MT

cell differentiation : principles and applications of science

cells and genes

  • the nucleus of all human cells contain 23 pairs of chromosomes
  • these chromosomes are made of DNA
  • the DNA contains information in the form of genes
  • each gene contains a particular characteristic
  • genes controls the activities inside the cell
  • genes code for production of proteins inside the cell
  • these proteins have an effect on function of cells and are often enzymes
  • there are approximately 20,000 different genes in a human and all human cells process all 20,000 genes
  • in a developing red blood cell the gene for producing haemoglobin (a protein) would be switched on
  • in a developing bone cell this same gene is switched off

type of tissues

  • epithelial tissue - this is a tissue that either covers or lines an organ for example - blood vessels or the lining of gut
  • epithelial tissues forms the inner surface of glads that secrete substances such as sweat and digestive enzymes
  • simple epithelial : squamous, cuboid, columnar, ciliated
  • muscle tissues : skeletal muscle - movement (attached to the bone)
  • cardiac muscle - in the heart
  • smooth muscle - in the walls of artery,gut and the bladder
  • nervous tissue : transmit nerve impulses to the brain and they are the body’s communication system
  • connective tissue : any supporting tissue in an organism
  • consists of a non-living supporting matrix ; often containing protein fibers
  • living cells are present within in matrix
  • these cells often produce the matrix
  • includes : bones, cartilages, tendons, ligaments, blood, areolar tissue, adipose tissue
  • tendons are attached muscles to the bone
  • ligaments also attach to the bone
  • areolar tissue holds things together eg: skin and muscle in a chicken
  • adipose is a fatty tissue