BIOL/BCHM 111 2024 Lectures 13-24 PDF

3/19/24 BIOL/BCHM 111 2024 Lectures 13-24 Ashley Garrill [email protected] SBS Room 420 Metabolism, energetics and memb...

3/19/24 BIOL/BCHM 111 2024 Lectures 13-24 Ashley Garrill [email protected] SBS Room 420 Metabolism, energetics and membrane transport https://www.youtube.com/watch?v=HT_Zs5FK DZE 1 A bit of background about me n BSc Leeds UK: Genetics and Plant Biology (1986) n PhD Liverpool UK: Genetics and Microbiology (1990) n Research positions in Canada (Toronto) and Australia (Adelaide) prior to UC 2 1  3/19/24 A bit of background about me n My research group looks at the cell biology and biophysics of pathogenic microorganisms n How they grow and cause disease n Fungi and oomycetes – myrtle rust and kauri dieback 3 A bit of background about me n In the movie we’re using a device called Lab-on-a-Chip to measure forces exerted by oomycete hyphae n Very small – a few µN n But because exerted over a small surface area – a huge pressure n Equivalent to an elephant standing on your big toe!!! n So they can force their way into plant tissue 4 2  3/19/24 Lectures n Please ask questions at any stage and remember – THERE IS NO SUCH THING AS A SILLY QUESTION n I will usually recap the previous lectures material at the start of each lecture n There is a question box if you don’t want to ask in the lecture n Also put in any music requests (for the start of the lecture) and also favourite animals/plants/microbes n I’ll try to incorporate as many of these into the lectures as I can – to try to put the concepts we cover into real life examples (e.g.today I’ll use meerkats and birds of paradise) 5 Reading for next 2 weeks n Biology 2e – WEB https://openstax.org Chapters 6 (Metabolism) and 7 (Cellular Respiration) n Biology: A Global Approach. (Global Edition) 11th Edition. Campbell et al. – Chapter 6 (Energy and Life) and Chapter 10 (Respiration) 6 3  3/19/24 What you need to know by the end of the lecture today § Cells need to do work to live § Movement, transport, chemical synthesis § Metabolism is the collection of chemical reactions that transform matter in a cell and enable work § Metabolic pathways can be catabolic or anabolic and these may be coupled § Metabolic pathways are controlled to meet the needs of the cell § Control occurs through the regulation of enzymes 7 From Grant’s lectures…. % by weight Living organisms are composed of lifeless molecules – Albert Lehninger Figure 2-29 Molecular Biology of the Cell (© Garland Science 2008) 8 4  3/19/24 Are our cells just bags of chemicals? No – a bag of chemicals is just a bag of chemicals - a cell is living Living cells/organisms can do all sorts of cool stuff – and that’s how we try to define life!! To carry out all these properties/processes of life - cells have to do work. 9 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n Cells need to move organelles (a specialised subunit in a cell that performs a function) around. n Here is a movie of vesicles (small organelle) moving around in a nerve cell n Why do they do this? 10 5  3/19/24 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n Certain organelles are used to move things (e.g. proteins, membrane). Sometimes these are moved from the nucleus to the outside of the cell. Sometimes from the outside of the cell to the nucleus. n Vesicular trafficking. 11 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n Sometimes big cells need to mix things around (organelles, nutrients, biomolecules). n This cell is Elodea (Canadian pond weed) n Cytoplasmic streaming 12 6  3/19/24 3 Types of Work n Movement n Membrane Transport n Chemical synthesis kinesin n These intracellular movements are powered by motor proteins n Kinesin, dynein, myosin n Move along tracks inside the cell – microtubules and microfilaments (cytoskeleton) 13 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n Entire cells also need to move – cell motility n This is a neutrophil (part of your immune system) chasing a bacteria 14 7  3/19/24 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n Cell motility is also a normal part of development n Cells move to their correct location in an embryo n These cells are moving and forming the lateral line in a Zebrafish - they will enable the fish to detect water movements 15 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n How do cells move? n Their cytoskeleton “pushes” the front end of the cell forward and also “pulls” the back of the cell forward. n Actin enabling cell motility (3:33) 16 8  3/19/24 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n Other cells use cilia or flagella to swim n Tetrahymena - a ciliated protist n If you do 300 level cell biology, we use Tetrahymena in two lab classes. 17 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n And in multicellular animals we move due to muscle contraction n Meerkats J 18 9  3/19/24 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n Movement of molecules or ions across membranes n Important to maintain osmotic balance with solution outside the cell n If not - cells can burst or shrivel up n Probably evolved very early in evolution 19 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n ~50% of energy used by your brain simply used to move Na+ and K+ across cell membranes n Important in nerve cells and nerve impulses n Na pump 20 10  3/19/24 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n In your muscle cells a Ca2+ pump is very important n It keeps Ca2+ levels in the cells very low (moves Ca2+ out) n Then they can respond to a sudden increase in Ca2+ and contract 21 3 Types of Work n Movement n Membrane Transport n Chemical synthesis n In Grant’s lectures he will have covered the importance of making macromolecules from monomer subunits n Polysaccharides from sugars, proteins from amino acids and nucleic acids from nucleotides 22 11  3/19/24 3 Types of Work Growth and development Energy processing Regulation Order Think about how Evolutionary adaptation movement, membrane Response to the environment transport and chemical Reproduction synthesis enable some of the characteristics of life in the bird of paradise dance video music https://www.youtube.com/watch?v=nWfyw51DQfU&list=RDCMUCwmZiChSryoWQCZMI QezgTg&start_radio=1&t=0 23 3 Types of Work Growth and development – movement of cells in development. Chemical synthesis for growth Energy processing – membrane transport Think about how Regulation – chemical synthesis, membrane movement, membrane transport (production movement of hormones) transport and chemical Order – chemical synthesis to create ordered synthesis enable some of cells/organs etc Evolutionary adaptation – chemical synthesis – the characteristics of life advantageous mutations passed onto offspring in the bird of paradise Response to the environment – movement dance video (muscle contraction), membrane transport (nerve impulses) Reproduction - movement (motility of sperm cells) 24 12  3/19/24 Work… Cells can do work because they can transform molecules and energy 25 Transformation of molecules n Molecules are transformed (i.e. slightly modified) via chemical reactions that occur within a cell 26 13  3/19/24 Transformation of molecules n Reactions are controlled n Typically by proteins called enzymes – typically specific n Catalyse reactions – decrease time taken to come to equilibrium (speed up reactions) 27 Transformation of molecules n First reaction in glycolysis n Glucose converted to glucose-6- phosphate n Catalysed by the enzyme hexokinase 28 14  3/19/24 Transformation of molecules n If glucose, hexokinase and ATP were isolated in a test tube n Reaction would come to equilibrium 29 Transformation of molecules n In a cell the reaction doesn’t come to equilibrium – metabolic disequilibrium n Glucose-6-phosphate is the substrate for the second reaction in glycolysis n Metabolic pathway 30 15  3/19/24 Metabolism n All of the metabolic pathways in a cell constitute its metabolism Fig. 6.1 The inset shows the first two steps in the catabolic pathway that breaks down glucose. 31 Metabolism and Energy n Metabolic pathways can be catabolic n Break complex molecules into simpler ones n Are spontaneous n Yield energy 32 16  3/19/24 Metabolism and Energy n Or Anabolic n Build complex molecules from simple ones n Are non-spontaneous n Cost energy 33 Metabolism and Energy n Energy coupling Energy derived from catabolic pathways can be used to drive anabolic pathways Energy carriers: ATP, NADH, NADPH ATP NADH 34 17  3/19/24 Metabolic Regulation n Pathways are regulated - depending on the energy needs of the cell/organism n Regulated via enzymes n Allosterically n Covalently n Genetically 35 Metabolic Regulation 36 18  3/19/24 Metabolic Regulation n If you’ve had no breakfast and then eat a crème egg…. n Energy levels low thus the sugar in the egg will be broken down via catabolic pathways for energy Fig. 6.1 The inset shows the first two steps in the catabolic pathway that breaks down glucose. 37 Metabolic Regulation n Enzymes which catalyse the reactions that break down sugar are sensitive to the energy status and are switched on Fig. 6.1 The inset shows the first two steps in the catabolic pathway that breaks down glucose. 38 19  3/19/24 Metabolic Regulation n If you have just eaten breakfast n Energy levels high n Don’t need the energy from the egg immediately so…. 39 Metabolic Regulation n Glucose in the egg will be converted to glycogen (storage carbohydrate). n Anabolic pathway. Enzymes that do this Fig. 6.1 The inset shows n the first two steps in the catabolic pathway that breaks down glucose. are switched on 40 20  3/19/24 Metabolic Regulation n Glucose in the egg will be converted to glycogen (storage carbohydrate). n Anabolic pathway. n Enzymes that catalyse sugar breakdown are Fig. 6.1 The inset shows switched off the first two steps in the catabolic pathway that breaks down glucose. 41 Metabolic Regulation n Cells are able to control their metabolism by regulating enzymes. n This ensures that they have the materials and energy to do work and hence be alive. Fig. 6.1 The inset shows the first two steps in the catabolic pathway that breaks down glucose. 42 21