DIR Return Create A Forum - Home
       ---------------------------------------------------------
       DSO Science Forum
  HTML https://myscifriend.createaforum.com
       ---------------------------------------------------------
       *****************************************************
   DIR Return to: SCIENCE FORM 4
       *****************************************************
       #Post#: 396--------------------------------------------------
       Re: Tugasan Chapter 3 Tingkatan 4 PD
       By: afiqq Date: March 14, 2011, 9:43 am
       ---------------------------------------------------------
       JAGEN
       AFIQQ
       4PD
       gene is a unit of heredity in a living organism. It normally
       resides on some stretches of DNA and RNA that codes for a type
       of protein or for an RNA chain that has a function in the
       organism. Living things depend on genes, as they specify all
       proteins and functional RNA chains. Genes hold the information
       to build and maintain an organism's cells and pass genetic
       traits to offspring, although some organelles (e.g.
       mitochondria) are self-replicating and are not coded for by the
       organism's DNA. All organisms have many genes corresponding to
       many different biological traits, some of which are immediately
       visible, such as eye color or number of limbs, and some of which
       are not, such as blood type or increased risk for specific
       diseases, or the thousands of basic biochemical processes that
       comprise life.
       Mitosis is the process by which a eukaryotic cell separates the
       chromosomes in its cell nucleus into two identical sets in two
       nuclei. It is generally followed immediately by cytokinesis,
       which divides the nuclei, cytoplasm, organelles and cell
       membrane into two cells containing roughly equal shares of these
       cellular components. Mitosis and cytokinesis together define the
       mitotic (M) phase of the cell cycle—the division of the
       mother cell into two daughter cells, genetically identical to
       each other and to their parent cell. This accounts for
       approximately 10% of the cell cycle.
       Meiosis  is a special type of cell division necessary for sexual
       reproduction. In animals, meiosis produces gametes like sperm
       and egg cells, while in other organisms like fungi it generates
       spores. Meiosis begins with one diploid cell containing two
       copies of each chromosome—one from the organism's mother
       and one from its father—and produces four haploid cells
       containing one copy of each chromosome. Each of the resulting
       chromosomes in the gamete cells is a unique mixture of maternal
       and paternal DNA, ensuring that offspring are genetically
       distinct from either parent. This gives rise to genetic
       diversity in sexually reproducing populations, which enables
       them to adapt during the course of evolution.
       Heredity is the passing of traits to offspring (from its parent
       or ancestors). This is the process by which an offspring cell or
       organism acquires or becomes predisposed to the characteristics
       of its parent cell or organism. Through heredity, variations
       exhibited by individuals can accumulate and cause some species
       to evolve. The study of heredity in biology is called genetics,
       which includes the field of epigenetics.
       A chromosome is an organized structure of DNA and protein that
       is found in cells. It is a single piece of coiled DNA containing
       many genes, regulatory elements and other nucleotide sequences.
       Chromosomes also contain DNA-bound proteins, which serve to
       package the DNA and control its functions.
       
       
       *****************************************************
   DIR Next Page