Cell Structure, Function and Properties PDF

CELL STRUCTURE, FUNCTION AND PROPERTIES MOHD AMINUDIN MUSTAPHA  OBJECTIVES CELL STRUCTURE & FUNCTION Describe the fundamental properties of cells. Differentiate between the features of prokaryotes and eukaryotes....

CELL STRUCTURE, FUNCTION AND PROPERTIES MOHD AMINUDIN MUSTAPHA  OBJECTIVES CELL STRUCTURE & FUNCTION Describe the fundamental properties of cells. Differentiate between the features of prokaryotes and eukaryotes. Explain the cellular components and their functions in animal and plant cells. Describe animal tissues and organ systems. 2  CELL THEORY CELL STRUCTURE & FUNCTION Organisms can be classified as unicellular or multicellular. The development of cell theory began with Robert Hooke in 1665. Energy flow (metabolism and biochemistry) occurs within cells. 3  CELL THEORY CELL STRUCTURE & FUNCTION Cells contain hereditary information (DNA) passed from cell to cell during division. Cells have various types and shapes based on their functions and positions. The small size of cells provides a large surface area to volume ratio, increasing the diffusion rate across them. 4 CELL STRUCTURE & FUNCTION PROKARYOTIC CELLS Unicellular organisms, including bacteria and archaebacteria. Non-living cell walls made of peptidoglycan, located outside the plasma membrane, maintain cell shape and provide protection. 5  PROKARYOTIC CELLS CELL STRUCTURE & FUNCTION Some bacteria, called Gram- negative bacteria, have an additional membrane layer containing lipopolysaccharide. cell wall cell cell membrane membrane The type of cell wall (Gram- lipopolysaccharide negative or Gram-positive) helps in disease diagnosis. Bacteria are stained with Gram stain: cell wall Outer membrane Gram-positive bacteria appear purple, and Gram-negative bacteria appear pink. 6  PROKARYOTIC CELLS CELL STRUCTURE & FUNCTION Prokaryotic cells are simple, lacking membrane-bound organelles and a nucleus enclosed by a membrane. These cells have a higher metabolic and growth rate, but a shorter generation time compared to eukaryotes. Some cells have capsules for extra protection and flagella or pili for movement in liquid environments. 7  PROKARYOTIC CELLS CELL STRUCTURE & FUNCTION Reproduction occurs by binary fission, a form of asexual reproduction producing genetically identical offspring. Under ideal conditions, binary fission can occur every 20 minutes, creating large numbers of bacteria quickly. 8  EUKARYOTIC CELLS CELL STRUCTURE & FUNCTION Include plants, animals, fungi, slime molds, protozoa, and algae. Larger than prokaryotic cells, bounded by plasma membranes, with some cells having cell walls outside the plasma membrane. Possess a distinct nucleus enclosed by a nuclear envelope and membrane-bound organelles. Undergo meiosis and mitosis for growth and 9 reproduction. CELL STRUCTURE & FUNCTION CELL STRUCTURE & FUNCTION PLANT CELLS Regular in shape due to cell walls. The nucleus is surrounded by a nuclear envelope, a double membrane structure perforated with nuclear pores. 11  PLANT CELLS CELL STRUCTURE & FUNCTION Contain chlorophyll in chloroplasts, essential for photosynthesis. Mature cells have large central vacuoles important for maintaining cell turgidity. 12  PLANT CELLS CELL STRUCTURE & FUNCTION Cytoplasm is separated from the external environment by the plasma membrane. Adjacent plant cells are connected by the middle lamella and plasmodesmata, allowing cytoplasmic connection and substance exchange. 13  ANIMAL CELLS CELL STRUCTURE & FUNCTION Enclosed by plasma membranes with no cell walls, resulting in smaller and irregular shapes compared to plant cells. Movement is assisted by flagella (e.g., sperm cells). 14  ANIMAL CELLS CELL STRUCTURE & FUNCTION Have a pair of centrioles next to the nucleus and store food as glycogen in the cytoplasm. Contain membranous organelles, but no chloroplasts. Most metabolic activities occur in the cytoplasm. 15 CELL STRUCTURE & FUNCTION  CELL WALL CELL STRUCTURE & FUNCTION A tough, rigid, non-living structure giving plant cells their defined shapes. Young cells have a thin, primary cell wall allowing growth; fully grown cells add a secondary cell wall, often hardened by lignin. 17  CELL WALL CELL STRUCTURE & Maintains cell shape, supports growth, provides mechanical strength, FUNCTION and prevents bursting. Protects against pathogens and mechanical stress, acts as a carbohydrate reserve. 18  PLASMA MEMBRANE CELL STRUCTURE & FUNCTION Encloses the cytoplasm, providing shape and protection. Semi-permeable, allowing selective material passage. Composed of a phospholipid bilayer with embedded proteins, described by the Fluid Mosaic Model. 19  PLASMA MEMBRANE CELL STRUCTURE & FUNCTION Integral proteins act as enzymes, pumps, carriers, channels, and receptors, while peripheral proteins are attached to the inner or outer membrane surface. Glycoproteins and glycolipids act as chemical receptors and in cell recognition. Cholesterol reduces membrane flexibility and permeability. regulating the fluidity of cell membranes and maintaining the structure integrity 20  CYTOSKELETON CELL STRUCTURE & FUNCTION Made of filamentous protein networks, providing mechanical support and maintaining cell shape. Fixes organelle locations and aids substance movement within the cell. 21  CYTOSKELETON CELL STRUCTURE & FUNCTION Microfilaments support muscle contraction. Microtubules maintain cell shape and assist in chromosome separation. Intermediate filaments prevent excessive stretching and fix organelle positions. 22  NUCLEUS CELL STRUCTURE & FUNCTION The largest and most prominent organelle in eukaryotic cells, containing DNA and directing cellular activities. Surrounded by a double nuclear envelope with pores for molecule movement. Continuous with the rough endoplasmic reticulum and containing ribosomes on its outer surface. Stores genetic material, directs protein synthesis, and regulates cell metabolism. 23 The nucleolus synthesizes ribosomal RNA subunits for protein synthesis.  ENDOPLASMIC RETICULUM (ER) CELL STRUCTURE & FUNCTION Network of membranous tubules and flattened sacs (cisternae), continuous with the nuclear envelope. Rough ER (RER) with ribosomes synthesizes and transports secretory proteins. Smooth ER (SER) lacks ribosomes and facilitates diverse metabolic activities, including hormone production and lipid synthesis. 24  GOLGI BODY CELL STRUCTURE & FUNCTION Consists of flattened membranous sacs (cisternae) that modify, sort, and distribute proteins from the rough ER to various destinations. 25  RIBOSOMES CELL STRUCTURE & FUNCTION Small granules found in all cells; synthesizing proteins based on mRNA genetic information using amino acids from the cytoplasm. 26  LYSOSOMES CELL STRUCTURE & FUNCTION Dark, spherical bodies containing hydrolytic enzymes to digest macromolecules, recycle old organelles, and digest dead cell remains. 27  MITOCHONDRIA CELL STRUCTURE & FUNCTION Bounded by two membranes, with an outer smooth membrane and an inner folded membrane (cristae) enclosing the mitochondrial matrix. The powerhouse of the cell, metabolizing glucose and fatty acids to produce ATP. 28  CHLOROPLAST CELL STRUCTURE & FUNCTION Found in plant cells and green organisms, containing DNA, RNA, and ribosomes, and responsible for photosynthesis. Enclosed by two membranes, with internal thylakoid membranes forming grana where photosynthetic pigments like chlorophyll are embedded. 29  EPITHELIAL TISSUES CELL STRUCTURE & FUNCTION Cover the exterior of the body and line internal organs and cavities. Epithelium consists of one or more layers of cells. Squamous: flattened cells resembling floor tiles. Cuboidal: cube-shaped cells resembling dice. Columnar: pillar-like, rectangular-shaped cells standing on end like bricks. 31  SQUAMOUS EPITHELIUM CELL STRUCTURE & FUNCTION Composed of thin, smooth, and strong sheets of cells. Found in the endothelium of blood vessels and the outer layer of Bowman’s capsule. Facilitates diffusion across its thin structures, smoothens fluid passage, and lubricates movements across adjacent surfaces. 32  CUBOIDAL EPITHELIUM CELL STRUCTURE & FUNCTION Located in the lining of collecting ducts, nephron tubules, salivary glands, and sweat glands. Provides protection to underlying tissues. Aids in the absorption and transport of filtered substances in kidney tubules. 33  COLUMNAR EPITHELIUM CELL STRUCTURE & FUNCTION Secretes digestive juices and absorbs nutrients. In the intestine, it secretes digestive enzymes and absorbs the products of digestion. Often contains mucus-secreting goblet cells. 34  STRATIFIED EPITHELIUM CELL STRUCTURE & FUNCTION Composed of several layers of cells, forming a tough, impervious barrier. The outermost layer, known as the generative layer, is in an active state of mitotic cell division. Provides protection from abrasion. 35  STRATIFIED EPITHELIUM CELL STRUCTURE & FUNCTION Stratified Squamous: Found in the epidermis of the skin and the lining of the esophagus. Stratified Cuboidal: Found in the excretory ducts of sweat glands. Stratified Columnar: Found in the secretory ducts of the mammary glands. 36  PSEUDOSTRATIFIED EPITHELIUM CELL STRUCTURE & FUNCTION Appears layered, but each cell touches a basement membrane, connecting the epithelium to underlying connective tissues. Found in the trachea, bronchi, and bronchioles. 37  CARTILAGE CELL STRUCTURE & FUNCTION A specialized, hard, and flexible tissue that withstands mechanical stress without permanent distortion. Mostly found in joints such as gliding and hinge joints. Acts as a shock absorber, cushioning bones during movement. 38  CARTILAGE CELL STRUCTURE & FUNCTION Produced by chondrocytes, which secrete a protein matrix without calcium carbonate. Nourished by nutrients diffused from capillaries in adjacent perichondrial connective tissues or synovial fluid. Three types of cartilage based on variations in their matrix composition: hyaline, elastic, and fibrous. 39  HYALINE CARTILAGE CELL STRUCTURE & FUNCTION The most common form, found on the articulating surfaces of bones, the walls of large respiratory passages, and the ventral portion of the sternum. 40  ELASTIC CARTILAGE CELL STRUCTURE & FUNCTION Contains many elastic fibers, giving it a yellowish color. Found in the auricle of the ear, ear canal, Eustachian tube, and epiglottis. 41  FIBROUS CARTILAGE CELL STRUCTURE & FUNCTION Contains a dense network of collagen fibers. Found in the intervertebral discs, ligament attachments to cartilaginous bone surfaces, and the pubic symphysis. 42  BONES CELL STRUCTURE & FUNCTION Act as levers, converting muscle contraction into movement. Hydroxyapatite, made from calcium and phosphate, gives bone its hardness. There are two forms: spongy bone and compact bone. Spongy bones are found in the center of flat bones and the ends of long bones. 43  BONES CELL STRUCTURE & FUNCTION Compact bones are formed by osteocytes located in the lacunae, which are arranged in concentric circles around the Haversian canals. Haversian canals contain blood vessels and nerves. Osteocytes secrete a matrix of calcium phosphate, carbonate, and protein. Osteocytes communicate and receive nutrition through canaliculi, thin channels penetrating the matrix. 44  NERVE TISSUES CELL STRUCTURE & FUNCTION Composed of nerve cells called neurons and neuroglial cells. Neurons are specialized for the conduction of nerve impulses. Neuroglial cells surround neurons, providing support and protection. 45  NEURONS CELL STRUCTURE & FUNCTION A typical neuron has three main features: Cell body: Contains the nucleus. Dendrites: Extend from the cell body and bring impulses toward it. Axon: A single long fiber that carries impulses away from the cell body. 46  NEURONS CELL STRUCTURE & FUNCTION Neurons transmit impulses to other neurons, muscles (at neuromuscular junctions), and glands. Efferent/Motor Neurons: Transmit impulses from the nervous system to muscles and glands. Afferent/Sensory Neurons: Conduct impulses from receptor organs to the central nervous system. Intermediary/Relay Neurons: Receive impulses from sensory neurons or other relay neurons, existing in various shapes 47 with one or more dendrites or axons.  NEUROGLIAL CELLS CELL STRUCTURE & FUNCTION Include Schwann cells, which produce the myelin sheath surrounding many axons in the peripheral nervous system. The myelin sheath is segmented by the nodes of Ranvier, facilitating faster impulse movement. Provide support, protection, and nourishment to neurons. Stimulate the formation of new synapses, modulate neuronal activity, repair damage, and supply neurons with materials from the 48 blood.  MUSCLE TISSUES CELL STRUCTURE & FUNCTION Smooth Muscle: Involuntary muscles that cannot be controlled voluntarily, found in the digestive tract, trachea walls, uterus, arteries, and bladder. Controlled by the brain via the autonomic nervous system, contracting rhythmically to produce waves of contraction like in peristalsis. 49  MUSCLE TISSUES CELL STRUCTURE & FUNCTION Striated Muscle: Also known as skeletal muscle due to its anatomical location, formed from a large number of muscle fibers, each a muscle cell, attached to bones via tendons, voluntary, and essential for support and motion. 50  MUSCLE TISSUES CELL STRUCTURE & FUNCTION Cardiac Muscle: Found only in the heart, striated but differs from skeletal muscle by being involuntary, generating longer electrical impulses and mechanical contractions, and spreading electrical activity from one cell to surrounding cells. It does not require brain impulses to contract and has its own pacemaker system to generate excitation. 51  BLOOD CELL STRUCTURE & FUNCTION Consists of fluid and cells flowing in one direction in a closed circulatory system. Bone marrow is the source of all blood cells. 52  BLOOD CELL STRUCTURE & FUNCTION Red Blood Cells (Erythrocytes): Formed in bone marrow, lack a nucleus, filled with oxygen-carrying protein hemoglobin, biconcave disc shape providing a large surface for oxygen delivery and flexibility in narrow capillaries. They survive in circulation for about 120 days. 53  BLOOD CELL STRUCTURE & FUNCTION White Blood Cells (Leukocytes): Found in circulation but can migrate to tissues to perform various functions, forming the body's defensive mechanism at a cellular level. Classified as granulocytes or agranulocytes based on the presence or absence of visible granules in the cytoplasm. 54  GRANULOCYTES CELL STRUCTURE & FUNCTION Have granules in their cytoplasm, formed in bone marrow, and include neutrophils, eosinophils, and basophils. 55  NEUTROPHILS CELL STRUCTURE & FUNCTION Highly mobile and very active, capable of leaving blood vessels to enter tissue space, and perform phagocytosis containing several lysosomes. 56  EOSINOPHILS CELL STRUCTURE & FUNCTION Play significant roles in defending against parasitic infections and contributing to allergic reactions and inflammation. 57  BASOPHILS CELL STRUCTURE & FUNCTION Capable of leaving blood vessels to enter tissue space, containing histamine, serotonin, and heparin, which are inflammatory chemicals. 58  AGRANULOCYTES CELL STRUCTURE & FUNCTION Do not have granules in their cytoplasm, including lymphocytes and monocytes. 59  LYMPHOCYTES CELL STRUCTURE & FUNCTION Have little cytoplasm closely wrapping around the nucleus, produced in lymph nodes, spleen, bone marrow, and intestinal mucosa. They mature in the thymus (T-lymphocytes) and bone marrow (B-lymphocytes). B- lymphocytes transform into plasma cells, producing antibodies to protect against various infections. 60  MONOCYTES CELL STRUCTURE & FUNCTION Have highly variable morphology and size, migrating to tissues like the liver, lymph nodes, and lungs, where they can stay for days or years. Actively phagocytic, ingest particulate matter, process antigens, and are involved in antigen presentation to B- and T-lymphocytes. 61