Cell Theory PDF

CELL THEORY Biology - 12 STEM CELL Principle 2: The cell is the Smallest living unit, with a capacity to fundamental unit of life. It is the survive and reproduce on its own. smallest unit...

CELL THEORY Biology - 12 STEM CELL Principle 2: The cell is the Smallest living unit, with a capacity to fundamental unit of life. It is the survive and reproduce on its own. smallest unit of structural and functional unit in all organisms. General Functions of the cell Principle 3: Cells come from Regulation of the Internal Environment pre-existing cells. Homeostasis ○ An organism’s ability to keep a Timeline of Cell History constant internal state. 1600s - Simple Microscope was Maintenance of these conditions invented by Leeuwenhoek is important because most cells of an organism require a specific set 1665 - Discovery of cells by Robert of conditions to function normally. Hooke Acquisition and Utilization of Energy 1838 - Plant cells were discovered by (for cellular activities) Matthias Schleiden. ○ Chemical Energy - It is stored in 1839 - Animal cells were discovered the bonds present in food by Theodor Schwann molecules and will be converted 1858 - Biogenesis was proposed by by the cells into more usable Rudolf Virchow forms. Energy is needed by various cells to perform their functions. History of the Development of cell Heart cells to pump blood theory Intestinal cells to digest Zacharias Janssen (1585-1632) food ○ is generally believed to be the Skeletal cells to initiate first investigator to invent the motion compound microscope. Nerve cells to conduct However, because the information accomplishment is generally agreed among historians to be Responsiveness to their environment (to external stimuli) dated in the 1590s, most A cell must first be able to determine the scholars believe that his changes that have taken place before father, Hans, must have deciding the necessary responses that played an important role in the will ultimately result in the maintenance of creation of the instrument. normal internal conditions. Robert Hooke (1635-1703) ○ observed cork under the microscope. Francesco Redi (1626-1697) ○ disproved the spontaneous generation theory. Anton van Leeuwenhoek (1632-1723) ○ Was known as the “Father of Protection and Support Microbiology.” He observed Creates immune cells microorganisms by using his own practical microscope. He The Three Principles of Cell Theory made more than 500 optical Principle 1: Every living organism lenses. He also created at consists of one or more cells. least 25 single-lens microscopes, of differing  CELL THEORY Biology - 12 STEM types, of which only nine have 1. Cell (Plasma) Membrane survived. These microscopes 2. Nucleus were made of silver or copper 3. Cytoplasm (liquid surrounding the frames, holding hand-made nucleus) lenses. Those that have survived are capable of Overview of the regions of the Cell magnification up to 275 times. The cell consists of both Matthias Schleiden (1804-1881) membrane-bound and ○ proposed that all plants are non-membrane-bound organelles. composed of cells. Theodor Schwann (1810-1882) ○ In 1838 Matthias Schleiden had stated that plant tissues were composed of cells. Schwann demonstrated the same fact for animal tissues, and in 1839 concluded that all tissues are made up of cells: this laid the foundations for the cell theory. Rudolf Virchow (1821-1902) ○ proposed that all cells come Rough endoplasmic reticulum from pre-existing cells. Smooth endoplasmic reticulum Golgi Apparatus Vacuole Plasma membrane Mitochondria Cell Wall Microbody Ribosomes Nucleus Structure Components of the Plasma Membrane 1. Structure of the Plasma Membrane COMPONENTS OF THE CELL: Cell Membrane or Plasma membrane separates the cytoplasm from external MAJOR PARTS OF THE CELL environment. It protects the cells. Cells Compromises of the following: Our cells also rely on biomolecules ○ Phospholipid, cholesterol, that provide shape and rigidity to membrane protein, glycolipids, them. In addition, our cells manage to glycoprotein. become selective to the molecules ○ Phospholipids that will move through them. Each of the phospholipids consist Major Divisions of the cell of the ff: Head region Phosphate group  CELL THEORY Biology - 12 STEM Hydrophilic- Impermeable- water-loving can’t pass Tail region through alone ○ Two fatty acid chains but with the aid ○ Hydrophobic- water repelling of the transport protein. Phospholipids make up the phospholipid bilayer ○ Two phospholipid layers ○ Phosphate heads- facing the cytoplasm and the cell's exterior ○ Fatty acids tails- looks like a sandwich The fluid mosaic model describes the membrane structure. ○ Jonathan Singer and Garth Nicholson- proponents who came up with the “fluid mosaic model.” 3. Roles of membrane proteins ○ Mosaic- because of the diverse presence of different biomolecules (protein, sugar, cholesterol, etc) ○ Fluidity- Because of the natural viscosity of the plasma membrane. Membrane fluidity is determined by: ○ The “kinks” in the fatty acid The intracellular space is the tails of the phospholipids. cytoplasm. Kinks- Sharp twist or Transport cellular protein- may either curve be in a carrier or channel protein that ○ The cholesterol molecules act will help diff. molecules enter. as regulators of fluidity. Membrane proteins: 2. Roles of Lipid Bilayer Selective permeability is an important property of the lipid bilayer. ○ Selective permeability- It allows certain molecules to pass through the cell. Not all can go in or out of the cell. Permeable- can pass through the cell.  CELL THEORY Biology - 12 STEM Channel proteins- passageway of a Forms spindle fibers that move certain molecule with the aid of the chromosomes. membrane protein. Carrier proteins- The ones that will 2. Microfilaments change the conformation to transport molecules. Cell recognition proteins- Will detect the invading pathogens. Receptor proteins- binding of molecules to trigger responses The Cytoskeletal Elements The cytoskeletal elements can be observed by using fluorescence They consist of long fibers to techniques. actin protein, making them the This consists of a network of protein thinnest cytoskeleton. fibers that gives the cell its structural They facilitate the movement framework. of the cells and organelles. In addition to providing a structural They also change their shape. framework to the cell, the cytoskeleton also serves other functions such as the movement of 3. Intermediate filaments organelles, macromolecules, and chromosomes. Helps maintain cell shape. Anchors the nucleus. Intermediate filaments provide 1. Microtubules structural integrity to the plasma membrane. Structural Components of the Cytoplasm Tubulin- helically arranged globular proteins that make up the microtubules. A microtubule is a helix of a-tubulin and 𝛃-tubulin This is where all different subcellular subunits. structures are suspended. It radiates from the centrosomes.  CELL THEORY Biology - 12 STEM It is composed of cytosol, a semifluid have their own specific functions that solution that consists of water and work for different cellular processes inorganic and organic molecules.. All the metabolic reactions occur here. Subcellular Organelles Three Groups Genetic control of the cell- nucleus and ribosomes Endomembrane system- endoplasmic reticulum (rough and smooth), lysosomes, Golgi body, vesicles Energy houses- mitochondria and chloroplasts Structure of the Nucleus Structural components of the cell This is a prominent, usually oval wall structure in a eukaryotic cell, The cell wall is a rigid structure that It is located in almost the center of the surrounds the cell membrane. cell. It helps maintain the shape of cells Houses the DNA and the resynthesis and prevent them from bursting. (?) of ribosomes and proteins Peptidoglycan- makes up the cell wall of most bacteria. ○ The rigid envelope that surrounds the cytoplasmic membrane which also serves as protection against the bacterial cells from environmental stress. Chitin- what the cell wall of some fungi is made of. It’s most abundant in Parts of the Nucleus Amino polysaccharide polymer, in Nucleoplasm- the semifluid matrix nature Nuclear envelope- separates the In plant cells, the cell wall consists of nucleus from the cytoplasm. mesh-like cellulose fibers. It prevents Nuclear pores- the permitted it from bursting. passage of the ribosomal subunits and the mRNA out of the nucleus to COMPONENTS OF THE CELL II: the cytoplasm. They allow the SUBCELLULAR ORGANELLES exchange of materials through the nuclear envelope. The cell can be compared to a factory building. It creates a barrier that collects all its machinery and employees in their proper places. In a cell, the organelles represent the machinery and employees that work in a factory building. These organelles  CELL THEORY Biology - 12 STEM Function of the Ribosomes Lysosomes “Little stomach” “lyso” means breaking things apart and “somes” means body. They release hydrolytic enzymes that destroy pathogens that may enter the cell. Phagocytosis- lysosome digesting Ribosomes is the organelles that use food. instructions from the nucleus, written Autophagy- lysosome breaking down in mRNA, to build proteins. damaged organelles. Free and Bound Ribosomes ○ Free ribosomes- are found in Peroxisomes the cytosol. ○ Bound ribosomes- attached to the endoplasmic reticulum. The Endomembrane System These contain enzymes (hydrogen peroxide). These are small organelles that carry oxidation reactions that break fatty and amino acids. They also detoxify many poisons that enter the body. Endoplasmic reticulum Vacuoles Rough ER has thousands of ribosomes attached to the outer surface which give this organelle a “rough” appearance. Produces proteins. Smooth ER does not have attached ribosomes. Produces lipids. Golgi bodies Serve as the storage of water, organic This serves functions similar to a nutrients, a variety of salt sugar, and warehouse and processing center, weak acids processing products of the ER. Also a membrane-bound sack and Serve as the sorting, tagging, storage and transport. packaging, and distribution of lipids. Mitochondria “Powerhouse of the cell.” ATP- is found in the inner part, which is the main energy-carrying molecule. No movement is allowed without energy. Uses oxygen and carbon dioxide as waste products.  CELL THEORY Biology - 12 STEM Chloroplast specific organs or to develop into This is unique to plant and algae cells tissues. Cell Differentiate- a process that allows the stem cells to transform into different types of cells. Pluripotent- unique features of the cell. They have the potential to be any type of cell in the body. 2 Types of Stem cells Embryonic stem cells ○ used for research purposes. From embryos and are harvested from fertilized eggs. Adult (or somatic) stem cells ○ Present throughout the human body. They exist to repair and maintain surrounding specialized tissues. Bone cells Bones are types of mineralized connective tissue and a major CELL TYPES: CELL component of the skeletal system. SPECIALIZATION AND Bone cells form bone, which is MODIFICATION composed of a matrix of collagen and Types of Animal Cells calcium phosphate minerals. Somatic (body) cells and germinal ○ osteoid - the organic (sex) cells substance in the bone matrix ○ Somatic- mitosis ○ Germinal- meiosis 3 types of bone cells Osteoclasts Stem cell ○ decompose bone for Unique cells of the body in that they consumption and assimilation are unspecialized (haven’t formed into (taking nutrients). A different types of cells) and have the multinucleate cell that secretes ability to develop into several different acids and enzymes to dissolve types of cells. bone matrix. Have the ability to differentiate or ○ Osteoblasts- Immature bone develop into specialized cells for cells that secrete organic components of the matrix.  CELL THEORY Biology - 12 STEM ○ Osteocytes- mature bone cell Smooth muscle cells that maintains the bone matrix. Blood cells Vital to life since it transports oxygen ○ are cells that are not striated. and fights infections. Smooth muscle tissue is an Produced by the bone marrow. involuntary muscle that lines Red blood cells (erythrocytes) body cavities and forms the ○ transport oxygen throughout walls of many organs (kidney, the body and will also intestines, blood vessels, lung determine the blood type of a airways, etc) person. Concave and structure with 5 million cells per blood sample. Fat Cells (Adipocytes) White blood cells (leukocytes) Contain droplets of stored fat ○ fight infections inside the body (triglycerides) that can be used for (immune system cells) that energy. destroy pathogens. ○ Neutrophils- 40-70% of all the white blood cells are this. ○ Lymphocytes- 18% and 42% of WBC. Natural killer cells. ○ Monocyte- Kill or alert the other cells that there are invaders to help destroy them to avoid infections. Skin Cells ○ Platelets- Help clot blood to Keratinocytes prevent excessive blood loss ○ The most abundant epidermal due to broken blood vessels. cells, they function mainly to Muscle cells (myocytes) produce keratin. Skeletal muscle cells Melanocytes ○ are covered by connective ○ protects us from the UV, and tissue, which protects and release pigments. supports the muscle bundles. Merkel Cells Cardiac muscle cells ○ reactant when skin feels pain. ○ form involuntary cardiac Langerhans Cells muscle found in the heart. ○ fight against pathogens. Gives synchronization in the heartbeat.  CELL THEORY Biology - 12 STEM Nerve Cells (Neurons) Nerves send signals among the brain, spinal cord, and other body organs via nerve impulses. Consists of two major parts; ○ Cell body- Contains the neurons ○ Nerve processes- "finger-like" projections from the cell body that are able to conduct and transmit signals. Endothelial cells From the inner lining of the cardiovascular system and lymphatic system structures. Regulates the blood pressure, movement of macromolecules, etc Sex Cells (Gametes) Reproductive cells are produced in male and female gonads. Male sex cells (sperm) ○ May flagellum (tail) Female sex cells (ova)