GN 301 Module 2: Cell Types and Components

Cell Components and Purpose

• Nucleus: houses cell’s genome and acts as the cell’s control center
• Cytoplasm: gel-like fluid in the cell where growth and replication are carried out
• Ribosomes: site of protein synthesis
• Endoplasmic Reticulum – smooth: synthesizes and concentrates substances needed by cell
• Endoplasmic Reticulum – rough: has ribosomes and is involved with the production, folding, and dispatch of some proteins
• Golgi Apparatus: receives protein from the ER and sorts them for transport to different locations, also stores lipids after their production
• Mitochondria: generates ATP for the cell to use as power
    * Leber’s Disease: When there are genetic mutations in mitochondrial DNA, this leads to Leber’s disease
• Plasma Membrane
    * Phospholipid bilayer: Located on the plasma membrane with phosphates on top and bottom and lipids sandwiched in the middle, because they don’t like water
    * Hydrophobic: water-fearing tails
    * Hydrophilic: water-loving heads
• Lysosomes: rid cells of waste products and uses its digestive enzymes to break down macromolecules
    * Tay Sach’s Disease
      * Tay-Sachs disease is a genetic disorder that is caused by a deficiency of an enzyme called hexosaminidase A (Hex A), which is normally found within the ==lysosomes== of cells. Lysosomes are small, membrane-bound organelles within cells that contain a variety of enzymes, including Hex A, which are responsible for breaking down and recycling cellular waste products.

      In people with Tay-Sachs disease, the gene that codes for Hex A is mutated, which leads to a decrease or absence of functional Hex A in lysosomes. As a result, a particular type of ==fatty substance called GM2 ganglioside accumulates== in the lysosomes of certain cells, especially in the brain and nervous system. Over time, the accumulation of GM2 ganglioside leads to the progressive destruction of nerve cells, causing a range of symptoms such as developmental delay, muscle weakness, loss of vision and hearing, and eventually death.

Ion Channels

• Sodium channel: transmit depolarizing impulses through cells to enable cognition and locomotion; inherent ability to detect pain
• Potassium channel: controls the transportation of K+ ions influx and outflux of cells
• Chloride channel: regulates cell volume, proliferation, and secretion of salt
• Long Q-T Syndrome: Long QT syndrome is usually caused by a faulty gene inherited from a parent. The abnormal gene affects the heart's electrical activity.
    * Q-T Interval is a measurement on an electrocardiogram that detects electrical properties of heart rate. Individuals with Long Q-T syndrome can get a very fast heart rate while they sleep.
• Cystic Fibrosis: Symptoms and Challenges
    * Cystic fibrosis (CF) is a genetic disorder that is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This gene encodes a protein called the cystic fibrosis transmembrane conductance regulator, which is a ==chloride channel== that is found in the membranes of certain cells in the body, such as those in the lungs and pancreas.
    * In people with CF, the mutations in the CFTR gene result in the production of a dysfunctional or nonfunctional CFTR protein. One of the key roles of the CFTR protein is to transport chloride ions out of cells and into the surrounding fluids, such as mucus. In CF, the defective CFTR protein leads to a decrease in the movement of chloride ions, which in turn affects the composition and consistency of fluids in the body.
    * In the lungs, the decreased movement of chloride ions results in the production of abnormally thick and sticky mucus, which can block the airways and create an environment that is conducive to bacterial growth and infection. This can lead to chronic lung infections, inflammation, and damage to lung tissue.
    * In the pancreas, the decrease in chloride ion movement can also affect the composition of digestive fluids, leading to a buildup of thick and sticky mucus in the pancreas that can block the ducts and prevent digestive enzymes from reaching the small intestine. This can result in malabsorption of nutrients and poor growth.