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Biological Processes: Biological activities and function of the whole organism in human, animal, microorgansims, and plants, and of the biosphere.

Ionic Bonds

JoVE 10665

When atoms gain or lose electrons to achieve a more stable electron configuration they form ions. Ionic bonds are electrostatic attractions between ions with opposite charges. Ionic compounds are rigid and brittle when solid and may dissociate into their constituent ions in water. Covalent compounds, by contrast, remain intact unless a chemical reaction breaks them.

Ionic bonds are reversible electrostatic interactions between ions with opposing charges. Elements that are the most reactive (i.e., have a higher tendency to undergo chemical reactions) include those that only have one valence electron, (e.g., potassium) and those that need one more valence electron (e.g., chlorine). Ions that lose electrons have a positive charge and are referred to as cations. Ions that gain electrons have a negative charge and are called anions. Cations and anions combine in ratios that result in a net charge of 0 for the compound they form. For example, the compound potassium chloride (KCl) contains one chloride ion for each potassium ion, because the charge of potassium is +1 and the charge of chloride is -1. The compound magnesium chloride (MgCl2) contains two chloride ions for each magnesium ion because magnesium’s charge is +2. The electrostatic forces holding ionic compounds together are strong when the compounds are in solid form. Since t

 Core: Chemistry of Life

Overview of Biosensing

JoVE 5794

Biosensors are devices that use a wide range of biological processes and physical properties in order to detect either a biological molecule, such as a protein or cell, or a non-biological molecule, such as a chemical component or contaminant. This interdisciplinary field utilizes electrical, optical, electrochemical, or even mechanical properties to detect the presence…

 Bioengineering

What is Biology?

JoVE 10647

Biology is the natural science that focuses on the study of life and living organisms, including their structure, function, development, interactions, evolution, distribution, and taxonomy. The scope of the field is extensive and is divided into several specialized disciplines, such as anatomy, physiology, ethology, genetics, and many more.

All living things share a few key traits: cellular organization, heritable genetic material and the ability to adapt/evolve, metabolism to regulate energy needs, the ability to interact with the environment, maintain homeostasis, reproduce, and the ability to grow and change. Despite its complexity, life is organized and structured. The cell theory in biology states that all living organisms are composed of one or more cells. The cell is the basic unit of life, and all cells arise from previously existing cells. Even single-celled organisms, such as bacteria, have structures that allow them to carry out essential functions, such as interacting with the environment and carry out chemical reactions that maintain life, or metabolism. In multicellular organisms, cells work together to form tissues, organs, organ systems, and finally, entire organisms. This hierarchical organization can extend further into populations, communities, ecosystems, and the biosphere. An organism’s genetic material, the biologi

 Core: Scientific Inquiry

Diffusion

JoVE 10700

Diffusion is the passive movement of substances down their concentration gradients—requiring no expenditure of cellular energy. Substances, such as molecules or ions, diffuse from an area of high concentration to an area of low concentration in the cytosol or across membranes. Eventually, the concentration will even out, with the substance moving randomly but causing no net change in concentration. Such a state is called dynamic equilibrium, which is essential for maintaining overall homeostasis in living organisms. Diffusion plays an integral role in biological processes such as respiration, the process by which organisms exchange gases with their environment. After breathing in air, the concentration of oxygen in the alveoli, air sacs of the human lung, is higher than the oxygen concentration in the blood. Consequently, oxygen diffuses down its concentration gradient into the blood. In order to get into body tissue, oxygen and other nutrients carried in the blood must diffuse into tissues down their concentration gradients. Metabolic waste such as carbon dioxide diffuses from tissues into capillaries where the carbon dioxide concentration is less than that inside body tissues. Blood carrying carbon dioxide is then pumped to the lungs where carbon dioxide readily diffuses into alveoli that have a lower concentration of the gas than blood. Carbon dioxide

 Core: Membranes and Cellular Transport

Expression Profiling with Microarrays

JoVE 5547

Microarrays are important tools for profiling gene expression, and are based on complementary binding between probes that are attached to glass chips and nucleic acids derived from samples. Using these arrays, scientists can simultaneously evaluate the expression of thousands of genes. In addition, the expression profiles of different cells or tissue types can be compared, …

 Genetics

RNAi in C. elegans

JoVE 5105

RNA interference (RNAi) is a widely used technique in which double stranded RNA is exogenously introduced into an organism, causing knockdown of a target gene. In the nematode, C. elegans, RNAi is particularly easy and effective because it can be delivered simply by feeding the worms bacteria that express double stranded RNA (dsRNA) that is complementary to a gene of interest. First,…

 Biology I

Invasion Assay Using 3D Matrices

JoVE 5645

The extracellular matrix (ECM) is a network of molecules that provide a structural framework for cells and tissues and helps facilitate intercellular communication. Three-dimensional cell culture techniques have been developed to more accurately model this extracellular environment for in vitro study. While many cell processes during migration through 3D matrices…

 Cell Biology

Yeast Reproduction

JoVE 5097

Saccharomyces cerevisiae is a species of yeast that is an extremely valuable model organism. Importantly, S. cerevisiae is a unicellular eukaryote that undergoes many of the same biological processes as humans. This video provides an introduction to the yeast cell cycle, and explains how S. cerevisiae reproduces both asexually and sexually Yeast reproduce asexually …

 Biology I

What is an Electrochemical Gradient?

JoVE 10699

Adenosine triphosphate, or ATP, is considered the primary energy source in cells. However, energy can also be stored in the electrochemical gradient of an ion across the plasma membrane, which is determined by two factors: its chemical and electrical gradients.

The chemical gradient relies on differences in the abundance of a substance on the outside versus the inside of a cell and flows from areas of high to low ion concentration. In contrast, the electrical gradient revolves around an ion’s electrical charge and the overall charges of the intracellular and extracellular environments. The electrical gradient of a positively-charged ion flows from positive to negative regions, while the reverse is true for negatively-charged ions. It is the combined action of these electrical and chemical factors that determine the ultimate direction of an electrochemical gradient. When an ion moves along this path, down its electrochemical gradient, energy is freed that can then power diverse biological processes.

 Core: Membranes and Cellular Transport

C. elegans Chemotaxis Assay

JoVE 5113

Chemotaxis is a process in which cells or organisms move in response to a chemical stimulus. In nature, chemotaxis is important for organisms to sense and move toward food sources and move away from stimuli that may be toxic or harmful. Chemotaxis is also important at the cellular level. For example, chemotaxis is required for the movement of sperm toward an egg prior to fertilization. In…

 Biology I

First Law of Thermodynamics

JoVE 10726

The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed. This can be demonstrated within a classic food web where light energy from the sun is harnessed as radiant energy by plants, converted into chemical energy, and stored as complex carbohydrates. The vegetation is then consumed by animals and during the digestion process, the sugars release energy as heat. The sugars also produce chemical energy that either gets used up doing work, stored in macromolecules like glycogen and fatty acids or are consumed by a predator. The waste products and dead organic matter from animals are then decomposed by bacteria and fungi and returned to the soil to provide food for plants to grow and the cycle continues. During the process of photosynthesis, the photons are used to make complex carbohydrates that the plants use to live and grow, and oxygen is released into the atmosphere. The plants eventually become food for animals—herbivores—and during the digestion process, the sugars are broken down and energy is released—either as heat or to provide chemical energy from glucose, to drive cellular processes that allow the animal to survive and reproduce. It can also be stored in macromolecules as chemical energy. For example, glycogen can be stored in the liver or muscles and can be quickly accessed in tim

 Core: Metabolism

Synthetic Biology

JoVE 5792

This video presents synthetic biology and its role in bioengineering. Synthetic biology refers to the methods used to genetically modify organisms in order to make them capable of producing large quantities of a product. This product could be a protein that the cell already makes, or a new protein that has been encoded in a newly-inserted DNA sequence.


 Bioengineering

Gene Silencing with Morpholinos

JoVE 5326

Morpholino-mediated gene silencing is a common technique used to study roles of specific genes during development. Morpholinos inhibit gene expression by hybridizing to complementary mRNAs. Due to their unique chemistry, morpholinos are easy to produce and store, which makes them remarkably cost effective compared to other gene silencing methods.


This video reviews proper…

 Developmental Biology

Genetic Screens

JoVE 5542

Genetic screens are critical tools for defining gene function and understanding gene interactions. Screens typically involve mutating genes and then assessing the affected organisms for phenotypes of interest. The process can be “forward”, where mutations are generated randomly to identify unknown genes responsible for the phenotypes, or it can be…

 Genetics

Types of Hormones

JoVE 10988

Hormones can be classified into three main types based on their chemical structures: steroids, peptides, and amines. Their actions are mediated by the specific receptors they bind to on target cells.

Steroid hormones are derived from cholesterol and are lipophilic in nature. This allows them to readily traverse the lipid-rich cell membrane to bind to their intracellular receptors in the cytoplasm or nucleus. Once bound, the cytoplasmic hormone-receptor complex translocates to the nucleus. Here, it binds to regulatory sequences on the DNA to alter gene expression. Peptide hormones are made up of chains of amino acids and are hydrophilic. Hence, they are unable to diffuse across the cell membrane. Instead, they bind to extracellular receptors present on the surface of target cells. Such binding triggers a series of signaling reactions within the cell to ultimately carry out the specific functions of the hormone. Amine hormones are derived from a single amino acid, either tyrosine or tryptophan. This class of hormones is unique because they share their mechanism of action with both steroid as well as peptide hormones. For example, although epinephrine and thyroxine are both derived from the amino acid tyrosine, they mediate their effects through diverse mechanisms. Epinephrine binds to G-protein coupled receptors present on the surface of the plasma membran

 Core: Endocrine System

Zebrafish Maintenance and Husbandry

JoVE 5152

The zebrafish (Danio rerio) is a powerful vertebrate model system for studying development, modeling disease, and screening for novel therapeutics. Due to their small size, large numbers of zebrafish can be housed in the laboratory at low cost. Although zebrafish are relatively easy to maintain, special consideration must be given to both diet and water quality to in order to optimize …

 Biology II

In ovo Electroporation of Chicken Embryos

JoVE 5156

Electroporation is a technique used in biomedical research that allows for the manipulation of gene expression via the delivery of foreign genetic material into cells. More specifically, in ovo electroporation is performed on early developing chicks (Gallus gallus domesticus) contained within their eggshells. In this procedure, DNA or knockdown constructs are first injected…

 Biology II

What is the Endocrine System?

JoVE 10875

The endocrine system sends hormones—chemical signals—through the bloodstream to target cells—the cells the hormones selectively affect. These signals are produced in endocrine cells, secreted into the extracellular fluid, and then diffuse into the blood. Eventually, they diffuse out of the blood and bind to target cells which have specialized receptors to recognize the hormones. While most hormones travel through the circulatory system to reach their target cells, there are also alternate routes to bring hormones to target cells. Paracrine signaling sends hormones out of the endocrine cell and into the extracellular fluid where they affect local cells. In a form of paracrine signaling, called autocrine signaling, hormones secreted into the extracellular fluid affect the cell that secreted them. Another type of signaling, synaptic signaling, involves the release of neurotransmitters from neuron terminals into the synapse—a specialized junction that relays information between neurons—where they bind to receptors on neighboring neurons, muscle cells, and glands. In neuroendocrine signaling, neurosecretory cells secrete neurohormones that travel through the blood to affect target cells. Overall, endocrine signaling has a slower effect than other types of signaling because it takes longer for hormones to reach the target cel

 Core: Endocrine System

Electrochemical Biosensing

JoVE 5796

Electrochemical biosensors detect the binding of a target molecule by sensing an oxidation-reduction event. These sensors paved the way for modern biosensing after the invention of the glucose biosensor. This video will introduce electrochemical biosensing, show the workings of the glucose biosensor, and discuss how electrochemical biosensors are used in cancer…

 Bioengineering

Creating Objects and Object Categories for Studying Perception and Perceptual Learning

1Brain and Behavior Discovery Institute, Georgia Health Sciences University, 2Vision Discovery Institute, Georgia Health Sciences University, 3Department of Opthalmology, Georgia Health Sciences University, 4Intelligent Systems Laboratory, Palo Alto Research Center, 5Pattern Recognition Systems, Palo Alto Research Center, 6Department of Psychology, University of Minnesota

JoVE 3358

 Neuroscience

Computer-assisted Large-scale Visualization and Quantification of Pancreatic Islet Mass, Size Distribution and Architecture

1Department of Medicine, University of Chicago, 2Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 3Department of Surgery, University of Chicago, 4Diabetes Division, University of Massachusetts

JoVE 2471

 Biology

Chemically-blocked Antibody Microarray for Multiplexed High-throughput Profiling of Specific Protein Glycosylation in Complex Samples

1Institute for Hepatitis and Virus Research, 2Department of Microbiology and Immunology, Thomas Jefferson University, 3Drexel University College of Medicine, 4Van Andel Research Institute, 5Institute for Hepatitis and Virus Research, Serome Biosciences Inc.

JoVE 3791

 Biology

Atomic Absorbance Spectroscopy to Measure Intracellular Zinc Pools in Mammalian Cells

1Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 2Department of Chemistry, Skidmore College, 3Candiac MR Center, Beth Israel Deaconess Medical Center, 4Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Guerrero

JoVE 59519

 Biochemistry

Quantitative Cell Biology of Neurodegeneration in Drosophila Through Unbiased Analysis of Fluorescently Tagged Proteins Using ImageJ

1Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 2School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University

JoVE 58041

 Neuroscience

Adenofection: A Method for Studying the Role of Molecular Chaperones in Cellular Morphodynamics by Depletion-Rescue Experiments

1Département de biologie moléculaire, biochimie médicale et pathologie, Faculté de médecine, Centre de recherche sur le cancer de l'Université Laval, 2Oncology, Centre de recherche du CHU de Québec, Université Laval, 3Laboratoire d'études moléculaires des valvulopathies (LEMV), Groupe de recherche en valvulopathies (GRV), Quebec Heart and Lung Institute/Research Center, 4Department of Surgery, Université Laval

JoVE 54557

 Biology

Novel Atomic Force Microscopy Based Biopanning for Isolation of Morphology Specific Reagents against TDP-43 Variants in Amyotrophic Lateral Sclerosis

1School for Engineering of Matter, Transport and Energy, Arizona State University, 2Department of Neurology, Georgetown University Medical Center, 3Department of Pathology, Georgetown University Medical Center

JoVE 52584

 Bioengineering

Automation of a Positron-emission Tomography (PET) Radiotracer Synthesis Protocol for Clinical Production

1SOFIE, 2Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), 3Ahmanson Translational Imaging Division, University of California, Los Angeles (UCLA), 4Crump Institute for Molecular Imaging, University of California, Los Angeles (UCLA)

JoVE 58428

 Chemistry

In Vitro Biochemical Assays using Biotin Labels to Study Protein-Nucleic Acid Interactions

1State Key Laboratory of Reproductive Medicine, Nanjing Medical University, 2The Affiliated Hospital of Hangzhou Normal University, 3School of Life Science and Technology, ShanghaiTech University, 4Department of Tissue and Embryology, School of Basic Medical Sciences, Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan University

JoVE 59830

 Genetics
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