Cell Theory and Proponents PDF

**General Biology 1/Reviewer/1^st^ Quarter** **Cell Theory and the Proponents** **Cell -The basic fundamental unit of life** **1.Cell is the simplest and smallest life form.** - **Cell is life.** **2. Cell makes up life living organisms.** - **Cell is the building blocks of life.** **...

**General Biology 1/Reviewer/1^st^ Quarter** **Cell Theory and the Proponents** **Cell -The basic fundamental unit of life** **1.Cell is the simplest and smallest life form.** - **Cell is life.** **2. Cell makes up life living organisms.** - **Cell is the building blocks of life.** **Cell Theory (Unifying Theory in Biology) -Postulates of Cell Theory** **1. Cell is the basic and fundamental unit of life.** **2. All living organisms are composed of cells.** **3. Cells arise from pre-existing cells.** **All living organisms have Cells. Biogenesis "Life can only come from another life"** **Theory of Spontaneous Generation (Abiogenesis):** **-Hypothetical process by which living organisms develop from non-living matter.** **-Persisted until 17th century** **-Proposed by Aristotle (384-322BC)** **"Life arose from non-living material if the materials contained pneuma ("vital heat")** **Evidences of spontaneous generation by Aristotle:** **1.** **Fish appeared in puddles of water 2.** **Maggots in decomposing meat** **Arguments in Spontaneous Generation:** **-Jan Babtista van Helmont (7^th^ Century)** - **Mice in rags and wheat kernels** **-Francisco Redi (1626-1697)** **Refute the idea that maggots spontaneously generated on meat left out open in the air** **Predicted preventing flies from direct contact on meat would prevent appearance of maggot** **Meat in the Jar Experiment** **-Maggots could only form when flies were allowed to lay eggs on the meat. Not a product of spontaneous generation** **-John Needham (1713-1781)** **Tries to prove spontaneous generation** **Boil broth in animal and plant matter** **-Lazzaro Spallanzani (1729-1799)** **Did not agree with Needham** **Experimented with heated broths.** **-This experiment suggested that microbes were introduced into the flask from the air** **Results contradicted Needham** **Needham's counterargument** **Needham argued that life originates from a "life force" that was destroyed during Spallanzani's extended boiling.** **Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation.** **-Louis Pasteur (1825-1895)** Disproved spontaneous generation using "Swan-necked experiment" -Since no microbes can enter the flask, if there is no growth of microbes then it is impossible for life to come from any "life force" (nowhere) **DEVELOPMENT OF CELL THEORY** **CELL THEORY TIMELINE** 1\. Zaccharias Janssen- Invention of the 1^st^ microscope 2, Robert Hooke- First to discover and describe the cells. Coined the term cells Hooke used oak cork tissues Cella = small rooms -\> Cells Published his observations in his book Micrographia in 1665 3\. Antonie van Leuwenhoek- First to see living and motile cells/organisms under the microscope. Discovered bacteria, and protists -\> animalcules 4\. Matthias Jakob Schleiden- Suggested that all elements of plants are made of cells Theodore Schwann- Realized that all animals are made of cells. Became major proponents of cell theory: - Cell is the basic and fundamental unit of life - All organisms are made up of cells 5\. Rudolf Virchow- Coined the latin phrase "Omnis cellula e cellula" which means ''Cells come from pre-existing cells'' Plagiarized the idea of Robert Remak 6\. Robert Remak- Challenged spontaneous and came up with the 3^rd^ postulate "Cells come from pre-existing cells" 7\. Louis Pasteur- Disproved the theory of spontaneous generation once and for all through a swan neck flask experiment **Modern Postulates of Cell Theory** 1\. All cells have the same basic chemical composition 2\. Hereditary information (DNA) is passed on from cell to cell 3\. Energy flow occurs within the cell **Cell Structure and Organelles** Cell organelles- Subcellular structures which are separated internally into numerous membranous compartments. "Little organ" **-Non-Membrane Bound Organelles** Function: Maintain Cell Integrity Protection Support Movement **Plasma/Cell Membrane** Serves as barrier separating the inside and outside of the cell Phospholipid bilayer structure Described as fluid mosaic Protection of Cell Amphipatic which means: Prevents unwanted and toxic molecules from coming in Prevents entrance of foreign materials and pathogens **SELECTIVELY PERMEABLE** Only allows the passage of specific molecules an inhibits others. **MAINTENANCE FOR THE CELLULAR ENVIRONMENT** Cell Recognition and signaling. Cell membrane contains cell receptors (proteins and carbohydrates) which is used for recognition of other cells and molecules, identification, send signals, and communication. **Cell Wall (Plants Only)** Made up of Cellulose A rigid **SEMI-PERMEABLE** outer layer of **PLANT CELLS** For protection, shape, and structural support of plants **Cytoplasm** Clear, semi fluid space Site for metabolic reactions Houses organelles Flexible cellular framework composed of: **-Microtubules** Made up of **tubulin proteins.** For structural support and organization Movement of cell (Flagella and Cilia) Transport of organelles Movement of chromosomes during cell division **-Microfilaments** Made up of **actin proteins** Help maintain shape Engulfing and secretion via cell membrane Assist in cell movement Contraction of cell **-Intermediate Filaments** Made up of **mixed proteins** Support Holds and keep organelles in place **Cilia and Flagella** Elongated structures made of microtubules Cilia- Hair like structure For locomotion and food collection Flagella- Whip like structure Mainly for locomotion **Centrosomes** Composed of spindle-fibers, centrioles, and microtubules **-Membrane Bound Cell Organelles** Function: Maintain Cell Function Manufacturing Processing Energy Transport **Nucleus "Control Center"** -Spherical -double-membrane(bilayer) -Stores genetic material (DNA: chromatin) -Pre-assembly points for ribosomal units -Ribosomes transcript mRNA which passes through **[nuclear pore]** to proteins which are responsible for cellular functions DNA (genetic info) mRNA PROTEINS **NUCLEOLUS** Site for production and assembly of ribosomes **Endoplasmic Reticulum "Manufacturing and transport center"** -Complex labyrinth (cisternae) -branches out to cytoplasm -membrane-bound (bilayer) -continuous with nucleus **Rough ER** -storage for proteins and enzymes -synthesize proteins -attachment site for ribosomes **Smooth ER** \- synthesizes, manufactures modify and transports lipids \- Steroid metabolism \- No ribosomes -Transports macromolecules -Aids in the detoxification of wastes and harmful chemicals **Golgi Apparatus "Delivery and Packaging Center"** -Stacks of disk-like membranes (cisternae) -Modifies, sorts, and packages proteins and lipids (mostly from ER) for transport to target destinations **Vesicles "Transporting Organelles"** -bud off from the cisternae of ER and Golgi -membrane-bound (bilayer) sacs -contain enzymes or secretory products -transport manufactures materials -storage -site for digestion **ENDOMEMBRANE SYSTEM** **Nucleus ERGolgiPlasma Membrane** Collection of organelles that help modify each other. **Mitochondria "Powerhouse of the Cell"** -elongated organelle -membrane-bound (bilayer) -membrane-bound (bilayer) Site for cellular respiration: converts energy from food (glucose) to energy (ATP) Cellular respiration review (article) \| Khan AcademyATP = energy currency of the cell Inner layer is the site for cellular respiration Folding increases surface area of production of ATP -\> more energy!! **Chloroplast** ONLY IN PLANTS -oval-shaped organelle -membrane-bound (bilayer) Site for photosynthesis: converts light energy into chemical energy (sugar)  **Lysosome** -membrane-bound (bilayer) sphere -contains hydrolytic enzymes (hydrolases) Digestion/ breaking down of wastes, obsolete/damaged cell parts, unwanted materials inside the cell and other materials for secretion or recycling. -Sends signaling enzymes if the cell should undergo APOPTOSIS/ Cell death **Peroxisome** -contains catalytic enzymes (catalase) Metabolizes lipids (fatty acids) and amino acids through oxidation Detoxify poisons (eg reactive oxygen species, H202) **Vacuole "Water storage center"** Animals: small and numerous Plants: one and large Protists: Contractile -membrane surrounded sac (single membrane) -occupies huge portion of the plants Storage site of water, food and other compounds **Provides shape and structural support for plant cells** **Water fills the vacuole until it becomes [turgid]**