L1. The cell-BREO.pdf

Cell Biology BHS012-1 Lecture 1: The Cell Dr Ria Diakogiannaki School of Life Sciences [email protected] 1  Unit Information BHS012-1: Cell Biology Unit co-ordinator: Dr Ria Diakog...

Cell Biology BHS012-1 Lecture 1: The Cell Dr Ria Diakogiannaki School of Life Sciences [email protected] 1  Unit Information BHS012-1: Cell Biology Unit co-ordinator: Dr Ria Diakogiannaki Courses present: – Biochemistry – Biomedical Science – Biological Science – Food and Nutrition Science – Pharmaceutical and Chemical Sciences – Pharmacology and Health Science 2  Unit Aims To provide a basic outline of the cell as the fundamental unit of life and how it impacts on all areas of biology. To introduce sub-cellular organisation, the variety of cell types and to relate cellular structure to function. Understand the basic ideas of cellular differentiation and specialisation from stem cells to terminally differentiated cells. To provide a basic understanding of cellular signalling and the immune system. 3  Course overview Lecture 1 The Cell Lecture 2 Cell membranes and transport Lecture 3 Information flow and vesicular transport Lecture 4 Endoplasmic reticulum & Golgi: structure and function Lecture 5 Mitochondria and chloroplast Lecture 6 Cytoskeletal structure and function Lecture 7 Cellular communication Lecture 8 G-proteins, Tyrosine Kinases, NO Lecture 9 Neural transmission Lecture 10 Immune system part 1 Lecture 11 Immune system part 2 Lecture 12 Immune system practical applications 4  Timetable 12 Lectures w39-49 + 2 online lectures Friday 10am-12pm in A004 5 Tutorials w40, 42, 44, 46, 48 Friday 3-4pm in A004 5  Unit Assessments All assessments are compulsory Must be submitted on time 1.Data exercise: 40% (ER stress) 2.Exam: 60% (1h, MCQs Date & time TBC) 6  Assessment 1 You will be provided with: ✓Assessment brief ✓Data to analyse ✓Written instructions Submission before 10am Friday 1st November 2024  BREO www.breo.beds.ac.uk Central place to go for : Unit information Lecture notes Instructions for assessments Assessment submission Announcements Reading lists  Lecture 1 The Cell: Prokaryotic and Eukaryotic  Learning Outcomes After studying this topic, you should be able to: Understand the key discoveries that led to the concept of cells as the fundamental units of life Outline the domains of life and link these to phylogenetic ideas of evolution Describe the main characteristics of, and differences between, prokaryotic and eukaryotic cells. List the major compartments and organelles of a eukaryotic cell and their principle functions. Understand the reasoning for current theories explaining the origin of organelles within eukaryotic cells.  Discovery Of Cells Microscope invented : –Zaccharias Janssen, Hans Janssen, 1590s Cells first described : –Robert Hooke Micrographia, 1665 Live cells described : –Antony van Leeuwenheok, 1674  Cell Theory Cell Theory : –Matthias Schleiden, –Theodor Schwann, 1838 Cells are the basic structural and physiological units of all living organisms. Cells are both distinct entities and building blocks of more complex organisms. Spontaneous Generation Of Cells Francesco Redi,1668 : – Rotting meat in a sealed jar or a jar covered with gauze does not produce maggots. – Whilst rotting meat in a jar open to flies does. – Thus, maggots don‘t spontaneously generate. – But what of the newly found micro-organisms? Louis Pasteur, 1862 : – Sterile broth protected from dust in air does not become contaminated. – Sterile broth open to dust does. – Thus, bacteria do not spontaneously arise, but grow from other bacteria (from the dust).  Common Cell To Common Ancestor Charles Darwin,1859: – Proposed evolution of life from common ancestor. – Explained the similarity of cells between different creatures. Phylogeny – Classification of Life Linnaeus Haeckel Chatton Copeland Whittaker Woese et al. Woese et al. 1735 1866 1925 1938 1969 1977 1990 2 kingdoms 3 kingdoms 2 empires 4 kingdoms 5 kingdoms 6 kingdoms 3 domains Eubacteria Bacteria (not Prokaryota Monera Monera Protista Archaebacteria Archaea treated) Protista Protista Protista Fungi Fungi Vegetabilia Plantae Plantae Eukarya Plantae Plantae Plantae Animalia Animalia Animalia Animalia Animalia  Genetic Understanding Of Cells Gregor Mendel,1865 : – Defined the rules of inheritance and the concept of discrete hereditary traits. – Identified dominant and recessive traits. William Bateson,1905 : – Popularised the ideas of Mendel. – Coined the terms genetics, gene and allele. Wilhelm Johannsen,1909 : – Coined the terms phenotype and genotype. Trees! Tree of Life : Ernst Haeckel, 1866 (after Darwin, 1859 Origin of Species) Modern tree based on genetic data  Modern Cell Theory Cells are the basic structural and physiological units of all living organisms. Cells are both distinct entities and building blocks of more complex organisms. All cells come from pre-existing cells. All cells are similar in chemical composition. Most of the chemical reactions of life occur within cells. Complete sets of genetic information are replicated and passed on during cell division.  Evolution of life 3 domains of life Bacteria Archaea Majority of cell mass and diversity of life is single celled! Eukarya Complex cell structure, larger cells Allowed multicellular life to evolve  Diversity of Life A) Archaea B) Eubacteria C) Protist D) Plants E) Fungi F) Insect (invertebrate) G) Animals (vertibrate)  The Cell: Prokaryotic and Eukaryotic Evolution of life – Timescales – Oxygenation and Energy Comparison of prokaryotic and eukaryotic organisms and cells. Introduction to major intracellular compartments. Origin of eukaryotic cells.  The Cell A cell consists of a concentrated solution of chemicals essential for its survival, surrounded by a selectively permeable membrane. An organism consists of one or more cells, which form a system capable of replication and renewal. Unicellular organisms are individual cells capable of all processes essential for life. Multicellular organisms consist of specialised cells which, between them, are capable of all processes essential for life. Evolution Of A Cell How are chemical reactions isolated from the environment? Fatty acids have polar ends and non-polar tails. The non-polar tails avoid water by adopting a spherical, bilayer conformation. Water can be both trapped within the sphere and held without. This creates a lipid encased bubble (cell) of water and solutes. Allows water soluble compounds to be concentrated and separated  The Evolving Cell Earliest prokaryotic fossils First photosynthesising prokaryote Multicellular life arose Original cellular life likely arose Earliest eukaryotic fossils  The Evolving Cell Original cellular life likely arose ~ 4 billion years ago. Earliest prokaryotic fossils ~ 3.5 billion years ago. First photosynthesising prokaryote ~ 2.7-3 billion years ago. Earliest eukaryotic fossils ~ 1.7 billion years ago (but eukaryote evolution may have been almost 3 billion years ago). Multicellular life arose ~ 1 billion years ago. Life, DNA, Proteins & The Central Dogma Life is a set of chemical reactions catalysed within the cell The reactions are largely catalysed by proteins DNA is the material of heritability, allowing information encoding the proteins from one generation to the next Replication of DNA allows the information to be passed to new cells Proteins are made through transcription of the information to RNA that allows translation of the genetic code to form proteins from amino acid building blocks  Life, oxygen & energy Early life lived in water and depended on energy from chemical compounds such as sulphur or iron (chemoautotrophs) Evolution of photosynethic reactions derived energy from light and used water as an electron acceptor, producing O2 Oxygen rapidly rose, producing first mass extinction – toxic to many anaerobes! Marine extinction intensity Aerobic respiration evolved, allowing more energy to be produced from oxidation of carbon compound (glucose) Eukaryotes and then complex life could then evolve (visible life) 5 Great extinctions of Phanerozoic Era  Prokaryotes Organisms: Bacteria & archaea Cell size: 1 to 10 µm. Metabolism: Aerobic or anaerobic. Organelles: Usually absent. DNA: Circular DNA in cytoplasm. Transcription: RNA & protein synthesised in the same compartment. Cytoplasm: No cytoskeleton (ish), cytoplasmic streaming, endocytosis or exocytosis. Cell division: Binary Fission or Budding. Organisation: Unicellular. Prokaryote Cell Structure Capsule Cytoplasm Ribosomes Nucleoid Plasma membrane Flagellum Peptidoglycan Cell wall Outer membrane  Prokaryotic Components Pili - hair-like appendages on surface of cell used for conjugation (bacterial genetic transfer) or adhesion (often called fimbriae). Made from protein Pilin. Ribosomes – RNA / protein structures used to make proteins from mRNA (translation). Nucleoid – location of main DNA of cell. Plasmid – small circular DNA with extra genes. Flagellum – complex tail-like structure used for motility.  Gram Positive & Negative Cells Bacteria have a lipid membrane and a peptidoglycan layer. Some bacteria have an additional outer membrane. Outer membrane prevents Gram staining (crystal violet dye uptake).  Eukaryotes Organisms: Protists (unicellular), fungi, plants and animals. Cell size: 10 to 100 µm. Metabolism: Primarily Aerobic. Organelles: Many. DNA: Very long DNA containing many non-coding regions; organised into chromosomes and bounded by nuclear envelope. Transcription: RNA synthesised & processed in nucleus; proteins synthesised in cytoplasm. Cytoplasm: Cytoskeleton made of protein filaments; cytoplasmic streaming; endocytosis & exocytosis. Cell division: Mitosis or meiosis. Organisation: Mainly multicellular, differentiation of function  A Eukaryotic Cell (Animal) Cytoskeleton Nucleolus Nucleus Plasma membrane Rough endoplasmic reticulum Mitochondrion Smooth endoplasmic Centriole reticulum 2011 Sinauer Associates, Inc Peroxisome Golgi Ribosomes apparatus  A Eukaryotic Cell (Plant) Smooth Free endoplasmic Vacuole Ribosomes Nucleolus reticulum Cell wall Nucleus Rough endoplasmic reticulum Chloroplast Plasma Mitochondrion membrane Golgi 2011 Sinauer Associates, Inc Plasmodesmata apparatus  Major Intracellular Components & Organelles Of Eukaryotes Plasma membrane Additionally in plants only: Nucleus Plastids eg. chloroplasts Cytoskeleton Cell wall – cellulose, pectin, Mitochondria lignin Endoplasmic reticulum Large vacuole – structure as – Rough well as storage – Smooth Plasmodesmata – Golgi apparatus communication and transport Lysosomes Peroxisomes Ribosomes Advantages Of Cell Compartments Concentrates chemicals in one area thus speeding up reaction kinetics. Separates certain biochemical reactions which require different conditions (eg pH). Prevents unwanted chemical interactions. Separates processes of transcription (RNA production) and translation (protein production), thus providing greater control and regulation.  Cell Membranes Phospholipid bilayer. Dynamic. Selectively permeable. – Passive transport of lipid soluble molecules. – Water soluble molecules actively transported across. Contains embedded proteins and glycoproteins, such as enzymes, transporters and receptors.  Cell Nucleus Surrounded by a nuclear envelope. Double membrane. Size 3-10 µm. Contains chromosomal DNA. DNA packaging – chromatin (DNA + proteins, mainly histones). Contains nucleolus. Ribosome production. Site of DNA replication and transcription. Communicates with cytosol via nuclear pores.  Cell Nucleus Nucleolus Nucleoplasm Rough endoplasmic reticulum Nuclear pore Ribosomes Inner Outer membrane membrane  Cytoskeleton Skeleton of the cell – maintains structure – molecular railways for transport Consists of : – microtubules (25 nm diameter) - tubulin; – actin filaments (8 nm diameter) - actin; – intermediate filaments (10 nm diameter) - eg keratin, laminin. Responsible for cell movement/structural changes e.g. muscle contraction, cell division, endocytosis  Endoplasmic Reticulum Large membrane system comprising sheets, sacs (cisternae) and tubes. Has structural continuity with outer membrane of nuclear envelope. – Rough ER : Generally formed of sheets. Studded with ribosomes. Main function is synthesis of proteins for secretion. – Smooth ER : Generally tubular. No ribosomes. Main function is lipid metabolism.  ER-Golgi Network Rough endoplasmic reticulum Protein containing vesicle Golgi apparatus Smooth endoplasmic Delivery of protein reticulum within or outside cell  Golgi Apparatus The “Post Office” of the Cell Another membrane system, composed of stacked, membrane-bounded flattened sacs (1 µm diameter). Involved in modifying, sorting and packaging macromolecules. Vesicles (the cell’s “Packets”) get secreted or delivered to other organelles. Surrounded by many membrane-bounded vesicles, 50 nm diameter and larger, carrying material between Golgi and cell. Golgi Apparatus Origin Of Internal Membranes Infolding of the cell’s plasma membrane creates extensive invaginated membrane surfaces. These membranes seal off the nucleus from the cytoplasm. Further membrane structures evolve into ER and Golgi.  Lysosomes And Endosomes Lysosomes : – Membrane-bounded vesicles 0.2 to 0.5 µm in diameter. – Contain hydrolytic enzymes involved in intracellular digestion. – Cell ‘waste basket’. Endosomes : – Membrane bound compartments which endocytosed material must pass through prior to reaching lysosomes. – Can be divided into “early” and “late” endosomes.  Lysosomes And Endosomes Golgi apparatus Primary lysosome Secondary lysosome Phagosome (endosome) Release of digested Release of molecules undigested inside cell molecules outside cell  Peroxisomes Single membrane-bounded vesicles 0.2 to 1.7 µm in diameter. Contain oxidative enzymes that generate/destroy hydrogen peroxide. Involved in metabolism of long chain fatty acids (beta oxidation). Thought to be derived from the ER, although some suggestion of an endosymbiotic origin.  Vacuoles Animal cells : – Small. – Storage of nutrients, metabolites and waste products. Plant cells : – Large (