endomembrane system

Question 1

which organelles are present in the endomembrane system and why?

Answer 1

ER, Golgi apparatus , lysosome and vacuole. the function in a co ordinated manner

Question 2

what are the three main structures found in ER?

Answer 2

1) cisternae
2) vesicles
3) tubules

Question 3

what are tubules?

Answer 3

they are branched or unbranched structure that forms a reticular system with cisternae and vesicles. they are free of ribosome and are common in lipid and sterol synthesizing cells

Question 4

what are cisternae?

Answer 4

they are long, flat ,parallel and sac like inter connected structure. they 60s ribosomes an is involved in protein synthesis. they are usually in cells that have synthetic role like cells of pancreas and brain.

Question 5

what are vesicles ?

Answer 5

they are oval membrane bound vacuolar structure . they are free from ribosomes. they are abundant in pancreas and they are the only ER structure found in spermatozoa

Question 6

what are luminal compartment?

Answer 6

its is the space enclosed by the ER

Question 7

what are extra luminal space?

Answer 7

area in the cytoplasm outside the ER

Question 8

what is ser?

Answer 8

its is a smooth membranous structure free of ribosome. muscle cells are rich in ser and are call sacroplasmic

Question 9

ser present in the muscle cell are called?

Answer 9

sarcoplasmic reticulum

Question 10

what are the functions of ser?

Answer 10

1) detoxification drug
2) synthesis of steroids and lipids
3) protein synthesised by rer passes through it
4) release and uptake Ca^+2 for contraction of muscle

Question 11

what is rer?

Answer 11

it is a granular membranous structure with ribosomes they are extensive and continuous from the outer nuclear membrane. they contain to protein (ribophorin 1 and ribophorin 2) for the attachment of 60s and 80s.

Question 12

which glycoproteins are required for the attachment of 60s and 80s ribosome?

Answer 12

ribophorin 1 ad ribophorin2

Question 13

what are the functions of rer?

Answer 13

1) they produce the precursor enzymes for the production of lysosomes and golgi complex
2) they are present in cell that are actively involved secretion and synthesis.
3) they give rise to ser

Question 14

who was golgi body named after ?

Answer 14

golgi body was named after Camilo Golgi its discoverer, he described it as densely stain reticular structure present near the nucleus.

Question 15

explain the structure of golgi cisternae?

Answer 15

they are smooth flat parallel sac like structure arranged in stacks. they form a extensive network near the nucleus in a concentric pattern . there are 4-8 cisternae in a stack.their structure resembles ser

Question 16

what is the size of cisternae?

Answer 16

they are 0.1 micro meter - 0.5 micrometer in diameter

Question 17

what are the two faces of golgi body?

Answer 17

1)cis face or the forming face
2)trans face or the mature face
these faces are interconnected but are different

Question 18

what are the four main structures present in golgi body

Answer 18

cisternae,tubules,vesicles and golgi vacuoles

Question 19

explain what tubules in golgi body are ?

Answer 19

these are small flat interconnected structure arising from the periphery of golgi body due to fenestration

Question 20

what are vesicles of golgi body?

Answer 20

they are large rounded sacs present at the end of cisternae

Question 21

what are the two types of vesicles(golgi body)

Answer 21

• smooth vesicles: they are smooth surfaced secretory vesicles they contain secretory granules
• coated vesicles: they are rough surfaced, they are spherical protutuberence arising from tubules of golgi body

Question 22

what are golgi vacuoles?

Answer 22

they are vacuoles present produced t the maturing face.they are filled with granules or amorphous substance.they some time act as lysosomes.

Question 23

what are functions of golgi body?

Answer 23

1)processing , packaging and transporting materials for secretion. they are delivered to intercellular or extracellular targets.
2) cisternea modifies the protein produces by ER
3) it is an important site for the production of glysoprotein(glycolisis of protein)
and glycolipids(glycosidation of protein)
4)the acrosome of sperm cells are modified golgi body
5)they help in formation of plasma membrane during cytokinesis

Question 24

what is the process of formation of glycolipid called?

Answer 24

glycosidation of protein

Question 25

what is the process of formation of glycoproteins called?

Answer 25

glycolistaion of protein

Question 26

explain the structure of lysosomes?

Answer 26

they are sac like structure evenly distrubuted in the cytoplasm. they contain hydrolytic enzymes . hey are formed in the process of packaging in the golgi body.

Question 27

what are the hydrolytic enzymes present in lysosomes?

Answer 27

hydrolases- proteases, carbohydrases and lipases

Question 28

what ph is lysosomes and how do they maintain t?

Answer 28

lysosomes are acidic in ph and they can digest lipids, nucleic acid , carbohydrate , protein . they maintain their ph by pumping H+ ions into them.

Question 29

what are primary lysosomes?

Answer 29

they are newly formed lysosomes formes at the trance face of golgi body . their enzymes are inacti.ve .

Question 30

what are secondary lysosomes?

Answer 30

they are heterophagosomes or digestive vacuoles. they are formed when primary lysosomes fuse phagosomes. they contain enzymes required to digest materials.

Question 31

what are residual lysosomes?

Answer 31

they are secondary lysosmes containing undigested materials. residual bodies pass outwardly. they come in contact with plasma lamella and throws undigested material outside the cell through ephagy or exocytosis.

Question 32

what are autophagic vacuoles?

Answer 32

they are primary lysosomes fused with old or dead organelles , which surround it with vacuolar membrane and digests it by autolysis or autodigestion. this how larval organs disappears during metamorphosis. like tail in frog.

Question 33

which lysosome is known as suicidal bag?

Answer 33

autophagic lysosome

Question 34

which organelle shows polymorphism ?

Answer 34

lysosome show polymorphism

Question 35

what are vacuoles?

Answer 35

they are membrane bound space that contain cell sap , excretory material and other material that is not useful to the cell. they are sap vacuoles

Question 36

describe vacuoles present in plant cells?

Answer 36

vacuoles present in plant cell are centrally located and can occupy up to 90% of the cell's volume. they have a membrane called tonoplast which facilitates the movement of ions against the concentration gradient into the vacuole. thus their concentration is significantly higher in the vacuoles.

Question 37

what are contractile vacuoles?

Answer 37

they are present in amoeba and help it in excretion.

Question 38

what are food vacuoles?

Answer 38

in protist they are formed by engulfing food particle

Question 39

what are are gas vacuoles ?

Answer 39

they are membraneless vacuoles present in prokaryotes, they provide buoyancy and help it in floating in water. they are pseudo vacuoles.

Question 40

Why are gas vacuoles called Pseudovacuoles?

Answer 40

since they do not have a true membrane