Cell Size and Scale Some cells are visible to the unaided eye The smallest objects that the unaided human eye can see are about 0.1 mm long. That means that under the right conditions, you might be able to see an ameoba proteus, a human egg, and a paramecium without using magnification. A magnifying glass can help you to see them more clearly, but they will still look tiny. Smaller cells are easily visible under a light microscope. Mitosis and Meiosis - Comparison Chart, Video and Pictures Cells divide and reproduce in two ways: mitosis and meiosis. Mitosis is a process of cell division that results in two genetically identical daughter cells developing from a single parent cell. Meiosis, on the other hand, is the division of a germ cell involving two fissions of the nucleus and giving rise to four gametes, or sex cells, each possessing half the number of chromosomes of the original cell. Mitosis is used by single-celled organisms to reproduce; it is also used for the organic growth of tissues, fibers, and membranes.
plant structure bi Seed Plant Overview: The plant body consists of two basic parts--- the shoot system and the root system Shoot system is above ground and includes organs such as leaves, buds, stems, flowers, and fruits The functions of the shoot system include photosynthesis, reproduction, storage, transport, and hormone production The root system is below ground and includes roots as well as modified stem structures such as tubers and rhizomes The functions of the root system include anchorage, absorption, storage, transport, and production of certain hormones Seed plants contain 2 types of vascular tissue (xylem & phloem) to help transport water, minerals, & food throughout the root & shoot systems Plant cells have several specialized structures including a central vacuole for storage, plastids for storage of pigments, and a thick cell wall of cellulose Plant cells are all box-shaped in appearance Meristems: Root Tip with Meristems Specialized Plant Cells:
Atavism Early embryos of various species display some ancestral feature, like the tail on this human fetus. These features normally disappear in later development, but it may not happen if the animal has an atavism. Atavism is the tendency to revert to ancestral type. FDA urged to approve 'three-parent embryos' The United States should permit scientists to implant embryos with DNA from three genetic parents into women with certain diseases who otherwise wouldn’t be able to conceive a healthy child, an expert panel said Wednesday. The technique could open a new frontier in reproductive medicine and upend the fundamental truth of sexual reproduction, which merges DNA from one father and one mother to create a baby. The new procedure, which federal regulators are reviewing, would create an embryo with genetic material from two women and one man.
Cell nucleus HeLa cells stained for the cell nucleus DNA with the BlueHoechst dye. The central and rightmost cell are in interphase, thus their entire nuclei are labeled. On the left, a cell is going through mitosis and its DNA has condensed. Because the nuclear membrane is impermeable to large molecules, nuclear pores are required that regulate nuclear transport of molecules across the envelope. The pores cross both nuclear membranes, providing a channel through which larger molecules must be actively transported by carrier proteins while allowing free movement of small molecules and ions. Movement of large molecules such as proteins and RNA through the pores is required for both gene expression and the maintenance of chromosomes.
Active and Passive Transport Active and passive transport are biological processes that move oxygen, water and nutrients into cells and remove waste products. Active transport requires chemical energy because it is the movement of biochemicals from areas of lower concentration to areas of higher concentration. On the other hand, passive trasport moves biochemicals from areas of high concentration to areas of low concentration; so it does not require energy. Process There are two types of active transport: primary and secondary. In primary active transport, specialized trans-membrane proteins recognize the presence of a substance that needs to be transported and serve as pumps, powered by the chemical energy ATP, to carry the desired biochemicals across.
Motion: Laws of Motion There was this fellow in England named Sir Isaac Newton. A little bit stuffy, bad hair, but quite an intelligent guy. He worked on developing calculus and physics at the same time. Drug made in Ireland shuts down the extra chromosome cause of Down Syndrome Researchers at the University of Massachusetts have shown that it is possible to shut down the extra chromosome that causes the developmental problems and intellectual disabilities in people with Down syndrome Photo by: Google Images A new drug manufactured by the Elan Corporation in Ireland that could be used to treat Down Syndrome and the medical problems that accompany it, will soon be tested by the Down Syndrome Program at Massachusetts General Hospital. According to the Boston Globe researchers at the University of Massachusetts have shown that it is possible to do what had once seemed unthinkable, to shut down the extra chromosome that causes the developmental problems and intellectual disabilities in people with Down syndrome. If successful the new approach could perhaps short-circuit some of the manifestations of Down syndrome itself. (People with Down syndrome are born with three, not the usual two, copies of chromosome 21.)