Cell Theory and History PDF

**CELL THEORY** =============== - The most accepted and recognized concept in Science. - Major evolution in Microscope Technology. - Study of the concepts of living organisms and their environment. - Contributed to the study of medicine, human disease, and microbiology. **3 TENETS O...

**CELL THEORY** =============== - The most accepted and recognized concept in Science. - Major evolution in Microscope Technology. - Study of the concepts of living organisms and their environment. - Contributed to the study of medicine, human disease, and microbiology. **3 TENETS OF THE CELL THEORY** 1. All living organisms are made up of cells. 2. The cell is the basic unit of life. 3. All cells come from pre-existing cells. **HISTORY OF THE CELL THEORY** ============================== **Hans Janssen** and **Zaccharias Janssen** *(1590s)* - Invented the compound microscope **Robert Hooke** *(1665)* - Author of Micrographia "Small Drawings" - Member of the Royal Society - Coined the term "Cell" after discovering box-like structures in a cork (using a compound microscope with a magnification of 30x), which reminded him of cells in a monastery. - Comes from the Latin word "Cellula," which means "small room." **Anton Van Leeuwenhoek** *(1674)* - Dutch Microscopist - Father of Microbiology - Invented his own version of a microscope with a magnification of 300x - Named protozoa/bacteria (found in his dental scrapings) "Animalcules," because of their resemblance to animals - Discovered that they are "motile" and reported to the Royal Society that motility is a quality of life. - Credited for making the first observations of red blood cells and sperm cells. **Robert Brown** *(1827-1833)* - Discovered the **Brownian Motion** from pollen grains that jiggled in water - Random movement displayed by small particles that are suspended in fluids. - Discovered the nucleus. **Matthias Jakob Schleiden** and **Theodore Schwann** *(1838)* - Schleiden was a German botanist who proposed that all plants were composed of cells. - Author of "*Contributions of Phytogenesis*" - Recognized the importance of nucleus (1831, discovered by Robert Brown) - Schwann was a German zoologist and founder of modern histology who proposed that all animals were composed of cells. - Contributed to the germ theory of alcoholic fermentation. - Schwann cells - Coined the term metabolism **Theodore Schwann** *(1839)* - Proposed the classic cell theory: 1. All living things are made up of cells. 2. Cells are the basic unit of life. **Rudolf Virchow** *(1855)* - German physician, anthropologist, and father of pathology - Expounded his famous conclusion "Omnis cellula e cellula." (Cells all come from cells) which added the final tenet of the cell theory. **Louis Pasteur** *(1859)* - One of the founders of bacteriology - Further solidified biogenesis - Demonstrated the "Swan Neck Flask" experiment that showed minute organisms, such as protists and bacteria arising from pre-existing organisms. **CELL STRUCTURE AND FUNCTIONS** ================================ **Protection** -------------- - **Plasma Membrane**  - Plays a role in maintaining **homeostasis** *(balance or equilibrium)* within the cell by controlling what goes in and out of the cell (molecules, ions, and gases). - The process of maintaining stable conditions inside a cell (or an entire organism). A diagram of a cell membrane Description automatically generated - Composed of a phospholipid bilayer implanted with proteins. - The building blocks of all cell membranes are phospholipids that consist of a **glycerol** molecule, **two fatty acids** (unsaturated and saturated), and a **phosphate group**. - **Phospholipid Bilaye**r - **Head** or **Polar** *(Glycerol & Phosphate Group)* - "Hydrophilic," is the ability to mix well, dissolve, or to be attracted to water. - **Tails** or **Nonpolar** *(Fatty Acids)* - "Hydrophobic," or lacking an affinity for water.  - **Cell Wall** Cell Wall \| Introduction, Structure & Function - A rigid layer that provides protection, rigid support, and shape to the cell. - All plants, algae, and fungi (and 90% of bacteria) have cell walls. - **Composition** - Plants and Algae = Polysaccharides - Fungi = Chitin - Bacteria = Peptidoglycan - **Stomata** are gateways found in cell walls. - **Cytoplasm**  - Surrounds all the internal cell structures in both prokaryotes and eukaryotes. - **Cytosol** is the fluid portion of the cytoplasm. - Cytoplasm -- Organelles = Cytosol **Genetic Control** ------------------- - **Nucleus** Molecular Expressions Cell Biology: The Cell Nucleus - Stores the cell's hereditary material, or DNA *(Deoxyribonucleic acid)*. - Coordinates the cell's activities (growth, metabolism, protein synthesis, and reproduction). - **DNA** - Holds the blueprint for all living organisms. - Composed of Sugar, Phosphate groups, and Nitrogen bases. 1. Adenine-Thymine *(Uracil in RNA)* 2. Cytosine-Guanine - **Genes** - Specific sequences present at the start of DNA which encodes specific proteins. - **Histone** - Basic protein that helps condense DNA into chromatin. - **Nucleosome** - Formed by multiple Histones. - **Chromatin** - The dense string-like fiber within a chromosome consists of DNA and protein. - **Chromosome** - The DNA molecule is packed into thread-like structures. - The first 22 are called **Autosomes.** - The 23^rd^ is called the **Sex Chromosome.** - **Karyotpying** - The pairing and ordering of Chromosomes.  - **Nuclear Envelope** - Encloses the DNA and separates it from the cytoplasm. - **Nuclear Pore** - Regulates cellular transportation between the nucleus and cytoplasm. - **Nucleolus** - Organelle within the nucleus that manufactures Ribosomal RNAs (*Ribonucleic acid).* Nuclear membrane - Simple English Wikipedia, the free encyclopedia **Endomembrane System** ----------------------- - **Endoplasmic Reticulum** - Network of hollow membrane tubules that facilitate the manufacture and transport of all essential molecules for the cell. - Connects nuclear envelope and cell membranes. - **Cisternae** - A series of flattened and stacked pouches. - **Lumen** - Is the inside space of a tubular structure. - **Vesicles** - Store and transport materials within the cell. - **Rough ER** - Contains ribosomes, pancreas *(insulin),* plasma, and WBCs. - **Smooth ER** - The site of lipid metabolism. - Mobilization of glucose from glycogen - Calcium storage - Drug detoxification  - **Golgi Apparatus** - Responsible for transporting, modifying, and packaging proteins and lipids into vesicles for delivery to targeted destinations. - **Cis Face** is the receiver. - **Trans Face** is the transporter. - **Vacuole**  - Fluid-filled sacs for storage surrounded by a membrane called Tonoplast. - Made of sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes. - **Animal cells** have multiple small vacuoles. - **Lysosome** Lysosome \| Definition, Function & Structure - Lesson \| Study.com - Contains lysozyme and other digestive enzymes. - Break down food, bacteria, and worn-out cell parts. - Apoptosis *(suicide),* autolysis *(homicide),* and phagocytosis *(vore)* - Self-digestion or self-eating - **Peroxisome** - Where Hydrogen Peroxide is both generated and broken down - Lipid Catabolism **Energy-Processing Organelles** -------------------------------- - **Mitochondria** - Generate chemical energy in the form of ATP (Adenine Triphosphate). - Contains Ribosomes and DNA.  - **Chloroplasts** - Types of plastids which help plants convert solar energy to chemical energy. - Contains ribosomes and DNA. Molecular Expressions Cell Biology: Plant Cell Structure - Chloroplasts **Support, Movement, and Intercellular Movement** ------------------------------------------------- - **Centrosome and Centriole** - Bundle of 9 triplet Microtubules made of Mitotic Spindle Fibers. - Assists in cell division. - **Cilia and Flagellum** - Allows the cell to move (9+2 Pattern) - **Eukaryotic Flagellum** - Whip-like movement - Composed of the protein tubulin. - **Bacterial Flagellum** - Clockwise/Counter-Clockwise Movement - Composed of the protein flagellin. - **Cilia** - Shorter and numerous - Motile: Bacteria - Non-motile: Trachea  - **Cytoskeletion** - Provides mechanical support - **Intermediate Filaments** - Resist mechanical stress - **Microtubules** - Cellular Transport - **Microfilaments** - Internal cell movement Cytoskeleton \| 1.4K plays \| Quizizz - **Cell Surfaces and Junctions** - Form extracellular connections between adjacent cells - **Plant Cells** - **Plasmodesmata** - Allows intercellular communication between cells.  - - **Animal Cells** - **Tight Junctions** - prevent leakage of solutes and water and seals between the epithelial cells. - **Adhesion Junctions** - Joining the acting filament in the neighbor cell. - **Gap Junction** - Linkage of the two adjacent cells. **PROKARYOTES VS EUKARYOTES** ============================= +-----------------------------------+-----------------------------------+ | PROKARYOTES | EUKARYOTES | +===================================+===================================+ | - Bacteria | - Protists | | | | | - True Bacteria | - Amoeba, Protozoa | | | | | - Archaeans | - Fungi | | | | | - Cells that can survive in | - Mushrooms, Yeast | | harsh environments. | | | | - Animalia | | | | | | - Plantae | +-----------------------------------+-----------------------------------+ | "Pro," meaning *primitive*, and | "Eu," meaning *well-defined*, and | | "karyo," meaning *nucleus*, as | "karyo," meaning *nucleus*. | | Prokaryotes are one of the most | | | ancient groups of living | | | organisms on earth. | | +-----------------------------------+-----------------------------------+ | Prokaryotes are always | Eukaryotes are often multi-celled | | unicellular and less complex.   | organisms (protists are examples | | | of eukaryotic cells that are | | | unicellular) that are 100 to | | | 10,000 times larger than | | | prokaryotic cells. | +-----------------------------------+-----------------------------------+ | No membrane-bound organelles | Membrane-bound organelles | +-----------------------------------+-----------------------------------+ | No Nucleus *(Nucleoid Region)* | Has nucleus | +-----------------------------------+-----------------------------------+ **TRANSPORT MECHANISMS *(CELLULAR TRANSPORT)*** =============================================== - The collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes. - The **SOLUTE** is the substance being dissolved. - The **SOLVENT** is the substance that dissolves. - **\ CONCENTRATION** is the amount of substance in a particular area. - **DYNAMIC EQUILIBRIUM** - Where particles continue to move rapidly, no further change in concentration will occur. **Passive Transport** --------------------- - Movement is from high concentration to low concentration (Diffusion). - No energy (ATP) required. - All about balance. - **Simple Diffusion** - Movement of small molecules/solutes (CO2, O2, N2) that are nonpolar and lack a charge across a semi-permeable membrane without the help of a protein channel. - Diffusion occurs because molecules are in constant motion. Simple diffusion- Definition, principle, examples, applications - **Facilitated Diffusion** - Movement of molecules/solutes (glucose, amino acids, ions) that are polar and have a charge across a semi-permeable membrane with the help of membrane transport proteins.  - **Osmosis** - Movement of water molecules (solvent) from a point of higher concentration through a semi-permeable membrane. Osmosis - Wikipedia - **Aquaporin** - Integral membrane proteins that serve as channels in the transfer of water. - Intestines absorb water through osmosis - Kidney cells retain water through osmosis. - **Tonicity** - Strength of solution in reaction to osmosis. - Concentration of solution to another. - **Hypertonic** - Less concentration of water compared to that in the cytoplasm. - Causes removal of water molecules in the cytoplasm of animal cells and deformation of the cell. - In plant cells, the removal of water molecules causes the cell membrane to be pulled away from the cell wall (Plasmolysis). - In RBCs, the process of deformation is called crenation.  - **Hypotonic** - More water inside the cell than inside the cytoplasm, causing it to burst (Cytolysis). Hypertonic Hypotonic and Isotonic Solutions with Examples \| Movement of Molecules - **Isotonic** - A solution with the same concentration of water and other solutes as the cytoplasm of the cell. - A cell in an isotonic solution remains unchanged; no swelling/shrinking.  **Active Transport** -------------------- - Movement of substances through cell membranes directions against the concentration gradient. - From low to high concentration. - Involves transport proteins (pumps) - Energy (ATP) is required. - From ATP to ADP because of the use of a phosphate group. Active Transport - Definition And Types Of Active Transport - **Active Transport in Humans** - Needed in nerve and muscle cells. - Potassium ions tend to move toward the cell (acute metabolic alkalosis) - **Alkalosis** - Abnormally high pH in blood. - Sodium ions constantly move out of the cell despite its high concentration outside. **Bulk/Vesicular Transport** ---------------------------- - **Endocytosis** - Cell membrane bends inwards or invaginates, forming a vesicle containing the macromolecules to be transported. - **Phagocytosis** - Cells take in large particles or solids by infolding the cell membrane to form endocytic vesicles. - Exhibited by WBCs (Macrophage; pseudopodia, "false feet")  - **Pinocytosis** - Process of taking in fluids into the cell by invaginating the cell membrane. - Cells lining the intestines and plant root cells ingest liquid substances. Pinocytosis - Wikipedia - **Receptor-Media Endocytosis** - Very specific as to what it takes in. - Specific proteins (ligands) that are exposed to the fluids outside of the cell will allow substances to attach to them. - Metabolizes hormones and proteins.  - **Exocytosis** - Materials for export like proteins are secreted out of the cell. **HISTOLOGY** ============= - Branch of biology that deals with tissues. **Cell** - Basic unit of life. **Tissue** - A group of specialized cells that work together for a particular function. **Organ** - A distinct structure made up of different tissues that have a specific function. **Organ System** - A collection of organs that carry out specific functions within an organism. **Organism** - A living thing that carries out all of life's functions. **Different Tissues in our Body** ================================= **Epithelial Tissues** ---------------------- - Characterized by closely joined cells with tight junctions. - Seen outside the body as coverings or as linings of organs and cavities (basically covers things). - Act as protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception. ### **Types of Epithelial Tissues** **Cuboidal** - A single layer of cells that are approximately as tall as they are wide, with spherical and centrally placed nuclei. - Secretory, absorptive, or excretory functions. - Mostly seen in the: - Surface of the ovaries - Renal tubule walls---located in our urinary systems - Internal walls of the seminiferous tubules of the male testes - Pancreas - Salivary gland - Parts of the eye - Follicles of the thyroid **Simple Columnar** - A single layer of brick-shaped cells that helps in secretion and active absorption. - The height of the cell exceeds the width of the ovoid nuclei (they're taller than they are wide). - The nucleus is in the basement membrane and the shape of the nucleus is oval or oblong. - Mostly seen in the digestive system: - Stomach - Small and Large Intestine - Upper Cervix **Simple Squamous Epithelium** - A single layer of plate-like cells that help exchange materials through diffusion. - Secretes lubricating substances - Allows diffusion and filtration - Found in the Circulatory and Respiratory System: - Blood and lymphatic vessels - Air sacs of lungs - Lining of the heart **Stratified Squamous** - Multilayered and regenerates quickly; acts as protection against abrasion. - Mostly seen in the - Esophagus - Mouth - Vagina - Integumentary System - Urethra Pin page +-----------------------------------+-----------------------------------+ | Non-Keratenized | Keratinized | +===================================+===================================+ | It is a stratified squamous | It is a stratified squamous | | epithelium that lacks keratin | epithelium that has keratin | | protein. | protein. | +-----------------------------------+-----------------------------------+ | Made of living cells. | Made of dead cells (because of | | | the deposition of keratin). | +-----------------------------------+-----------------------------------+ | Moist layer that is permeable to | Dry layer that is impermeable to | | water. | water. | +-----------------------------------+-----------------------------------+ | Forms a less effective barrier. | Forms an effective barrier. | +-----------------------------------+-----------------------------------+ | Oral Cavity, Pharynx, Esophagus, | **Layers of the Epidermis:** | | Distal ureters, Vagina, External | | | female genitalia | Stratum Basale, Stratum Spinosum, | | | Stratum Granulosum, Stratum | | | Lucidun, Stratum Corneum | +-----------------------------------+-----------------------------------+ - **Keratinized cells in our body/epidermis:** - **S. Basale** - Continuously divide by mitosis to give rise to keratinocytes. - **S. Spinosum** - Partly responsible for the skin's strength and flexibility. - **S. Granulosum** - Help form a waterproof barrier that functions to prevent fluid loss from the body. - **S. Lucidum** - Lowers the effects of friction in the skin, especially in regions like the soles of the feet and palms of the hands. - **S. Corneum** - Topmost, non-living, cellular layer of the epidermis.  **Pseudo-Stratified Columnar** - Single layer of cells; may just look stacked because of varying height; usually lined with cilia. - Secretes mucus which is moved with cilia. - The cilia is located in the Trachea. - Mostly seen in the: - Trachea - Most of the Respiratory Tract (Ciliated) **Connective Tissues** ---------------------- - Connects, separates, and supports all other types of tissues in the body. - Function and involve parts of the body Adipose Tissues. ### **Types of Connective Tissues** #### **Connective Tissue Proper** - **Dense Irregular Connective Tissue** - Made of Type 1 Collagen Fiber. - Found in high concentrations in body parts where support is needed to prevent the forces that pull in multiple directions. - This is for making skin resistant to tearing. - Used to prevent scratches. - Mostly seen in the: - Dermis - Glandular Tissues - Walls of the Organs - Whites of the Eyes Dense irregular connective tissue - **Dense Regular Connective Tissue** - Made of Type 1 Collagen Fiber. - Found in areas of the body where large amounts of tensile strength are required. - Mostly seen in the: - Ligaments - Tendons  - **Loose Connective Tissue** - Also known as areolar connective tissue. - Most common type of connective tissue. - Holds organs in place. - Mostly seen in the: - Lamina propria of the alimentary and respiratory tracts - Mucous membranes of reproductive and urinary tracts - Glands - Mesentery - Dermis Loose connective tissue - Wikipedia - **Reticular Connective Tissue** - Produced by modified fibroblasts called reticular cells. - Reticular meshes filter lymph and provide a microenvironment for the passage and attachment of white blood cells. - Mostly seen in the: - Red Bone Marrow - Lymph Nodes - Spleen  #### **Specialized Connective Tissue** **Blood** - Specialized connective tissue within the circulatory system. - Made up of plasma (fluid portion). - **3 Major Parts:** - **Erythrocytes** *(RBCs)* - Transport oxygen throughout the body and deliver carbon dioxide to the lungs to eliminate it during exhalation. - The lack of iron in RBCs lead to iron deficiencies and peeling of the skin in the lips. - **Hemoglobin** is the pigment that gives RBCs their red color. - **Leukocytes** *(WBCs)* - Help fight infections, diseases, bacteria, and viruses; Acts as defense. - **Thrombocytes** *(Blood Platelets)* - Responsible for blood clotting. - The body's natural bandage to stop bleeding. **Bone** - Mineralized connective tissue made by bone-forming cells called osteoblasts which deposit collagen. - Serve as storage site for calcium and phosphate, alongside its weight bearing and protective functions. - **Osteoblasts** are responsible for bone forming - **Osteocytes** are made of osteoblasts; cells in our bones. - **Osteoclasts** damage the bone. Bone connective tissue - Sciencetopia **\ Cartilage** - Functions as cushion between bones - **Kinds of Cartilage** - **Hyaline** - Found in the Nose, Ribs, Larynx, and Trachea. - Consists of Hyaline Cartilage. - **Elastic** - Mostly seen in the Ears. - Also known as yellow fibrocartilage. - **Fibrocartilage** - Mostly seen in the Intervertebral Discs or Spinal Column.  #### **Adipose Tissue** - Energy-storing connective tissue. - Consists of adipocytes: cells filled with lipids. - Cushions and insulates the body. - **Kinds of Adipose Tissue** - **Subcutaneous Fat** - Located in the deepest layer of the skin (hypodermis). - **Visceral Fat** - Mostly seen inside the Belly, Liver, and the Intestines. What is Subcutaneous Fat and How Can I Get Rid Of It? - InBody USA - **Breast Tissue** - Part of our mammary gland. **Muscle Tissues** ------------------ - Composed of long cells called muscle fibers that allow the body to move voluntarily and involuntarily. - **Properties:** - Excitability - Contractibility - Extensibility - Elasticity ### **Types of Muscle Tissues** **Skeletal Muscle** - Move bones and other structures. - Multi-nucleated; Striated; Voluntary Movements - Attached to the skeleton. **Cardiac Muscle** - Forms the muscular wall of the heart. - One nucleus; Striated; Involuntary **Smooth Muscle** - Only tissue in the body that can contract and therefore move the other parts of the parts of the body. - One nucleus; Not Striated; Involuntary - Mostly seen in the: - Middle layer wall of most blood vessels (tunica media) - Muscular part of the wall of the digestive tract - Uterus **Nerve Tissues** ----------------- - Composed of nerve cells called neurons and glial cells that function as support cells. - Transmit information throughout the body in the form of electrical signals or nerve impulses. - **Neurons** - Nerve cells that send messages all over your body. - **Neuroglial Cells** - Cells of the nervous system that are not involved in the conduction of nervous impulses. - Smaller than neurons, and do not have axons or Dendrites.