Biochemistry Cell Organization & Structure PDF

Biochemistry CELL ORGANIZATION & STRUCTURE 4. Golgi apparatus 5. Endoplasmic reticulum Cell is composed of various parts. 6. Peroxisomes/Microbodies/Microsomes Cell is made up of 3...

Biochemistry CELL ORGANIZATION & STRUCTURE 4. Golgi apparatus 5. Endoplasmic reticulum Cell is composed of various parts. 6. Peroxisomes/Microbodies/Microsomes Cell is made up of 3 basic components: 1. Plasma Membrane COMMON ORGANELLES OF EUKARYOTIC 2. Nucleus CELLS 3. Cytoplasm Organelles with membranes PROPERTIES & FUNCTION OF THE Nucleus – protecting, controlling access to DNA CYTOPLASM Endoplasmic Reticulum (ER) – Routing, modifying The jelly-like fluid consistency component of the new polypeptide chains; synthesizing lipids; other cytoplasm is the cytosol while the metabolically active tasks components are organelles. Golgi body – Modifying polypeptide chains; sorting, shipping proteins and lipids 1. Chemical composition: Vesicles - Transporting, storing, or digesting  Macromolecules: Carbohydrates, Proteins, substances in a cell, other functions. Lipids, Enzymes & Hormones Mitochondrion – Making ATP by sugar breakdown  Micromolecules: Cat-ions- Na+, K+, Mg2+, Chloroplast – Making sugar in plats, some protists Ca2+, An-ions – Cl-, PO4-, HCO3- Lysosome – Intracellular digestion  Water: Bound or fixed; Free Peroxisome – Inactivation toxins Vacuole – Storage 2. Physiological properties a) Irritability Organelles without membranes a. capacity to respond stimulus Ribosomes – Assembling polypeptide chains b) Conductivity Centriole – Anchor for cytoskeleton a. ability to transmit electrical impulses throughout the cell from origin of CYTOPLASMIC INCLUSION BODIES stimuli c) Respiration - non-membrane bound structure found in the a. external (exchange of gases between cytoplasm. body and environment 1. water vacoules b. Internal (between cell and blood 2. secretory granules plasma) 3. pigments d) Secretions and Excretion 4. lipid droplets a. secretions (hormones and enzymes) 5. CHO (glycogen, starch) b. excretion (waste product of metabolism) Other structures/parts e) Absorption 1. Centrioles a. phagocytosis (cell eating, particulate - involve in Mitosis and Meiosis matter) 2. Cytosol b. pinocytosis (cell drinking, dissolved - soluble extract of cytoplasm subst.) 3. Cytoskeletal structure f) Growth and Reproduction - Microtubules - Micrifilaments CYTOPLASMIC ORGANELLES A. Cytoplasmic organelles 1. Mitochondria a. sites of oxidative phosphorylation and sources of high energy phosphate bond (ATP) b. powerhouse of the cell 2. Ribosomes a. site for protein synthesis 3. Lysosomes a. contains hydrolytic or digestive enzyme Borga, BMLS 2-C  Biochemistry FUNCTIONS OF THE NUCLEUS Transport 1. Allows the organism to take up nutrients from the 1) Stores genetic information (DNA & RNA) external environment. 2) DNA replication occurs in the nucleus which is 2. Equally important as mechanism for removal of then passed to daughter cells. toxic materials from the interval environment, allowing 3) Enables the synthesis of nearly all proteins the cell to maintain an intracellular environment through the synthesis of RNA. compatible with life. 4) Houses the nucleolus which is the site of the production of ribosomes. Passive Transport 5) Selective transportation of regulatory factors  Only a few types of molecules, including O2, N2, and energy molecules through nuclear pores. H2O, urea and ethanol can cross in this manner.  3 types of passive transport STRUCTURE & FUNCTION OF PLASMA a) Diffusion MEMBRANE b) Osmosis c) Facilitated Diffusion Plasma Membrane - absolute requirement of all living organisms DIFFUSION - chief point of contact with the environment Net movement of like molecules or ions down a concentration gradient which is from high Functions: concentration to low concentration. 1) Transportation of nutrients 2) Location of a variety of crucial metabolic Factors affecting the rate of diffusion: processes 1. Extent of the concentration gradient a. synthesis of membrane lipids 2. Mass of the molecules diffusing b. wall murein synthesis 3. Temperature c. assembly and secretion of 4. Solvent density and solubility extracytoplasmic proteins 5. Surface area and thickness of the plasma 3) Important properties: membrane a. fluidity 6. Distance travelled b. stability c. selective permeability OSMOSIS Diffusion of water across a membrane Composition: Moves from HIGH water concentration to LOW 1. Phospholipids water concentration. 2. Peripheral proteins Water is attracted to solutes (like salt) so it will also 3. Integral proteins travel to areas of low solute concentration to high solute concentration. Lipids (20-30%) CHON (50-60%) CHO (10%) TONICITY OF THE SOLUTION IMPORTANCE OF CELLULAR PROTEINS 1. Isotonic 1. Structural support - A solution whose solute concentration is the 2. Recognition same as the solute concentration inside the 3. Communication cell. 4. Transport 2. Hypotonic - A solution whose solute concentration is lower Fluid Mosaic Model than the solute concentration inside a cell - most widely accepted model of the CM 3. Hypertonic - shows that the CM is a lipid bilayer with which - A solution whose solute concentration is proteins and lipids “float” freely higher than the solute concentration inside a cell. OSMOSIS IN RBC ONCE EXPOSED TO DIFFERENT SOLUTIONS Isotonic solution: no net movement of water. Equal amounts leaving and entering Hypotonic solution: Cytolysis (cell lysis) Borga, BMLS 2-C  Biochemistry Hypertonic solution: Plasmolysis (cell shrinkage) Active Transport  The transport process in which a substance moves across a cell membrane, with the aid of membrane proteins, against a concentration gradient with the expenditure of cellular energy.  Moves materials from LOW to HIGH concentration.  Movement of solute is AGAINST concentration gradient.  Proteins involved here are called as “pumps”  Transport of large molecules: monomers, and  ions such PO4-, HCO3-, Na+, K+   Passive Active Transport Transport ATP use Does not use Uses ATP ATP Concentration Go/with Against Gradient Molecules Simple/small Large/complex transported  FACILITATED DIFFUSION The transport process in which substance moves across a cell membrane, with the aid of protein from a region of high to low concentration without ATP involvement. Glucose, chloride ion and bicarbonate crosses membrane on this manner. Simple Transport The passage of materials is - require only a membrane spanning protein aided both by a concentration gradient and by a transport Group translocation protein. - involves a series of proteins in the transport event TYPES OF TRANSPORT PROTEINS ABC-system - involves a substrate-binding protein, a membrane transporter and an ATP-hydrolyzing protein. Channel proteins are embedded in the cell Simple Transport membrane & have a pore for materials to cross. Driven by Carrier proteins can proton gradient change shape to move material from one side of (proton motive the membrane to the force) other. Transport protein follows the saturation kinetics. Borga, BMLS 2-C  Biochemistry Other Active Transport System 1. Endocytosis (plasma membrane extend outward)  Cellular invagination a. Phagocytosis (Cell Eating)  Used to engulf large particles such as nutrients, bacteria, etc. into vesicles b. Pinocytosis (Cell Drinking)  Materials dissolve in water to be brought into cell as a vesicle  Most common form of endocytosis. Sodium – Potassium Pump c. Carrier mediated (using receptors)  Uptake of materials is mediated by receptor proteins expressed on the surface of the cell. 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential. Chemical Modification Transport  Also referred to as Group translocation - A molecule is transported into the cell while being modified - Both the membrane and the cytoplasm 2. Exocytosis (secretion) are intimately involved in the transport  Molecules are moved out of the cell by - Found exclusively in prokaryotes vesicles that fuse the with the plasma membrane.  This is how many hormones are secreted and how nerve cells communicate with each other.  Excretion of waste product Phosphotransferase system Phosphoenolpyruvate + sugar (outside) pyruvate + sugar -P ATP-binding cassette (ABC-type) transporter - More than 200 different systems have been identified in prokaryotes - Transporter systems exist for organic, inorganic nutrients and trace metals - Periplasmic binding proteins exhibit extremely high substrate affinity. Borga, BMLS 2-C