Structure and function of lysosome

This Power Point Presentation (PPT) entitled “ Structure and Function of Lysosome”includes 43 slides with following sub- heads.
DEFINITION
INTRODUCTION/ STRUCTURE OF LYSOSOME
DISCOVERY OF LYSOSOME
DISTRIBUTION/LOCATION OF LYSOSOME
ORIGIN/ SYNTHESIS OF LYSOSOME
SHAPE AND SIZE OF LYSOSOME
CHEMICAL COMPOSITION OF LYSOSOME
LYSOSOMES ARE KNOWN AS SUICIDE BAGS
HOW THE CELL IS PROTECTED FROM LYSOSOME RUPTURE
COMMON FUNCTION OF LYSOSOME
TYPES OF LYSOSOME
DISORDERS IN HUMAN RELATED WITH LYSOSOME
SUMMARY
QUESTIONS
BOOKS CONSULTED
REFERENCES

1. STRUCTURE AND FUNCTION OF LYSOSOME By Prof (Dr.) Ichha Purak Department of Botany Ranchi Women’s College, Ranchi

2. 8/20/2020 Structure and function of Lysosome 2 CONTENTS DEFINITION INTRODUCTION DISCOVERY OF LYSOSOMES DISTRIBUTION / LOCATION OF LYSOSOME ORIGIN / SYNTHESIS OF LYSOSOME SHAPE AND SIZE OF LYSOSOME CHEMICAL COMPOSITION OF LYSOSOME LYSOSOMES ARE KNOWN AS SUICIDE BAGS HOW THE CELL IS PROTECTED FROM LYSOSOME RUPTURE COMMON FUNCTIONS OF LYSOSOME TYPES OF LYSOSOMES DISORDERS IN HUMAN RELATED WITH LYSOSOME SUMMARY QUESTIONS BOOKS CONSULTED REFERENCES

3. 8/20/2020 Structure and function of Lysosome 3 The term Lysosome is derived from Greek word lysis ( means destroy or dissolve) and soma ( means body ). Lysosome is an organelle which can break down almost all types of macromolecules ( as Nucleic acids, proteins, polysaccharides, lipids etc .). Lysosomes are spherical, membrane bound organelles which are generated from trans Golgi apparatus ,cut off as vesicles. Lysosome enclose or contain a number of ( about 50) hydrolytic enzymes and so function as part of the recycling system of the cell cleaning up debris and wastes . The Lysosomes are made up for intracellular and extracellular digestion . DEFINITION

4. 8/20/2020 Structure and function of Lysosome 4 INTRODUCTION/STRUCTURE OF LYSOSOME The cytoplasm of animal cells contain one to many tiny, spheroid or irregular shaped , membrane bounded vesicles or organelles known as lysosomes. They digest the material taken in by endocytosis ( such as phagocytosis, endocytosis and pinocytosis), parts of the cell (by autophagy) and extracellular substances. Lysosomes are membrane enclosed compartments having hydrolytic enzymes used for controlled intracellular digestion of macromolecules at acidic pH (about 5 in its interior) The acidic environment of lysosome is due to ATP-dependent proton pumps which are present in the membrane of lysosome, which accumulates protons (H+) inside the lysosomes.

5. 8/20/2020 Structure and function of Lysosome 5 DISCOVERY OF LYSOSOMES Lysosomes were discovered by a Belgian biologist, Christian de Duve in 1950s. De duve was awarded a share of 1974 Nobel Prize for Physiology and Medicine for his discovery of lysosomes and other organelles known as peroxisomes Lysosomes were initially discovered by the biochemical fractionation of cell extracts. Later on they were seen clearly under electron microscope as membrane enclosed vesicles.

6. 8/20/2020 Structure and function of Lysosome 6 DISTRIBUTION/LOCATION OF LYSOSOME Lysosome is a membrane bound organelle found in many animal cells. Lysosomes are absent in erythrocytes. Lysosomes are distributed through out cytoplasm or between trans face of Golgi Apparatus and Plasma membrane Lysosomes are generally not present in plant cells . In plant cells delicate membranous cavities are found known as vacuoles. In young plant cells ( meristematic cells) numerous small vacuoles are present along with cell organelles like mitochondria , plastids , microbodies etc. In mature plant cell (permanent tissue) small vacuole fuse to form large vacuole , as a result the cell organelles and nucleus are pushed towards plasma membrane . In plant cells role of lysosome is undertaken by the vacuoles. Vacuoles also contain hydrolytic enzymes Vacuole is filled with cell sap and help in excretion of waste and excess water. Cell sap has many organic and inorganic substances.

7. 8/20/2020 Structure and function of Lysosome 7 In plants, vacuoles serve many functions, which make them multifunctional organelles . However, they also have basic properties similar to lysosomes found in the cells of animal. Vacuoles are also of acidic nature and contain various hydrolytic enzymes for breaking different types of molecules There are different types of vacuoles that serve different functions in plant cells . Sap vacuoles - these vacuoles store salt, minerals and nutrients. Contractile vacuoles - involved in osmoregulation and excretion,They are formed and burst after some time, take up the function of excretion and osmoregulation . Food vacuoles - involved in the digestion of nutrients , these vacuoles contain digestive enzymes that digest these nutrients.

8. 8/20/2020 Structure and function of Lysosome 8 BIOGENESIS / SYNTHESIS OF LYSOSOME Primary lysosomes originate from the Golgi apparatus (Trans side) in the form of vesicles Lysosomes appear initially as spherical bodies about 50-70nm in diameter and are bounded by a single membrane. Several hundred lysosomes may be present in a single animal cell. lysosomes are formed by the fusion of transport vesicles budded off from the trans Golgi network with endosomes, which contain molecules taken up by endocytosis at the plasma membrane. Lysosome membrane and the enzymes present within are synthesized separately .

9. 8/20/2020 Structure and function of Lysosome 9 Lysosome proteins are synthesized as other proteins but on ribosomes attached to Endoplasmic Reticulum. The mRNA after transcription from DNA segments and translocation to cytosol attach with smaller subunit of ribosome and due to presence of signal codons in mRNA, ribosome becomes attached to Endoplasmic Reticulum , to complete synthesis of polypeptide in its lumen. Polypeptide becomes tagged with mannose-6-phosphate within the Golgi apparatus and is then targeted to lysosome . As a result , vesicles containing these enzymes bud off from the Golgi apparatus. The enzymes which help in attachment of mannose-6-phosphate are N- aetyleglucoseamine phosphotransferse and N- acetyleglucosamine phosphoglycosidase .

10. 8/20/2020 Structure and function of Lysosome 10 lysosome formation Lysosomes form by budding off from the membrane of the trans-Golgi network. Macromolecules (i.e., food particles) are absorbed into the cell in vesicles formed by endocytosis . The vesicles fuse with lysosomes, which then break down the macromolecules using hydrolytic enzymes . COURTSEY Encyclopædia Britannica, Inc .

11. 8/20/2020 Structure and function of Lysosome 11 Lysosomes are usually meeting places where several streams of intracellular traffic take place . Digestive enzymes are delivered to them by a route that leads outward from the ER via the Golgi apparatus This vesicle, now in the cytoplasm, then binds with a late endosome which is another acidic, membrane-bound organelle . The late endosome has proton pumps within its membrane that keep its internal environment acidic. The low pH causes dissociation of the protein from the mannose-6-phosphate receptor. This receptor can then be recycled back to the Golgi apparatus . The phosphate group is also removed from the mannose-6-phosphate tag, to prevent the whole protein returning to the Golgi apparatus.

12. 8/20/2020 Structure and function of Lysosome 12 The late endosome can eventually mature into a lysosome, after it has received the enzymes from the Golgi apparatus . Lysosomes act as the waste disposal system of the cell by digesting obsolete or un-used materials in the cytoplasm, from both inside and outside the cell . Material from outside the cell is taken-up through endocytosis, while material from the inside of the cell is digested through autophagy SHAPE AND SIZE OF LYSOSOME Lysosomes are acidic membrane bound spherical or irregular organelles about 1 μ m in diameter The size of lysosomes varies from 0.1 μ m to 1.2 μ m . Lysosomal enzymes are synthesized in the endoplasmic reticulum (ER), transported to the Golgi apparatus, and then tagged for lysosomes by the addition of mannose-6-phosphate label.

13. 8/20/2020 Structure and function of Lysosome 13 CHEMICAL COMPOSITION OF LYSOSOMES Lysosomes contain a number ( about 50-60) of Acid hydrolases such as nucleases, proteases, glycosidases , lipases, phosphatases, sulfatases and phospholipases . These enzymes take up the function of degrading or breaking macromolecules or biological matter. The acid hydrolases are hydrolytic enzymes that are active under acidic conditions. The lumen is maintained at an acidic pH by an H+ ATPase in the membrane that pumps H+ into the lysosome Figure 13-31 Lysosomes From : Molecular Biology of the Cell. 4th edition.Alberts B, Johnson A, Lewis J, et al.New York: Garland Science; 2002 Transport from the Trans Golgi Network to Lysosomes

14. 8/20/2020 Structure and function of Lysosome 14 The lysosomal enzymes are grouped in six main categories Nucleases - Nucleases are important enzymes that hydrolyze nucleic acids. Nucleases are divided in to deoxyribonuclease (acts on DNA) and ribonuclease which hydrolyses RNA. Hydrolysis action on nucleic acids results in the production of sugars, nitrogen bases as well as phosphates. Proteases - Proteases includes enzymes like collagenase and peptidases that acts on proteins converting them to amino acids Glycosidases - Glycosidases like beta galactosidase act on the glycosidic bonds of polysaccharides converting polysaccharides to monosaccharides . For instance, the enzyme galactosidase acts on such bonds converting lactose to glucose and galactose . Phosphatases - Good examples of Phosphatases are acid phosphodiesterases . These are important enzymes that act on organic compounds releasing phosphate in the process if the compound has a phosphate group. Lipases - Lipases include esterases and phospholipiases that act on lipids to produce acids and alcohol Sulphatases - Sulphatases are enzymes that act on organic compounds to release sulphates

15. 8/20/2020 Structure and function of Lysosome 15 LYSOSOMES ARE KNOWN AS SUICIDE BAGS   Lysosomes can digest materials taken up from outside the cell, but some times when they burst ,their enzymes digest their own cell so are called suicidal bags of the cell. Lysosomes cannot digest themselves - Most of the proteins present in its membrane contain high amounts of carbohydrate-sugar groups . Because of the presence of these groups, digestive enzymes are unable to digest the proteins present on the membrane. HOW THE CELL IS PROTECTED FROM LYSOSOME RUPTURE Lysosomes contain a wide variety of hydrolytic enzymes (acid hydrolases) that break down macromolecules such as nucleic acids, proteins, and polysaccharides. These enzymes are active only in the lysosome’s acidic interior; their acid-dependent activity protects the cell from self-degradation in case of lysosomal leakage or rupture, since the pH of the cell is neutral to slightly alkaline.

16. 8/20/2020 Structure and function of Lysosome 16 COMMON FUNCTION OF LYSOSOME The main function of lysosomes is the digestion of internal (non-functional cell organelles) and external (food, bacteria, leukocytes, debris) material. The processed material is either released to the cytoplasm, secreted, or stored in lysosomes. Lysosomes break down macromolecules into their constituent parts, which are then recycled and reused The hydrolytic enzymes contained within the lysosome allow foreign particles to be destroyed . Lysosomes play an important role in phagocytosis . When macrophages phagocytose foreign particles, they contain them within a phagosome . The phagosome then bind with a lysosome to form a phagolysosome .

17. 8/20/2020 Structure and function of Lysosome 17 These enzymes are critical in oxygen-independent killing mechanisms. Lysosomes also help to defend against pathogen entry via endocytosis by degrading pathogens before they reach the cytoplasm . Lysosomes are heterogenous in shape and size. Diversity of lysosomes reflect wide variety of digestive functions mediated by acid hydrolases for intra and extracellular debris . There are a number of processes through which lysosomes digest material. These include: Endocytosis In endocytosis, invagination of the plasma membrane of the cell results in the creation of an endocytic vesicle that engulfs different types of extracellular molecules. In phagocytosis (a type of endocytosis) large molecules/microorganisms like bacteria are engulfed in a vacuole ( phagosome ). In pinosomes (another type of endocytosis) a small amount of the surrounding fluid and solute molecules are pinched off as pinosomes ( pinocytic vesicle).

18. 8/20/2020 Structure and function of Lysosome 18 TYPES OF LYSOSOMES A) There are two types of lysosomes : Secretory lysosomes and Conventional Lysosomes Secretory lysosomes are found in different cells as the Immune system such as T lymphocytes, derived from the hemopoietic cell line .Secretory lysosomes are a combination of conventional lysosomes and secretory granules. They differ from conventional lysosomes in that they contain the particular secretory product of the cell in which they reside . Conventional lysosomes are involved in the dismantling and re-cycling of various substrates presented to them through endocytocis , phagocytosis and by autophagosomes . They are responsible for returning many amino acids to the system.

19. 8/20/2020 Structure and function of Lysosome 19 B) There are two other types of lysosomes : Primary lysosomes (storage grannules ) - are formed from Golgi apparatus appearing as small vesicles. These lysosomes and are surrounded by a single phospholipid layer and contain acid hydrolases. Secondary lysosomes (Digestive vacuoles) - are formed when primary lysosomes fuse with phagosomes / endosome . Endosomes are formed by invagination of plasma membrane carrying some extracellular particles . Compared to primary lysosomes, secondary are larger in size and capable of releasing their content (enzymes) outside the cells where they degrade foreign material.

20. 8/20/2020 Structure and function of Lysosome 20 Lysosomal storage diseases are genetic disorders in which a genetic mutation affects the activity of one or more of the acid hydrolases. In such diseases, the normal metabolism of specific macromolecules is blocked and the macromolecules accumulate inside the lysosomes, causing severe physiological damage or deformity. DISORDERS /DISEASES IN HUMAN RELATED WITH LYSOSOME LSDs are inherited disorders resulting from a lack of specific enzymes that break down certain lipids (fats) or carbohydrates (sugars) in the body cells. The scientific community has identified more than 40 types of lysosomal storage diseases, which show various types of symptoms if some hydrolases for destroying macromolecules are not synthesized in the cell .

21. 8/20/2020 Structure and function of Lysosome 21 Following are some examples of Types of Lysosomal Storage Diseases/ Disorders Gaucher disease Niemann -Pick disease Tay -Sachs disease Fabry disease Mucopolysaccharidoses (MPS) diseases Pompe disease Hurler's disease Inclusion –cell disease (I-cell disease)

22. 8/20/2020 Structure and function of Lysosome 22 Gaucher disease is an autosomal recessive inherited disorder of metabolism where a type of fat (lipid) called glucocerebroside ,accumulates in the cell as it cannot be degraded due to enzyme glucocerebrosidase is not formed by the cell . A person will get Gaucher Disease if both parents are carriers of the disease. Major signs and symptoms of Gaucher’s disease include enlargement of liver and spleen , a low number of red blood cells ( anaemia ), decrease in blood platelets ,lung disease, and bone abnormalities such as bone pain, fractures, and arthritis. Disease can be managed upto some extent by enzyme replacement therapy although it is expensive and enzymes are to be administered by intravenous infusion

23. 8/20/2020 Structure and function of Lysosome 23 Niemann -Pick is a rare, inherited disease that affects the body's ability to metabolize fat (cholesterol and lipids) within cells. Niemann -Pick disease also called sphingolipidose in which harmful quantities of fatty substances or lipids, accumulate in the spleen, liver, lungs, bone marrow, and brain. The Niemann -Pick gene mutations are passed from parents to children as autosomal recessive inheritance. This means that both mother and father must have defective form of the gene and pass it to child to become affected.

24. 8/20/2020 Structure and function of Lysosome 24 Tay -Sachs disease is a rare disorder passed from parents to child. The gene that is mutated in individuals with Tay –Sachs disease, is HEXA,which codes for enzyme (N- acetylhexosaminidase A(Hex-A) which cleaves a terminal N- acetylgalactosamine group from a brain ganglioside GM2 , changes to brain ganglioside GM3 (Figure 4.5 from I Genetics by P J Russel ) but when gene is defected, enzyme is not formed and Ganglioside GM2 accumulates and causes Tay Sach Disease . S o level of unprocessed gangliosides increases in child’s brain causing neurons to swell and produce different clinical symptoms. A cherry- coloured spot on the retina, surrounded by a white circle helps early diagnosis of the disease.

25. 8/20/2020 Structure and function of Lysosome 25 Courtsey : iGenetics by P J Russel

26. 8/20/2020 Structure and function of Lysosome 26 Fabry disease is caused by mutations in the GLA gene. This gene provides instructions for making an enzyme called alpha- galactosidase A which normally breaks down a fatty substance called globotriaosylceramide . Mutated GLA gene alters the function of enzyme preventing breakdown of globotriaosylceramide , so accumulates in cells lining blood vessels skin,kidneys,heart and nervous system. Fabry disease may cause pain, especially in the hands and feet, clusters of small, dark red spots on the skin called angiokeratomas , a decreased ability to sweat ( hypohidrosis ), cloudiness of the front part of the eye (corneal opacity), and hearing loss .

27. 8/20/2020 Structure and function of Lysosome 27 Mucopolysaccharidoses (MPS) diseases is caused by absence or malfunctioning of lysosomal enzyme needed to break down glucosaminoglycans (GAGs) or muopolysaccharides . These long chain sugars occur within cells of bone, cartilage ,tendons , cornea, skin and connective tissue and in fluids that lubricate joints. Because of absence of enzyme , GAGs collect in the cells, blood and connective tissues which affect organ and system functioning Pompe disease is caused when enzyme that can break down glycogen is not synthesized . Too much of glycogen accumulated damages muscles and organs . This disease causes muscle weakness and trouble breathing and mostly affects liver and heart . Pompe disease results from a mutation in the GAA gene that allows the complex sugar glycogen to accumulate in and damage muscles .

28. 8/20/2020 Structure and function of Lysosome 28 Hurler’s disease also known as mucopolysaccharidopsis Type IH (formerly known as gargoylism ) is a genetic disorder that results in build up of large sugar molecules called glycosaminoglycans in lysosome . The inability to break down these molecules result in variety of symptoms, caused by damage of organ systems such as nervous system , skeletal system, eyes and heart . Hurler syndrome was first described by German pediatrician, Gertrud Hurler in 1919. It is one of the 11 disorders of the mucopolysaccharidoses (MPS ).

29. 8/20/2020 Structure and function of Lysosome 29 . . Inclusion –cell disease (I-cell disease )is caused by a mutation in the GNPTA gene that leads to a deficiency in the enzyme UDP-N-acetylglucoseamine-1-phosphotransferase . I-cell disease is inherited as an autosomal recessive genetic trait. In this disease almost all of the hydrolytic enzymes are missing from the lysosome of fibroblasts and their undigested substrates accumulate in lysosomes . I-cell disease ( mucolipidosis II) is a rare inherited metabolic disorder characterized by coarse facial features, skeletal abnormalities and mental retardation. The symptoms of I-cell disease are similar to but more severe than those of Hurler syndrome.

30. 8/20/2020 Structure and function of Lysosome 30 Summary Lysosomes process unwanted material into other substances that can be utilized by the cell . Lysosomes behave as cell’s recycling centre . Lysosomes perform intracellular digestion of macromolecules of the cell. Lysosomes contain unique membrane proteins and variety of hydrolytic enzymes . The acidic pH ( about 5 ) of lysosome is maintained by an ATP driven H+ pump in the lysosomal membrane. Lysosomal proteins are synthesized on ribosome attached to ER ,transported through Golgi apparatus and then carried from the trans Golgi network to late endosomes by means of clathrin -coated transport vesicles. The proteins destined for lysosomes are tagged by mannose -6-phosphate for packaging into specific departing vesicles for lysosomal hydrolases.

31. 8/20/2020 Structure and function of Lysosome 31 Enzymes in the Golgi recognize and tag lysosome-bound proteins by phosphorylating the mannose residues. The lysosomal hydrolases contain N-linked oligosaccharides that are covalently modified in a unique way in the cis Golgi network so that their mannose residues are phosphorylated. The mannose-6-phosphate groups are recognized by the mannose-6-phosphate receptors (MPR) at the TGN The mannose -6-phosphate receptors shuttle back and forth between the trans Golgi network and these endosomes. The low pH in the late endosome dissociates the lysosomal hydrolases from these receptors, making the transport of the hydrolases unidirectional

32. 8/20/2020 Structure and function of Lysosome 32 MCQs (Multiple Choice Questions ) on LYSOSOMES 1 . Which of the following organelle control intracellular digestion of macromolecules with the help of hydrolytic enzymes? a) Plastid b) Peroxisome c) Lysosome d) Actin 2. Which of these are not the hydrolytic enzymes of lysosome? a) Lipases b) Sulfatases c) Phosphatases d) Aldolase 3.Digestion of cell’s own component is known as__________ a) Autophagy b) Heterophagy c) Phagocytosis d) Pinocytosis 4. What is amphisome ? a) Early endosome b) Fusion of endosome and autophagosome c) Vacuole d) The bigger size of lysosome 5 . Name the single membrane which surrounded the vacuoles? a) Contractile vacuole b) Meninges c) Tonoplast d) Sarcolemma

33. 8/20/2020 Structure and function of Lysosome 33 6. Which of the following pumps excess water out of the cell? a) Contractile vacuole b) Lysosome c) Peroxisome d) Vacuoles 7. Which of the following organelle works as a lysosome in the plants? a) Contractile vacuole b) Peroxisome c) Plastid d) Vacuole 8. Lysosomes were discovered by a) Haekal b) De Duve c) De Vries d) Puekinje 9. Which of the following statements is incorrect with reference to lysosome a) They are filled with acid hydrolase and other enzymes b ) they are monomorphic and uniform in structure and function c) They may be autophagic They can digest proteins,nucleic acids ,lipids and polysaccharides 10. Lysosomes are present in all except a. muscle cells b. acinar cells c. erythrocytes d. hepatocytes 11. Which of the following is the function of lysosomes a. autophagy b. autolysis c. digestion d. all of the above 12. Lysosomes are involved in a. Extracellular digestion b. Intracellular digestion c. both (a) and (b ) d. none of the above

34. 8/20/2020 Structure and function of Lysosome 34 13.Who identified lysosome a . Novikoff b. Claude c. Palade d. none of the above 14. The main function of lysosome is a) Digestion b) Replication c) Translation d) Translocation 15. Scavenging of worn out cell parts and denatured proteins in the cells is done by a) Vacuoles b) Golgi bodies c) Lysosome d) Endoplasmic reticulum 16. What would happen if lysosome get ruptured inside the cells in which they are present a) Cells will swell b) cells will shrink c) Cells will die d) Nothing would happen 17. Three of the following statements regarding cell organelles are correct while one is wrong. Which one is wrong a) Lysosomes are double membrane vesicles budded off from golgi apparatus and contain digestive enzymes b) Endoplasmic reticulum consists of a network of membranous tubules and helps in transport,synthesia and secretion c) Leucoplast are bound by two membranes lack pigment but contain their own DNa and protein synthesizing machinery d) Sphaerosomes are single membrane bound and are associated with synthesis and storage of lipids 18. Microbodies differ from lysosomes in that a) Microbodies are surrounded by a single unit membrane while lysosome membrane is double b) Microbodies are surrounded by double membrane while lysosome membrane is single unit c) Microbodies contain lytic enzymes while lysosome do not d) Lysosome contain lytic enzymes while microbodies do not 19. The organelle whose major function is storage of hydrolytic enzymes are a) Centriole b) Chromoplasts c) Lysosome d) Chloroplast 20. The cellular role for lysosome is not a) Ingestion of foreign bodies b ) Digestion of aged organelles c) Cell destruction during developmeny d ) Osmoregulation

35. 8/20/2020 Structure and function of Lysosome 35 21. Which is concerned with autolysis a) Ribosome b)Golgi bodies c) Lysosome d) Oxysome 22. Lysosome along with the food content is called a) Primary lysosome b) Secondary lysosome c) Residual bodies d) Cytosome 23. The cell organelle showing extensive polymorphism is a) Dictyosoe b) Chloroplasts c) Lysosome d) Ribosome 24. The Lysosomes are known as suicidal bags because of a) Catalytic enzymes b) Hydrolytic enzymes c) Parasitic on nucleus d) Proteolytic enzymes 25. Secondary lysosomes are also called a) Autophagic vacuoles b) Lipofusion granules c) Residual body d) Heterophagosomes 26. The ‘marker’ enzymes of lysosome is a) Lysozyme b) Acid protease c) Acid phosphatase d) Beta galactosidase 27. Lysosomes are generally found in a) Animal cell b) Plant cell c) Both a) and b) d) Bacterial cells 28.A lysosome in which intracellular organelle is digested is called a) Primary lysosome b) Secondary lysosome c) Autophagosome d) None of the above 29. Which of the following cell organelle is having single layered unit membrane a) centrosome b) Lysosome c) Mesosome d)Nucleus 30. Which of the following organelle is called as the “ perinulear dense bodies”? Lysosome b) Nucleolous c) peroxisome d) all of these 31. Which is the enzyme used as a marker for the lysosome a) Pyruvate dehydrogenase b) Phospholipase c) Acid phosphatase d) Succinate dehydrogenase 32. The pH of lysosome is neutral b) acidic c) basic d) depends on the cell cycle 33 . The staining technique used to locate lysosome is a) Janus Green staining b) Bismarck stain c) Gamori stain d) Osmium tetroxide

36. 8/20/2020 Structure and function of Lysosome 36 34. The acidic pH of lysosome is due to deposition of waste materials b) presence of hydrolytic enzymes which has an acidic optimum pH c) presence of anabolic enzymes which has an acidic optimum pH d) All of these 35. Which of the following organelle is called as the “ suicidal bags of the cell ? Lysosome b) Lysosome and Golgi c) Lysosome and ER d) Lysosome and mitochondria 36. Which of the following is the function of lysosome a) autophagy b) autolysis c ) digestion d) all of these 37. During protein targeting, lysosomal proteins are tagged with a) sialic acid b) KDEL sequence c) mannose-6-phosphate d) glycolipids 38. Which of the following is not a disease associated with lysosome malfunctioning a) Tay -Sachs disease b) I-cell disease c) Pompe’s disease d) Marfan syndrome 39. Lysosomes involved in extracellular digestion are present in a) cardiac cells b) sperm c) zygote d) All of these 40. The acidic pH in the lysosome is maintained by GTP dependent proton pump in the lumen b) ATP dependent proton pump on the membrane c) HCl in lysosome d) all of these 41. Lysosomal membrane is rich in cardiolipin b) sialic acid c) sterols d) all of these 42. The main function of lysosomes is ____________ a) excretion b) synthesis c) mobility d) digestion 43. Where is the proton pump located in a lysosome? a) cytosol b) membrane c) attached with enzymes d) extracellularly connected 44. In autophagy, the organelle’s to be ingested are covered by a ______________ a) protein coat b) oligosaccharides c) double membrane d) single membrane 45. After the digestive process in an autophagolysosome is over, it is termed as _______________ a) autophagosome b) residual body c) endosome d) peroxisome 46. Gaucher disease is caused due to deficiency of ______________ a) hexosaminidase A b) lysosomes c) glucocerebrosidase d) mannose phosphate

37. 8/20/2020 Structure and function of Lysosome 37 47. Which of the following organelle is called ‘Suicidal Bag’ a. Mitochondria b. Endoplasmic reticulum c. Lysosome d. Ribosome 48. In the ‘I-cell disease’, lysosomes are ___________ a) absent b) bloated c) short-lived d) immobile 49. Lysosomal storage disorders are caused due to ______________ a) absence of lysosomes b) absence of a single lysosome c) absence of integral membrane proteins d) accumulation of lipofuschin granules Answers : Note : Options in red colour are correct choice for MCQs

38. 8/20/2020 Structure and function of Lysosome 38 Answer the following Questions What is lysosomes and its function? Why is the lysosome important? Where is the lysosome located? What are lysosomes made of? How big is a lysosome? Why lysosomes is known as suicidal bag? How are lysosomes created? Do lysosomes have DNA? Who discovered the lysosome? Are lysosomes phagocytes? Do lysosomes kill viruses? What do lysosomes break down ?

39. 8/20/2020 Structure and function of Lysosome 39 How do lysosomes break down proteins? Is lysosome present in human body ? Which enzymes are present in lysosome? What is stored in lysosomes? Do lysosomes contain nucleic acids? Can lysosomes destroy an entire cell? How do lysosomes maintain their pH? What diseases are caused by lysosomes? Do eukaryotic cells have lysosomes? What do lysosomes do in apoptosis? Where do lysosomes receive material from? How many enzymes are present in lysosomes? How do lysosomes protect the body?

40. 8/20/2020 Structure and function of Lysosome 40 Write short notes on the following a ) Types of lysosomes b) Primary lysosome c) Secondary lysosome d) Chemical composition of lysosomes e) Enzymes present in lysosome f)) Lysosomes as suicide bags g) Functions of lysosome h) Shape of lysosome i) size of lysosome j) Intracellular digestion by lysosome k) Acid hydrolase enzyme of lysosome l) Similarity of lysosome and vacuole in plant cells m) Autophagosome n ) Autophagy o) I-cell disease p ) Phagocytosis q) Phagolysosome

41. BOOKS CONSULTED Cell and molecular biology Concepts and Experiments Gerald Karp 5th Edition 2007 John Willey and Sons, Inc Cell and Molecular biology By P K Gupta: Rastogi Publications Biocyclopaedia Is online for students and researchers in Biology Biocyclopedia.com Cell Biology by Dr S P Singh and Dr B S Tomar Rastogi Publication,Meerut,U P ,India Cell Biology 1997 Dr SC Roy and Dr K K De New Central Book Agency (P ) Ltd. Kolkatta , India Molecular Cell Biology. 4th edition.2000 H Lodish , A Berk and S L Zipursky W. H. Freeman; New York . Section 5.4 Organelles of the Eukaryotic Cell Lysosomes Are Acidic Organelles That Contain a Battery of Degradative Enzymes Lysosome : British Society for Cell Biology Molecular Biology of the Cell. 4th edition. Alberts B, Johnson A, Lewis J, et al.New York: Garland Science; 2002. The Cell: A Molecular Approach. 2nd edition. Cooper GM.Sunderland (MA): Sinauer Associates; 2000.Lysosome (Figure : 9.35,9.36 and 9.37) 8/20/2020 Structure and function of GA 41 iGenetics A molecular Approach Third Edition Peter J Russell Benjamin Cummmings,New York

42. 8/20/2020 Structure and function of Lysosome 42 REFERENCES Bainton , D.F. (1981) The discovery of lysosomes. J. Cell Biol. 91 : 66s–76s HSU VW, Lee S Y and Yang J S( 2009) Pathways of vesicular transport by the specific vesicle-coating proteins .Nature Reviews, Molecular Cell Biology 10: 360-364 Trivedi et al 2020 Lysosomal Biology and Function: Modern View of Cellular Debris Bin. Cells 1-35 Review Article De Duve C ( 2005). "The lysosome turns fifty". Nature Cell Biology. 7 (9): 847–849. Novikoff A B, Beaufay H and De Duve C (1956) . Electron microscopy of lysosome rich fractions from rat liver . The Journal of Biophysical and Biochemical Cytology. 2:179-184 Novikoff A B 1976 In Lysosome and Storage Diseases H G Hers and F Van Hoof Editors .Academic Press, New York. 1-41 Rogers K (2019) Lysosome Biology from Encyclopaedia Britannica Hurler, G. (1919). "Über einen Typ multipler Abartungen, vorwiegend am Skelettsystem". Zeitschrift für Kinderheilkunde. 24 (5–6): 220–234.

43. 8/20/2020 Structure and function of Lysosome 43 THE END THANKS Courtsey : The Cell: A Molecular Approach. 2nd edition Cooper GM . Sunderland (MA): Sinauer Associates; 2000. From :The discovery of lysosomes by D F Bainton (1981)