Lesson 2

• The CELLS, is taken from a Latin word, cella which means the ‘small room’ is the simplest structural, functional, and biological unit of all living forms.
• The human body contains more than 100 trillion cells, with 200 different types of cells
• A single cell divides to make two cells and these two cells then divide to make four cells, and so on. We call this process "cell division" and "cell reproduction,"
• cell- basic unit of life
• cytology-study of cells
• Antoine Van Leeuwenhoek-First to device his own light microscope ●Revealed a wide variety of organisms not visible to the naked eyes
• Antoine Janssens/ zacharias- first discover the microscope
• Robert Hooke-Observed tiny slices of cork through a microscope/ use the word cell
• Robert Brown- discovered the nucleus of the cell
• felix dujardin- viewed living cells
• matthians jacob schleidan- plans are made of cell
• spontaneous generation- the idea that living things can arise from non-living matter
• theodore schwann- animal cells
• biogenesis- the process of creating new organisms from pre-existing organisms
• Cell membrane/plasma membrane/plasmalemma ● For support and protection the outermost covering of animal cell, semipermeable, thin and flexible
• nucleus-Control center of the cell which directs cell division since it contains the heredity information in the form of genes
• Outer nuclear membrane 🗆 Nuclear membrane that is continuous with a system of the endoplasmic reticulum.
• Inner nuclear membrane 🗆 Nuclear membrane that is continuous and composed of membrane system with DNA as the principal nucleic acid, some RNA, and protein
• Chromatin is clumped of a dense granular, threadlike network which is transformed into chromosomes during mitosis. It also contains the genes which carry the genetic information necessary for replication and protein synthesis.
• Nucleolus - A small spherical body within the nucleus where ribosomal subunits are formed.
• 3. Cytoplasm ● The living substance of the cell ● The protoplasm that surrounds the nucleus of the cell which contains the organelles and inclusion bodies. ● Physiological properties of the cell
• Cell division This is the ability of the cell to grow to a limited extent and produce new cells
• Contractility The ability of the cell to be stimulated so as to shorten and return to its original length when stimulus is removed
• Conductivity The ability to transmit a wave of excitation throughout the substance of the cell
• Irritability This is the property that enables the cell to respond to stimulus
• Secretion Cells that can synthesize useful substances from those that they absorb and can give of these substances as secretory products.
• Absorption and Assimilation Living cells can take food and other substances and utilize it
• Excretion The ability of the cell to eliminate waste materials
• Respiration This is taking in of oxygen and using this for oxidation of food substances with resulting liberation of energ
• Mitochondria/Chondrisomes- Functions: Serve as the power of the cell (production of energy in the form of ATP; support the mechanical and chemical work performed by the cell
• Golgi apparatus/dictyosomes- Function: for packaging of food materials
• Endoplasmic reticulum- Function: Transport substances throughout the cell.
• Ribosome- Function: Site of protein synthesis
• Cell wall- Function: Provides structural strength and protection against pathogens
• Nucleus- Function: Control center of the cell, contains DNA which carries genetic information
• Rough or granular ER- RER is active in the secretion of protein such as pancreatic exocrine cells and liver cells
• Smooth or granular ER- site of the synthesis of steroid hormones such as that of the adrenal glands;
• rough er- attach ribosome
• smooth er - near in cell membrane
• ‘cristae’ (this folds contain enzymes which are used in the conservation of food energy by the cell to do cellular work