Transcript Slide 2
Lab Exercise # 2 Zoo- 103 Lab Exercise # 2 • Cells were discovered in 1665 by a British scientist named Robert Hooke. • He was able to observe the cell with the use of the microscope. Zoo- 103 Lab Exercise # 2 Zoo- 103 Definition of Cell A cell is the smallest unit that is capable of performing life functions. Cells are the basic unit of life All organisms are made up of cells All cells come from pre-existing cells Lab Exercise # 2 The Cells Zoo- 103 Basic structural and functional unit of life The Tissues Cells group together to form tissues The Organ Different tissues combine together to form an organ The System Different organs combine together to form a system The Body Different systems combine together to form an animal or organism Lab Exercise # 2 Zoo- 103 Some cells are capable to live independent which called single celled or unicellular organisms like the protozoa. Classification of the cell 1- Prokaryotic cell: they are devoid of the true nucleus. 2- Eukaryotic cell: they have true nucleus (surround by nuclear membrane). Structure of the cell: the true cell consist of three parts 1- The Central part (nucleus). 2- The Peripheral part (cytoplasm). 3- The Cell membrane encases both of these parts. Lab Exercise # 2 Zoo- 103 • Contain nucleus and organelles surrounded by membranes • Most living organisms, example: humans • Usually larger than prokaryotic cells Plant Animal CELL DIVISION Amitosis Mitosis Amitosis Direct cell division It is simple division It occurs in lower animals such as amoeba Meiosis Mitosis The term mitosis (mitos= threads, sis= process) It occurs in somatic cells of the body Mother cell gives two daughter cells each one contains diploid number of chromosomes (2n) This type of cell division : responsible for growth of the organism and repair of damaged tissues. Mitosis can be divided into stages • Prophase • Metaphase • Anaphase • Telophase Prophase stage- mitosis cell division Chromosome become visible Centriole divides in two halves Nuclear membrane disappears Each pair of centrioles move to one pole of dividing cell Metaphase stage- mitosis cell division Each chromosome divides in two chromatids The chromosomes are align at the equatorial (middle) plate of the cell Spindle fibres attaches the chromosomes at centromere Anaphase stage- mitosis cell division Halves of the chromosomes go to the opposite poles Two paws of the chromosomes are formed Telophase stage- mitosis cell division Two daughter nuclei are formed Chromosomes in the nuclei disappeared Nuclear membrane and nucleolus reappear Daughter nuclei are identical and copy of their mother cell Lab Exercise # 2 Zoo- 103 HISTOLOGY is the branch of Biology that studies the microscopic structure of the tissues, organs and systems under the microscope Type of Tissues Epithelial Tissue Muscular Tissue Skeletal Muscle Compound Neuron Cardiac Muscle Hyaline Cartilage Simple Nervous Tissue Connective tissue Blood Simple epithelial Compound Epithelial Single layer of cells more than one layer of cell Fibrous connective tissue is characterized by an abundance of fibres with fewer cells. It is called fibrous or collagenous connective tissue because of the abundance of collagen (collagenous) fibres. Little intercellular substance is present. Lab Exercise # 2 Zoo- 103 The Connective Tissue Hyaline Cartilage • Hyaline cartilage is covered externally by a fibrous membrane, called the perichondrium. • The chondrocytes cells are round or oval in shape and are located in group of two or four in each cavity, Lacunae. • It contains lots of empty spaces in between the cells. The matter that support the cells and cavities is thick and is called the matrix. Lab Exercise # 2 Zoo- 103 The Muscular Tissue Striated Muscle Skeletal muscle Skeletal muscle is made up of individual components known as muscle fibers. Each muscle fiber is formed of still finer fibers, myofibrils. The identifying features of these muscles are haphazard distribution of nuclei among the muscle fibers. The fibers are also transversely marked with lines or striations, dark and light bands. Each muscle fiber is encased in a membrane, myolemma. What is blood made up of? An adult human has about 4–6 liters of blood circulating in the body. Blood consists of several types of cells floating around in a fluid called plasma. The red blood cells (RBCs) contain haemoglobin, a protein that binds oxygen. RBCs transport oxygen to, and remove carbon dioxide from the tissues. The white blood cells fight infection. The platelets help the blood to clot, if you get a wound for example. Lab Exercise # 2 Zoo- 103 The Nervous Tissue Neurons Nucleus Dendrites • These are unit of Nervous Tissue and are specialized in function and shape. • The neurons or the nerve cells are star shaped bodies with few microns in diameter. • The sharp protrusions of these cells are named as dendrites and the number of such spine like extensions varies from 5 to 7. • Centrally, the star shaped mass is loaded with a small nucleus and cytoplasm around the nucleus