Answer to Question #127597 in Cell Biology for masterji

Question

Cytoskeleton are found within various organism and cells. Describe how cytoskeleton helps in i) movement of flagellated bacterium Vibrio cholerae, ii) the protection of our respiratory tract and iii) the contraction of our muscle cells.

Answer 1

1.Movement of flagellated bacterium Vibro cholerea

The cytoskeleton is  defined as the system of protein filaments that enable the cell to insure its structural integrity and morphology, exert forces, and produce motion. The cytoskeleton  functions to secure certain organelles in specific positions, and to allow cytoplasm and vesicles to move within the cell. It also enables unicellular organisms to move independently. There are three types of fibers within the cytoskeleton: microfilaments, also known as actin filaments, intermediate filaments, and microtubules

 Bacteria, like eukaryotes, employ cytoskeletal elements to perform many functions, including cell morphogenesis, cell division, DNA partitioning, and cell motility. Microtubules are specialized cytoskeleton fibers used by  Vibrio cholerae located at one of their poles and are used to propel the bacteria hence causing its movement . They support movement through whip-like motion of flagella and cilia. The propulsion mechanism relies on the presence of a rotary molecular motor located in the cell membrane, and which is sensitive to modifications of the chemical environment of the cell.

2. How cytoskeleton protects the respiratory tract

The respiratory tract especially the bronchus are lined with  actin cytoskeleton fibers .These fibers helps in regulating  protrusion, adhesions, contraction, and retraction of the  airway smooth muscles cells  from  front to the rear.  They  form hair-like projections called cilia that move microbes and debris up and out of the airways.  These cilia move mucus and particles out of the bronchi and bronchioles back up to the throat where it is swallowed and eliminated via the esophagus.

Also scattered throughout the cilia are goblet cells that secrete mucus which helps protect the lining of the bronchus and trap microorganisms.  In the nasal cavity, hairs and mucus trap small particles, viruses, bacteria, dust, and dirt to prevent entry. If particulates make it beyond the nose or enter via the mouth, the bronchi and bronchioles contain several protective devices.

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3. How cytoskeleton help in contraction of muscle cells

The muscle cell cytoskeleton consists of Microfilaments, also known as actin filaments, which are types of fibers within the cytoskeleton. Their primary function is to link, anchor or tether structural components inside the cell..  Actin filaments have a number of important roles in the cell. They serve as tracks for the movement of a motor protein called myosin, they are  involved in many cellular events requiring motion. Together with myosin, actin are plentiful in muscle cells, where they form organized structures of overlapping filaments called sarcomeres. When the actin and myosin filaments of a sarcomere slide past each other, they cause  muscles to contract.