General Science: Microorganism

Saturday, October 3, 2009

Scope and importance of botany

Botany is the scientific study of plant life. As a branch of biology, it is also called plant science(s), phytology, or plant biology.

Botany covers a wide range of scientific disciplines that study plants, algae, and fungi including: structure, growth, reproduction, metabolism, development, diseases, and chemical properties and evolutionary relationships between the different groups.

The study of plants and botany began with tribal lore, used to identify edible, medicinal and poisonous plants, making botany one of the oldest sciences. From this ancient interest in plants, the scope of botany has increased to include the study of over 550,000 kinds or species of living organisms.

Scope and importance of botany

As with other life forms in biology, plant life can be studied from different perspectives, from the molecular, genetic and biochemical level through organelles, cells, tissues, organs, individuals, plant populations, and communities of plants. At each of these levels a botanist might be concerned with the classification (taxonomy), structure (anatomy and morphology), or function (physiology) of plant life.

Historically, botany covers all organisms that were not considered to be animals. Some of these "plant-like" organisms include fungi (studied in mycology), bacteria and viruses (studied in microbiology), and algae (studied in phycology). Most algae, fungi, and microbes are no longer considered to be in the plant kingdom. However, attention is still given to them by botanists, and bacteria, fungi, and algae are usually covered in introductory botany courses.

The study of plants has importance for a number of reasons. Plants are a fundamental part of life on Earth. They generate the oxygen, food, fibres, fuel and medicine that allow higher life forms to exist. Plants also absorb carbon dioxide through photosynthesis, a minor greenhouse gas that in large amounts can effect global climate. It is believed that the evolution of plants has changed the global atmosphere of the earth early in the earth's history and paleobotanists study ancient plants in the fossil record. A good understanding of plants is crucial to the future of human societies as it allows us to:

* Produce food to feed an expanding population
* Understand fundamental life processes
* Produce medicine and materials to treat diseases and other ailments
* Understand environmental changes more clearly

Friday, October 2, 2009

CELLULAR BIOLOGY

Aristotle concluded that living things arise from non-living material - spontaneous generation.

Alhazen (965 – 1040) or Abu Ali Hasan Ibn al-Haitham, an Iraq physicist. His book Kitab-al-Manadhirn was translated into Latin and greatly influenced western science. He is the first to state that eyes received light being reflected off an object, which had a major impact on the development of the first microscope. As a nice to know, he is the one responsible for geometry!

Jan Baptist van Helmont (1579 - 1644) - wrote a recipe for making rice: Throw grains and old rags into the corner of a room

Francesco Redi - (1626 - 1697) In 1660 Challenges spontaneous generation. Raw meat and fly maggot experiment – . Critics say Redi’s source of error was the removal of air, which contains an "active principle"

Anton van Leeuwenhoek - (1632 - 1723) 1700 used a single lens microscope to describe single celled organisms. He called them “animalcules.” Friend of Robert Hooke.

First to describe the cellular nature of living things
First to see bacteria and protozoa

Marcello Malpighi (1628 – 1694) An Italian physiologist who used lenses to study plants and animals. He is considered the father of microscopic anatomy. He was a member of the Royal Society in England. He discovered capillaries and completed Harvey’s theory on blood circulation in his book De Pulmonibus in 1661. He published Anatomia Plantarum, which includes his discovery of the stomata on plant leaves.

Robert Hooke (1635 to 1703) Published Micrografia in 1665- book of objects he looked at under a compound microscope he designed and built. He coined the word cell describe the features of plant tissue (cork).

John Needham (1713 to 1781) Experimented to prove spontaneous generation occurred. Heated broth in a glass flask and then corked the glass so no air would get in. Bacteria still grew in flask. Needham’s source of error was that he did not boil the broth long enough.

Lazzaro Spallanzani (1729 to 1799) Repeated Needham’s experiment, but properly boiled the broth and thus refuted spontaneous generation.

Jean-Baptiste Lamarck (1744 – 1829) “Lamarckism” is the theory that acquired characteristics can be passed on (inherited).

Matthias Schleiden and Theodor Schwann (In 1838 to 1839) - two German scientists that viewed many organisms under microscope and concluded that all plants and animals were composed of cells.

Louis Pasteur (1822 to 1895) In 1861 Disproved spontaneous generation once and for all using curved neck flasks.

Rudolf Ludwig Karl Virchow (1821 – 1902) Stated that all new cells are formed by the division of previously existing cells.

Thomas Henry Huxley (1825 to 1895) In 1870 is the first to use the word biogenesis, which states that all living things arise only from other living things.

August Weismann (1834 to 1914) Stated all cells coming from pre-existing cells (Virchow) trace their ancestry to an ancient cell (application of Evolution to cells). Weismann eliminated the idea of inheritance of acquired characteristics from being accepted. To prove his theory, Weismann cut the tails of mice and bred them over several generations, but all the mice were born with tails. This showed that acquired traits are not passed down to offspring.