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This document is a lecture on cell biology, covering topics such as cell theory, cell structure, and cell function. It introduces the basic concepts of cell biology and explains these concepts in detail.
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eek 1 | Introduction to Cell and W F or example, In arms, the flat cells (which should be able to protect us from Molecular...
eek 1 | Introduction to Cell and W F or example, In arms, the flat cells (which should be able to protect us from Molecular Biology environmental factors) are in the _______________________________________ epidermis, in the dermis, there are cuboid cells and spongy cells, and as we proceed ells and the structures they compromise are C to musculoskeletal cells, cruciform cells too small (they should be able to contract and relax) A handful of pioneering scientists had used their are observed handmade microscopes to uncover a world that Neurons – have synapses that transmit would never have been revealed to the naked eye and receive nerve impulses for transfer of I. Robert Hooke (1665)- looked upon slices information and locomotion. of cork C4 Plants can compartmentalize II. Anton van Leeuwenhoek- animalcules, oxygenation and reduction of Theory of Pangenesis,Bovine cells are carbohydrates. round and circular III. Matthias Schleiden/Theodore Schwann ells Possess a Genetic Program and the C - formulated 2 tenets of the Cell theory Means to Use It A. All organisms are composed of Organisms are built according to one or more cells information encoded in a B. The cell is the structural unit of life collection of genes, which are (the basic unit in which it was able constructed of DNA to produce all functions of all The less tolerance of errors in the organisms) nature and interactions of the IV. Rudolf Virchow- third tenet of the cell parts; theory And the more regulation or control A. Cells can arise only by division that must be exerted to maintain from a pre-existing cell the system Cell is the basic unit of life ignal transduction- how the nucleus knows S Unlike the parts of a cell, which simply that it’s coming from its environment deteriorate if isolated,whole cellscan be Example: Excess/Lacking genetic isolated from an organism and cultured in material (nullisome/trisomy), there are a laboratory where they will grow and higher chances that they are aborted, if reproduce for extended periods. ever born, they have a lower lifespan Deathcan also be considered one of the Depending on its phenotype, they can also most basic properties of life because only produce maintenance. a living entity faces this prospect. Example: Lactose Operon The first culture of human cells obtained from a malignant tumor from Henrietta ells Are Capable of Producing More of C Lacks was begun by George and Martha Themselves Gey of Johns Hopkins University in 1951 Mitosis/Meiosis To die, one must also be simple to live. Reproduce by division, a process in which the contents of a “mother” cell are ells are Highly Complex and Organized C distributed into two “daughter” cells that The more complex a structure: are genetically identical to their mother The greater the number of parts that must cells be in their proper place; The genetic material is faithfully There is less tolerance for errors in the duplicated, and each daughter cell nature and interactions of the parts; receives a complete and equal share of And the more regulation or control that genetic information must be exerted to maintain the system Cells Acquire and Utilize Energy 1 L ight energy is converted by ○ E xample:Plants do not have an photosynthesis into chemical energy that immune system but they have is stored in energy-rich carbohydrates, programmed cell death. If there’s a such as sucrose or starch (for pathogen that touches the surface maintenance and also reproduction, and of the leaf, it will try to attack the movement of nutrients to other parts of the adjacent cells of the plant. The cell) plant will kill the adjacent cells For most animal cells, energy arrives found in the opposite direction of prepackaged, often involves form of the the cell. Since the cells are dead, sugar glucose the pathogens can no longer Glucose is disassembled in such way that attach to the dead cells within the its energy content can be stored in a plant. readily available formed called ATP Cells are Capable of Self-Regulation Cell Carry Out a Variety of Chemical Reactions Each type of cellular activity requires a Cells function like miniaturized chemical unique set of highly complex molecular power plants tools and machines - the products of eons All chemical changes that take place in of natural selection and biological cells require enzymes - molecules that evolution greatly increase the rate at which a They can start to evacuate when it comes chemical reaction occurs to the presence of the pests, while doing The sum total of the chemical reaction in a catabolism and anabolism, can do cell cell represents that cell’s metabolism division while multiplying their protein contents if they are expressed. Cells Engage in Mechanical Activities The most fit mutation becomes the norm, Cells are sites of bustling activity for example in photosynthesis, it makes Materials are transported from place to you more compatible in your environment place, structures are assembled and then that is receiving sunlight -Natural rapidly disassembled, and, in any case, Selection. the entire cell moves itself from one site to another Initiated by changes in the shape of “motor” proteins ○ E.g.Cilia for amoeba Cells never stop producing materials. Golgi Apparatusbecomes the shipment for the desired products Cells Evolve Changes in cell metabolism that are led by It is presumed that cells evolved from motor proteins. some type of precellular life forms from non-living organic materials that were Cells Are Able to Respond to Stimuli present in the primordial seas. A single celled protist moves away from According to one of the tenets of modern object in its path or moves toward a biology, all living organisms have evolved source of nutrients from a single, common ancestral cell that Most cells are covered with receptors that lived more than three billion years ago interact with substances in the environment in highly specific ways Cells may respond to specific stimuli by altering their metabolic activities, moving from one place to another, or even committing suicide 2 L ast universal common ancestor (LUCA) - ○ S uch as the production of ATP, term used in… NADPH, and NADH Similar mechanism of photosynthesis ○ Prokaryotes may lack chlorophyll, they harness light energy Similar mechanisms for synthesizing and inserting membrane proteins Proteasomes of similar constructions Differences of Two Cell Types Eukaryotic cell Prokaryotic cell ivision of cells into D Nucleoid nucleus and cytoplasm omplex C Ribosomes C ells are able to evolve if we look at membranous cytoplasmic housekeeping genes, e.g, enzymes organelles needed from glycolysis, all those enzymes are found in all organisms both pecialized S o specialized N prokarytic/eukaryotic. Looking at those cytoplasmic organelles for sequencing, there are more things organelles photosynthesis common between all living organisms. mitochondria and photosynthesis Meaning we can trace it back in evolution throughLUCA. LUCA is a term used in ytoskeletal system C imple compositions S Phylogeneticsin which we can trace the (may move through of locomotory branch points of one organism to another. flagella/cilia) organelles -flagellin omplex flagella and C eptidoglycan cell P Two Kinds of a Cell cilia wall (Rigid Cell Wall) 1. Eukaryotic Cell 2. Prokaryotic Cell Phagocytosis Asexual reproduction Similarities of the two Cellulose cell walls Plasma membrane of similar construction Sexual reproduction Genetic information encoded in DNA using identical genetic code ○ Same codon preference - codons Type of Prokaryotic Cells found in prokaryotes that may code 1. Domain Archaea different amino acids that might be a. Species that live in extremely different of those found in inhospitable environments eukaryotic b. They are often referred to as Similar mechanisms for transcription and “Extremophiles” translation of genetic information c. Methanogens- prokaryotes ○ They both have ribosomes, they capable of converting CO2 and H2 both have transcription gases into methane (CH4) gas machineries d. Archaic- lives in extreme Shared metabolic pathways conditions, such as halophiles, ○ Both do respiration, the only thermophiles, cryophiles, and often difference is energy source referred to as extremophiles, such Similar apparatus for conservation of as methanogens that can chemical energy as ATP synthesize methane gas from 3 arbon dioxide and H2 gases. c n a small number of “representative o Depending on the organisms models.” involved, they can be used in carbon production and absorption in the environment. 2. Domain Bacteria a. Includes the smallest known cells in the world -mycoplasma b. Lack cell walls (A)Arabidopsis thaliana- apatella for the c. A genome with fewer than 500 production of petals genes (B)Yeasts - easily reproduced due to its size d. Present in every conceivable (C)C. elegans habitat on Earth. Even in the (D)Drosophila- their eyes can be found at the respiratory tract, gastrointestinal, back, if the disks are swapped. and skin. (E)Mice and Rabbits (Mammals) - for testing we usually use Sprague rats Type of Eukaryotic Cells (F)Danio rerio(zebra fish) - can be used for In many regards, the most complex research eukaryotic cells are not found inside of plants or animals, but rather among the How smol is small? unicellular protists An alternate pathway has led to the evolution of multicellular organisms in which different activities are conducted by different types of specialized cells As a result of differentiation, different types of cells acquire a distinctive appearance and contain unique materials. ○ E.g. bones - bones are made up of calcium, and it allows the reproduction of red blood cells and the rigidity of the bones. T wo units of linear measure are most commonly used to describe structures within a cell: themicrometer (μm)and nanometer (nm). Oneμmis equal to 10^-6 meters, and one nm is equal to 10^-9 meters. Theangstrom (Å), which is equal to one-tenth of a nm, is commonly employed by molecular biologists for atomic dimensions. One angstrom is roughly equivalent to the diameter of a hydrogen atom. Model Organisms Cell and molecular biologists have pecial Topics: Viruses, Stem Cells and S focused considerable research activities Endosymbiosis 4 Viruses Responsible for dozens of human Viroids diseases, includingAIDS, polio, An infectious agent consisting of a small influenza, cold sores, measles,and a circular RNA molecular that totally lacks a few types ofcancer. protein coat. ○ HIV is the virus of AIDS. T.O. Dienercoined the termviroid. Occur in a wide variety of very different The RNAs of viroids range in size from shapes, sizes, and constructions, but all of about 240 to 600 nucleotides, one tenth them share certaincommon properties. the size of the smaller viruses. All viruses are obligate intracellular Viroids- Obligatory Parasites; Small RNA parasites; that is, theycannot reproduce virus, smaller than Viruses. They are unless present within a host cell. already RNA, they can easily infect one Virusis a genetic material coated with cell to another since they are ready for protein, this genetic material might be translation. Viroids can slip through RNA or DNA. As they enter the host, they connecting appendages of the cell. are able to release the genetic material into the cytoplasm of the host to translate. Stem Cells These proteins may be able to replicate Hematopoietic stem cellsin the bone and be coated inside the cytoplasm. They marrow are an example of an adult stem explode inside and infect other cells. cell Obligatory parasites- they need a host Stem cells are defined as to thrive undifferentiated cellsthat ○ Are capable of self-renewal, that is, production of more cells like themselves, and ○ Are multipotent, that is, are capable of differentiating into two or more mature cell types Inside the bone marrow, we have Hematopoietic Stem Cells or Adult Stem Cells, they do not differentiate because it D epending on the specificity of the virus, is essential to constantly replenish the the host may be a plant, animal, or amount of RBCs in our bodies. They bacterial cell. produce nucleated RBCs, once done, they Outside of a living cell, the virus exists as are out o the Hematopoietic Stem Cells a particle, orvirion, which is little more Once the RBCs are found in the than a macromolecular package bloodstream, they are slowly being Sometimes, we have viruses that can endonucleated. affect multiple targets. Outside of a living cell, it can only exist as a virion. This virion can be destroyed by a lot of objects or dehydration that can be associated with sanitization. Embryonic Stem Cells 5 E mbryonic stem (ES) cells, which are a Endosymbiont Theory type of stem cell isolated from very young Ancestral eukaryotes came from large mammalian embryos prokaryotes that ingested aerobic The egg would be allowed to develop to prokaryotes. an early embryonic stage, and the ES Mitochondria- The prokaryotes are able cells would be removed, cultured, and to create energy without energy that induced todifferentiateinto the type of becomes mitochondria. The heterotrophic cells needed by the patient prokaryote digested food that gives food Ethical considerations to the mitochondria. Chloroplast- Photosynthetic cyanobacteria entered the macrophage Induced Pluripotent Stem Cells The cells are not initially totipotent but pluripotent, plural, it can differentiate into multiple functions. Unlike ES cells, the generation ofiPS cellsdoes not require the use of an embryo. eek 2 | The Cellular Basis of W This feature removes all of the ethical Life reservations that accompany work with ES Microscopes cells and also make it much easier to developed for clearer view of cells and generate these cells in the lab. cellular structure Undifferentiated iPS cells may give rise to The first microscopes were Light teratomas. Microscopes (LM), visible light passes The usage of chemicals may activate through a specimen, then through glass cancer genes is the sought problem lenses, and finally is projected into the viewer's eye Light microscopes can magnify effectively to about 1,000 times the actual size of the specimen arameters in Microscopy P 1. Magnification - is the ratio of an object’s imagesizetoitsrealsize(increaseinanobject's image view compared with its actual size. 2.Resolution- isameasureoftheclarityofthe image; it istheminimumdistancetwopointscan Endosymbiont Theory 6 e separated and still be distinguished as b separate points. Microscopes have limitations human eyeandmicroscopehavelimitsof resolution–the ability to distinguish between small structures Therefore, the LM cannot provide the details of a small cell structure. Depth of field - can be increased to improve focus In 1950s, scientists started using the electron microscope (EM) to view the ultrastructure of cells Instead of light, EM uses a beam of electrons EM can: ○ resolve biological structures as small as 2 nm ○ can magnify up to 100,000 times Types of Electron Microscope 1. Scanning Electron Microscope - detailed architecture of cell surfaces 2. Transmission Electron Microscope - details of internal cell structure ifferentialinterference(LM)amplifiesdifferences D in density sothatstructuresinlivingcellsappear three-dimensional. Using LM, scientists studied: microorganisms animal and plant cells some structures within cells In 1800s, studies lead to cell theory which states that all living organisms are composed of cells these cells arise from pre-existing cells mall size o S f cells relates to the n eed to exchange materials across the p lasma membrane. 7 Cell size must be large enough to house DNA,proteins, and structures needed to survive and reproduce but remain small enough for an efficient Surface-Volume (SV) ratio. Parts of a Prokaryotic Cell Plasma membrane Functional Compartments of Eukaryotic Cells 1. The nucleus and ribosomes are responsible forgenetic control. 2. The endoplasmic reticulum, lysosome, vacuoles, and peroxisomes are responsible for the manufacture, Parts of a Eukaryotic Cell (Animal and Plant) distribution, and breakdown of molecules. 3. Mitochondria in all cells and chloroplasts in plant cells are involved in energy processing. 4. Structural support, movement, and communication between cells are functions of the cytoskeleton, plasma membrane, and cell wall. Nucleus most noticeable organelle in a cell separated by a nuclear envelope DNA is separated into chromatin fibers with histone proteins (octamer for supercoiling of DNA) 8 s tudded with of nuclear poresfortransfer R, Golgi, Lysosomes function inthedistribution E of DNA of materials. ○ Retroviruses can surpass… ○ can be managedthroughCRISPR (gene-editing) and stem cell Endoplasmic Reticulum Largest component of ES Ribosomes Extensive network of flattened sacs and involvedin cell protein synthesis tubules responsible in creating the polypeptide Smooth ER:no ribosomes used for translation to proteins Rough ER:w/ ribosomes cells that make a lot of proteins have a ○ Growing polypeptides grow here. large number of ribosomes (e.g., Protists Glycoprotein binds folding. undergopolycistronictranscription:mRNA codes for more than one protein ) The ER is a biosynthetic workshop In eukaryotes, they are monocistronic SER: lipids store Calcium ions because the mRNA codes for only one RER: marks additional membrane & protein. secretory proteins some are free (in the cytosol), some are bound to the endoplasmic reticulum or nuclear envelope Endomembrane System Cytoplasm - region between the plasma membrane and the nucleus ES components are suspended in the cytosol Region where cell metabolic processes occur Some are physically converted …. . N 1 uclear envelope : synthesis 2. ER, Golgi apparatus, lysosomes: distribution Golgi Apparatus 3. Vacuoles : storage Molecularwarehouse&processingstation 4. Plasma membrane: export of molecules for products manufactured by ER Ships in the forms of vesicles; has any organelles are connected in the M receiving and shipping side Endomembrane System (ES) Many membranes are part of the ES Some membranes are physically connected, or pinch off asvesicles The ES includes Nuclear envelope - synthesis ER Golgi apparatus - detects where material will go; sorting center Lysosome - vesicle containing enzymes that degrade food Vacuoles - storage Plasma membrane - export of molecules 9 RNA → nuclear pore → m translated by ribosomes in the RER → polypeptide chain/ rotein is synthesized in the RER → Golgi p Apparatusidentifiesthetagandsorts→secretes as a vesicle Lysosome Membrane-enclosed sac of digestive Mitochondria enzymes made by RER and processed Carry out cellular respiration in all in the Golgi Apparatus eukaryotes Fuse w food vacuoles & digested food Cristae enhances surface area which Destroy bacteria engulfed by WBCs increases ATP production Fusse w/ other vesicle containing Cellular respiration converts chemical damaged organelles for recycling energy in the form of ATP Chloroplasts Convertlightenergytochemicalenergy of sugar molecules Photosynthesizing organelles of plants & algae Vacuoles Large storage spaces Someprotistshavecontractilevacuoles, which eliminate water from the protists The Endomembrane System 10 itochondria & chloroplasts have own DNA M Microtubules (Endosymbiont Theory) Shape & support *anaerobic* bacteria & *anaerobic* Tracks along which organelles quipped photosynthetic eukaryote with motor proteinsmove Grow out from centrosomes, whichcontainapair of centrioles 25 nm in length Intermediate Filament Reinforce cell shape, anchor some organelles Often more permanent fixtures in cell Does not undergo repaironcebrokenbut instead is replaced in sets 10 nm Microfilaments Support cell shape Motility 7 nm in diameter The Cell’s Internal Skeleton Cilia & Flagella Cytoskeleton - network of protein fibers, Cilia- propel protists organizes structures ○ Other protists may move using Microtubules- made of tubulin flagella; longer than cilia and Intermediate filaments- fibrous protein limited to 1 or a few Microfilaments- actin filaments Both are composed of microtubules wrapped in an extension of the plasma membrane 9+2 pattern: a ring of microtubule doublets surround a pair of central microtubules 11 Scaffolding For Biochemical Activities There are some proteins embedded on the membrane that act as chaperones for proper folding of the mechanisms and amino acids. o E.g., Pieces of amino acid and polypeptide chain sent by Golgi apparatus can form one functional protein in a form ofsubunit ▪ Subunits – forms proteins that are functional and could send certain signal or have D yneins movebybendingmotorproteins enzymatic functions calleddynein feet Proteins found on the cell surface acts as a scaffolding for the recruitment of other ○ These feet attach to and exert a proteins. sliding force on an adjacent o These otherproteinscanrecruitmore doublet proteinsinaprocesscalledmolecular ○ This “walking” causes the docking. ▪ Molecular docking – microtubules to bend technique used to look into ○ Releases ATP when used protein assemblies and how they occur real time; how to trigger certain assemblies to Summary make certain reaction Genetic control: nucleus, ribosome function/happen more inside Manufacture & storage: ER, Golgi, the cell Lysosomes, Peroxisomes .g., Assemblies for E Signal Energy Processing: mitochondria, transduction/Nerve chloroplast Impulse – available for scaffolding Structural Support:cytoskeleton Movement: cilia & flagella Selective Permeability Protein found in cell membranes only acts in places where only certainmaterialscanenter and exit the cell –specificallythosematerials Week 3 | The Cell Surface needed in catabolism or anabolism. o E.g., Carbohydrates, for Enzymatic The Cell Surface Activities (like antibodies) n Overview of Membrane Functions A Solute Transport in Osmosis Studies on Plasma Membrane Structure Go towards hypertonic environment – to The Chemical Composition of Membranes higher solute concentration When cell enters: An Overview of Membrane Functions o In Hypotonic Solution – water goes inside the cell Compartmentalization o InIsotonicSolution–levelisequal;no One of the main functions of membrane pressure The cell is in itself is a system, a o In Hypertonic Solution – solute is microenvironment for the organelles, abundant in the environment, water separated from the rest of the human body. goes out to the environment o Whathappensinsideonecelldoesnot affect the cell adjacent to it, unless Responses to External Stimuli signaling is present. Virions and Viroidin Plants ▪ E.g., Tubers – presence of o Do apoptosis (programmed cell death) non-photosynthetic cells in a Since plants don’t have an immune system, plant together with a oncebacteria,fungiorpathogensarepresent, photosyntheticcell.Theyhave thoseaffectedcellsandthecellsadjacenttoit low photosynthetic efficiency killthemselvestonotspreadandonlylocalize because of non-expressive the pathogenic effect. chlorophyll; thus it is mainly for storage for photosynthetic Intercellular Interaction products. E.g., Exchange of impulses in nerves Compartmentalization is brought aboutbythe o Such as use ofsphingolipids– propertiesof cellular membranes. particular in nerve function 12
