Mitochondrion, Endoplasmic Reticulum and Golgi (Week 4) - Teesside University PDF

The Mitochondrion, Endoplasmic Reticulum and Golgi Mrs Cassy Ross Week 4 – Cell Biology SCI1023-N-GJ1-2021 2022 Learning Outcomes • Define the mitochondrion, endoplasmic reticulum and golgi and its location in the cell • Composition of those organelles • Specific functions of each organelle Do y...

The Mitochondrion, Endoplasmic Reticulum and Golgi Mrs Cassy Ross Week 4 – Cell Biology SCI1023-N-GJ1-2021 2022 Learning Outcomes • Define the mitochondrion, endoplasmic reticulum and golgi and its location in the cell • Composition of those organelles • Specific functions of each organelle Do you remember the cell? A eukaryotic cell is packed full of membranes These are double-membrane organelles Mitochondria are remnant bacteria - Size = 1-2um - Outer membrane - Inner membrane (Cristae) - Inter membrane space - Matrix Mitochondria under the microscope Transmission electron micrograph Mitochondrial features Figure 14-8 (part 1 of 2) Molecular Biology of the Cell (© Garland Science 2008) There are hundreds of mitochondria per cell Mitochondrial staining shows abundance Mitochondria stained red DNA (nucleus) is stained green Over 500 mitochondria in mammalian cells Mitochondria produce ATP ATP – Adenosine triphosphate • • ATP is vital for many biochemical reactions ATP is the energy currency of the cell (the power!) How does ATP provide energy? It’s all in the covalent bond between the 2nd and 3rd phosphate Adenine A lot of energy Some energy A little energy Phosphate group Phosphate group Phosphate group Pi = PO43- Gamma Beta Alpha Ribose The gamma phosphate hates ATP and wants to leave it!! ADP (Adenosine diphosphate) Phosphate group Phosphate group Beta Alpha Gamma phosphate is released P Adenine Ribose ADP (Adenosine diphosphate) Energy is released! Phosphate group Adenine Phosphate group Ribose Gamma phosphate is released P Breaking the phosphate bond… Pi = PO43- ATP Pi Adenine P gamma P beta P P Ribose alpha Adenine P beta Energy P Ribose alpha ADP ATP and ADP cycling in the cell • Cells are constantly cycling ADP and ATP Full charge Requires energy Releases energy Flat • REVERSIBLE REACTION Facts about ATP? • ATP is the energy currency of all life • A cell uses 10,000,000 (107) ATP per second • A typical human turns over 900,000,000,000,000,000,000 ATP per second • We turnover our own bodyweight in ATP each day • Separating just one chromosome requires 50 billion ATP • Some enzymes carry out 10,000,000 reactions per second Phillips R, Milo R. A feeling for the numbers in biology. Proc Natl Acad Sci U S A. 2009;106(51):21465-71. Core biochemical reactions in cell KEGG:https://www.genome.jp/kegg How is the cell powered? ATP – Adenosine triphosphate ? How is the energy from ATP used? Several mechanisms: 1. Causes conformational changes in proteins and molecules 2. Activates molecules by phosphorylating them 3. ATP places stresses on molecular bonds Zhang et al (2017), Cell: 170:483 What happens when we exercise? …ATP changes the conformation of myosin in our muscle cells? Breakdown of ATP and Cross Bridge Movement During Muscle Contraction - YouTube Unfortunately, cells cannot store ATP But can make it, how? Cellular respiration The main function of cellular respiration is to break down glucose to form energy. Hydrolysing glucose – convert into energy (ATP) Cellular respiration Glucose is transferred in to ATP via three separate stages: 1. Glycolysis 2. Krebs cycle 3. Electron transport chain Glycolysis Breaking of glucose 6 carbon ring into two 3carbon molecules Pyruvic acid (Pyruvate) In the Cytosol of cell, glycolysis converts glucose into pyruvate through a series of 10 enzymatic reactions Glycolysis Glucose ATP ADP Hexose Kinase Glycolysis Glucose ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Glycolysis Glucose ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Fructose-6-phosphate ATP ADP 3. Phosphofructokinase Glycolysis Glucose ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Fructose-6-phosphate ATP 3. Phosphofructokinase ADP Fructose-1,6-bisphosphate 4. AldoLase Glycolysis Glucose ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Fructose-6-phosphate ATP 3. Phosphofructokinase ADP Fructose-1,6-bisphosphate 4. AldoLase Glyceraldehyde 3phosphate Dihydroxyacetone phoshpate 5. Triosephosphate isomerase Glycolysis Energy consumption phase ATP used up! Glucose ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Fructose-6-phosphate ATP 3. Phosphofructokinase ADP Fructose-1,6-bisphosphate 4. AldoLase Glyceraldehyde 3phosphate Dihydroxyacetone phoshpate 5. Triosephosphate isomerase At this point in Glycolysis, glucose has been metabolised into two phosphates AND two ATPs have been consumed Glycolysis 1,3-BisPhosphoGlycerate Glucose 2NAD+Pi ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Fructose-6-phosphate ATP 3. Phosphofructokinase ADP Fructose-1,6-bisphosphate 4. AldoLase Glyceraldehyde 3phosphate Dihydroxyacetone phoshpate 5. Triosephosphate isomerase 2NADH 6. Dehydrogenase Glycolysis 1,3-BisPhosphoGlycerate Glucose 2NAD+Pi ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Fructose-6-phosphate ATP 3. Phosphofructokinase ADP Fructose-1,6-bisphosphate 4. AldoLase Glyceraldehyde 3phosphate Dihydroxyacetone phoshpate 5. Triosephosphate isomerase 6. Dehydrogenase 2NADH 3-PhosphoGlycerate 7. Phopshogylcerate kinase Glycolysis 1,3-BisPhosphoGlycerate Glucose 2NAD+Pi ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Fructose-6-phosphate ATP 3. Phosphofructokinase ADP Fructose-1,6-bisphosphate 4. AldoLase Glyceraldehyde 3phosphate) Dihydroxyacetone phoshpate 5. Triosephosphate isomerase 6. Dehydrogenase 2NADH 3-PhosphoGlycerate ADP 7. Phopshogylcerate kinase ATP 2-PhosphoGlycerate 8. Phopshogylcerate Mutase Glycolysis 1,3-BisPhosphoGlycerate Glucose 2NAD+Pi ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose Fructose-6-phosphate ATP 3. Phosphofructokinase ADP Fructose-1,6-bisphosphate 4. AldoLase Glyceraldehyde 3phosphate Dihydroxyacetone phoshpate 5. Triosephosphate isomerase 6. Dehydrogenase 2NADH 3-PhosphoGlycerate ADP 7. Phopshogylcerate kinase ATP 2-PhosphoGlycerate 8. Phopshogylcerate Mutase PhosphoEnolPyruvate 9. Enolase - Lyase Glycolysis 1,3-BisPhosphoGlycerate Glucose 2NAD+Pi ATP 1. Hexose Kinase ADP Glucose-6-phosphate 2. Isomerase - PhosphoGlucose 6. Dehydrogenase 2NADH 3-PhosphoGlycerate ADP 7. Phopshogylcerate kinase ATP 2-PhosphoGlycerate Fructose-6-phosphate ATP 8. Phopshogylcerate Mutase 3. Phosphofructokinase ADP PhosphoEnolPyruvate Fructose-1,6-bisphosphate 4. AldoLase ADP 9. Enolase - Lyase ATP Glyceraldehyde 3phosphate Dihydroxyacetone phoshpate 5. Triosephosphate isomerase Pyruvate 10. Kinase – pyruvate kinase Energy production phase ATP synthesised Glycolysis Net products from Glycolysis = Glycolysis Glucose 2 Pyruvate 2 NADH 2 ATP Glucose 2 ATP 2NADH 2 pyruvate Glycolysis: the first step of glucose oxidation • • • • • • Important for all life If oxygen is absent, glycolysis is the only way the cell makes ATP Glycolysis = “splitting of sugar” – glucose is split into 2 molecules of pyruvate Occurs in the cell cytosol Does not require oxygen (anaerobic) Glycolysis makes just 2 ATP by substrate-level phosphorylation……phosphate is transferred to ADP from a substrate Glycolysis Glycolysis Pathway Made Simple !! Biochemistry Lecture on Glycolysis - YouTube Do you remember the structure of ATP? Cellular respiration Glucose is transferred in to ATP via three separate stages: 1. Glycolysis 2. Krebs cycle 3. Electron transport chain These two stages are aerobic processes Krebs cycle • Hans Krebs discovered complex cycle in 1937 • Occurs in the inner membrane of the mitochondria • Generates energy through oxidation of acetyl coa • Production of amino acids and other raw materials Concept of the Krebs cycle Sugar (glucose) Initial metabolic pathways Krebs cycle Initial metabolic pathways Initial metabolic pathways Hydrolysing glucose ….and if oxygen is available: pyruvate enters the mitochondrial Kreb’s cycle and gets hydrolysed GLUCOSE Glycolysis Lactic acid Oxygen LDH available 2xPyruvate The Kreb’s cycle has 3 names, used interchangeably: - Kreb’s cycle - Tricarboxylic acid cycle - Citric acid cycle CO2 +NADH fully oxidised Pyruvate Acetyl-CoA Kreb’s cycle PDH (many enzymes) Mitochondrial Matrix 1ADP 3NAD+ 1FAD 1ATP 3NADH 1FADH2 +2CO2 Occurs in the inner mitochondrial membrane Krebs cycle Krebs Cycle - YouTube Check your understanding…. Glycogen 2NAD+ Glycolysis Glucose 2ATP Fermentation 2Pyruvate Organic molecule 2NADH When oxygen is available Kreb’s cycle and electron transport chain ……..in the MITOCHONDRIA Cellular respiration Glucose is transferred in to ATP via three separate stages: 1. Glycolysis 2. Krebs cycle 3. Electron transport chain Electron transport chain (E.T.C) • Comprises a series of proteins complexes - complex I to complex IV • Two mobile carriers (shuttling proteins) – Ubiquinone(Q) and Cytochrome c • Electrons are passed from NADH – to complex I; from FADH2 to complex II • Protons (H+) are pumped out into IMS • Complex IV reduces O2 to water with 4 electrons Electron transport chain (E.T.C) How Mitochondria Produce Energy - YouTube POISONS: Cyanide and Carbon monoxide Cyanide and carbon monoxide • Acts on complex IV • Stops all electrons being passed to oxygen What will the symptoms be from poisoning ? • Lactic acidosis – high lactate in the blood • No ATP – affects the CNS and heart Using the proton gradient to make heat • Electron flow generates heat • Mitochondria can be miniheaters • Produces heat in fat cells Phones get hot because of electron flow • The uncoupling protein is a heater! http://jeb.biologists.org/content/217/12/2032 Klingenspor, M. and Fromme, T. (2012) NET OUTPUTS – A SUMMARY Electron shuttles span membrane 2 NADH Glycolysis 2 Pyruvate Glucose 2 NADH Pyruvate oxidation 2 Acetyl CoA + 2 ATP Maximum per glucose: CYTOSOL MITOCHONDRION 2 NADH or 2 FADH2 6 NADH 2 FADH2 Citric acid cycle Oxidative phosphorylation: electron transport and chemiosmosis + 2 ATP + about 26 or 28 ATP About 30 or 32 ATP Just remember: Mitochondria • Organelle present in all eukaryotic cells • Has double membrane • Main mitochondrial function (in the inner membrane): • Synthesis of ATP ADP Pyruvate + O2 ATP CO2 + H2O Mitochondrial disease • Symptoms of mitochondrial disease vary hugely depending on the actual syndrome or underlying genetic mutation that has caused it • One example: Alpers’ Syndrome • Mitochondrial DNA depletion: It is most often caused by mistakes in the DNA of a gene called POLG • The three major clinical features associated with Alpers’ syndrome are severe epilepsy, loss of developmental skills (developmental regression) and liver failure Our eukaryote is almost complete Proteins Week 10: Gene expression Transcription ATP DNA Week 5: Nucleus and DNA Sending and receiving goods Proteins destined to be exported passage through - The Rough Endoplasmic Reticulum (ER) - The Golgi (the cell’s mail room) Smooth ER is involved in lipid synthesis Endoplasmic reticulum Rough ER Smooth ER • Secreted into extra cellular environment • Become integral proteins in cell membrane • Remain in ER, golgi or lysosomes • Post translational modification of proteins • Synthesis lipids - Including those that will end up being part of cell membrane and those secreted from the cell • Metabolise carbohydrates • Aids in detoxification of drugs and other toxins If proteins need to be secreted from the cell 1. mRNA export 2. mRNA binds ribosome ribosome mRNA Nucleus Rough ER If proteins need to be secreted from the cell ribosome AA1 AA2 3. Protein starts to be produced on ribosome AA3 Ribosome/mRNA/Protein mRNA Nucleus Rough ER If proteins need to be secreted from the cell SRP ribosome AA1 AA2 AA3 Ribosome/mRNA/Protein mRNA Nucleus 4. Secreted proteins have a secretion signal 5. Signal recognition ER translocase particle binds protein and delivers it to ER translocon Rough ER If proteins need to be secreted from the cell SRP ribosome AA1 AA2 AA3 Ribosome/mRNA/Protein ER translocase mRNA Nucleus Rough ER If proteins need to be secreted from the cell - Secreted proteins use the ER-Golgi route - For secreted proteins…… ribosome AA1 AA2 AA3 AA1 Ribosome/mRNA/Protein mRNA Nucleus AA2 AA3 Rough ER appearance Electron micrograph Animation of Translation and protein delivery to rough ER The Golgi is the cell’s post-room • Looks like a stack of pancakes – has a cis side and a trans side CIS = this side TRANS = the other side • Receives transport vesicles containing protein from the rough ER • Modifies the proteins – eg. glycosylated • Sends proteins to various places in the cell – endosomes, lysosomes, plasma membrane, mitochondria The Golgi is the cell’s post-room Check your understanding…. Multiple choice questions on Mito-ER-Golgi! https://forms.office.com/Pages/ResponsePage.aspx?id=W xHSQ16ltkad97AziOz8YHPKVJ7iwLlEi3zi7EZn_8pURVJ OTlRCU0tXQU01M0xHOVhVSThZSFZUMi4u Any questions? [email protected] Video: if we have time…… Thank you!