Introduction to Cell Biology and Biochemistry PDF

Introduction to Cell Biology and Biochemistry Cells: The Fundamental Units of Life Dr Andrea Knight  Topic 1 - Cells: The Fundamental Units of Life Learning objectives for the topic, by the end of the week you will be able to: Apply the fundamental principles of biol...

Introduction to Cell Biology and Biochemistry Cells: The Fundamental Units of Life Dr Andrea Knight  Topic 1 - Cells: The Fundamental Units of Life Learning objectives for the topic, by the end of the week you will be able to: Apply the fundamental principles of biology to gain understanding of how cells and organisms work Outline Cell Theory Distinguish between prokaryote and eukaryote cells Using specific examples, discuss how cells perform different jobs Describe the components of eukaryotic cells and how they contribute to overall function  Five Principals of Biology All living things are composed of cells, the Cell Theory basic unit of life Characteristics of living organisms are controlled by Gene Theory genes passed on from one generation to the next Evolutionary Characteristics of living organisms change over BIOLOGY Theory time through natural selection and adaptation Tendency to maintain equilibrium between interdependent Homeostasis elements of processes and systems Laws of The transfer of energy from one form to another within a Thermodynamics system  1. Cell Theory Cell theory originally arose from theories proposed by Schwann, Schleiden, and Virchow in the early 1800’s: Cells are the basic unit of life All living organisms are made of cells Cells arise from pre-existing cells @betascienceart @aaandmoore  What is a cell? All Cells: Are separated from their environment by a plasma membrane Contain DNA as a store of genetic material. This material is used to guide the synthesis of RNA and proteins. The molecular relationship between DNA, RNA, and protein is the basis of a cells’ ability to self-replicate  Modern Additions to Cell Theory The cell contains hereditary information (DNA) which is passed from cell to cell during cell division All cells are similar in terms of chemical composition and metabolic activities @EMBL Energy flow occurs within cells Energy is required and transformed in biological systems Related to this: All basic chemical and physiological functions are carried out inside cells Cell activity depends on the activities of sub-cellular structures  Composition of Cells Cell Theory: All cells are similar in terms of chemical composition and metabolic activities nature.com Structure determines function! All Cells Need Energy Cell Theory: Energy is required and transformed in biological systems To undergo mitosis To maintain homeostasis To make more energy Active transport Specialist activities Nerve transmission Muscle contraction Bioluminescence  2. Gene Theory Characteristics of living organisms are controlled by genes passed on from one generation to the next Genome (sum of all genetic material in an individual) is used to store, express, and utilise genetic information Growth and behavior of organisms is mediated by gene expression Storage and transmission of information occurs across generations Eukaryotes: Meiosis & Mitosis Prokaryotes: Binary fusion  3. Evolutionary Theory Characteristics of living organisms change over time through natural selection and adaptation Diversity of life evolved over time by processes of mutation, selection, genetic change, and inheritance Fundamental organizing principle of biological phenomena Supported by evidence drawn from: molecular genetics, developmental biology, biochemistry, zoology, agronomy, botany, systematics, ecology, palaeontology Essential to understanding biological systems at all levels  4. Homeostasis Tendency to maintain equilibrium between interdependent elements of processes and systems Homeostasis: A system is maintained in a steady-state Requires positive and negative feedback mechanisms Example: Thermoregulation in humans Example: Oxygen levels on Earth Most living things need oxygen to breath, so remove oxygen from the environment Plants, algae produce oxygen when they convert CO2 to water and sugar The two processes balance each other out, so oxygen levels on Earth remain constant  5. Laws of Thermodynamics The transfer of energy from one form to another within a system Thermodynamics is the science between work, temperature and energy Biological systems grow and change - chemical transformation pathways governed by laws of thermodynamics Energy can neither be created or destroyed, but can only be transferred from one form to another Within any particular isolated system, the entropy always increases Cells: The Fundamental Units of Life Central Dogma: Information Flow  Phylogenetic Tree tes ryo ka Pro  Two basic types of organisms Prokaryotes Eukaryotes Single-celled Single-celled & multicellular Bacteria & Archaea Protists, Fungi, Plants & Animals  Two basic types of cells Absence or presence of a nucleus is basis of classification Prokaryotic Cells Eukaryotic Cells No nucleus Nucleus (DNA free in cytoplasm) Cell wall in some cells Cell wall (fungi and plant cells) No membrane-bound organelles Membrane-bound organelles (ribosome is the only organelle) Reproduce by binary fission Reproduce by meiosis & mitosis Prokaryotic Cells No membrane enclosed organelles No nuclear membrane = no nucleus DNA is usually a single circular chromosome and typically lacks histones Ribosome (site of protein synthesis) is the only ‘organelle’ Simple cytoplasm, no cytoskeleton Flagella (motility) Cell wall Plasma membrane Cell division by binary fission No sexual recombination, transfer of DNA only from one generation to the next Binary Fission Eukaryotic Cells Contains membrane enclosed organelles, eg: Nuclear membrane Mitochondria, chloroplasts (plant cells) Golgi, ER, lysosomes DNA is organised in multiple linear chromosomes with histones Larger Ribosomes (site of protein synthesis) Complex cytoplasm and cytoskeleton Complex flagella (involved in signalling) Cell wall (plant cells) Plasma membrane (plant and animal cells) Cell division by mitosis Sexual recombination by meiosis Eukaryotic Cells: Animal vs. Plant Cells Both Animal Cell Plant Cell Nucleus Many small vacuoles Plasma Membrane Chloroplasts Centriole Mitochondria Large central vacuole Centrosome Ribosomes Cell Wall Secretory Vesicles E.R. Plasmodesmata Flagella/cilia Golgi Endosymbiont Theory: Mitochondria & Chloroplasts Mitochondria evolved from aerobic prokaryote Chloroplasts evolved from photosynthetic prokaryote Alberts et al Essential Cell Biology 5th Edition Multiple Choice Question: Prokaryote cells include: a) Bacteria and plants b) Archaea and Bacteria c) Fungi and Algae d) Protists and Bacteria Multiple Choice Question: Which of the following cells do NOT have a cell wall? a) Yeast b) Escherichia coli c) Cardiac Myocytes d) Staphlococcus aureus  Unicellular vs. Multicellular Organisms Unicellular Multicellular Complex single cell that carries out all the Specialisation of cells – different cells functions of the organism perform different functions and organised Swim, hunt, mate, eat other microorganisms into tissues Frank Fox www.mikro-foto.de  Key concept: Structure & Function Basic units of structure define function of all living things Structure: an objects form, composition, arrangement Function: an objects job, role, task, responsibility Structural complexity and information built upon combinations of subunits create diverse and dynamic physiological responses Fundamental structural units and molecular and cellular processes are conserved throughout evolution Example: Immune response White blood cell (orange) cell attacking breast cancer cell Breast cancer cell breaking up into fragments (bubble- like structures) absorbed by body's macrophage cells Magnification: 5 000x Multicellular Organisms: Cells specify in particular jobs https://www.southampton.ac.uk/biu/galleries/sem.page, sciencephoto.com  FERTILISATION SURFACE AREA GAS EXCHANGE Human ovum with sperm Microvilli epithelial cells Network of capillaries Magnification: 1100x in gallbladder in alveolus in lung Magnification: 3000x Magnification: 400x TRANSPORT MOVEMENT FILTRATION EM capillaries and RBC Muscle fibres Kidney & renal cortex Magnification: 3000x Magnification: 360x Magnification: 8000x  Cell Specialisation: Compartmentalisation & Organelles Compartmentalisation separates cells into different parts to generate microenvironments within the cell that enables specific processes to occur more efficiently Enables specific conditions to enable processes and also prevent those processes from disrupting function of other organelles/structures Example: Lysosome Structure: membrane bound vesicles with proton pumps embedded in the membrane that enables low pH to be maintained within the lysosome Function: degradation of internalised material (pathogens) and endogenous proteins by pH sensitive enzymes  Functional Barriers: Membranes Functional barriers = enable compartmentalisation Comprise of phospholipids embedded with proteins Semi-permeable Regulates the transport of molecules entering and exiting the compartment  The Nucleus Contains DNA (genetic information) Nuclear membrane, enables compartmentalisation Nuclear pores control transport of molecules into/out of the nucleus Site of DNA replication and RNA transcription  The Cytoskeleton Actin filaments Microtubules Nucleus @cytoskeletown Gives structure Enables movement Enables organisation Enables cell division Comprises of microtubules, actin filaments, intermediate filaments  Protein Synthesis and Trafficking Protein Synthesis: Ribosomes – complexes of protein and RNA Rough Endoplasmic Reticulum – network of branching membranes associated with ribosomes Protein processing (glycosylation) and secretion Golgi – stacks of of flattened cisternae (membrane vesicles) Lipid synthesis Smooth Endoplasmic Reticulum – network of branching membranes and associated enzymes  The Power Plants: Mitochondria & Chloroplasts Mitochondria Chloroplast Site of ATP production (energy) Site of photosynthesis and energy production Double membraned organelle Double membraned organelle Inner membrane contains enzymes for Contains pigments to absorb light and enzymes ATP synthesis to catalyse ox-reduction reactions sciencephoto.com Waste Disposal Systems: Lysosome & Proteosome Lysosome Structure: membrane bound vesicles with proton pumps embedded in the membrane that enables low pH to be maintained within the lysosome Function: degradation of internalised material (pathogens) and endogenous proteins by pH sensitive enzymes Proteosome Structure: complexes of enzymes that break peptide bonds Function: degradation of proteins  Cell-to-Cell Contacts Adhesive molecules enable cells to maintain cell-to-cell contact and interact with the extracellular matrix Integrins: transmembrane proteins that interact with actin cytoskeleton and extracellular matrix Adherins Junctions & Desmosomes: provide mechanical support and signalling signals Gap Junctions: involved in cellular communication and create a narrow pore between cells that permit movement of small molecules Tight Junctions: also known as occluding junctions as they form junctions so tight that not even ions can pass across the junction. nature.com  Extracellular Matrix Cottignoli et al 2015 DOI:10.1155/2015/542687 Network of macromolecules that provide structural support to surrounding cells Not only a physical scaffold, but also responsible for biochemical and biomechanical signals that are required for tissue homeostasis and differentiation From Specialised Cells to Organisms  Learning Outcomes Apply the fundamental principles of biology to gain understanding of how cells and organisms work Outline Cell Theory Distinguish between prokaryote and eukaryote cells Using specific examples, discuss how cells perform different jobs Describe the components of eukaryotic cells and how they contribute to overall function