037 - Cell Communication

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Paul Andersen discusses cell communication. He begins by explaining how he communicates with other individuals using various forms of electronic communication. He them explains how cells communicate when the distance between them is big, small, and zero. He explains how antigen presenting cells pass information on antigen structure by touching in the immune response. He explains how neurotransmitters are used to transfer and manipulate nerve signals. And he finally explains how the endocrine system sends messages throughout the body.
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036 - Evolutionary Significance of Cell Communication

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Paul Andersen describes how cell communication is used in both single-celled and multicellular organisms. He starts by describing the symbiotic relationship between the bobtail squid and the bacteria Vibrio fisheri. He explains how bacteria use quorum sensing to communicate between each other and respond to changes in their environment. He also explains how multicellular organisms (like humans) can coordinate activities. He explains how epinephrine release from the adrenal gland can trigger a series of signal transduction pathways that can eventually lead to the release of glucose from the liver.
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034 - Mechanisms that Increase Genetic Variability

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Paul Andersen describes mechanisms that increase the genetic variation within a population. He begins by discussing how horizontal transfer can move genetic material between bacteria. Transformation, transduction, and conjugation in bacteria are all included. He also explains how crossing over, random assortment, and random fertilization can maintain genetic variation in eukaryotes. He also explains how inbreeding can decrease the fitness of an individual.
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032 - Signal Transmission and Gene Expression

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Paul Andersen explains how signal transmission is used to alter both cellular function and gene expression. He uses the example of epinephrine release in humans and how it is used in the fight or flight response. Epinephrine causes liver cells to release glucose that is normally stored as glycogen when they receive the signal of epinephrine. They are also able to create different enzymes when receiving this signal. The signal transduction pathway and the importance of CyclicAMP is included.
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030 - Advanced Genetics

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Paul Andersen explains important concepts that can not be explained by simple Mendelian genetics. He begins with a discussion of polygenic inheritance and uses a simulation on height to show how a bell shape curve of phenotypes is produced. He then discusses the importance of linked genes and those that are found on the sex chromosome. A simple punnett square showing the inheritance of the color blind gene is included.
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029 - Mendelian Genetics

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Paul Andersen explains simple Mendelian genetics. He begins with a brief introduction of Gregor Mendel and his laws of segregation and independent assortment. He then presents a number of simple genetics problems along with their answers. He also explains how advances in genetic knowledge may lead to ethical and privacy concerns.

 

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028 - Cell Cycle, Mitosis and Meiosis

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Paul Andersen explains how the cell cycle is used to create new cells. The creation of identical diploid daughter cells, through mitosis, is described. The creation of unique haploid daughter cells, through meiosis is also described. The importance of cyclin and cyclin dependent kinases to regulate the cell cycle is included.
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027 - DNA and RNA - part 2

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Paul Andersen continues his description of DNA and RNA. He begins with the structure of DNA and RNA and moves into the process of DNA Replication. He also describes the central dogma of biology explaining how DNA is transcribed to mRNA and is finally translated into proteins. He also introduces genetic engineering and explains how transformation is used to create insulin.
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026 - Behavior and Natural Selection

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Paul Andersen explains how the behavior of various organisms is shaped by natural selection. The action of phototropism and the timing of photoperiodism have both been shaped by the relative availability of light. Courtship in the bower bird determines the success of offspring. And finally pollination represents the combined success of the coevolution between insects and flowers.
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024 - Development: Timing and Coordination

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Regulation of Timing and Coordination in Development - Paul Andersen explains how genes control the timing and coordination of embryo development. Seed germination initiates the discussion of cell differentiation. The SRY gene and genetic transplantation shows the importance of embryonic discussion. Cell deat is also an important part of development that is regulated by microRNA. HOX genes (a form of homeotic genes) is also discussed.
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023 - Plant and Animal Defense Mechanisms

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Paul Andersen describes how plants and animals defend themselves against pathogens. He begins by discussing the hypersensitive response in plants as a nonspecific form of immune response. He then discusses both the humoral and cell-mediated immune response in mammals. A brief discussion of the chicken pox, small pox and HIV is included.
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022 - Homeostatic Disruptions

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Paul Andersen explains how disruptions in homeostasis can affect biological systems at all levels. He uses the example of dehydration in animals to explain how disruptions at the cellular level can affect an organism. He also uses the example of the invasive brown tree snake in Guam to explain how disruptions can affect entire ecosystems.
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