Cell Physiology Archives | School Portal NG

COMPARISON BETWEEN ANIMAL CELL AND PLANT CELL Plant Cell & Animal Cell Cell Specialisation Cells are specialised to perform different functions in both plants and animals Example; Palisade cells have many chloroplasts for photosynthesis Root hair cells are long and thin to absorb water from the soil Red blood cells have hemoglobin which transports oxygen Sperm cells have a tail to swim to the egg Multicellular organisms cells that perform the same function are grouped together to form a tissue Each tissue is therefore made up of cells that are specialised to carry out a particular function. Organs An organ is made up of different tissues e.g. the heart, lungs, kidneys and the brain in animals and roots, stems and leaves in plants Organ systems Organs which work together form an organ system Digestive, excretory, nervous and circulatory in animals and transport and support system in plants organism. Different organ systems form an organism Practical Activities Observation and Identification of parts of a light microscope and their functions A light microscope is provided Various parts are identified and observed Drawing and labelling of the microscope is done Functions of the parts of the microscope are stated Calculations of total magnification done using the formula Eye piece lens magnification x objective lens magnification Preparation and Observation of Temporary Slides of Plant Cells A piece of epidermis is made from the fleshy leaf of an onion bulb It is placed on a microscope slide and a drop of water added A drop of iodine is added and a cover slip placed on top Observations are made, under low and medium power objective The cell wall and nucleus stain darker than other parts A labeled drawing is made The following are noted: Nucleus, cell wall, cytoplasm and cell membrane Observation of permanent slides of animal cells Permanent slides of animal cells are obtained e.g. of cheek cells, nerve cells and muscle cells The slide is mounted on the microscope and observations made under low power and medium power objectives Labeled drawings of the cells are made A comparison between plant and animal cell is made Observation and Estimation of Cell Size and Calculation of Magnification of Plant Cells Using the low power objective, a transparent ruler is placed on the stage of the microscope An estimation of the diameter of the field of view is made in millimeters This is converted into micrometres (1mm1000u) A prepared slide of onion epidermal cells is mounted The cells across the centre of the field of view are counted from left and right and top to bottom The diameter of field of view is divided by the number of cells lying lengthwise to give an estimate of the length and width of each cell Cell Physiology Meaning of cell physiology The term physiology refers to the functions that occur in living organisms Cell physiology refers to the process through which substances move across the cell membrane Several physiological processes take place inside the cell e.g respiration Oxygen and glucose required enter the cell while carbon (IV) oxide and water produced leave the cell through the cell membrane Structure and properties of cell membrane The cell membrane is the protective barrier that shelter cellular contents Movement of all substances into and out of the cells takes place across the cell membrane It is made up of protein and lipid molecules Lipid molecules have phosphate group attached to it on one end They are then referred to phospholipids The phospholipids are arranged to form a double layer The ends with phosphate group face outwards the proteins are scattered throughout the lipid double layer Some of these proteins act as carrier molecules that channel some material in and outside the cells The cell membrane allows certain molecules to pass through freely while others move through with difficulty and still others do not pass through at all This is selective permeability and the cell membrane is described as semi-permeable Properties of cell membrane Permeability The cell membrane is semi-permeable it allows small molecules that are soluble in lipid to pass through with more ease than water soluble molecules this is due to the presence of the phospholipids double layer Polarity. The cell membrane has electrical charges across its surface it has positive charged ions on the outside and negatively charged ions on the inside this property contributes to electrical impulses sent along nerve cells Sensitivity to changes in temperature and pH Very high temperatures destroy the semi-permeability nature of the cell membrane because the proteins are denatured by extreme pH values have the same effect on the membrane permeability Physiological processes Some of the physiological processes include diffusion, osmosis and active transport. Also See: THE DIFFERENCES BETWEEN ANIMALS AND PLANTS DETERMINATION OF THE GENOTYPE OF A DOMINANT PHENOTYPE VARIATION IN POPULATION CLASSIFICATION OF ANIMALS AND ORGANIZATION OF LIFE CLASSIFICATION OF LIVING ORGANISMS