MC-1-LEC_LESSON-2_CELLULAR-LEVEL-OF-ORGANIZATION.pdf

LESSON 2: CELLULAR LEVEL OF ORGANIZATION 1st Semester | A.Y. 2024-2025 THREE MAIN PARTS OF THE CELL OBJECTIVES 1. Plasma Membrane...

LESSON 2: CELLULAR LEVEL OF ORGANIZATION 1st Semester | A.Y. 2024-2025 THREE MAIN PARTS OF THE CELL OBJECTIVES 1. Plasma Membrane 2. Cytoplasm ▪ Name and describe the three main 3. Nucleus parts of a cell. ▪ Distinguish between cytoplasm and cytosol PLASMA MEMBRANE ▪ Explain the concept of selective ▪ Lipids, carbohydrates, proteins permeability ▪ Flexible outer surface of the cell that separates the Cell's inner and outer CELLS environment external environment [water is the cell’s outer environment] ▪ Selective barrier that regulates what comes in out of the cell ▪ best described using the Fluid Mosaic Model MAIN STRUCTURES OF THE PLASMA MEMBRANE ▪ smallest living unit inside the body ▪ Best described CELL THEORY o building blocks of all organisms o comes from division of pre-existing cells o smallest units that carry important life 1. LIPID BILAYER essential physiological functions ▪ consists of two back-to-back layers o each cell maintains homeostasis made up of three lipid molecules inside cellular level ▪ lipids are amphipathic- has polar and TWO GENERAL CLASSES OF CELLS nonpolar ends ▪ SEX CELLS 1. Phospholipids -75% [contains - Produced from Gonads phosphorus] - Sperm and oocyte 2. Cholesterol-20% steroids with oH or - Gametes/ germ cells hydroxyl group] ▪ SOMATIC CELLS 3. Glycolipids-5% Lipids attached with - body cells except sex cells Carbohydrates 2. MEMBRANE PROTEINS LECTURE 2 | MC 1 LEC Ars ▪ Integral proteins 3. MEMBRANE OF CARBOHIDRATES o -proteins that penetrate the bilayer ▪ 3% of the weight of plasma membrane up to the fatty acid tails and are ▪ GLYCOCALYX firmly embedded. ▪ layers by the large extension from the ▪ Peripheral Proteins outer surface of the membrane formed o Loosely embedded proteins that by carbohydrates. stick on polar heads & membrane lipids or with integral proteins outer SOLUTIONS I TERMINOLOGY surface of the membrane at the ▪ Solvent-liquid dissolver usually water] inner or other surface of membrane ▪ Solute-particle or gas dissolved material ▪ Functions ▪ Concentration- Amount of solute in the o Ion Channels given amount of Solvent ▪ pores or holes through which specific ions, such as potassium TRANSPORT ACCROSS THE PLASMA ions can flow to get into or out of MEMBRANE the cell; very selective ( only single Certain substances must move into the cell type of ion can pass trhu) to support metabolic reactions o Carriers/ transporters ▪ moving a polar substance or ion from one side of the membrane to the other. o Receptors ▪ receptor of ligans, serve as cellular recognition sites o Linkers ▪ which anchor proteins in the plasma membranes of neighboring ▪ PASSIVE TRANSPORT cells o substance moves down its concentration or electrical gradient to MEMBRANE PERMEABILITY cross the membrane with its own kinetic energy. SELECTIVE PERMEABILITY ▪ ACTIVE TRANSPORT At the lipid bilayer portion of the membrane o Drive the substance uphill against its ▪ PERMEABLE TO concentration or electrical gradient o Nonpolar charged molecules such as using cellular energy (ATP) oxygen, carbon dioxide and steroids ▪ IMPERMEABLE TO o Ions and large uncharged polar molecules such as glucose. LECTURE 2 | MC 1 LEC Ars PASSIVE TRANSPORT TYPES OF DIFFUSION Diffusion 1. SIMPLE DIFFUSION random mixing of particles in a solution a. passive process caused by the particle’s kinetic energy. b. substances move freely through lipid substance moves down its concentration bilayer alone gradient. c. no help prom membrane transport proteins FACTORS AFFECTING DIFFUSION RATE d. Requirements for simple diffusion i. Concentration gradient of solute FACTORS DIFFUSION RATE AFFECTING present Steepness of Steeper-Slower rate ii. Solute can diffuse across a Concentrating Less Steep-Faster membrane if membrane is present Gradient Rate Temperature Higher-faster rate 2. FACILITATED DIFFUSION Lesser- Slower rate a. substance move through the lipid bilayer by a channel/carrier protein [Diffusion rate occurs faster during fever] b. uses a medium, mostly ion channels Mass of Diffusing Larger -slower Substance Smaller- faster 3. OSMOSIS a. diffusion where there is net movement [smaller molecules of a solvent through a selectively diffuse more rapidly permeable membrane than larger ones] b. Moves from an area of higher water Surface Area Larger -faster concentration to an area of lower Smaller- slower water concentration. [Air sacs in the lungs have a large surface TYPES OF SOLUTIONS area available for 1. ISOTONIC (Same) diffusion of oxygen a. solutions which maintain its original from the air into the blood] shape and volume Diffusion Longer Distance- 2. HYPOTONIC (Low) Distance Slower Rate a. solutions that have lower Smaller Distance- concentration of solutes than cytosol Faster Rate inside RBCs. [diffusion across a b. water molecules enter the cells faster plasma membrane than they leave, causing the RBCs to takes only a fraction swell and eventually to burst. Because of a second because it contains no solutes, water continues the membrane is so thin] LECTURE 2 | MC 1 LEC Ars to enter cells until they finally burst, or o very large molecules around plasma lyse membrane with a different sort of help i. HEMOLYSIS: Ruptures Of RBCS o ENDOCYTOCIS 3. HYPERTONIC (High) ▪ vesicle transport that mover a a. higher concentration of solute than substance into the ell cytosol inside RBCS. ▪ PHAGOCYTOSIS b. RBC undergoes crenation Form of endocytosis in which c. CRENATION: cells shrink and their the cell engulfs large solid shapes change particles, such as worn-out cells, whole bacteria or ACTIVE TRANSPORT viruses (Ex. Macrophages) energy solute is required for carrier proteins o EXOCYTOSIS to move across the membrane against the ▪ Vesicle transport that moves the concentration agent substance out of the cell. SOURCES OF CELLULAR ENERGY TYPES OF CARRIER PROTEINS ▪ PRIMARY ACTIVE TRANSPORT/ATP ▪ Symporters: transporters that move two o energy derived from hydrolysis of ATP substances in the same direction changes the shape of a carrier protein ▪ Antiporters: transporters that move two o this pumps a substance across a substances in the opposite direction. plasma membrane against concentration agent CYTOPLASM o Na+ or H+ is established ▪ SECONDARY TRANSPORT o Energy stored in ionic concentration gradient o Indirectly uses energy obtained from the hydrolysis of ATP o Energy stored in Na+ or H+ ▪ Consist of all the cellular contents concentration is used to derive other between the plasma membrane and substances across the membrane nucleus against their own concentration ▪ General term for the material between agents. the plasma membrane and the o uses a medium, mostly ion channels membrane that surrounds the nucleus ▪ VESICULAR TRANSPORT o form of Active transport LECTURE 2 | MC 1 LEC Ars TWO COMPONENTS 1. Microfilament 1. CYTOSOL o provide mechanical support a. Intracellular Fluid that is b. Fluid portion of the cytoplasm that o responsible for the cell's basic surrounds the organelles. Organelles strength and shape are suspended in here. o Microfilament contains c. Constitutes about 55% total cell microvilli w/c are microscopic volume fingerlike projections of the d. First surface for chemical reaction plasma membrane 2. ORGANELLES 2. Intermediate Filament a. specified structures within cells that o help stabilize the portion of have characteristic chapes organelles such as the nucleus b. perform specific functions and help attach cells to one maintenance and reproduction in another. cellular growth. 3. Microtubules o largest component of the cytoskeleton TWO TYPES OF ORGANELLES o long unbranched hollow tubes 1. Non-membranous composed mainly of the protein a. not completely enclosed by tubulin. membranes and their components o Tubulin – required for cell have direct contact w/ the cytosol division and DNA segregation 2. Membranous o function in the movement of a. isolated from the cytosol thru organelles such as secretory phospholipid membranes vesicles, of chromosomes during cell division, and of NON-MEMBRANOUS ORGANELLES specialized cell projections, 1. CYTOSKELETON such as cilia and flagella. ▪ frameworks of cells ▪ network of protein filaments that extends 2. MICROVILLI/MICROVILLUS throughout the cytosol Necessary for absorption 3 TYPES OF CYTOSKELETONS Greatly increases the surface area of the cell exposed to the extracellular movement. many in intestines 3. CENTROSOME Region of cytoplasm located next to the nucleus in a cell LECTURE 2 | MC 1 LEC Ars TWO COMPONENTS i. Only example of flagellum in the human body ii. Sperm cells’ tails propel the sperm toward the oocyte in the uterine tube. 5. RIBOSOMES ▪ Responsible for protein synthesis ▪ Name of these tiny organelles reflects their high content of one type of ribonucleic acid, ribosomal RNAA (rRNA) 1. CENTRIOLES 6. PROTEASOMES a. Cylindrical structures, each ▪ Contain assortment of protein composed of nine clusters of three digesting enzymes called microtubules (triplets) arranged in a “proteases” circular pattern. ▪ Removes or recycles damaged or 2. PERICENTRIOLAR MATERIAL denatured proteins a. surrounds the centrioles b. contains hundreds of ring-shaped MEMBRANOUS ORGANELLES complexes composed of the protein 1. ENDOPLASMIC RETICULUM tubulin. ▪ Network of membranes in the form of 4. CILIA AND FLAGELLA flattened sacs or tubules. ▪ extends from the nuclear envelope A. CILIA that surrounds the nucleus a. numerous, short-hairlike projections ▪ Specialized regions of the ER that extend from the surface of the cell synthesize proteins, carbohydrates b. provides steady movement of fluid and lipids along the cell's surface. ▪ Can store synthesized molecules c. The nicotine from cigarettes damages ▪ Can travel place to place the cilia. ▪ Can absorb drugs and toxins and B. FLAGELLA neutralize them with enzymes a. Longer than cilia ▪ FUNCTIONS: b. Generates forward motion along its o Synthesis axis by rapidly wiggling in a wavelike o Storage pattern o Transport c. Sperm Cell’s Tail o Detoxification LECTURE 2 | MC 1 LEC Ars 2 CLASSIFICATIONS 1. Smooth Endoplasmic Reticulum a. involved in the synthesis of lipids, fatty acids and carbohydrates." 2. Rough Endoplasmic Reticulum. a. The site where newly synthesized proteins are chemically modified and packaged for export towards the ▪ Suicide bag Golgi Apparatus. ▪ has 6O kinds of powerful digestive and hydrolytic enzymes that can break 2. THE GOLGI APPARATUS down a wide variety of molecules once it fuses with vesicles formed during endocytosis/ phagocytosis process ▪ can engulf another organelle digest it, and return life digested components to the cytosol for reuse 4. PEROXISOMES /MICROBODIES ▪ organelle that looks a bit like a stack of ▪ Group of organelles similar in structure dinner plates to lysosomes, but smaller. ▪ Composed of 5-6 cisternae ▪ where detoxification of alcohol and ▪ CISTERNAE: fluid filled cavities other damaging substances occurs ▪ FUNCTIONS: ▪ Abundant in the liver. o Modifies and packages secretions o Adds/ removes carbohydrates to or 5. MITOCHONDRIA from protein o Renews or modifies the plasma membrane o Package special enzymes within vesicles 3. LYSOSOMES ▪ Produces energy in the form of ATP ▪ Powerhouse of the cell ▪ Most ATP is formed in the mitochondria, but the first step is in the cytosol called “glycolysis” LECTURE 2 | MC 1 LEC Ars ▪ Glycolysis- breaking down of glucose i. Continuous with the Rough ER of molecule into two molecules of the cytoplasm and is studded pyruvate, mitochondria then absorb the B. INNER STRUCTURE pyruvate. a. lined by nuclear lamina. Nuclear lamina maintains the shape of the NUCLEUS nucleus and acts as a scaffold to ▪ largest structure in the cell organize DNA in the nucleus. ▪ control center of all cellular operations b. encases a jellylike Fluid called ▪ stores all information needed for nucleoplasm synthesis C. NUCLEOPLASM STRUCTURE a. dark staining spherical bodies Fond within the nucleus where ribosomal subunits are assembled. b. Contain the DNA that issues genetic instruction for synthesizing ribosomal RNA c. Other nuclear elements are suspended in the nucleoplasm. D. CHROMATIN Composed of approximately a. 30% DNA 1. NUCLEAR ENVELOPE b. 60% globular histone proteins which ▪ surrounds the nucleus which encloses Package and regulate the DINA its ointments, including the DNA c. 10% RNA chains, newly formed or ▪ connected through the endoplasmic forming reticulum 2. NUCLEAR PORES CELL GROWTH & REPRODUCTION ▪ where communication between the CELL CYCLE nucleus and cytoplasm takes place. the series of changes a cell goes ▪ nuclear envelope is punctuated by through from the time it is formed until it nuclear pores. reproduces SOMATIC CELL DIVISION CONTENTS OF THE NUCLEUS ▪ Cell cycle in which a somatic cell A. NUCLEAR ENVELOPE duplicates its contents and divides into a. double membrane barrier separated two by a Fluid Filled space ▪ 23 pairs of Chromosome b. OUTER STRUCTURE ▪ homologous chromosome /HOMOLOGS LECTURE 2 | MC 1 LEC Ars ▪ contains two sets of chromosomes, called DIPLODS TWO MAJOR PERIORS OF CELL CYCLE 1. INTERPHASE ▪ Cell Formation to cell division ▪ metabolic phase or growth phase ▪ The period between mitotic divisions is mostly for somatic cells. ▪ SUB PHASES: G1, S, G2 o G- gaps ▪ Prophase: nucleus swells o S- synthesis ▪ Metaphase: chromosome appear and o Chromatin is reproduced only in s line up along the equator of the nucleus phase (1LINE) ▪ Anaphase: splitting of chromosome from the centromere. Each chromatid is connected to fiber (spindle fiber) poles (spindles) ▪ Telophase: disappearance of chromosomes and reappear as two daughter cells. ▪ G1 phase. The cell grows. ▪ CYTOKINESIS: division of a cell’s ▪ S phase. The cell makes copies of its cytoplasm and organelles into two chromosomes. Each chromosome now identical cells. This process usually consists of two sister chromatids. begins in late anaphase with the ▪ G2 phase. The cell checks the formation of a cleavage furrow, a slight duplicated chromosomes and gets indentation of the plasma membrane, ready to divide. and is completed after telophase 2. MITOTIC PHASE ▪ RESULTS: 2 IDENTICAL 46 CHROMOSOMES ▪ nuclear Division (mitosis 1 and EACH (diploid) Cytoplasmic division (Cytokinesis) REPRODUCTIVE CELL DIVISION ▪ Results into new organism through union of 4 two gametes one produced by each parent LECTURE 2 | MC 1 LEC Ars TWO MAJOR STAGES MEIOSIS I MEIOSIS II