CELLULAR MODIFICATIONS

• Cellular modifications are specialized processes or modifications re-acquired by the cell after cell division where the newly formed cells are structurally modified so they can perform their function efficiently and effectively.
• Cellular modification is needed by an organism to adapt and respond to the changing environment in order to survive.
• MODIFIED CELLS IN ANIMALS:

  • Microvilli
  • Cilia
  • Stereo cilia
  • Muscle cells
  • Red blood cells
• MODIFIED CELLS IN PLANTS:

  • Trichomes
  • Guard cells
  • Root hair cells
• Microvilli is a plasma membrane cell that increases the surface area of eukaryotic cells.
• Microvilli is characterized by folded fingerlike projections and has a dense bundle of cross-linked actin filaments which serves as its structural core.
• Microvilli's functions are absorption, secretion, cellular adhesion, and mechano-transduction (where the cells convert mechanical stimulus to chemical activity).
• Microvilli is usually found in small intestine enterocyte, kidney proximal tubule, in sensory cell of the inner ear, in the cell of taste buds and olfactory receptor cells.
• A good example of microvilli cells are found in the lining of the small intestines, the organ that absorbs nutrients from digested food.
• Microvilli also acts as anchors for sperm cells that have penetrated the extracellular coat of egg cells.
• Cilia are tail like projections found in eukaryotic cells.
• Cilia helps in preventing accumulation of dust in breathing tubes by creating a thin layer of mucus along tubes.
• There are two types of cilia: motile which is mobile and non-motile.
• The two functions of the two types of cilia are either they move through the cell or act as sensory organisms.
• Motile cilia are used to move cells throughout certain parts of the organisms-mostly animals.
• In mammals, for example, cilia are found along the lining of trachea and are used to sweep mucus and dirt out of the lungs.
• The cilia act as a sweeper, moving objects throughout the body.
• Cilia is also responsible for moving ova down the fallopian tube.
• Non-motile cilia are usually found in the eyes and the nose to trap dirt and other objects.
• In the nose, the non-motile act as olfactory sensors.
• Stereo cilia are different from cilia they are more closely related to microvilli.
• Stereo cilia has distinctive characteristics, their length and lack of motility.
• Stereo cilia are basically an apical modification of the cell.
• Stereo cilia are mechano-sensing organelles of hair cells, which respond to fluid pressure in numerous types of animals for various functions, primarily hearing.
• This pressure and mechanical stimuli are turned by the stereo cilia into electric messages, or neuronal signals, through the microvilli that make up stereo cilia rods.
• In the human body, stereo cilia are found on the cochlea in the inner ear, ductus deferens, and epididymis.
• Muscle is for contraction and when this contraction is coordinated, it results in movement.
• The muscle cell is generally elongated and elastic containing mitochondria in large number.
• The cell elongated and elastic feature helps muscle tissues to contract and relax.
• Contraction and relaxation of muscle tissues help in movement.
• The large number of mitochondria is very important in tissue respiration in the muscle cell because energy is required for muscle to contract.
• A red blood cell is a tiny, disc-like cell (biconcave shape) which has no nucleus.
• In the cytoplasm of RBC, there is a red pigment called hemoglobin.
• Each RBC lives for about four months after which, it breaks down.
• The red hemoglobin changes to a yellow pigment which is excreted in the bile.
• The iron from the hemoglobin is stored in liver.
• RBCs are made by the bone marrow of certain bones in the skeleton.
• RBC has biconcave shape to increase its surface area thus diffusion of oxygen in and out of the red blood cell becomes easy.
• When RBCs are modified or differentiated, they lose their nucleus, hence more oxygen can be transported.
• By having no nucleus, it enables an RBC to squeeze through small blood capillaries.