Anatomy & Physiology Lecture 4: Cellular Level of Organization PDF

ANATOMY & PHYSIOLOGY LECTURE BIO1214 LEC 04: THE CELLULAR LEVEL OF ORGANIZATION I. The Cell Membrane and Its Involvement in Transport A. Structure and Composition of the Cell Memb...

ANATOMY & PHYSIOLOGY LECTURE BIO1214 LEC 04: THE CELLULAR LEVEL OF ORGANIZATION I. The Cell Membrane and Its Involvement in Transport A. Structure and Composition of the Cell Membrane B. Membrane Proteins C. Transport across the Cell Membrane II. The Cytoplasm and Cellular Organelles A. Organelles of the Endomembrane System B. Organelles for Energy Production and Detoxification C. The Cytoskeleton ​ INTRACELLULAR FLUID (ICF) & EXTRACELLULAR FLUID III. The Nucleus and DNA (ECF) — same in composition A. Organization of the Nucleus and Its DNA ○ INTERSTITIAL FLUID – ECF NOT contained within ​ the blood vessels IV. Protein Synthesis PLASMA – ECF in blood vessels A. From DNA to RNA: Transcription ○ Because of membrane ‘s hydrophobic core, polar B. From RNA to Protein: Translation molecules to dissolve in aq ICF and ECF cannot V. Cell Replication readily diffuse across the core of the membrane A. The Cell Cycle == effective barrier for molecules B. DNA Replication C. Cell Cycle Control Cell membrane remains fluid – bc of cholesterol ○ Lipids and proteins are not rigidly locked in place VI. Cellular Differentiation A. Stem Cells MEMBRANE PROTEINS HOMEOSTASIS — dynamic state of balance within parameters that TRANSMEMBRANE PROTEINS — spans the membrane from inside are compatible with life and outside Can serve as both receptor and ion channel THE CELL MEMBRANE AND ITS INVOLVEMENT IN TRANSPORT 1. CHANNEL PROTEINS – allow select materials (ions etc) to Separates the inner content of the cell to its external pass in or out environment 2. RECEPTORS – found on extracellular ; bind specific Regulates which materials can pass in or out molecule outside and translate it to chemical reaction Consists of a phospholipids, cholesterol, and proteins inside the cell a. LIGAND – binds and engages the receptor PHOSPHOLIPID MOLECULE i. RECEPTOR-LIGAND INTERACTION – eg. nerve cells & neurotransmitters Makes up 50% of cell membrane weight 3. GLYCOPROTEINS – carbs + proteins Polar (negatively charged) phosphate head = hydrophilic Carbons act as tags (uncahrged, nonpolar) Fatty acid tails = hydrophobic a. GLYCOCALX – many glycoproteins that act as oat Phospholipids are amphiphatic —- orients their bind to another cell, contain receptors hydrophobic regions against water and hydrophilic regions for proteins, act as enzyme, product of exposed to water genetic make up Human tissues are aqueous PERIPHERAL PROTEINS — do not extend across membrane ; either in or out lang COURSE CODE: COURSE TITLE LESSON # 1  ANATOMY & PHYSIOLOGY LECTURE BIO1214 DIFFUSION — movement from area of high conc to low conc Continues until no gradient remains EQUILIBRIUM – state at where there is no net movement in any direction ○ For every molecule that moves in one direction, there is an equal amount of movement in another direction Oxygen and CO2 (small, nonpolar) can easily diffuse ○ More O2 inside than outside the cell bc of use during metabolism ○ More CO2 (by product of metabolism) in the TRANSPORT ACROSS THE CELL MEMBRANE cytoplasm SELECTIVELY PERMEABLE (membrane) — only small and FACILITATED DIFFUSION (PASSIVE) – diffusion using the assistance of nonpolar molecules can cross the bilayer transmembrane proteins ○ Freely permeable — lipids, oxygen, carbon polar/ionic = hydrophilic, cant pass thru the phospholipid dioxide, alcohol bilayer easily ○ Water soluble polar — glucose, amino acids, ions They need assistance of facilitation = needs assistance bc they are repelled by eg. glucose (large and polar) into the cell hydrophobic tails ○ Glucose transporter facilitates its inward Molecules typically move from an area of higher diffusion concentration to an are of lower concentration PASSIVE TRANSPORT – movement of substances across the membrane that does not require energy ACTIVE TRANSPORT – requires energy (ATP) CONCNETRATION GRADIENT – difference in concentration of a substance across space ○ Molecules will move from more conc to less conc until they are equally distributed OSMOSIS — diffusion of water through a semipermeable membrane More solute in the solution, the lower the conc of water molecules ISOSMOTIC – two solutions with the same concentration of solutes HYPEROSMOTIC – solution with more solute HYPOOSMOTIC – solution with less Eg. blood plasma is typically hyperosmotic to interstitial fluid PASSIVE TRANSPORT COURSE CODE: COURSE TITLE LESSON # 2  ANATOMY & PHYSIOLOGY LECTURE BIO1214 TONICITY — osmolarity of the extracellular fluid compared to the ANTIPORTERS – utilize the conc gradient of one molecule inside of the cell to move a second molecule against its conc gradient ; transports two substances in opposite directions ○ ISOTONIC — conc of water is same as the outside and inside of cell ENDOCYTOSIS — process of cell taking in a material by enveloping it ○ HYPERTONIC — conc of solutes is higher in ECF ; water will in the cell membrane and pinching off the membranous envelope ; move towards the hypertonic ECF = cell loses volume/will envelope and contents becomes a vesicle shrink (crenation) Required cellular energy (active transport) ○ HYPOTONIC — solution has lower conc of solutes, Water ○ VESICLE — sac inside the cell made of same lipid will travel diffuse into the cell through aquaporins = cells bilayer as cell membrane swell and burst ○ Brings materials into the cell so it can be broken down or digested PHAGOCYTOSIS — endocytosis of large particles ○ Eg. immune cells invading pathogens PINOCYTOSIS — “cell drinking” ; brings fluid containing ACTIVE TRANSPORT dissolved substances into a cell through membrane-bound vesicles Transport of substance from lower conc to higher conc, RECEPTOR-MEDIATED ENDOCYTOSIS — membrane ATP is required receptors trigger the cell to invaginate the membrane to Requires help of protein carrier take in the ligand Movement AGAINST its concentration gradient EXOCYTOSIS — cell exports material b wrapping it in a vesicle and PUMPS — proteins that move molecules against conc fusing it with the plasma membrane gradient Vesicle releases its content to the interstitial fluid/ECF and Eg. sodium–potassium pump — transports sodium (3 Na) vesicle membrane becomes part of the cell membrane out of a cell while moving potassium (2 K)into the cell ○ ELECTRIC GRADIENT — difference in electric charge across the membrane SECONDARY ACTIVE TRANSPORT — active transport pump THE CYTOPLASM AND CELLULAR ORGANELLES establishes a conc gradient that is used in the transport of a secondary molecules like glucose SYMPORTERS – active transporters that move two substances in the same direction COURSE CODE: COURSE TITLE LESSON # 3  ANATOMY & PHYSIOLOGY LECTURE BIO1214 CYTOPLASM – watery inside, including compartments and ORGANELLES FOR ENERGY PRODUCTION AND DETOXIFICATION organelles HEPATOCYTES – cells in liver that detoxify toxins CYTOSOL – jelly-like substance that provides fluid medium LYSOSOMES – digests unwanted/damaged components for biochemical reactions and functions of the cell ○ Orginating from golgi ; containing digestive NUCLEUS – largest; containing DNA enzyme ○ Important for breaking down material taken ORGANELLES OF THE ENDOMEMBRANE SYSTEM from outside the cell in phagocytosis ENDOPLASMIC RETICULUM – system of channels that is continuous ○ AUTOLYSIS – form of apoptosis ; when lysosomes with the membrane of the nucleus are triggered to release their digestive enzyme Covers nucleus and is composed of the same lipid bilayer into the cytoplasm which kills the cell Provides membranous passages ; function in transporting, synthesizing, and storing materials PEROXISOMES – membrane-bound organelle containing Its winding structure provides larger surface area mostly enzymes ○ Perform lipid metabolism and chemical ROUGH ER — Closer to nuclear memberane detoxification ○ Studded with RIBOSOMES – nonmembranous ○ Enzymes transfer hydrogen atoms from various organelles that synthesize proteins molecules to oxygen, producing hydrogen ○ Primary job is to synthesize (translation) and peroxide (H2O2) modify proteins ○ Neutralized poisons like alcohol/harmful toixins ○ GLCYOSYLATION – adding sugars to protein SMOOTH ER — lipid/phospholipid synthesis as well as steroid hormones ○ Storage closet for some (eg. skeletal muscle cells) ○ Metabolizing some carbs ○ breaking down certain toxins GOLGI APPARATUS – where proteins made by RER are sent after they are packed into vesicles Sorting, modifying, shipping off products of rough ER MITOCHONDRIA – energy transformer CIS-FACE — closer to nucleus and ER that recieves ○ Consists of two lipid bilayer:inner and outer products in vesicles ○ INNER — highly folded (CRISTAE) ; where most TRANS-FACE – where products are released and repacked biochemcial reactions of cellular reaction takes into new vesicles place COURSE CODE: COURSE TITLE LESSON # 4  ANATOMY & PHYSIOLOGY LECTURE BIO1214 Reactions convert energy stored Found where great surface area is required nutrient molecules (glucose) into ATP - (small intestine cells) proving energy for the cell 2. CILIA – composed of microtubles THE CYTOSKELETON capable of movement Sweep material off the cell surface Helps cell maintain their structure ; dyamic Epithelial cells (airways - move waste materials) Made up of fibrous proteins providing structural support 3. FLAGELLA – very long ; only found in sperm in humans ; ○ Critical for motility, reproduction, and transport propel the sperm to the egg of substances and organelles Forms complex, threadlike network consisting of three diff protein-based filaments: microfilaments, intermediate filaments, and microtubules 1. MICROTUBULES – structural filament composed of protein subunits (tubulin) ○ MOVE MATERIALS ○ Maintains cell shape and structure ○ Resists compression of cell ○ Play a role in positioning organelles ○ Provides the tracks along which vesicles and genetic material can be pulled 2. CENTRIOLES – 2 indentical microtubules ; serve as cellular orgination point for microtubules Assists with the separation of DNA during cell division Can elongate out from centrioles as tubulin Vesicles move around the cell along microtubules carried subunits are added; pwede rin ishorten by motor proteins (kinesis and dyneins) 3. MICROFILAMENTS – composed of actin protein ; thinner MOVE THE WHOLE CELL THE NUCLEUS AND DNA Cell division — actin microfilaments work with NUCLEUS another protein to create a cleavage furrow Largest and most prominent 4. INTERMEDIATE FILAMENTS – composed of keratin protein Contains cells genetic information Impt for maintaining cell shape and structure GENOME — set of genetic instructions of organism (DNA Resist force that could pull cell apart in nucleus) Help anchor organelles together within a cell DNA stores the blueprint for instructions kung ano link cells to other cells by forming cell to cell gagawin at ipoproduce ng cell junctions CELL SURFACE SPECIALIZATIONS ORGANIZATION OF THE NUCLEUS AND ITS DNA 1. MICROVILLI – tiny numerous projections on the surface of NUCLEAR PORE — passageway for proteins, RNA and cells solutes bet cytoplasm and nucleus functions to expand surface area NUCLEOPLASM – parang cytoplasm ; includes building Anchored by actin filaments BUT NOT capable of blocks of nucleic acids movement NUCLEOLUS – manufacturers RNA needed for construction of ribosomes COURSE CODE: COURSE TITLE LESSON # 5 ANATOMY & PHYSIOLOGY LECTURE BIO1214 HISTONE – protein where cells store their DNA if not PROTEIN SYNTEHSIS replicating NUCLEOSOME – single, wrapped DNA-histone complex CHROMATIN – loosely organized DNA ; condenses to become chromosomes during division Sequence of bases of DNA determine the genetic code ○ Two strands complement each other ○ Double helix ; composed of alternating sugar and phosphate group ○ 4 types of nitrogenous bases: A,G = larger ; CT = smaller == has to pair PROTEOME – full complement of protein GENE – segment of DNA ; providing genetic material to build a protein COURSE CODE: COURSE TITLE LESSON # 6  ANATOMY & PHYSIOLOGY LECTURE BIO1214 ○ Composed of many bases in unique sequences = mRNA leaves nucleus, ready for translation in the provides code for building a protein, with cytoplasm multiple amino acids in the proper sequence All of DNA of the genome is in the nucleus Unless replicating, cell has only one copy of its genome Proteins are made in the ribosomes = a copy of a single gene is made into messenger RNA (mRNA) to exit in the nuclear pore FROM DNA TO RNA: TRANSCRIPTION mRNA – single stranded nucleic acid, carries copy of During translation, mRNA transcript moves through a genetic code for single gene ribosome in RER or cytosol RNA ○ tRNA pairs appropriate amino acids to the mRNA Single stranded, no complementary strand sequence Ribose sugar contain additional oxygen Contains Uracil instead of T mRNA = transports copy of genetic code from DNA to cytoplasm rRNA = makes up ribosomes ;reads genetic code from mRNA tTRNA = adds amino acids to proteins GENE EXPRESSION Process of making a molecular product from a gene Begins with transcription (producing mRNA) Complementary DNA strand needs to be separated to make a copy of DNA ○ Requires several enzymes to unzip ○ Base code of gene is used as template STAGE 1: INITIATION – two complementary strands of DNA are separated and PROTEIN RNA polymerase begins to synthesize complementary RNA molecule STAGE 2: ELONGATION – RNA polymerase adds new nucleotides to FROM RNA TO PROTEIN: TRANSLATION growing strand TRANSLATION — synthesis of cain of amino acids Pre-mRNA contains coding (exons) and noncoding (introns) (polypeptides) in the ribosome regions = removed/spliced from the pre-mRNA transcript rRNA – RNA that make up sub units of a ribosome ○ Spliceosomes – cuts out the introns and ○ Ribosomes provides space for translation reconnect the exons tRNA – brings amino acids to the growing polypeptide ○ Remaining exons are spliced for multiple protein strand and place them into sequence variations ANTICODON – sequence of three nucleotides on tRNA ; ○ Creates mature mRNA molecule ready for complementary to three nucleotides (codon) on mRNA translation STAGE 3: TERMINATION – RNA polymerase reaches end of gene ; TRANSLATION STAGE 1: INITIATION – ribosome subuntis assemble RNA polymerase and mRNA transcript are released from DNA strand around mRNA transcript COURSE CODE: COURSE TITLE LESSON # 7  ANATOMY & PHYSIOLOGY LECTURE BIO1214 STAGE 2: ELONGATION – tRNA molecules are attached to the ribosome If tRNA anticodon matches mRNA, tRNA attaches its amino acids to the growing polypeptide chain Requires enzymes and energy STAGE 3: TERMINATION – process continues until stop codon is reached Translation stops and newly synthesized protein is released CELL REPLICATION Cells that do not undergo cell replication – gqametes, rbcs, neurons, some muscle cells SOMATIC CELLS – body cells = contains 46 chromosomes During S phase, new DNA genome is made ○ DIPLOID – 46 = 2 copies of chroms, one copy Helicase unwinds into two to act as templates from each parent Results to two copies of each chromosome – one strand of ○ HOMOLOGOUS (pair) – two copies of a single original chromosomes found in each somatic cell (23 homologous pairs) STAGE 1: INITIATION – two complementary DNA strands are ○ HAPLOID – 23 separated and stabilized with enzymes GAMETE CELLS – sex cells , producing eggs ang sperm STEP 2: ELONGATION – DNA polymerase adds correct bases to the CELL CYCLE – life cycle of a cell from single to two new template strand, making new double strand daughter cells STAGE 3: TERMINATION – replication ends once two original strands are bond to their own finished complement (until entire genome is THE CELL CYCLE replicated) 1. INTERPHASE – cell is not replication ; most cellular life Preparing to replicate = copy its genome THE STRUCTURE OF CHROMOSOMES 2. MITOSIS – division that results in the formation of two new cells ; nucleus breaks down into two new nuclie CYTOKINESIS – division of cytoplasm into two new cells 3. MEIOSIS – germ cells give rise to egg and sperm cells ; cells contain half the original amount of DNA Once replication is complete, cell is ready to divide SISTER CHROMATID – replicated copy of chromosome CENTROMERE – binds the sister chromatids together MITOSIS AND CYTOKINESIS INTERPHASE MITOTIC PHASE – includes both mitosis and cytokinesis G1 PHASE – “gap” phase ; first phase after cell is born ○ MITOSIS takes about one to two hours in human ○ cells are growing, making proteins, carrying out cell functions S PHASE – “synthesis phase” ; when cell replicates its DNA INTERPHASE – DNA is in chromatin form G2 PHASE – 2nd gap phase ; cell prepares for mitosis DNA REPLICATION COURSE CODE: COURSE TITLE LESSON # 8 ANATOMY & PHYSIOLOGY LECTURE BIO1214 ○ CLEAVAGE FURROW — contractile band made of microfilaments that forms around the midline during cytokinesis and squeezes two cells apart CELL CYCLE CONTROL Loss of cell cycle control can lead to cancer MECHANISMS OF CELL CYCLE CONTROL Environmental factors ○ Growth factors/hormones and signals from other cells ○ Number of cells in the environment CONTACT INHIBITION– prevents cells from replicating if there are cells all around (factor of cancer and other tumor) ○ Surface area-to-volume ratio – large cells is inefficient bc it takes alot of energy to manage PROPHASE – chromatin condenses into chromosomes and transport materials ○ Sister chromatids are linked to each other and to the microtubules at centromere CELLULAR DIFFERENTIATION ○ Nucleolus and nuclear membrane disappears ○ Reorganization of cell’s cytoskeleton to facilitate movement of chromosomes (cant move on its own) ○ CENTRIOLES move apart and head towards the poles MICROTUBULES extend from centrioles MITOTIC SPINDLE – composed of centrioles and their microtubules which arranges and pulls apart chromosomes CELLULAR DIFFERENTIATION – unspecialized cells become specialized with distinct functions METAPHASE – sister chromatids are pulled into the middle STEM CELLS – can become any cell of the cell ○ cells that are unspecialized and replicates as ○ Nagreready to pull apart sister chromatids many times instead of becoming more specialized ANAPHASE – microtubules shorten = pulls chromosomes ○ Embryonic stem cells can differentiate to the sides/poles ○ Adult stem cells cannot become any cell but are ○ Each end receives one of the sister chromatids to rather limited to cell groups/lineage ensure that each cell contains identical genetic Differentiation process: genes that are needed for the role material becomes activated while ung hindi ay tinuturn off (eg. muscle cells & melanin) TELOPHASE – events of prophase reverse ○ TRANSCRIPTION FACTORS – proteins that either ○ Nuclear membrane begins to form at the ends of promote or inhibit the expression of a gene the dividing cells = encloses chromosomes ○ Genes that are deactivated/turned off becomes ○ DNA uncoils into chromatin highly condensed (packed tightly) = not ○ Nucleoli and new nuclei expressed/transcribed ○ Mitotic spindle breaks apart ○ End: new cell has complement DNA, organelles, membranes, and centrioles COURSE CODE: COURSE TITLE LESSON # 9