Show Advanced Search


Containing Text
- - -
Filter by author or institution
Filter by publication date
October, 2006
Filter by journal section

Filter by science education

Oxygen: An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.

Dissolved Oxygen in Surface Water

JoVE 10016

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University

Dissolved oxygen (DO) measurements calculate the amount of gaseous oxygen dissolved in surface water, which is important to all oxygen-breathing life in river ecosystems, including fish species preferred for human consumption (e.g. bluegill and bass),…

 Environmental Science

Stoichiometry, Product Yield, and Limiting Reactants- Concept

JoVE 11141

Chemical equations represent how a chemical reaction proceeds from reactants to products through physical or chemical change using chemical formulas.

Stoichiometry is a term that describes the relative quantities of reactants and products in a chemical reaction. It is based on the Law of Conservation of Mass, which is a fundamental law that states that matter is neither created…

 Lab: Chemistry

Detecting Reactive Oxygen Species

JoVE 5654

Reactive oxygen species are chemically active, oxygen-derived molecules capable of oxidizing other molecules. Because of their reactive nature, there are many deleterious effects associated with unchecked ROS production, including structural damage to DNA and other biological molecules. However, ROS can also be mediators of physiological signaling. There is accumulating…

 Cell Biology

Synthesis of an Oxygen-Carrying Cobalt(II) Complex

JoVE 10430

Source: Deepika Das, Tamara M. Powers, Department of Chemistry, Texas A&M University

Bioinorganic chemistry is the field of study that investigates the role that metals play in biology. Approximately half of all proteins contain metals and it is estimated that up to one third of all proteins rely on metal-containing active sites to…

 Inorganic Chemistry

Cellular Respiration- Concept

JoVE 10567

Autotrophs and Heterotrophs

Living organisms require a continuous input of energy to maintain cellular and organismal functions such as growth, repair, movement, defense, and reproduction. Cells can only use chemical energy to fuel their functions, therefore they need to harvest energy from chemical bonds of biomolecules, such as sugars and lipids. Autotrophic organisms, namely…

 Lab Bio

Redox Reactions- Concept

JoVE 11144

Oxidation and Reduction

Some chemical reactions can be classified as reduction-oxidation reactions, or redox reactions. Oxidation is the process of an atom losing one or more electrons, and reduction is the process of an atom gaining one or more electrons.

Oxidation States

Each atom in a molecule has its own oxidation state or oxidation number. The oxidation state…

 Lab: Chemistry

Physiology of the Circulatory System- Concept

JoVE 10625


Conditions in the external environment of an organism can change rapidly and drastically. To survive, organisms must maintain a fairly constant internal environment, which involves continuous regulation of temperature, pH, and other factors. This balanced state is known as homeostasis, which describes the processes by which organisms maintain their optimal internal…

 Lab Bio

Gas Exchange and Transport

JoVE 10884

Gas exchange, the intake of molecular oxygen (O2) from the environment and the outflow of carbon dioxide (CO2) into the environment, is necessary for cellular function. Gas exchange during respiration occurs largely via the movement of gas molecules along pressure gradients. Gas travels from areas of higher partial pressure to areas of lower partial pressure. In mammals, gas exchange occurs in the alveoli of the lungs, which are adjacent to capillaries and share a membrane with them. When the lungs expand, the resultant decrease in pressure relative to the atmosphere draws oxygen into the lungs. Air entering the lungs from the environment has a higher oxygen concentration and a lower carbon dioxide concentration than the oxygen-depleted blood that travels from the heart to the lungs. Thus, oxygen diffuses from the alveoli to the blood in the capillaries, where it can be delivered to tissue. Carbon dioxide, by contrast, diffuses from the capillaries to the alveoli, where it can be expelled through exhalation. Gas flow is determined by the pressure gradient of each gas, with each gas moving down its gradient. The pressure exerted by an individual gas in a mixture of gases is its partial pressure, and each gas moves from a higher to a lower partial pressure. Thus, the movement of O2 and CO2 are not directly related

 Core: Biology

Chemical Reactions

JoVE 10662

A chemical reaction is a process by which the bonds in the atoms of substances are rearranged to generate new substances. Matter cannot be created or destroyed in a chemical reaction—the same type and number of atoms that make up the reactants are still present in the products. Merely the rearrangement of chemical bonds produces new compounds.

A chemical reaction takes starting materials—the reactants—and changes them into different substances—the products. The identities of the elements are the same on both sides of the equation, but they are arranged in different substances after the reaction takes place. In chemical reactions, the bonds between the atoms are broken and reformed which means that the shared electrons among the atoms are rearranged. Reactions can be spontaneous, or they might only occur in the presence of an energy source—such as heat or light. Additionally, macromolecules can act as enzymes—catalysts that greatly speed up chemical reactions. Most biological reactions would take far too long to complete without enzymes. Some types of reactions will proceed irreversibly until all of the reactants are used up, while others are reversible, with the products able to be converted back into the reactants if conditions change. Certain types of chemical reactions, such as combustion reactions or precipitation r

 Core: Biology
More Results...