Biology : Credo Topic Pages for Biology

Molecular Biology is the study of the molecular basis of life, particularly using modern methods of working with DNA, to look at the structure and function of the components of living cells and to answer wider biological questions.

Condition in which the concentration of hemoglobin in the circulating blood is below normal.

Basic biological unit of which all plant and animal tissues are composed.

In biology, process by which substances are taken into the cell.

Maintenance of a constant environment within and around living cells, particularly with regard to pH, salt concentration, temperature, and blood sugar levels.

Process of nuclear division in a living cell by which the number of chromosomes is reduced to half the original number.

Cytoplasmic organelle of all eukaryotic cells engaging in aerobic respiration, and the source of most ATP in those cells.

Process of nuclear division in a living cell by which the carriers of hereditary information, or the chromosomes, are exactly replicated and the two copies distributed to identical daughter nuclei.

Transfer of a liquid solvent through a semipermeable membrane that does not allow dissolved solids (solutes) to pass. Osmosis refers only to transfer of solvent; transfer of solute is called dialysis.

Genetics is the branch of biology that studies heredity.

From Gale Encyclopedia of Public Health
Genomics is the study of a genome, the complete collection of genes present in an organism.

From the Encyclopedia of the Human Genome
The development and/or application of computational tools and approaches for expanding the use of biological data, including those to acquire, store, organize, archive, analyze or visualize such data.

One of two or more alternative forms of a gene at a given position (locus) on a chromosome, caused by a difference in the sequence of DNA. This is best explained with examples.

Structures in a cell nucleus that carry the many thousands of genes, in sequence, that determine the characteristics of an organism. There are 46 chromosomes in a normal human cell.

Exact replica - in genetics, any one of a group of genetically identical cells or organisms. An identical twin is a clone; so too are bacteria living in the same colony.

The process of asexual reproduction observed, for example, in bacteria and other unicellular micro-organisms which divide by simple fission, so that the daughter cells are genetically identical to each other and to the parent (except when mutation occurs). In higher organisms, genetically identical individuals may be produced by cloning.

Molecular basis of heredity. It is a complex giant molecule that contains, in chemically coded form, the information needed for a cell to make proteins.

Study of human genetics and of methods to improve the inherited characteristics, physical and mental, of the human race.

Basic unit of inherited material, encoded by a strand of DNA and transcribed into RNA. In higher organisms, genes are located on linear chromosomes.

All-inclusive term that describes the deliberate manipulation of genetic material by biochemical techniques. It is often achieved by the introduction of new DNA, usually by means of a virus or plasmid. This can be for pure research, gene therapy, or to breed functionally specific plants, animals, or bacteria.

Or DNA profiling, any of several similar techniques for analyzing and comparing DNA from separate sources, used especially in law enforcement to identify suspects from hair, blood, semen, or other biological materials found at the scene of a violent crime

Transmission from generation to generation through the process of reproduction in plants and animals of factors which cause the offspring to resemble their parents. That like begets like has been a maxim since ancient times.

he Human Genome Project is a huge international scientific project that began in 1990. Its aim is to map all the genes on the human chromosomes.

In genetics, a stretch of DNA that interrupts the coding parts (exons) of a gene but apparently carries no genetic information. Introns, discovered in 1977, are at first transcribed into messenger RNA (mRNA) but removed before translation.

In biology, a sudden, random change in a gene, or unit of hereditary material, that can alter an inheritable characteristic.

Any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis.

Allele (alternative form of a gene) that will show in the (phenotype observed characteristics of an organism) only if its partner allele on the paired chromosome is identical. Such an allele will not show if its partner is of a different, dominant type, that is if the organism is heterozygous for a particular characteristic.

Process of "shuffling" of genes by which new combinations can be generated.

The process by which a living organism produces other organisms more or less similar to itself.

Reproduction that does not involve the manufacture and fusion of sex cells (gametes) from two parents.

Name for the developing young of an animal or plant. In its widest definition, the embryo is the young from the moment of fertilization until it has become structurally complete and able to survive as a separate organism.

In sexual reproduction, the union of two gametes (sex cells, often called egg or ovum, and sperm) to produce a zygote, which combines the genetic material contributed by each parent.

Organ that attaches the developing embryo or fetus to the uterus (womb) in placental mammals (mammals other than marsupials, platypuses, and echidnas).

In biology, the male gamete of animals before fertilization in sexual reproduction.

The study of the classification and nomenclature of organisms. The principles of taxonomy were established in the 18th century by the work of Linnaeus.

Method of biological classification that uses a formal step-by-step procedure for objectively assessing the extent to which organisms share particular characteristics, and for assigning them to taxonomic groups called clades.

[Lat.,=pore bearer], animal phylum consisting of the organisms commonly called sponges.

From Gale Encyclopedia of Nursing and Allied Health:
Microbiology is the scientific study of microorganisms.

Virology is the study of viruses and their role in disease.

Acute infectious disease of animals that can be secondarily transmitted to humans. It is caused by a bacterium (Bacillus anthracis) that primarily affects sheep, horses, hogs, cattle, and goats and is almost always fatal in animals.

Protein molecule produced in the blood by lymphocytes in response to the presence of foreign or invading substances (antigens); such substances include the proteins carried on the surface of infecting micro-organisms.

Microscopic single-celled organisms lacking a membrane-bound nucleus. Bacteria, like archaea, certain fungi, and viruses, are micro-organisms - organisms that are so small they can only be seen using a microscope.

Acute viral infection of the mucous membranes of the nose and throat, often involving the sinuses. The typical sore throat, sneezing, and fatigue may be accompanied by body aches, headache, low fever, and chills.

Ability of an organism to resist disease by identifying and destroying foreign substances or organisms. Although all animals have some immune capabilities, little is known about nonmammalian immunity.

Branch of medicine that studies the response of organisms to foreign substances, e.g., viruses, bacteria, and bacterial toxins.

Or flu, acute, highly contagious disease caused by a virus; formerly known as the grippe. There are three types of the virus, designated A, B, and C, but only types A and B cause more serious contagious infections.

Infectious parasitic disease of the tropics transmitted by mosquitoes, marked by periodic fever and an enlarged spleen.

Any of a group of chemically similar substances obtained from molds of the genus Penicillium that were the first antibiotic agents to be used successfully in the treatment of bacterial infections in humans.

Term applied to any epidemic disease with a high mortality rate, but it usually refers to bubonic plague. This is a disease transmitted by fleas (carried by the black rat), which infect the sufferer with the bacillus Yersinia pestis.

Viral disease of the central nervous system that can afflict all warm-blooded creatures. It is caused by a lyssavirus.

Any of the pathogenic bacteria, parasitic to humans, that belong to the genus Staphylococcus. The spherical bacterial cells (cocci) typically occur in irregular clusters [Gr. staphyle=bunch of grapes].

Any of a group of gram-positive bacteria, genus Streptococcus, some of which cause disease. Streptococci are spherical and divide by fission, but they remain attached and so grow in beadlike chains.

Means of producing immunity against pathogens, such as viruses and bacteria, by the introduction of live, killed, or altered antigens that stimulate the body to produce antibodies against more dangerous forms.

Parasite with a noncellular structure composed mainly of nucleic acid within a protein coat.

From The Macmillan Encyclopedia:
The study of fungi. Its most important sections are medical and agricultural mycology, since fungi cause many diseases in humans, animals, and plants.

Kingdom of heterotrophic single-celled, multinucleated, or multicellular organisms, including yeasts, molds, and mushrooms. The organisms live as parasites, symbionts, or saprobes.

Type of basidium fungus characterized by spore-bearing gills on the underside of the umbrella- or cone-shaped cap. The name toadstool is popularly reserved for inedible or poisonous mushrooms, but this classification has no scientific basis.

From Dictionary of Microbiology & Molecular Biology
Parisitology is the study of parasites.

Plant or animal that at some stage of its existence obtains nourishment from another living organism called the host. Parasites may or may not harm the host, but never benefit it.

Bilharziasis, or snail fever, parasitic disease caused by blood flukes, trematode worms of the genus Schistosoma. Three species are human parasites: S. mansoni,S. japonicum, and S. haematobium.

Infectious disease caused by a protozoan organism, the trypanosome, which exists as a parasite in the blood of a number of vertebrate hosts. The three variations of the disease that predominate in humans are transmitted by an insect vector.

Evolution is the process by which life has developed by stages from single-celled organisms into the multiplicity of animal and plant life, extinct and existing, that inhabits the Earth.

The adjustment of living matter to environmental conditions and to other living things either in an organism's lifetime (physiological adaptation) or in a population over many many generations (evolutionary adaptation).

Concept of evolution developed in the mid-19th cent. by Charles Robert Darwin. Darwin's meticulously documented observations led him to question the then current belief in special creation of each species.

Process by which gene frequencies in a population change through certain individuals producing more descendants than others because they are better able to survive and reproduce in their environment.

Coloration or color pattern of an animal that affords it protection from observation either by its predators or by its prey. The most widespread form of protective coloration is called cryptic resemblance, in which various effects that supplement the similarity of color between the animal and its surroundings enable the creature to blend into the background of its habitat.