25.19: Glossary: B - Biology

25.19: Glossary: B - Biology

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25.19: Glossary: B

25.19: Glossary: B - Biology

It is another term for a test-cross.

Back Mutation:

Reverse the effect of a point or frame-shift mutation that had altered a gene thus it restores the wild-type phenotype.

Bacterial Artificial Chromosome (BAC):

A chromosome-like structure, constructed by genetic engineering. BAC is a cloning vector capable of carrying between 100 and 300 kilobases of target sequence. They are propagated as a mini-chromosome in a bacterial host. The size of the typical BAC is ideal for use as an intermediate in large-scale genome sequencing projects. Entire genomes can be cloned into BAC libraries, and entire BAC clones can be shotgun-sequenced fairly rapidly.


(simply phage) A virus that infects a bacterium and which is often used in molecular genetics experiments as a vector, or cloning vehicle. Recombinant phages can be made in which certain non-essential l DNA is removed and replaced with the DNA of interest. The phage can accommodate a DNA "insert" of about 15-20 kb. Replication of that virus will thus replicate the investigator's DNA.

Balbiani Ring:

It is an extremely large puff at a band of a polytene chromosome.

A pattern of light and dark regions by Giemsa staining that can serve as landmarks on chromosomes.

In molecular biology, this term refers to the purine bases adenine and guanine, and the pyrimidine bases uracil, thymine, and cytosine, or modification of these bases.


The initial cycles of PCR during which there is little change in fluorescence signal (usually cycles 3 to 15).

Baseline value: During PCR, changing reaction conditions and environment can influence fluorescence. In general, the level of fluorescence in any one well corresponds to the amount of target present. Fluorescence levels may fluctuate due to changes in the reaction medium creating a background signal. The background signal is most evident during the initial cycles of PCR prior to significant accumulation of the target amplicon. During these early PCR cycles, the background signal in all wells is used to determine the &lsquobaseline fluorescence&rsquo across the entire reaction plate. The goal of data analysis is to determine when target amplification is sufficiently above the background signal, facilitating more accurate measurement of fluorescence.

Base Pair (bp):

One pair of complementary nucleotides within a duplex strand of a nucleic acid. Under Watson-Crick rules, these pairs consist of one pyrimidine and one purine: i.e., C-G, A-T (DNA) or A-U (RNA).

Base Sequence:

The order of nucleotide bases in a DNA molecule.

Base Sequence Analysis:

A method, sometimes automated, for determining the base sequence.

Conformation of the Watson-Crick double helix in which the two strands form a right-handed double helix.

Bidirectional Replication:

It is accomplished when two replication forks move away from the same origin in different directions.

Binding Site:

A place on cellular DNA to which a protein (such as a transcription factor) can bind.


A coenzyme which is essential for carboxylation reactions.


The determination of the activity or concentration of a chemical by its effect on the growth of an organism under experimental conditions.


It is the structure containing all the four chromatids at the start of meiosis.


In molecular biology, a method developed to inject DNA into cells by mixing the DNA with small metal particles and then firing the particles into the host cell at very high sped.


A technique for detecting one RNA within a mixture of RNAs (a Northern blot) or one type of DNA within of a mixture of DNAs (a Southern blot). Blotting involves gel electrophoresis, transfer to a blotting membrane (typically nitrocellulose or activated nylon), and incubating with a radioactive probe. Exposing the membrane to X-ray film produces darkening at a spot correlating with the position of the DNA or RNA of interest. The darker the spot, the more nucleic acid was present there.

Blunt End:

A terminus of a duplex DNA molecule which ends precisely at a base pair, with no overhang in either strand. Some but not all restriction endonucleases leave blunt ends after cleaving DNA. Blunt-ended DNA can be ligated nonspecifically to other blunt-ended DNA molecules.

Blunt End Ligation:

It is a reaction that joins two DNA duplex molecules directly at their ends.

Refers to a short nucleic acid consensus sequence or motif that is universal within kingdoms of organisms. Examples of DNA boxes are the Pribow box (TATAAT) for RNA polymerase, the Hogness box (TATA) that has a similar function in eukaryotic organisms, and the homeo box.

Branch Migration:

It descibes the ability of a DNA strand partially paired with its complement in a duplex to extend its pairing by displacing the resident strand with which it is homologous.

Anaphase - a stage in mitosis where chromosomes begin moving to opposite ends (poles) of the cell.

Animal Cells - eukaryotic cells that contain various membrane-bound organelles.

Allele - an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome.

Apoptosis - a controlled sequence of steps in which cells signal self-termination.

Asters - radial microtubule arrays found in animal cells that help to manipulate chromosomes during cell division.

Biology - the study of living organisms.

Cell - the fundamental unit of life.

Cellular Respiration - a process by which cells harvest the energy stored in food.

Cell Biology - the subdiscipline of biology that focuses on the study of the basic unit of life, the cell.

Cell Cycle - the life cycle of a dividing cell, including Interphase and the M phase or Mitotic phase (mitosis and cytokinesis).

Cell Membrane - a thin semi-permeable membrane that surrounds the cytoplasm of a cell.

Cell Theory - one of the five basic principles of biology, stating that the cell is the basic unit of life.

Centrioles - cylindrical structures that are composed of groupings of microtubules arranged in a 9 + 3 pattern.

Centromere - a region on a chromosome that joins two sister chromatids.

Chromatid - one of two identical copies of a replicated chromosome.

Chromatin - the mass of genetic material composed of DNA and proteins that condense to form chromosomes during eukaryotic cell division.

Chromosome - a long, stringy aggregate of genes that carries heredity information (DNA) and is formed from condensed chromatin.

Cilia and Flagella - protrusions from some cells that aid in cellular locomotion.

Cytokinesis - the division of the cytoplasm that produces distinct daughter cells.

Cytoplasm - all of the contents outside of the nucleus and enclosed within the cell membrane of a cell.

Cytoskeleton - a network of fibers throughout the cell's cytoplasm that helps the cell maintain its shape and gives support to the cell.

Cytosol - semi-fluid component of a cell's cytoplasm.

Daughter Cell - a cell resulting from the replication and division of a single parent cell.

Daughter Chromosome - a chromosome that results from the separation of sister chromatids during cell division.

Diploid Cell - a cell that contains two sets of chromosomes—one set of chromosomes is donated from each parent.

Endoplasmic Reticulum - a network of tubules and flattened sacs that serve a variety of functions in the cell.

Gametes - reproductive cells that unite during sexual reproduction to form a new cell called a zygote.

Gene Theory - one of the five basic principles of biology, stating that traits are inherited through gene transmission.

Genes - segments of DNA located on chromosomes that exist in alternative forms called alleles.

Golgi Complex - the cell organelle that is responsible for manufacturing, warehousing, and shipping certain cellular products.

Haploid Cell - a cell that contains one complete set of chromosomes.

Interphase - the stage in the cell cycle where a cell doubles in size and synthesizes DNA in preparation for cell division.

Lysosomes - the membranous sacs of enzymes that can digest cellular macromolecules.

Meiosis - a two-part cell division process in organisms that sexually reproduce, resulting in gametes with one-half the number of chromosomes of the parent cell.

Metaphase - the stage in cell division where chromosomes align along the metaphase plate in the center of the cell.

Microtubules - fibrous, hollow rods that function primarily to help support and shape the cell.

Mitochondria - cell organelles that convert energy into forms that are usable by the cell.

Mitosis - a phase of the cell cycle that involves the separation of nuclear chromosomes followed by cytokinesis.

Nucleus - a membrane-bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction.

Organelles - tiny cellular structures, that carry out specific functions necessary for normal cellular operation.

Peroxisomes - cell structures that contain enzymes that produce hydrogen peroxide as a by-product.

Plant Cells - eukaryotic cells that contain various membrane-bound organelles. They are distinct from animal cells, containing various structures not found in animal cells.

Polar Fibers - spindle fibers that extend from the two poles of a dividing cell.

Prokaryotes - single-celled organisms that are the earliest and most primitive forms of life on earth.

Prophase - the stage in cell division where chromatin condenses into discrete chromosomes.

Ribosomes - cell organelles that are responsible for assembling proteins.

Sister Chromatids - two identical copies of a single chromosome that are connected by a centromere.

Spindle Fibers - aggregates of microtubules that move chromosomes during cell division.

Telophase - the stage in cell division when the nucleus of one cell is divided equally into two nuclei.


Q. Do Vaccines cause Autism? I have heard all over the news lately that the vaccines we give our children can cause Autism. Is this true? Is it dangerous? Should I vaccinate my one year old son?

Andrew Wakefield MD started the controversy when publish the idea in Lancet. He was paid 130,000 dollars to lie

Check this link for full story:

Q. Who Should Receive the Flu Vaccine? Should I go get vaccinated for the flu? I have been told it is advised only for certain people, so who should receive this vaccine?

A. before you would like to go on with any vaccination, you should check out this very long list of links and create your own opinion:

at the bottom you will also find links in english. vaccinations in general are very disputable/dubious and it is probably time that we learn about it.

Q. Does the flu vaccine protect from all kinds of flu? If I get a flu vaccine does that mean I am completely protected from getting the flu?


the tendency of biological systems to maintain relatively constant conditions in the internal environment while continuously interacting with and adjusting to changes originating within or outside the system. See also balance and equilibrium . adj., adj homeostat´ic. The term is considered by some to be misleading in that the word element- stasis implies a static or fixed and unmoving state, whereas homeostasis actually involves continuous motion, adaptation, and change in response to environmental factors.

It is through homeostatic mechanisms that body temperature is kept within normal range, the osmotic pressure of the blood and its hydrogen ion concentration (pH) is kept within strict limits, nutrients are supplied to cells as needed, and waste products are removed before they accumulate and reach toxic levels of concentration. These are but a few examples of the thousands of homeostatic control systems within the body. Some of these systems operate within the cell and others operate within an aggregate of cells (organs) to control the complex interrelationships among the various organs.

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25.19: Glossary: B - Biology

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For a complete list of acronyms only, go to Acronym List.

"A0" is a convenient way to refer to a new, renewal or revision application that has not been amended following the review of an application with the same project number.

The A1 suffix is typically seen as part of an application identification number or grant number and “A1” is often used to refer to a new, renewal, or revision application that is amended and resubmitted after the review of a previous application with the same project number.

A grant meeting the following criteria:

  1. Today's date is between the budget start and end dates.
  2. The grant has an eRA System (IMPAC II) application status code of "Awarded. Non-fellowships only." or "Awarded. Fellowships only."

Expenses incurred for the support of activities relevant to the award of grants, contracts, and cooperative agreements and expenses incurred for general administration of the scientific programs and activities of the National Institutes of Health.

The NIH Institute or Center (IC) to which the Center for Scientific Review (CSR) routes NIH grant applications for a funding decision. An IC may request to change this assignment if the application is more suited to another IC. Also referred to as primary assignment.

  • May be the same person as the signing official.
  • Resides in either the central research administration office or academic departments.
  • Create additional AO and PI accounts
  • Not authorized to transmit applications to the NIH.

A request for (or the award of) additional funds during a current project period to provide for an increase in costs due to unforeseen circumstances. All additional costs must be within the scope of the peer reviewed and approved project.

Includes: (1) projects relating to the etiology, epidemiology, natural history, diagnosis, treatment, or prevention of AIDS (2) various sequelae specifically associated with the syndrome and (3) preparation and screening of anti-AIDS agents as well as vaccine development, including both preclinical and clinical studies. Not all applications examining various influences on T-lymphocytes or retroviruses will be appropriate for the expedited AIDS review process. Applications only indirectly related to AIDS will be evaluated by established Scientific Review Groups (SRGs) appropriate to the scientific discipline during regular NIH review cycles and should not be submitted in response to the expedited AIDS receipt dates. Applicants are urged to take note of the yearly NIH Plan for HIV-Related Research and indicate how their application addresses the NIH priorities set forth in that Plan.  The Plan can be found on the NIH Office of AIDS Research homepage

A cost incurred by a recipient that is: (1) reasonable for the performance of the award (2) allocable (3) in conformance with any limitations or exclusions set forth in the Federal cost principles applicable to the organization incurring the cost or in the NoA as to the type or amount of cost (4) consistent with regulations, policies, and procedures of the recipient that are applied uniformly to both federally supported and other activities of the organization (5) accorded consistent treatment as a direct or indirect cost (6) determined in accordance with generally accepted accounting principles and (7) not included as a cost in any other federally supported award (unless specifically authorized by statute).

An ancillary study is an adjunctive or supplemental study to an ongoing study. An ancillary study may or may not be a clinical trial. Determine whether an ancillary study is a clinical trial by answering the four questions that define NIH clinical trials based on the information about the ancillary study alone, regardless of the clinical trial status of the parent trial. An ancillary clinical trial is a trial for which the answer to the four questions is ‘Yes’.

An ancillary clinical trial to a larger clinical trial may be considered an independent clinical trial if it includes an additional intervention to patients or a sub-population of patients within the larger clinical trial. An example of an ancillary study that is not a clinical trial could be research which involves analyses of stored samples collected in an ongoing clinical trial but no additional intervention to the human subjects/patients.

NIH accepts applications for most programs in three cycles. The applications received within a cycle are typically reviewed within the same council round. Many NIH Funding Opportunity Announcements are open for up to three years with standard due dates falling in each cycle.

  • type of application (1)
  • activity code (R01)
  • organization to which it is assigned (AI)
  • serial number assigned by the Center for Scientific Review (CSR) (183723),
  • suffix showing the support year for the grant (-01)
  • other information identifying a revision (S1), resubmission (A1), or a fellowship's institutional allowance. For contracts, the suffix is replaced by a modification number.

The Application Submission System & Interface for Submission Tracking (ASSIST) is a web-based system used to prepare grant applications using the SF424 Research & Related form set and to submit electronically through to NIH and other participating agencies. See Preparing Your Application Using ASSIST.

A single-digit code identifying the type of application received and processed. Application type codes include the following:

8=Change of Institute or Division (Type 5 transfer to another NIH IC)

9=Change of Institute or Division (Type 2 transfer to another NIH IC) 

Once an error-free application is submitted through to eRA, the eRA system assembles an application image and posts it in the PD/PI's eRA Commons account. The PD/PI, delegated Assistants, Administrative Officials (AOs) and Signing Officials (SOs) have 2 business days to view the assembled application in eRA Commons - just as a reviewer would see it. The application viewing window is linked to the time of submission, not the due date. It begins the day after the assembled application image is posted in eRA Commons and excludes weekends and Federal holidays.

Within the viewing window, an SO can Reject the application and stop it from moving further in the process. After the viewing window, the application automatically moves forward for further consideration and the submission process is complete.

An individual having prior substantial funding from NIH and, unless successful in securing a substantial research grant award in the current fiscal year, will have no substantial research grant funding in the following fiscal year.  

The dollar amount a grant award is reduced from the amount recommended by the study section (scientific review group). This is done so Institutes can maintain a sufficient number of grants in their portfolio and to combat inflation of grant costs.

Studies that prospectively assign human participants to conditions (i.e., experimentally manipulate independent variables) and that assess biomedical or behavioral outcomes in humans for the purpose of understanding the fundamental aspects of phenomena without specific application towards processes or products in mind.

Awards for candidates who wish to further develop their careers in biomedical, behavioral and clinical research. Applicants are generally required to hold a research or health&ndashprofessional doctoral degree or its equivalent eligibility for some CDAs is limited to only applicants with health professional doctoral degrees. See Career Development Awards.

The NIH component responsible for the receipt and referral of grant applications to the PHS, as well as the initial review for scientific merit of most applications submitted to the NIH.

As of July 2012, Central Contractor Registry (CCR) has been replaced with the System for Awards Management (SAM).

For the purposes of the NIH Policy and Guidelines on the Inclusion of Individuals Across the Lifespan as Participants in Research Involving Human Subjects, a child is defined as an individual under the age of 18 years. The intent of the NIH policy is to provide the opportunity for individuals, including children and older adults, to participate in research studies when there is a sound scientific rationale for including them and participation is appropriate under existing Federal guidelines. Thus, children must be included in NIH-conducted or supported human subjects research unless there are scientific or ethical reasons not to include them.

For the purpose of providing consent for research participation, the definition of a child stated within the DHHS Regulations (45 CFR part 46, Subpart D, Sec. 402) should be applied. Please see the NIH Human Subjects website or 45 CFR 46, Subpart D for more information.

Research with human subjects that is:

1) Patient-oriented research. Research conducted with human subjects (or on material of human origin such as tissues, specimens, and cognitive phenomena) for which an investigator (or colleague) directly interacts with human subjects. Excluded from this definition are in vitro studies that utilize human tissues that cannot be linked to a living individual. It includes: (a) mechanisms of human disease, (b), therapeutic interventions, (c) clinical trials, or (d) development of new technologies.

2) Epidemiological and behavioral studies.

3) Outcomes research and health services research

Studies falling under 45 CFR 46.101(b) (4) (Exemption 4) are not considered clinical research by this definition. 

A research study in which one or more human subjects are prospectively assigned to one or more interventions (which may include placebo or other control) to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes.

See Common Rule definition of research at 45 CFR 46.102(d)

See Common Rule definition of human subject at 45 CFR 46.102(f)

The term "prospectively assigned" refers to a pre-defined process (e.g., randomization) specified in an approved protocol that stipulates the assignment of research subjects (individually or in clusters) to one or more arms (e.g., intervention, placebo or other control) of the clinical trial.

An intervention is defined as a manipulation of the subject or subject's environment for the purpose of modifying one or more health-related processes and/or endpoints. Examples include, but are not limited, to: drugs/small molecules/compounds, biologics, devices procedures (e.g., surgical techniques) delivery systems (e.g., telemedicine, face-to-face) strategies to change health-related behavior (e.g., diet, cognitive therapy, exercise, development of new habits) and, treatment, prevention, and diagnostic strategies.

A health-related biomedical or behavioral outcome is defined as the pre-specified effect of an intervention on the study subjects. Examples include positive or negative changes to physiological or biological parameters (e.g., improvement of lung capacity, gene expression) psychological or neurodevelopmental parameters (e.g., mood management intervention for smokers reading comprehension and/or information retention) disease processes health-related behavior and, well-being or quality of life

Biomedical clinical trials of an experimental drug, treatment, device, or behavioral intervention may proceed through four phases:

Phase I. Tests a new biomedical intervention in a small group of people (e.g. 20-80) for the first time to determine efficacy and evaluate safety (e.g., determine a safe dosage range and identify side effects).

Phase II. Study the biomedical or behavioral intervention in a larger group of people (several hundred) to determine efficacy and further evaluate safety.

Phase III. Study to determine efficacy of the biomedical or behavioral intervention in large groups of people (from several hundred to several thousand) by comparing the intervention to other standard or experimental interventions as well as to monitor adverse effects, and to collect information that will allow the interventions to be used safely.

Phase IV. Studies conducted after the intervention has been marketed. These studies are designed to monitor the effectiveness of the approved intervention in the general population and to collect information about any adverse effects associated with widespread use. 

The involvement of a student, postdoctorate, or early career faculty member in a clinical trial led by their mentor or other investigator, with the goal of obtaining clinical trial experience relevant to their research interests and career goals. A clinical trial research experience is one in which the participant is supervised by a more experienced investigator and is intended to prepare the participant to potentially lead an independent clinical trial in the future. The applicant can be part of the clinical trial team and can use the data generated during the clinical trial research experience in his/her proposed research project. NIH expects the mentor to assume overall responsibility of the trial including registering and reporting in and obtaining IRB approval.

The Close Date of a funding opportunity announcement is the date the funding agency lists in as the last submission due date for the announcement.

  • identifying information (such as name or social security number) that would enable the investigator to readily ascertain the identity of the individual to whom the private information or specimens pertain has been replaced with a number, letter, symbol or combination thereof (i.e., the code) and
  • a key to decipher the code exists, enabling linkage of the identifying information with the private information or specimens.

Research that involves only coded private information/data or coded human biological specimens may not constitute human subjects research under the HHS human subjects regulations (45 CFR 46) if:

  • the specimens and/or information/data are not obtained from an interaction/intervention with the subject specifically for the research and
  • the investigator(s) cannot readily ascertain the identity of the individual(s) to whom the coded private information or specimens pertain (e.g., the researcher's access to subject identities is prohibited).

Individuals who provide coded information or specimens for proposed research and who also collaborate on the research involving such information or specimens are considered to be involved in the conduct of human subject research.

(See the following guidance from the Office for Human Research Protections (OHRP) for additional information and examples:

See  Council on Financial Assistance Reform

NIH CMO: The NIH Committee Management Officer is responsible for managing the implementation of the Federal Advisory Committee Act. The NIH CMO is responsible for developing and managing all committee management policy and procedure development for dissemination to all NIH IC staff as well as to Federal advisory committee members. The CMO reviews and finalizes all advisory committee charters and nomination slates for approval by the Secretary, DHHS or the Director, NIH and insures an accurate presentation of NIH committee activity on a public website managed by the General Services Administration.

I/C CMO: Each IC has a CMO or uses the resources of a service center to support the committee management function within the Institute or Center. The IC CMO is responsible for developing charters for committees, preparing nomination and appointment documents for membership to committees, providing technical assistance to committee members, providing initial review of conflict of interest disclosures and other responsibilities.

A set of FOAs that share a unified theme or initiative. These FOAs may use different activity codes. They are typically (but not always) published concurrently.

Featured Faculty

Stephen Schaeffer

2020 Graduate Program Chair Leadership Award

2019 Dean's Distinguished Faculty Mentoring Award

2016 Dean's Climate and Diversity Award

Michael Axtell

Beckman Young Investigator

Nita Bharti

Branco Weiss-Society in Science Fellow

Huck Early Career Professorship Chair

Color-related genes help explain how there are so many species of warblers

Elizabeth McGraw has been named head of the Department of Biology, effective April 1.

The new Center for Parasitic and Carnivorous Plants, led by Professor of Biology Claude dePamphilis, houses the world’s largest formal group of researchers studying these unique plants.

An international team explores how vector-borne diseases have influenced human history, with particular attention to how they have reinforced and exacerbated racism.

Glossary of Nuclear Science Terms

Absorber Any material that stops ionizing radiation. Lead, concrete, and steel attenuate gamma rays. A thin sheet of paper or metal will stop or absorb alpha particles and most beta particles. Alpha particle (alpha radiation, alpha ray) A positively charged particle (a Helium-4 nucleus) made up of two neutrons and two protons. It is the least penetrating of the three common forms of radiation, being stopped by a sheet of paper. It is not dangerous to living things unless the alpha-emitting substance is inhaled or ingested or comes into contact with the lens of the eye. Atom A particle of matter indivisible by chemical means. It is the fundamental building block of elements. Atomic number The number assigned to each element on the basis of the number of protons found in the element's nucleus. Atomic weight (atomic mass) Approximately the sum of the number of protons and neutrons found in the nucleus of an atom.

- B -

Background radiation The radiation of man's natural environment originating primarily from the naturally radioactive elements of the earth and from the cosmic rays. The term may also mean radiation extraneous to an experiment. Beta particle (beta radiation, beta ray) An electron of either positive charge (ß+) or negative charge (ß-), which has been emitted by an atomic nucleus or neutron in the process of a transformation. Beta particles are more penetrating than alpha particles but less than gamma rays or x-rays.

- C -

Contamination Radioactive material deposited or dispersed in materials or places where it is not wanted. Cow A radioisotope generator system. Curie (Ci) The basic unit used to describe the intensity of radioactivity in a sample of material. One curie equals thirty-seven billion disintegrations per second, or approximately the radioactivity of one gram of radium.

- D -

Daughter A nucleus formed by the radioactive decay of a different (parent) nuclide. Decay (radioactive) The change of one radioactive nuclide into a different nuclide by the spontaneous emission of alpha, beta, or gamma rays, or by electron capture. The end product is a less energetic, more stable nucleus. Each decay process has a definite half-life. Decontamination The removal of radioactive contaminants by cleaning and washing with chemicals. Density That property of a substance which is expressed by the ratio of its mass to its volume. Dose A general term denoting the quantity of radiation or energy absorbed in a specific mass.

- E -

Electromagnetic radiation Radiation consisting of electric and magnetic waves that travel at the speed of light. Examples: light, radio waves, gamma rays, x-rays. Electron An elementary particle with a unit electrical charge and a mass 1/1837 that of the proton. Electrons surround the atom's positively charged nucleus and determine the atom's chemical properties. Electron capture A radioactive decay process in which an orbital electron is captured by and merges with the nucleus. The mass number is unchanged, but the atomic number is decreased by one. Eluant Washing solution (The solution that is introduced into the cow). Eluate The washings obtained by elution (the solution that comes out of the cow). Elute To separate by washing (to milk). Excited state The state of an atom or nucleus when it possesses more than its normal energy. The excess energy is usually released eventually as a gamma ray.

- F -

Fission The splitting of a heavy nucleus into two roughly equal parts (which are nuclei of lighter elements), accompanied by the release of a relatively large amount of energy in the form of kinetic energy of the two parts and in the form of emission of neutrons and gamma rays. Fission products Nuclei formed by the fission of heavy elements. They are of medium atomic weight and almost all are radioactive. Examples: strontium-90, cesium-137.

- G -

Gamma ray A highly penetrating type of nuclear radiation, similar to x-radiation, except that it comes from within the nucleus of an atom, and, in general, has a shorter wavelength. Geiger counter A Geiger-Müller detector and measuring instrument. It contains a gas-filled tube which discharges electrically when ionizing radiation passes through it and a device that records the events. Generator A cow-a system containing a parent-daughter set of radioisotopes in which the parent decays through a daughter to a stable isotope. The daughter is a different element from that of the parent, and, hence, can be separated from the parent by elution (milking).

- H -

Half-life The time in which half the atoms of a particular radioactive nuclide disintegrate. The half-life is a characteristic property of each radioactive isotope. Health physics That science devoted to recognition, evaluation, and control of all health hazards from ionizing radiation.

- I -

Induced radioactivity Radioactivity that is created by bombarding a substance with neutrons in a reactor or with charged particles produced by particle accelerators. Ion An atomic particle that is electrically charged, either negative or positive. Ionizing radiation Radiation that is capable of producing ions either directly or indirectly. Irradiate To expose to some form of radiation. Isomer One of several nuclides with the same number of neutrons and protons capable of existing for a measurable time in different nuclear energy states. Isometric transition A mode of radioactive decay where a nucleus goes from a higher to a lower energy state. The mass number and the atomic number are unchanged. Isotope Isotopes of a given element have the same atomic number (same number of protons in their nuclei) but different atomic weights (different number of neutrons in their nuclei). Uranium-238 and uranium-235 are isotopes of uranium.

- K -

K-capture The capture by an atom's nucleus of an orbital electron from the first K-shell surrounding the nucleus. keV One thousand electron volts.

- L -

- M -

MeV One million electron volts. Microcurie (µCi) One millionth of a curie (3.7 x 10 4 disintegrations per second). Milk To elute a cow. Minigenerator A trademark of Union Carbide Corporation that is used to identify radioisotope generator systems for educational use.

- N -

Neutrino An electrically neutral particle with negligible mass. It is produced in many nuclear reactions such as in beta decay. Neutron One of the basic particles which make up an atom. A neutron and a proton have about the same weight, but the neutron has no electrical charge. Nuclear reactor A device in which a fission chain reaction can be initiated, maintained, and controlled. Its essential components are fissionable fuel, moderator, shielding, control rods, and coolant. Nucleon A constituent of the nucleus that is, a proton or a neutron. Nucleonics The science, technology, and application of nuclear energy. Nucleus The core of the atom, where most of its mass and all of its positive charge is concentrated. Except for hydrogen, it consists of protons and neutrons. Nuclide Any species of atom that exists for a measurable length of time. A nuclide can be distinguished by its atomic weight, atomic number, and energy state.

- O -

- P -

Parent A radionuclide that decays to another nuclide which may be either radioactive or stable. Photon A quantity of electromagnetic energy. Photons have momentum but no mass or electrical charge. Proton One of the basic particles which makes up an atom. The proton is found in the nucleus and has a positive electrical charge equivalent to the negative charge of an electron and a mass similar to that of a neutron: a hydrogen nucleus.

- Q -

- R -

Rad Radiation Absorbed Dose. The basic unit of an absorbed dose of ionizing radiation. One rad is equal to the absorption of 100 ergs of radiation energy per gram of matter. Radioactive dating A technique for estimating the age of an object by measuring the amounts of various radioisotopes in it. Radioactive waste Materials which are radioactive and for which there is no further use. Radioactivity The spontaneous decay of disintegration of an unstable atomic nucleus accompanied by the emission of radiation. Radioisotope A radioactive isotope. A common term for a radionuclide. Radionuclide A radioactive nuclide. An unstable isotope of an element that decays or disintegrates spontaneously, emitting radiation. Rate meter An electronic instrument that indicates, on a meter, the number of radiation induced pulses per minute from radiation detectors such as a Geiger-Muller tube.

- S -

Scaler An electronic instrument for counting radiation induced pulses from radiation detectors such as a Geiger-Muller tube. Scintillation counter An instrument that detects and measures gamma radiation by counting the light flashes (scintillations) induced by the radiation. Secular equilibrium A state of parent-daughter equilibrium which is achieved when the half-life of the parent is much longer than the half-life of the daughter. In this case, if the two are not separated, the daughter will eventually be decaying at the same rate at which it is being produced. At this point, both parent and daughter will decay at the same rate until the parent is essentially exhausted. Shielding A protective barrier, usually a dense material, which reduces the passage of radiation from radioactive materials to the surroundings. Source A radioactive material that produces radiation for experimental or industrial use. Spill The accidental release of radioactive materials. Stable Non-radioactive.

- T -

Tracer A small amount of radioactive isotope introduced into a system in order to follow the behavior of some component of that system. Transmutation The transformation of one element into another by a nuclear reaction.


Home Last Updated 11/18/04

Carbon-nutrient stoichiometry to increase soil carbon sequestration

The more stable fine fraction pool of soil organic matter (FF-SOM <0.4 mm) has more nitrogen, phosphorus and sulphur (N, P, S) per unit of carbon (C) than the plant material from which it originates and has near constant ratios of C:N:P:S. Consequently, we hypothesised that the sequestration of C-rich crop residue material into the FF-SOM pool could be improved by adding supplementary nutrients to the residues based on these ratios. Here we report on the effect of N, P and S availability on the net humification efficiency (NHE), the change in the size of the FF-SOM pool (as estimated by fine fraction C (FF-C)), following incubation of soil with wheaten straw. Four diverse soils were subjected to seven consecutive incubation cycles, with wheaten straw (10 t ha −1 equivalent) added at the beginning of each cycle, with and without inorganic N, P, S addition (5 kg N, 2 kg P and 1.3 kg S per tonne of straw). This nutrient addition doubled the mean NHE in all soils (from 7% to 15%) and when applied at twice the rate increased NHE further (up to 29%) for the two soils that received this treatment. The FF-N, -P and -S levels increased in concert with FF-C levels in all soils in close agreement with published stoichiometric ratios (C:N:P:S = 10,000:833:200:143). Microbial biomass-C (MB-C) levels were estimated during one incubation cycle and found to increase in parallel with FF-C from 448 μg MB-C g −1 soil (no nutrient addition) to 727 μg MB-C g −1 soil (plus nutrients) and 947 μg MB-C g −1 soil (plus 2× nutrients). There was a significant relationship between MB-C and the change in FF-C during that incubation cycle, providing evidence of a close relationship between the microbial biomass and FF-SOM formation. The two to four-fold increases in NHE achieved with nutrient addition demonstrated that inorganic nutrient availability is critical to sequester C into the more stable FF-SOM pool irrespective of soil type and C input. This has important implications for strategies to build soil fertility or mitigate climate change via increased soil organic C, as the availability and value of these nutrients must be considered.


► Hypothesis: nutrient availability (NPS) not just C inputs can limit humus formation. ► Supplementary nutrient addition doubled the humification efficiency. ► The humus-N, -P and -S levels increased in concert with humus-C levels. ► Nutrient availability is critical to the sequestering of C into soil humus fraction. ► Implications for strategies to increase long-term C sequestration in soils.

List of 10 Important Bacterial Diseases | Human Health | Biology

List of ten important bacterial diseases: 1. Pulmonary Tuberculosis 2. Diphtheria 3. Cholera 4. Leprosy 5. Pertussis 6. Tetanus 7. Plague 8. Gonorrhoea 9. Syphilis 10. Salmonellosis.

Bacterial Disease # 1. Pulmonary Tuberculosis:

Pathogen – Mycobacterium tuberculae

Epidemiology – Airborne & Droplet infection

Incubation Period – 2-10 weeks

Symptoms – Coughing chest pain and bloody sputum with tuberculin.

Prophylaxis – BCG vaccine Isolation, Health education.

Therapy – Streptomycin, para-amino salicylic acid, rifampicin etc.

Bacterial Disease # 2. Diphtheria:

Pathogen – Corynebacterium diphtheriae

Epidemiology – Airborne & Droplet infection

Incubation Period – 2-6 days

Symptoms – Inflammation of mucosa of nasal chamber, throat etc. respiratory tract blocked.

Therapy – Diphtheria antitoxins, Penicillin, Erythromycin.

Bacterial Disease # 3. Cholera:

Pathogen – Vibrio cholerae

Epidemiology – Direct & oral (with contaminated food & water)

Incubation Period – 6 hours to 2 – 3 days

Symptoms – Acute diarrhoea & dehydration.

Prophylaxis – Sanitation, boiling of water & cholera vaccine.

Therapy – Oral rehydration therapy & tetracycline.

Bacterial Disease # 4. Leprosy (Hansen’s Disease):

Pathogen – Mycobacterium leprae

Epidemiology – Slowest infectious & contagious

Incubation Period – 2-5 years

Symptoms – Skin hypopigmentation, nodulated skin, deformity of fingers & toes. Lepromin in skin tests.

Therapy – Dapsone, rifampicin, Clofazimine.

Bacterial Disease # 5. Pertussis (Whooping Cough):

Pathogen – Bordetella pertussis

Epidemiology – Contagious & Droplet infection

Incubation Period – 7-14 days

Symptoms – Whoops during inspiration.

Bacterial Disease # 6. Tetanus (Lock Jaw):

Pathogen – Clostridium tetani

Epidemiology – Through injury

Incubation Period – 3-21 days

Symptoms – Degeneration of motor neurons, rigid jaw muscles, spasm and paralysis.

Prophylaxis – ATS and DPT vaccines.

Therapy – Tetanus- antitoxins.

Bacterial Disease # 7. Plague:

Pasteurella (or Yersinia) pestis

Epidemiology – Indirect & inoculative (vector is rat flea)

Incubation Period – 2-6 days

Symptoms – Bubonic plague affects lymph nodes Pneumonic plague affects lungs and Septicemic plague causes anaemia.

Prophylaxis – Killing of rats & ratfleas, Plague- vaccine.

Therapy – Tetracycline, streptomycin, Chloromycetin.

Bacterial Disease # 8. Gonorrhoea:

Pathogen – Neisseria gonorrhoeae

Epidemiology – Sexual transmission

Incubation Period – 2-10 days

Symptoms – Inflammation of urinogenital tract.

Prophylaxis – Avoid prostitution.

Therapy – Penicillin & Ampicillin.

Bacterial Disease # 9. Syphilis:

Pathogen – Treponema pallidum

Epidemiology – Sexual transmission

Incubation Period – 3 weeks

Symptoms – Inflammation of urinogenital tract.

Prophylaxis – Avoid prostitution.

Therapy – Tetracycline & penicillin.

Bacterial Disease # 10. Salmonellosis:

Pathogen – Salmonella enteridis.

Epidemiology – Direct & oral

Incubation Period – 48 hours

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