PMP-101 Module Lecture 1: Introduction to Cell Biology PDF

PMP-101 Module 🔴L1 – Introduction to Cell Biology: Prokaryotes and Eukaryotes 30th Sep 2024 Dr. Giulio Nannetti [email protected] Patient Centred Integration Human Biology Clinical Integration within PMP-101 Mod...

PMP-101 Module 🔴L1 – Introduction to Cell Biology: Prokaryotes and Eukaryotes 30th Sep 2024 Dr. Giulio Nannetti [email protected] Patient Centred Integration Human Biology Clinical Integration within PMP-101 Module Pharmacy Human Biology Pharmacology & Therapeutics Cellular & Pharmacy Molecular Bioscience 🩺 Practice Integration with PMP-102 Module Pharmacology & Pharmaceutics Pharmaceutical Chemistry Therapeutics Pharmaceutical Chemistry Learning outcomes and lecture outline By the end of this session you will be able to: Critically appraise the concept of cells as fundamental units of life Outline the main features and structures of prokaryotic cells Identify the key components of the cytosol in eukaryotic cells and describe their associated functions Lecture outline Overview of Overview of Basics of prokaryotic eukaryotic cells cells cells Quiz Which biological component distinguishes the living from the non-living matter? Word cloud Introduction to cell biology Living things  ORGANISMS made of CELLS Smallest and fundamental units of LIFE New cells are only made from pre-existing cells Overview of Overview of Basics of cells prokaryotic cells eukaryotic cells  Unicellular vs. Multicellular organisms ORGANISMS Unicellular Multicellular Simpler organisms More evolute organisms One cell exerting all life functions Multiple cells with specialised functions  Bacteria  Pluricellular Fungi (e.g. moulds)  Protozoa  Plants  Unicellular Fungi (e.g. yeasts)  Animals/humans Escherichia Coli Paramecium Saccaromyces spp. (bacteria) (yeast) Onion cells (plants) Epithelial tissue (human) (protozoa) Cell specialisation in multicellular organisms The human body is made up of ~1013 cells, with 200 types of specialised cells Distinct cell types vary in size, shape, functions Cell shape and size determine a particular specialisation Cooperation of different specialised cells allows complex organisms to perform a wide range of functions. Examples of cell specialisations in the human body Cell Main function Unique characteristics  Red blood cells Biconcave shape  O2 / CO2 No nucleus Transport Contain haemoglobin Small and flexible  Neurons Thin and long cells  Propagation of Branched at their ends nerve impulse Different subcellular parts (action potential) Release of neurotransmitter signals Level of organisation in the human body The human body is organised into levels of increasing complexity Cell Tissue Organ Organ System Organism Example Myocardiocyte Cardiac Heart Cardiovascular Human (heart muscle cells) muscle tissue system Body increasing complexity Size of cells and microscopy Unit Abbreviation Value 1 centimeter cm 10−2 meter 1 millimeter mm 10−3 meter 1 micrometer µm 10−6 meter 1 nanometer nm 10−9 meter Remember: 1 meter (m) = 1000 millimetres (mm) 1 millimetre (mm) = 1000 micrometres (μm) 1 micron (μm) = 1000 nanometers (nm) Interactive tool to compare the sizes of organisms, cells, molecules and atoms Light microscope or optical microscope The light microscope: Is used to observe living cells in a tissue Its resolution limit is ~ 0.2μm (not suitable for organelles) Important Properties of microscopes  Magnification – the ratio of an object’s image to its real size (up to 1000 times).  Resolution –it is the ability to distinguish between two very closely positioned objects. Fluorescence microscope (extra material) A technique to make specific parts of a cell or tissue that uses fluorophore proteins or dyes under a special light causing the fluorescent molecules to absorb this light and emit visible light, which makes them glow.  Used to monitor the localisation of target labelled molecules within a cell/tissue Electron microscope (EM) EM use:  High resolution images of cell structures (e.g. organelles)  Living cells cannot be observed Resolution limit is ≈ 2 nm (nanometres) Two main EM biomedical applications:  Transmission EM (TEM)  to study organelles  Scanning EM (SEM)  to study the cell surface Prokaryotic and Eukaryotic cells Based on cellular structure, there are two distinct type of cells:  Prokaryotic cell  bacteria (unicellular organisms)  without nucleus  No internal compartments  NO organelles  Simple internal organisation  Eukaryotic (mammalian) cells  human cells (multicellular)  with nucleus  Internal membranes that enclose the organelles  Complex organisation Basic Components of a Cell From the structural point of view, every type of cell has:  Plasma membrane (covered in lecture 7)  Cytosol, a concentrated aqueous solution of chemicals  Ribosomes  GENOME  genetic information of a cell represented by DNA that carry hereditary information and define each species  Biological macromolecules Macromolecules in cells Cells of all organisms contain 4 major organic (carbon atoms) macromolecules  Carbohydrates/Polysaccharides  Lipids  Proteins  Nucleic acids Macromolecules are polymers made by specific repeating molecular units, monomers Monomers - mono- (one) and -mer (part)  building blocks or subunits  smallest units of molecules that can join with each other to form larger molecules, polymers Macromolecules in cells Cells link monomers together to form a polymer through polymerisation/condensation reactions (requiring energy) ANABOLISM CATABOLISM ANABOLISM Polymers are broken down into smaller molecules by hydrolysis (realising energy) CATABOLISM METABOLISM = catabolism + anabolism reactions METABOLISM Macromolecules in cells Polymerisation /condensation MONOMERS POLYMERS FUNCTIONS Hydrolysis  Sugars/Monosaccharides  Oligo/Polysaccharides o Energy source (Lecture 6)  Amino acids  Proteins – Peptides o Structure/Enzymes/Multiple functions (Lectures 4 and 5) (Lectures 4 and 5)  Fatty acids  Lipids o Energy storage/ (Lecture 6) (Lecture 7) Biomembranes/hormones  Nucleotides  Nucleic acids (DNA/RNA) o Store/encode genetic information/ (Lectures 3 and 6) (Lecture 3) energy transfer  Overview of Overview of Basics of prokaryotic eukaryotic cells cells cells Bacteria (as prokaryotic cells) will be discussed in detail in Semester 2. Here it is just to give you an overview  Prokaryotic cell structure - Overview  Smaller (0.1-5 μm) and simpler cells internal Intracellular compartment  Cytoplasm, nucleoid, ribosomes, plasmids, inclusion bodies  Lack of nucleus and organelles internal boundary/ coating layers  Plasma membrane (internal boundary)  Cell wall  Glycocalyx/capsule External appendages  Flagella, fimbriae, sex pili external Prokaryotic cell – Intracellular composition Cytoplasm  Internal content of the cell - site of many reactions Ribosomes  Composed of a large (50S) and a small subunit (30S)  Each subunit is made of rRNA and proteins  Involved in protein synthesis, translating mRNA code Bacterial DNA chromosome  Dispersed in a central cytoplasmic space - Nucleoid  Single circular DNA - not linked to histone proteins Inclusion bodies:  Aggregates of reserve material (Storing function) Plasmids: additional/accessory circular DNA  Confer new ability, such as degradative ability of antibiotics  drug resistance Prokaryotic cell – Surface layers Surface layers (from the internal to the external one) Plasma membrane. (internal boundary) Flexible lipid bilayer, as in eukaryotic cells (with no sterols).  Controls the movement of molecules (nutrients/waste)  sometimes, site of reactions (respiration/photosynthesis) Cell wall (Different composition in Gram+ve and –ve).  Rigid structure to preserve cell shape & integrity Glycocalyx (not always) Polysaccharides layer: Capsule (organised and stable) or Slime layer (loosely attached)  Protection against dehydration, immune system (phagocytosis) and antibiotics  Adherence factor Prokaryotic cell – Appendages Flagellum (pl. flagella) sex  Long and whip-like appendages  Used for cell motility (movement).  It is also a sensory structure to detect nutrients Fimbriae / pili  Short and thin projections  Used for attachment to a surface or other cells Sex pilus (pl. pili) -.  Rigid hair-like tubular structures (longer than fimbriae)  Use to facilitate genetic material transfer between two bacteria (through the conjugation process)  Overview of Overview of Basics of prokaryotic eukaryotic cells cells cells Eukaryotic cells can be compared to highly organized factories Eukaryotic cells - Overview  Focus on Mammalian/human cells Bigger and more elaborated than prokaryotes Cell wall is NOT present in human cells  but present in plant and fungal eukaryotic cells Contain a nucleus (or more nuclei) Many membrane-enclosed organelles  have specialised functions (like organs) Organelles ORGANELLES system  nucleus,  Mitochondria,  lysosomes,  endoplasmic reticulum,  Golgi apparatus,  peroxisomes General usefulness of organelles Plasma Membrane-bound intracellular components allowing membrane compartmentalisation nucleus Different enzymatic composition  occurrence of diverse metabolic reactions  specialised functions organelles Distinct eukaryotic organisms have different organelles  Lysosomes are only in animals and chloroplasts are only found in plants Cytoplasm Content inside the plasma membrane (covered in Lec. 7) excluding the nucleus Highly organised and dynamic It includes:  cytosol gel-like fluid (pH 7.2) to support organelles It includes ribosomes, cytoskeleton, enzymes, etc It is the site of many cellular activities:  Protein synthesis (Lec. 4) and degradation  Metabolic reactions (e.g. glycolysis)  Cell signalling pathways (Lec. 8)  distinct cell organelles enclosed by membranes (separated by the cytosol) Ribosomes Function: Cell machinery for protein synthesis (translation step – Lec. 4) Structure: Made by 2 subunits: large (60S) & small (40S)  forming 80S S refers to their sedimentation coefficients (indirect size measure)  bigger than the prokaryotic ones (50s and 30S  70S) Essential Cell Biology. 5th ed., 2019.  Both subunits are combinations of :  Ribosomal proteins +  ribosomal RNA (rRNAs) Types: Free floating in the cytosol or bound to the rough endoplasmic reticulum Cytoskeleton A network of protein filaments and tubules that provides structural support Functions Fluorescence  Structural support: cell shape & resists mechanical stress microscope  Intracellular transport: facilitates movement of organelles, vesicles, and molecules  Regulates cellular processes (eg cell division & motality) Structures - Composition 3 types of filamentous protein polymers (long repetitions of 1 or more proteins):  Microfilaments (7 nm in diameter),  Intermediate filaments (10 nm in diameter)  Microtubules (25 nm in diameter) Cytoskeleton - Microfilaments microvilli  MICROFILAMENTS (Actin filaments) STRUCTURE Long, thread-like filaments of 2 helical strands of actin protein repetitions - (7nm in ⌀) MAJOR FUNCTIONS Depending on interaction with actin binding proteins (e.g. myosin). Very dynamic- Rapid assembly and disassembly for quick rearrangements Electron microscope!  Muscle contraction  Assist with cell movement 7 nm  Support cell’s shape (e.g. microvilli in intestinal cells) Essential Cell Biology. 5th ed., 2019.  Cell division: formation of contractile ring in cytokinesis (Lec. 9) Cytoskeleton - Intermediate filaments  INTERMEDIATE FILAMENTS STRUCTURE Rope-like fibres formed by many long strands of several types of proteins (e.g. keratin) twisted together - (10nm in ⌀) MAJOR FUNCTIONS  Provide mechanical strength and stability to cells and tissues (abundant in muscle cells)  Anchor cells in extracellular matrix No effect in cell motility (not bound to motor proteins). More stable 10 nm Essential Cell Biology. 5th ed., 2019. Cytoskeleton - Microtubules  MICROTUBULES STRUCTURE Long and rigid hollow cylinders made by repetitions of two tubulin protein subunits (α & β) - (25nm in ⌀) MAJOR FUNCTIONS  Cell structural support  Intracellular transport (linked to motor proteins, e.g. kinesin, dynein) β-tubulin protofilament  Generate force and cell movement (cilia and flagella)  Cell divisions  forming Centrioles  DNA segregation (Lec. 8) α-tubulin Cytoskeleton defects can lead to cardiomyopathies, cancer, etc. Some anti-cancer drugs interfere with microtubule formation to block the uncontrolled cancer cell divisions.  PMP301 Quiz Which biological component distinguishes the living from the non-living matter? a) Cells b) Organs c) Organism d) Organ Systems Ranking e) Tissues Cells  Tissues  Organs  Organ Systems  Organism Quiz Which of the following is present in BOTH Prokaryotic and Eukaryotic Cells? a) Nucleus b) Cytoplasm Multiple choice c) Organelles d) Glycocalyx / Capsule Summary Cells are fundamental units of life which make up organisms (unicellular/multicellular) Various cell specialisations are required in multicellular organisms Cell macromolecules (proteins, nucleic acids, polysaccharides, lipids) are polymers (large chains) formed by monomers (units) All cells have plasma membrane, cytosol, ribosomes, DNA Prokaryotic has simpler cell organisation than eukaryotic cells. Prokaryotes do not have nucleus and organelles In Eukaryotic cells, the cytoplasm has dynamic activity and contains cell cytosol and all organelles except nucleus Essential readings for lectures 1 and 2  Option 1 - Essential Cell Biology (LINK). 5th ed. by Alberts et al. 2019 (or other editions)- Chapter 1 (without part on model organisms) and Chapter 2 (only the paragraph on Macromolecules in cells) – As an alternative:  Option 2 - Molecular Cell Biology by Lodish, et al. - Chapters 1.1 -1.3  9th ed., 2021(LINK) OR 8th ed., 2016 (LINK), OR previous editions  Option 3 - Molecular biology of the cell. Alberts et al.,(7th Ed. 2022 - LINK) or (6th Ed. 2015 - LINK)  The topics discussed in Lec. 1 and 2 are covered by any other biology University textbooks Please email me if you have any doubts or further queries - [email protected]