment, pheophytin a is a gray/brown pigment, and pheophytin b is a yellow/brown pigment. Chlorophyll a is the most common of six pigments, and exists in all plants that use photosynthesis. Chlorophylls are also responsible for the large amounts of yellows and greens that we see in nature.
The reason why there are several different pigments other than chlorophyll is because each of the pigments are able to absorb light to be used as energy in different ways. The different pigments absorb light from different parts of the spectrum more efficiently than other parts of the spectrum. For example, the carotene, or the orange pigment is able to absorb the light energy from other carotene portions of a wavelength much more effectively than pheophytin b, or the yellow/brown pigment.
Required Presentations:
Click on the links below to view the Module 3 presentations.
