General Biology
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Podcast Description
The podcasts on this page as specifically designed for general biology, provided by James R. Yount, PhD, at Brevard Community College, Titusville, Florida.
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| 1 | VideoSeparation of Candy Dyes | This video gives an overview of electrophoresis of food dyes used in two different common candies. The extraction was done by swirling two of the candies in a few drops of water, and the resulting solution was placed in the electrophoresis gel with a micropipet. For more details, go to my Classrooms site of Biology World and look in the General Biology lab manual. Quiz yourself after the movie: 1. Why is electrophoresis performed? 2. What causes different dyes to move different distances in the gel? SCRIPT OF PODCAST: To perform an electrophoresis of dyes, a gel try needs to be assembled and molten agarose poured into it. Once the agarose hardens the comb is carefully removed, which reveals wells in the agarose. Dye is extracted from candy with water and 20 µl are placed in each well. The gel goes into an electrophoresis chamber which is then filled with a buffer solution. the lid is placed on, and connected to a power supply at 110V. This gel was loaded with extracts from Skittles, a chemical dye mixture, and extracts from M&Ms. The idea is to separate dyes of different molecular weights. This gel ran for about 30 minutes - this video was sped up 2000%. Notice that the green dye at the arrow is splitting into blue and yellow. The brown is either pure or a mixture of similar molecular weights. The mix of red and green is showing three dyes, the blue and yellow as well as a single red. The dye mixture has four observable dyes, with on of them being positively charged. These three lanes are from three different candies, and bands from all of them are seen in the mixture lane. | 10/15/10 | Free | View In iTunes |
| 2 | VideoBasic Flower Structure | SCRIPT OF PODCAST: Hello, I’m Dr. Jim Yount, and welcome to Yount’s Biology World Digital Podcast, sponsored by Titusville Biology Department of Brevard Community College. Podcast: Basic Flower Structure James R. Yount, PhD Insects and plants have co-evolved for many thousands of years, since both were major colonizers of land ecosystems. As such, insects and other creatures learned to feed on plants, and plants have learned to attract them on purpose and provide them with food, called nectar, in order to coat them with pollen and get an aid in spreading their genetic material to the next flower. It is fascinating to watch the process, as long as you don’t get stung! It helps in working with flowers if you know some basic language and parts. even though flowers can look very, very different, they share basic structures. I’m going to show you Hibiscus, since they are big and easy to see! Hibiscus is a solitary flower, growing on a stalk called a peduncle. The peduncle terminates at the receptacle, which is what all the flower parts are attached to. Parts of a typical flower are divided into four whorls. The outermost whorl is usually green, and is called the calyx. Its separate parts are called sepals. The sepals originally formed as the outer covering of the flower bud. The next whorl is called the corolla, and its parts are called petals. Petals are often colorful and marked so as to attract pollinators. The sepals and petals together are called the perianth, and are regarded as the “sterile” parts of the flower. The next two whorls compose the sexual parts of the flower. Here I’ve dissected away two petals and part of the ovary so you can see better. The third whorl contains the male sexual structure. It is called the androecium (an-ˈdrē-shē-əm) , literally “house of man”, and consists of a set of stamens. A stamen is made of a filament and an anther, and it’s the anther that produces the pollen. Pollen is a container for sperm cells as well as the tube cell that will eventually burrow a tube for the pollen to follow to the egg. The fourth whorl is the gynoecium (ji-ˈnē-shē-əm), or “house of woman”. It consists of one or more carpals, which contain the ovules. A flower may have several carpals fused together. A single carpal or a bunch attached together is called a pistil. Atop the pistil are one or more stigmas,where the pollen lands. Stigmas are attached to the style, which the pollen must bore its way down to get to the ovules and fertilize the eggs. The ovules are covered by an ovary. Ovules contain eggs as well as the tissue that will develop into the seed once the egg is fertilized. The ovary will then develop into the fruit of the plant. Ovules really need to be magnified to see them clearly, so have a magnifying glass or dissecting scope available when you dissect flowers. It is also interesting to look at various shapes of pollen grains. Here is some Hibiscus pollen. There are many other things to learn about flower structure, such as type of inflorescences and flower regularity, but for now it’s fun just to watch the insects play with them and have some food! | 7/19/08 | Free | View In iTunes |
| 3 | VideoFour Basic Plant Types | There are currently twelve Phyla of plants that are traditionally divided into four basic groups based on vascularity, seed type, and seed enclosure. The “bryophytes”, which include the mosses, liverworts, and hornworts (Phyla Bryophyta, Hepaticophyta and Anthocerophyta, respectively) have some conducting tissue but lack the xylem and phloem tissues found in other plants. They reproduce sexually by spores. (16,000 species) The second group, the “seedless vascular plants”, have xylem and phloem but continue to reproduce sexually using spores. This group includes the ferns, whisk ferns, horsetails, and lycophytes (Phyla Pterophyta, Psilophyta, Sphenophyta, and Lycophyta). (12,000 species) The third group contains the gymnosperms, or “naked seeded” plants. These also possess true vascular tissue but have converted to use of a seed in sexual reproduction. Seeds are often borne with woody-scaled cones. This group contains the conifers, cycads, ginkgoes, and gnetophytes (Phyla Coniferophyta, Cycadophyta, Ginkgophyta, and Gnetophyta). (760 species) The last group contains only one Phylum: the Anthophyta. This group contains the flowering plants, all of which contain their seeds in an ovary so are referred to as angiosperms, or “enclosed seeded” plants. (235,000 species) | 9/7/07 | Free | View In iTunes |
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Photosynthesis: Oxygenic Reactions | SCRIPT OF PODCAST Hello, I’m Dr. Jim Yount, and welcome to Yount’s Biology World Digital Podcast, sponsored by the Virtual Campus of Brevard Community College. The Reactions of Oxygenic Photosynthesis James R. Yount, PhD This is an overview of the reactions of oxygenic photosynthesis. For this podcast I will focus on the reactions that take place in cyanobacteria and plants [and protists!], that is, the noncyclic pathway. This pathway involves the cleavage and oxidation of water to produce oxygen gas, so it is known as the oxygenic pathway. It is considered noncyclic because those electrons taken from water pass through the system once and are used later in molecule building. Photosynthesis can be divided into two stages: light dependent and light independent. The light dependent reactions are those that only take place when light is available. The main purpose of the light dependent reactions is to produce ATP and NADPH. These reactions take place on the thylakoid membrane. The purpose of the light independent reactions, also sometimes called the “dark reactions”, is to construct simple sugars using the ATP and NADPH that was produced using light. These reactions happen in the stroma. *** Now it would be best if you were looking at a diagram of the light reactions of photosynthesis. There are a series of drawings on my web site that will help you understand the process, and they are also synched to the audio of this podcast. A textbook diagram will also work well, and you might want to review chloroplast structure too while you are at it. The script of this podcast can be viewed on my web site. *** The light-dependent reactions of photosynthesis take place on the thylakoid membrane. Assemblies of photopigments, called photosystems, gather photons of light and use this energy to excite electrons. Photosystems are often made of several different photopigments to make light capture more efficient. If you have a textbook handy, pause here and study the structure of photosystems before proceeding. The first step of the light-dependent pathway is the excitation of electrons by light at photosystem II, or PSII. These electrons are conducted to a reaction center chlorophyll within the photosystem, and then passed to an electron carrier called plastoquinone. This carrier will later pass the electrons on to other molecules in the pathway, but I want to tell you about one more thing before we go there. The loss of electrons from PSII produces a very strong oxidative force, sort of an electron vacuum. These electrons are replenished by the oxidation of water, which produces hydrogen ions and oxygen molecules. Electrons taken from the oxygen ion allow the photosystem to continue to produce more excited electrons. Now, back to plastoquinone and our excited electrons. These electrons are now passed to an electron transport chain consisting of two cytochromes, b6 and f, so it is referred to as the b6f complex. As the electrons pass into this complex, their energy is extracted and used to pump hydrogen ions from the outside to the inside of the thylakoid. These hydrogen ions will build up inside, producing a gradient that will shove them out of the thylakoid through ATP synthase, producing ATP from ADP. This process should be familiar to you from your study of mitochondria. These high energy ATP molecules will be used later to make sugars in the Calvin cycle. Now our electrons have been exhausted, but they are seated at the doorsill of another photosystem, photosystem I, and they are carried to it by a membrane protein called plastocyanin. Electrons are being promoted at PSI just as they are in PSII, although the frequencies of light are a bit different, and the spent electrons that we have been following so far are used to replenish them. Once the electrons are promoted | 1/22/07 | Free | View In iTunes |
| 5 | VideoMicroscopy II: Using A Scope | Microscopy II shows using the scope from start to finish, including how to examine a slide. If you want a review of microscope parts first, see Microscopy I: Parts of the Microscope Target Audience: General Biology and all those who forgot everything since then. Quiz yourself after the movie: 1. How do you properly rotate the ocular mount? 2. When you first examine a slide, what objective should you begin with? Why? 3. Which focus control knob should you use on high magnification? 4. Why is it sometimes necessary to adjust the iris when changing magnification? 5. Describe how a microscope should be set up when it is put away. | 12/22/06 | Free | View In iTunes |
| 6 | VideoMicroscopy I: Microscope Parts | This is a brief movie illustrating the parts of the compound microscope. I used an Infinity binocular microscope, but the basic parts are similar from scope to scope. Microscopy II shows using the scope from start to finish, including how to examine a slide. Target Audience: General Biology and all those who forgot everything since then. Terms to watch for: Base, field diaphragm, substage condenser, iris diaphragm, stage, nosepiece, objective, ocular lens. Quiz yourself after the movie: 1. What are the various features of the scope that allow adjustment of light? Which should you reach for first? 2. How is a slide held on the stage, and how do you move the stage around? 3. How is the magnification by objectives related to the total magnification? 4. How are the ocular lenses adjusted to fit an individual user’s vision? | 12/22/06 | Free | View In iTunes |
| 7 | VideoFlorida Native Plant Gardens at BCC | In Florida, a land that Spanish explorer Ponce de Leon named “Land of Flowers” in 1513, non- native species imported from all over the world fill our nurseries, home centers, yards and parks and frequently escape into the wild. The ecological implications for the loss of native biological diversity are many. Not only can you beautify your home or workplace with color and diversity, but use of native plants also promotes the real Florida. In the Native Plant Gardening Project at BCC Titusville, we are committed to bringing people into closer contact with our natural plant heritage. Our gardens are for public display and relaxation as well as for educational use in training our biology and environmental science classes. Check out the Photos Native Garden that can be viewed elsewhere on this site (look in the top menu bar) for a more updated view - the gardens have changed a lot in a few years. For more information on Florida natives, see http://www.fnps.org/. Here are a few of the plants frequently found: Trees, Shrubs and Vines Walter’s viburnum (Viburnum obovatum) Firebush (Hamelia patens) Simpson’s stopper (Myrcianthes fragrans) Beautyberry (Callicarpa americana) Gopher apple (Licania michauxii) Dwarf blueberry (Vaccinium darrowi) Coral honeysuckle (Lonicera sempervirens) American wisteria (Wisteria frutescens) Cabbage palm (Sabal palmetto) Fringe tree (Chionanthus virginica) Smaller Plants Florida arrowroot (coontie) (Zamia pumila) Blanket flower (Gaillardia pulchella) Spiderwort (Tradescantia ohiensis) Scrub wort (Hypericum reductum) Black-eyed Susan (Rudbeckia hirta) Red (tropical) sage (Salvia coccinea) Tickseed (Coreopsis levenworthii) Beach sunflower (Helianthus debilis) Partridge-pea (Chamaecrista fasciculata) Scarlet milkweed (Asclepias curassavica) | 11/4/06 | Free | View In iTunes |
| 8 | VideoDNA Science: Restriction Enzyme Electrophoresis | Electrophoresis is an extremely powerful method of analyzing materials of different molecular weights. It can be used for diverse types of molecules such as dyes, DNA fragments, and proteins. This video demonstrates the cleaving of viral DNA into fragments using restriction enzymes, followed by electrophoresis of the fragments. Do do a really cool online “virtual” electrophoresis (it takes only 5-10 minutes), go to http://learn.genetics.utah.edu/units/biotech/gel/ !! This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 2.5 License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/2.5/ or send a letter to Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 94105, USA. | 10/30/06 | Free | View In iTunes |
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Cellular Metabolism: The Electron Transport Chain | Hello, I’m Dr. Jim Yount, and welcome to Yount’s Biology World Digital Podcast, sponsored by the Virtual Campus of Brevard Community College. Podcast: The Electron Transport System James R. Yount, PhD This is an overview of a generalized electron transport system, which is the final step in the full oxidative processing of glucose that begins with glycolysis. Eukaryotic cells carry out this process on the inner membranes of their mitochondria. In prokaryotes, this set of reactions happens on the plasma membrane. The electron transport system consists of a series of reactions that occur on several different enzyme complexes. During these reactions, the electron energy extracted from glucose and carried by NAD:H and FAD:H2 is used to power active transporters that force hydrogen ions against their concentration gradient into the intermembrane space. The purpose of this is to cram as many hydrogen ions into the space as possible. These ions are then allowed to diffuse back into the matrix through special channels that are linked to the enzyme ATP synthase, which uses this backflow power to produce ATP. *** Now it would be best if you were looking at a diagram of the electron transport system that also includes the manufacture of ATP. There is one included with this Podcast that is best seen on a computer. I also have one on the original website for this Podcast, but a textbook diagram will work, as well. *** The electron transport system consists primarily of five enzyme complexes that are embedded in the inner mitochondrial membrane. Let’s begin the discussion by considering what happens to a molecule of NAD:H in the mitochondrial matrix. NAD:H in the matrix, carrying a pair of high energy electrons, bonds to Complex I, which contains the enzyme NAD:H dehydrogenase. This complex, along with Complex II, transfers the high energy electrons from NAD:H to Coenzyme Q and begins the electron transport chain. As this transfer occurs, energy from the electrons’ passage is used to pump two hydrogen ions across the membrane and into the intermembrane space. These two hydrogen ions possess enough energy to power the formation of an ATP molecule later on. The oxidized NAD+ molecule may now return to pick up more electron pairs. Complex III is the next passage for the electron pair. This complex contains several cytochromes, which are iron-containing proteins that are classified by letter: some refer to this as the bc1 complex. Electrons are passed from coenzyme Q through this complex to cytochrome c, which is a loosely bound peripheral protein that shuttles electrons onward to the final complex. As the electrons pass through Complex III, another hydrogen pump is activated, and another pair of hydrogen ions is passed through the membrane to the intermembrane space. Complex IV, also known as cytochrome c oxidase, catalyzes the reaction between the soon-to-be-depleted electrons and oxygen molecules. Oxygen freely diffuses into the mitochondrion, is split into two oxygen atoms, and each atom is united with an electron pair by this complex, forming the oxygen ion. This ion is then bound to two hydrogen ions from the matrix, forming water. As the electron pair passes through cytochrome c oxidase, a final pair of hydrogen ions is passed through the membrane. Did you keep track of the number of hydrogen ions passed per NAD:H? If not, pause here and count them. Now, how about FAD:H2? This molecule does not have as much energy as NAD:H and can only power the pumping of four hydrogen ions across the membrane, not six like NAD:H can. FAD:H2 joins the electron transport chain at coenzyme Q, surrendering its electron pair here, so its electrons only pass through two pumps, not three. That’s OK, we can still get 2 ATP molecule later for each FAD:H2. The final complex is Complex V, a membrane pore | 9/21/06 | Free | View In iTunes |
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Cellular Metabolism: Krebs Cycle | SCRIPT OF PODCAST: Hello, I’m Dr. Jim Yount, and welcome to Yount’s Biology World Digital Podcast, sponsored by the Virtual Campus of Brevard Community College. Podcast: The Reactions of The Krebs Cycle James R. Yount, PhD This is an overview of the Krebs cycle, which is the next step in the full oxidative processing of glucose that begins with glycolysis. In the presence of oxygen, eukaryotic cells carry out this process in organelles called mitochondria. In prokaryotes, this set of reactions happens in the cytoplasm. It is also referred to as the citric acid cycle or the tricarboxylic acid cycle. I like Krebs Cycle best both because it honors Hans Krebs, who described the process in 1937, and because it is short and easy to say. In a brief, the Krebs cycle starts with the acceptance of acetyl coenzyme A by the enzyme citrate synthase. The acetyl coenzyme A is made in a short reaction previous to the Krebs cycle that oxidizes the pyruvate produced in glycolysis. This begins a series of reactions which will produce several energetic molecules including ATP, NAD:H, and FAD:H2. In this sense, the Krebs cycle is catabolic, but the Krebs cycle also spawns many precursors for anabolic reactions. I will not discuss the anabolic processes here. *** Now it would be best if you were looking at a diagram of the Krebs Cycle that also includes the oxidation of pyruvate. There is one included with this Podcast that is best seen on a computer. I also have one on the original website for this Podcast, but a textbook diagram will work, as well. *** After glycolysis, pyruvate is processed in the cytoplasm of prokaryotic cells. In eukaryotes, pyruvate enters the mitochondrion with the aid of a transporter that uses flow of hydrogen ions from the intermembrane space into the matrix to aid its passage. This is a form of active transport and therefore costs the eukaryotic cell a small amount of energy. Once in the mitochondrial matrix, pyruvate is bound by a very large molecule cluster called the pyruvate dehydrogenase multienzyme complex. It consists of three separate enzymes which do three things to pyruvate: (1) they pull off a carbon and two oxygens, releasing them as a carbon dioxide molecule, (2) they remove an electron pair and give it to NAD+, producing NAD:H, and (3) they bind the remains of the pyruvate, which is now a two-carbon acetyl group, to coenzyme A, forming acetyl-coenzyme A. This is the molecule that will introduce the acetyl group into the Krebs Cycle. Pause here and look over this reaction before you proceed. In the first step of the Krebs Cycle, the enzyme citrate synthase prepares to accept acetyl coenzyme A by first binding to the four carbon molecule oxaloacetate. Binding to oxaloacetate opens the binding site for acetyl coenzyme A on the enzyme. While they are all bound together, the acetyl group is transferred from acetyl-coA to the oxaloacetate, forming a molecule of citrate. At the end of this step, the citrate is released to go forward in the Krebs Cycle, and the original coenzyme A molecule is released to go and get more acetyl groups. There is a lot going on here - pause and study this reaction before you go on. The next two reactions prepare the citrate to be more easily oxidized, and just involve the removal of an alcohol functional group from carbon number 3, and, after literally flipping the molecule over like a pancake, its replacement on the next carbon down. This is carried out by the enzyme aconitase and involves the temporary loss of a water molecule. A question for you: why is the resulting molecule called isocitrate? Time to harvest another energy molecule. In the next step, the enzyme isocitrate dehydrogenase first oxidizes an alcohol group to a ketone, giving the resulting electron pair to NAD+ to form NAD:H. The intermediate molecule formed here i | 9/3/06 | Free | View In iTunes |
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Cellular Metabolism: Glycolysis | SCRIPT OF PODCAST: Hello, I’m Dr. Jim Yount, and welcome to Yount’s Biology World Digital Podcast, sponsored by the Virtual Campus of Brevard Community College. Podcast: The Reactions of Glycolysis James R. Yount, PhD This is an overview of glycolysis, the type you normally study in introductory biology and the one used by most living organisms, also known by those in the know as the Embden-Meyerhoff-Parnas pathway. There are other forms of glycolysis known but you probably won’t tackle those until you take a course in bacteriology. In a nutshell, glycolysis of this type begins with glucose and through a series of steps produces two smaller sugars, hence the name “glycolysis”, which literally means “glucose cleaving”. In the process, energy is gathered for use in the cell. This energy is in the form of adenosine triphosphate or ATP, which can be used immediately by the cell to power things, and as reduced nicotinamide adenine dinucleotide, or NADH. NADH contains high-energy electrons that can be used later to make more ATP or to power fermentation reactions. These reactions are carried out by ten different enzymes. These enzymes generally do one or more of the following things to their substrates: cleave it into two pieces, isomerize it into a different form, add or take away a phosphoryl group, oxidize it, or transfer a functional group from one part of the molecule to another. I will be pointing out which ones happen as we go. *** Now it would be best if you were looking at a diagram of glycolysis. To download a readable version, downloadable click Glycolysis w dihydroxyacetone.pdf. *** Glycolysis takes place in the cell’s cytoplasm, and begins when a molecule of glucose enters the cell or is made available inside from some other process. In the first reaction, the enzyme hexokinase binds an ATP molecule and literally clamps on the glucose. It then transfers a phosphoryl group from the ATP to the glucose, producing adenosine diphosphate also known as ADP, and a molecule of glucose-6-phosphate. Notice we are using up the cell’s energy here – it will be OK because we will make it up later – think of it as the match you need to use in order to get a woodpile burning. Question for you: why is the molecule called glucose-6-phosphate? In the second reaction, the enzyme phosphoglucose isomerase binds to the glucose-6-phosphate. Do you remember what isomers are? They are two different structures of a molecule with the same numbers of atoms. The enzyme phosphoglucose isomerase isomerizes the glucose-6-phosphate to form fructose-6-phosphate. Essentially, it rips open the ring between the oxygen and carbon-1, and binds the oxygen to carbon-2 leaving carbon-1 dangling. In the third reaction, which is very similar to the first, the enzyme phosphofructokinase binds an ATP molecule and fructose-6-phosphate. The enzyme then transfers a phosphoryl group from ATP to carbon-1 on the fructose, producing adenosine diphosphate and the molecule fructose-1,6-diphosphate. We have used up a second ATP, but we will get it back eventually. Have you noticed that enzymes that transfer phosphoryl groups are called kinases? Take a pause and compare the first and third reactions. In the fourth reaction we finally get to the sugar cleaving. The enzyme aldolase binds to fructose-1,6-diphosphate and splits it into two 3 carbon molecules. One of these is called glyceraldehyde-3-phosphate, also called G3P for short, which I like to call the molecular 2x4. You can use a wooden 2x4 to build just about anything (I once mad ea silverware drawer out of one), or you can burn it for energy. The remaining reactions of glycolysis will be based on this useful little fellow. The other molecule that is produced is called dihydroxyacetone phosphate. Since the r | 9/3/06 | Free | View In iTunes |
| Total: 11 Episodes |
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