Cells PDF - Lecture Notes

Cells Wednesday, September 6, 2023 11:38 AM Lecture 2 Lecture 1 PRINCIPLES OF CELL THEORY...

Cells Wednesday, September 6, 2023 11:38 AM Lecture 2 Lecture 1 PRINCIPLES OF CELL THEORY Lecture Objective: → Theodor Schwann: the cell is the smallest structural and functioned unit capable of carrying → Understand the three components of the cytoskeleton and their function out life processes → Know the composition of the cytosol → The functional activities of each cell depend on the specific structured properties of the cell → Explain what cellular metabolism is → Cells are the inning blocks of all plants and animals and bacteria organisms → Identify the stages of cellular respiration → The cell is the basic unit of life → Understand the glycolytic pathway → An organism's structure and function ultimately depend on the collective structural "bone and muscle" of the cell characteristics and functional capabilities of its cell CELL STRUCTURE AND FUCNTION: CYTOSKELETON → b/c of this continuity of life, the cells of all organisms are fundamentally similar in structure and function Microtubule Microfilaments → Largest of the 3 ( in size) → long, slender, hollow tubes composed of tubulin molecules CELL STRUCTURE AND FUNCTION → Maintain asymmetric cell shapes and coordinate complex cell movements → Smallest elements of the cytoskeleton ( in size) ○ Highways for transport of secretory resides within cell → Intertwined helical chains of actin ( present in all cells ) molecules; microfilaments → Trillions of cells in the human body classified into ~ 200 cell types → Main structural and functional component of cilia and flagella (allows them to move) composed of myosin molecules also present in muscle cells → This is based on specific variations in structure and function → Position cytoplasmic organelles ( ER, Golgi complex, lysosomes, and mitochondria) → Play vital role in various cellular contractile systems, including muscle contraction Despite variations, cells still share many common features: → Assemble into mitotic spindle and amoeboid movement (WBC or fibroblasts); serve as a mechanical stiffener for ○ Plasma membrane → Acts like a transport highway inside the cell microvilli ○ Cytosol ○ Microvilli increases surface area of the stomach ○ Nucleus § Actin stiffens it Intermediate filaments Nucleus → Surrounded by a double layered membrane Plasma membrane → Houses / contains the cell's genetic material, deoxyribonucleic acid (DNA) → Irregular, threadlike proteins → Thin membranous structure that encloses each cell → Serves as a genetic blueprint during cell replication → Help resist mechanical stress, gives strength → Composed mostly of lipid (fat) molecules (bilayer) → Made of keratin protein (found in our nails and hair) → Directs protein synthesis → Studded with proteins → Within the cell ○ Proteins play a function of communication and interact with its surroundings → Barrier separates the cell's contents from its surroundings → Selectively control movement of molecules into and out of the cell → Molecular highway → Dynein is the thing that moves the vesicle ( thing that needs to be transported ) along the microtubules (functions as a car) CELL STRUCTURE AND FUNCTION: CYTOSOL Golgi Complex → Consists of a stack of flattened, slight curved, membrane-enclosed sacs Cytosol = Cell Gel → Closely associated with the ER → The empty / remaining space inside the cell Endoplasmic reticulum → Job: modifies packages and distributes / sorts newly synthesized proteins → fluid filled membranous system Intermediary Dispersed within the cytosol Facilitate intracellular reactions involving → A protein and lipid producing factory metabolism enzymes degradation, synthesis, and transformation → Rough ER: of small organic molecules ○ Studded / surrounded with ribosomes Transport, secretory, Transiently formed, membrane - enclosed products Transport or store products being moved ○ Synthesizes proteins to be secreted to the exterior or to be incorporated into plasma and endocytic vesicles synthesized within or engulfed by the cell within, out of, or into the cell, respectively membrane or other cell components Inclusions (storage) Glycogen granules ( abundant amount found in muscle Store excess nutrients → Smooth ER: and liver cells ), fat droplets - lipids ○ Packages the secretory production into transport vesicles, which bud off and move to the Golgi complex ○ Has lost of lipids Ribosomes CELLULAR METABOLISM → Make protein 1. Transcribe DNA to RNA or mRNA ( in the nucleus) 2. mRNA leaves to the ribosomes and gets translated into protein or a series of amino acids INTERMEDIARY METABOLISM 3. Amino acids go through a process of folding and shaping before becoming a protein → Refers to the large set of chemical reactions inside the cell that involve the degradation, synthesis, and transformation of small organic molecules such as simple sugars, amino acids, and fatty acids → The intermediary metabolism occurs in the cytosol and involves thousands of enzymes Centrioles → A pair of cylindrical structures at right angles to each other → Form and organize microtubules during assembly of the mitotic spindle Anabolic - the process of building smaller molecules into bigger / complex molecules during cell division Catabolic - the process of breaking down larger molecules into smaller / simpler ones → Form cilia and flagella ( ex in male sperm ) ○ Allows them to move and expel foreign substances ATP → 1. This source of energy for the body is the chemical energy stored in the carbon bonds of ingested food → 2. Has to be extracted by the cell machinery and converted into a source of energy usable by the cell = high-energy phosphate bonds of Adenosine Triphosphate or ATP Inorganic phosphate, third phosphate hold immense power lol ○ Breaks down glucose ( 6 carbon molecule ) Lysosome ○ Harnesses energy → Small, membrane-enclosed, degradative organelles ○ from the breakdown of the carbon bonds → Break down organic molecules with powerful hydrolytic enzymes → Digestive system of the cell: destroy foreign substances (like viruses) → Body's common energy "currency" and cellular debris Cells "cash in" ATP to pay the energy → Contains enzymes that's job is to break down macromolecules "price" for: Maintaining structure, function and growth Peroxisomes → Membrane-enclosed sacs containing oxidative enzymes How is the ATP produced in the cell? ○ Oxidate substrate ○ Detoxify certain waste by oxidizing them → Creatine phosphate (CP) → Detoxify various wastes produced within the cell or foreign toxic → Anaerobic glycolysis - does not require oxygen compounds that have entered the cell → Aerobic metabolism ○ E.g. alcohol in beverages are toxic to cells but the oxidative → Most of the ATP production