Cell Organelles PDF

* THE CELL AND ORGANELLES Interior structure:- ⮚Cytoplasm ⮚Cytoskeleton (in eukaryotes) ⮚Organelles (in eukaryotes) – 3 groups:- ▪ Endomembrane system (Endoplamic reticulum, Golgi apparatus) ▪ Mitochondria and chloroplast ▪ Ribosomes and nucleus  *...

* THE CELL AND ORGANELLES Interior structure:- ⮚Cytoplasm ⮚Cytoskeleton (in eukaryotes) ⮚Organelles (in eukaryotes) – 3 groups:- ▪ Endomembrane system (Endoplamic reticulum, Golgi apparatus) ▪ Mitochondria and chloroplast ▪ Ribosomes and nucleus  * THE CELL AND ORGANELLES Class I: Endomembrane system iii. Lysosomes found in all animal cells and some plant cells. Animal cell contain several hundred. dark spherical bodies, smaller than mitochondria membrane-bound sac of digestive enzymes: digest macromolecules. optimum in acidic condition (pH 5)  * THE CELL AND ORGANELLES Class I: Endomembrane system iii. Lysosomes Function enzymes found in lysosomes such as lipases, carbohydrases and proteases - intracellular digestion. recycling centre for the organelles - old organelles are digested (autophagy), product reuse to form new organelle. digest the remains of dead cell (autolysis) SER The process - RER put the enzymes and membranes together, then Golgi apparatus chemically refine the enzymes and releases mature lysosomes.  * THE CELL AND ORGANELLES Class I: Endomembrane system iii. Lysosomes Class I: Endomembrane system iv. Vacuoles a membrane-enclosed fluid filled sac found in the cells of plants including fungi. can be large organelles occupying between 30% and 90% of a cell by volume. three main functions:- a) contribute to the rigidity of the plant using water to develop hydrostatic pressure (contractile vacuoles) b) store nutrient and non-nutrient chemicals (food vacuoles, central vacuoles) c) break down complex molecules (function = lysosomes in animal cell)  * THE CELL AND ORGANELLES Class I: Endomembrane system iv. Vacuoles tonoplast - a selective membrane enclosing the central vacuole (controls passage of chemicals through it in both directions, water can pass in and out freely but other small molecules are retained within the vacuole).  * THE CELL AND ORGANELLES Class II: Mitochondria and chloroplast function in energy production. contain own DNA and ribosome. believe to be endosymbiotic bacteria. (Endosymbiotic theory –independent bacteria that was engulf by a larger cell and became symbiotic organelles)  * THE CELL AND ORGANELLES i. Mitochondria rod-like structure occur in large numbers. More in animal cells compared to plant cells. 0.5-1.5µm wide and 3-10µm long. double-membrane : outer membrane is smooth, define the shape cristae, infolded inner membrane partially divide the matrix. inter-membrane space between outer and inner membrane Function - use glucose and fatty acids to produce ATP (energy) during cellular respiration (Krebs cycle and electron transport chain - ETC)  * THE CELL AND ORGANELLES i. Mitochondria know features plant cristae are tubular or villus-like, but sheet- like plates in animal. cristae facing the matrix covered with stalked particles (carrier proteins in electron transport chain). matrix contain enzymes, DNA and ribosomes  * THE CELL AND ORGANELLES ii. Chloroplast large, flat discs usually 5 μm in diameter and 2.3 μm thick. number vary from 1 to 50. has own DNA, RNA and ribosomes. chloroplast usually contain starch granules and oil droplets. Function convert light energy of the sun into sugars that can be used by cells. process is called photosynthesis by chlorophyll molecules in each chloroplast.  * THE CELL AND ORGANELLES ii. Chloroplast double membrane separated by intermembrane space stroma contain ribosomes, DNA and photosynthetic enzymes (stroma - dark reaction site) whole thing dark reaction dark reaction  * THE CELL AND ORGANELLES ii. Chloroplast internal membrane is called lamella which consist of thylakoids that stacks up to form grana. each chloroplast has about 50 grana - each granum (singular) has about 50 thylakoids. thylakoid membrane (surface) is the light reaction site. photosynthetic pigments (chlorophyll a, b, carotenoid), electron transport chain (ETC) are embedded within the thylakoid membrane.  * THE CELL AND ORGANELLES ii. Chloroplast  * THE CELL AND ORGANELLES Class III: Ribosomes and nucleus involved in protein synthesis (gene expression). nucleus contains the DNA that codes for the proteins that the ribosomes synthesize. dna>mrna>protein (DNA is transcribed into mRNA in the nucleus, and the mRNA exits the nucleus and travels to the ribosomes to be translated into amino acid sequence of the proteins)  * THE CELL AND ORGANELLES i. Nucleus largest organelle (6μm), first to be discovered enclosed by a nuclear envelope - double membrane perforated by nuclear pores (100nm). nuclear membrane is impermeable to large molecules nuclear pores - channel that allows free movement of small molecules and ions outer membrane is continuous with membrane of RER the space between the membranes i.e. perinuclear space is continuous with the RER lumen  * THE CELL AND ORGANELLES i. Nucleus nucleoplasm is the semi-fluid substance in the nucleus. nucleus contains mainly the genetic material in the form of chromatin or chromosomes contain nucleolus, function - synthesis ribosomes perinuclear space  * THE CELL AND ORGANELLES i. Nucleus Functions: Control center of the cell maintain the genetic material control gene expression (protein synthesis) mediate the replication of DNA during the cell cycle provides a site for genetic transcription (synthesis of mRNA) allowing gene regulation (e.g.: lac operon system) synthesis ribosomes (nucleolus)  * THE CELL AND ORGANELLES ii. Ribosome solid spherical granules (d = 20-25nm) made up of RNA and proteins an assembly of two ribosomal subunits synthesized in nucleolus (prokaryotes 30S + 50S → 70S, eukaryotes 40S + 60S → 80S) each subunit is released through nuclear pores either bound to RER or free in cytosol  * THE CELL AND ORGANELLES ii. Ribosome Function – synthesize protein based on genetic information carried by mRNA from nucleus. ribosomes joined amino acids to form polypeptide / protein proteins synthesized by cytoplasmic ribosomes (free) are used within the cell. protein from RER are exported out or inclusion of membrane, and digestive enzymes in lysosomes. * THE CELL AND ORGANELLES Protein synthesis nucleus Text cytoplasm protein APPLICATION  https://stemcellres.biomedcentral.com/articles/10.1186/s13287- 019-1165-5  https://www.mayoclinic.org/tests-procedures/bone-marrow- transplant/in-depth/stem-cells/art-20048117  https://biomaterialsres.biomedcentral.com/articles/10.1186/s40 824-018-0148-4 Thank you