Organelles PDF

ORGANELLES Assoc. Prof. Dr. Seda GÜLEÇ YILMAZ Faculty of Medicine Department of Medical Biology 1 The Cell Cells have evolved several strategies for isolating and organizing their chemical reactions: • The procaryotic and eukaryotic cells is to aggregate the different enzymes required to catalyze...

ORGANELLES Assoc. Prof. Dr. Seda GÜLEÇ YILMAZ Faculty of Medicine Department of Medical Biology 1 The Cell Cells have evolved several strategies for isolating and organizing their chemical reactions: • The procaryotic and eukaryotic cells is to aggregate the different enzymes required to catalyze a particular sequence of reactions into large, multicomponent complexes • The complexes are used in the synthesis of DNA, RNA, and proteins • A second strategy, which is most highly developed in eucaryotic cells, is to confine different metabolic processes, and the proteins required to perform them, within different membrane-enclosed compartments. 2 • A cell from the lining of the intestine contains the basic set of organelles found in most animal cells 3 The Main Functions of Membrane Enclosed Compartments of a Eukaryotic Cell Compartment Main Function Cytosol Contains many metabolic pathways, protein synthesis Nucleus Contains main genome Endoplasmic Reticulum Synthesis of most lipids Synthesis of proteins for distribution to many organelles and to plasma membrane Golgi Modification, sorting and packaging of proteins and lipids Lysosomes Intracellular degregation Mitochondria ATP synthesis by oxidative phosphorylation Peroxisomes Oxidation of toxic molecules Chloroplast (in plant cells) ATP synthesis and carbon fixation by photosynthesis 4 MEMBRANE-ENCLOSED ORGANELLES • Procaryotic cell usually consists of a single compartment, the cytosol, enclosed by the plasma membrane • Eucaryotic cells are subdivided by internal membranes 5 https://www.geeksforgeeks.org/prokaryotic-cells-and-eukaryotic-cells/ Eucaryotic Cells contain a basic set of membrane enclosed organelles • These organelles are surrounded by the cytosol, which is enclosed by the plasma membrane. • The nucleus is generally the most prominent organelle in eucaryotic cells. It is surrounded by a double membrane, known as the nuclear envelope, and communicates with the cytosol via nuclear pores that perforate the envelope. 6 Double membrane enclosed organelles • Mitochondria and chloroplasts are thought to have originated in a different way. • They differ from all other organelles in that they possess their own small genomes and can make some of their own proteins • The similarity of these genomes to those of bacteria and the close resemblance of some of their proteins to bacterial proteins strongly suggest that mitochondria and chloroplasts evolved from bacteria that were engulfed by primitive eucaryotic cells with which they initially lived in symbiosis 7 The Endosymbiotic Theory 8 https://learn.genetics.utah.edu/content/cells/organelles/ Nucleus • A prominent rounded structure near the center of cell • Nuclear material (chromatiın) consist of : • DNA • histones • various nuclear proteins Formation of scaffolding complexes for DNA Binding to spesific DNA sequences Participatiing transcription and replication 9 https://micro.magnet.fsu.edu/cells/nucleus/chromatin.html Endoplasmic reticulum (ER) • The endoplasmic reticulum is the most extensive membrane network in eucaryotic cellsVarious biosynthetic events ocur in ER • ER lumen has special characteristic and components Plant cell Animal cell 10 Endoplasmic reticulum (ER) Smooth ER • is generally used for the creation/ storage of lipids and steroids • Site of lipid biosynthesis • A major compartment for intracellular calcium storage • Family of detoxifying P450 enzyme originate • Enzymes are rapidly synthesized and degrated according to intacellular signals Rough ER • plays a significant role in the synthesis of various protein • Many ribosomes are bound • Biosynthesis of all membranes occurs in mage Credit: https://www.biologyexams4u.com/2014/02/functions-of-rough-endoplasmic 11 Ribosome • an intercellular structure made of both RNA and protein • the site of protein synthesis in the cell. • reads the mRNA sequence and translates that genetic code into a specified string of amino acids, which grow into long chains that fold to form proteins https://www.thoughtco.com/ribosomes-meaning-373363 12 Ribosome • is the cellular machinery responsible for making proteins • There are many ribosomes in each cell, each made up of two subunits. • two subunits lock around the messenger RNA and then reading each three-letter codon. • serves as a docking station for the transfer RNA that matches the sequence of bases on the messenger RNA. • Each three-letter codon on the messenger RNA pairs with the matching anticodon on a specific transfer RNA, and that specific RNA allows for the addition of a specific amino acid on the end of the growing protein chain • The ribosome then breaks up after the completion of the protein https://www.genome.gov/genetics-glossary/Ribosome 13 Golgi Complex (Apparatus) • composed of a set of flattened cisternae with dilated rims arranged in a stack • resides near the ER • diverse in structure depending on the cell type • often referred to as the carbohydrate factory of the cell https://www.news-medical.net/life-sciences/The-Endoplasmic-Reticulum-and-Golgi-Body-Whats-the-Difference.aspx 14 Golgi Complex (Apparatus) • functions as a factory in which proteins received from the ER are further processed and sorted for transport to their eventual destinations: • Lysosomes • plasma membrane • secretion • involved in processing the broad range of cellular constituents that travel along the secretory pathway https://www.ncbi.nlm.nih.gov/books/NBK9838/figure/A1501/?report=objectonly 15 Mitochondria • A double membrane-bound organelle • Function as the metabolic center of the cell • Site of ATP production • Requires a large number of enzymes, most of which must be imported from cytosol 16 https://www.thoughtco.com/mitochondria-defined-373367 Mitochondria • A large number of metabolic enzymes reside in matrix • Lipid oxidation • Carbohydrate oxidation • Tricarboxylic acid(TCA)Krebs cycle • The chaperone proteins found within mitochondria play significant protective roles in mitochondrial biogenesis, quality control, and stress response mechanisms 17 https://www.news-medical.net/life-sciences/What-are-Mitochondria.aspx Mitochondrial DNA  Mitochondrial DNA is the circular chromosome found inside the cellular organelles called mitochondria.  Offspring inherit mitochondria — and as a result mitochondrial DNA — from their mother (maternal transmission) 18 https://www.genome.gov/genetics-glossary/Mitochondrial-DNA Mitochondrial DNA • The mitochondrial genome is small in size, circular, and encodes relatively few proteins • The nucleus of eukaryotic cells contains the majority of the DNA in the cell – genomic DNA. 19 Mitochondrial DNA • Mitochondrial DNA (mtDNA) is generally assumed to be inherited exclusively from the mother. • On this basis, men with Leber's optic neuropathy and other mtDNA disorders have been told that there is no risk of their transmitting these disorders to their children 20 https://www.researchgate.net/publication/328639320_Mitochondrial_Aging_and_Metabolism_The_Importance_of_a_Good_Relationship_in_the_Central_Nervous_System/figures?lo=1 Peroxisomes • Single membrane-bound organelles • Its name is derived from the organelle’s high content of oxidase that generate toxic hydrogen peroxide • contain a variety of enzymes, which primarily function together to rid the cell of toxic substances https://micro.magnet.fsu.edu/cells/peroxisomes/peroxisomes.html 21 Peroxisomes • In liver and kidney cells carry out a large number of the body’s detoxification reactions. • catalase in peroxisomes degrades hydrogen peroxide to oxygen and water • enzymes in hepatocytes detoxify ingested alcohol by converting it to acetaldehyde https://arcr.niaaa.nih.gov/alcohol-organ-interactions-injury-and-repair/alcoholic-liver-disease-pathogenesis-and-current-management 22 Peroxisomes Biogenesis is adaptive response to environmental stimuli for growth and survival • Proliferation by budding from preexisting peroxisomes • Growth of the organelle by the import of peroxisomal matrix proteins https://www.researchgate.net/publication/326143740_Peroxisomes_role_in_cellular_ageing_and_age_related_disorders/figures?lo=1 23 Lysosomes • Major digestive organelles • Site of protein degradation yet, its own membrane structure seems resistant to digestion • Surrounded by single bilayer membrane that has unique characteristic • is a specific type of organelle that's very acidic. https://www.genome.gov/genetics-glossary/Lysosome 24 Lysosomes • Lysosome has to be protected from the rest of the inside of the cell • It stores the digestive enzymes that require acid • Those enzymes are called hydrolytic enzymes, and they break down large molecules into small molecules 25 https://link.springer.com/article/10.1007/s00441-020-03375-7 26 https://diffeology.com/difference-between-peroxisomes-and-lysosomes/ Centrioles • are paired barrel-shaped organelles located in the cytoplasm of animal cells near the nuclear envelope. • play a role in organizing microtubules that serve as the cell's skeletal system • help determine the locations of the nucleus and other organelles within the cell. 27 https://www.genome.gov/genetics-glossary/Centriole References • • • • • • • • • https://www.genome.gov/genetics-glossary/ Lippincott Illustrated Reviews Cell and Molecular Biology_2. edition • https://www.researchgate.net/publication/334179478_Stuck_on_sugars_how_carbohydrates_regulate_cell_adhesion_recognition_and_si gnaling Essential_Cell_Biology_Alberts-_Third edition Molecular Biology of The cell_Alberts_fifth edition Molecular Cell biology_Lodish_sixth edition http://cytochemistry.net/cell-biology/membrane.htm https://www.nature.com/articles/gt201741 https://www.researchgate.net/publication/10920750_Gene_Therapy_for_Psychiatric_Disorders/figures?lo=1 https://www.nature.com/scitable/topicpage/cell-membranes14052567/#:~:text=With%20few%20exceptions%2C%20cellular%20membranes,backbone%20of%20these%20membrane%20lipids. 28