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Cell structure & function | IGNOU Biochemitry • CHE9 (English/Hinglish)

Some important questions & answers.

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1. SOME IMPORTANT QUESTION - ANSWER FOR IGNOU BIOCHEMISTRY [CHE 9]
CELL STRUCTURE AND FUNCTION
Q. 1. What is cell theory? Who proposed it? [Cell theory या है और इसे कसने ता वत कया
था?]
Ans. The cell theory states that all living things are made of cells (unicellular or multicellular) and
cells are the basic structural and functional units of life and all cells come from pre-existing cells.
This concept was proposed by Schleiden and Schwann.
[Cell theory क
े अनुसार सभी जीव को शकाओं से बने ह और ये को शकाएं जीव क संरचना मक और या मक
इकाई ह I इन को शकाओं क उ प पूव पि थत को शकाओं से होती है। यह संक पना लाइडन और वान
(Schleiden and Schwann) वारा ता वत क गई थी I]
Q.2. (i) What are similarities and dissimilarities between prokaryotic and eukaryotic cells?
Give any three similarities and dissimilarities.(ii) Give three differences between plant cell
and animal cell. (iii) What is peptidoglycan?[(i) Prokaryotic और eukaryotic cells क
े बीच या
समानताय और अंतर ह, कोई तीन समानताय और अंतर बताय I (ii) Plant cell और animal cell क
े बीच तीन
अंतर बताय I (iii) Peptidoglycan या है?
Ans. (i)
Similarities between prokaryotic and eukaryotic cells:
1.Both prokaryotic and eukaryotic cells store information in genes.
[Prokaryotic और eukaryotic cells दोन म genetic information genes म store रहती है I]
2. Ribosomes are the centre of protein synthesis in both prokaryotic and eukaryotic cell
[दोन कार क cells म protein synthesis का क ribosomes होते ह I]
3. In both prokaryotes and eukaryotes proteins control the structure and functions in all cells.
[दोन कार क cells म proteins ह cell structure और functions को नयं त करती ह I]
Dissimilarities between prokaryotic and eukaryotic cells:
1. Prokaryotic cells have simple internal organisation whereas eukaryotic cells have complex
internal organisation.
[Prokaryotic cells का अ तःसंघठन (internal organization) simple होता है जब क eukaryotic cells का
अ तःसंघठन ज टल होता है I]
2. DNA is naked (no nuclear membrane) in prokaryotes while in eukaryotes DNA is covered by
nuclear membrane.
[Eukaryotic cell का DNA nuclear membrane से cover रहता है क तु Prokaryotic cell म DNA को घेरने
हेतु कोई nuclear nuclear membrane नह ं होती I]
3. Prokaryotic cells have no membrane bound organelles whereas eukaryotic cells have distinct
membrane bound organelles.
[Eukaryotic cells क
े अंदर membrane bound organelles होते ह जब क prokaryotic cells क
े अंदर ऐसे
कोई membrane bound organelles नह ं होते ह I]
(ii) Differences between plant cell and animal cell:
A. Plant cells have cell membrane surrounded by cell wall but animal cells have only cell
membrane.
[plant cell क cell membrane एक cell wall वारा घर रहती है जब क animal cell म क
े वल cell
membrane होती है, cell wall नह ं]
B. Plant cells have chloroplasts which are absent in animal cells.
2
[plant cell म chloroplast होता है जब क animal cell म chloroplast नह ं होता ]
C. Animal cells and plant cells both have peroxisomes whereas in plants only
glyoxysomes are present.
[animal cells और plant cells दोन म peroxisomes होते ह जब क plant cells म peroxisomes क
े
अनु प क
े वल glyoxysomes होते ह]
(iii) Peptidoglycan (murein) - The bacterial cell wall found on the outside of almost all bacteria's
cytoplasmic membrane is composed of peptidoglycan. Its primary role is to maintain cell
integrity by resisting turgor. Peptidoglycan is made up of linear polysaccharide strands that are
connected together by short peptides. The polysaccharide strands consist of alternating
N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc) residues linked by β1→4
glycosidic bonds. These polysaccharide strands are crosslinked in the cell wall by short
peptides.
[Peptidoglycan (murein) - Bacterial cell wall peptidoglycan क बनी होती है िजसका मुख काय cell
integrity को बनाए रखना होता है I Peptidoglycan linear polysaccharide strands का बना होता है जो
आपस म short peptides वारा जुड़े होते ह I ये polysaccharide strands N-acetylglucosamine
(GlcNAc) और N-acetylmuramic acid (MurNAc) क
े alternating residues (जो एक दूसरे से β1→4
glycosidic bonds वारा जुड़े होते ह) क
े बने होते ह और ये polysaccharide strands short peptides वारा
आपस म cross linked होते ह I]
Q.3. Mention five functions of cell membrane in eukaryotic cells. [एक eukaryotic cell क
cell membrane क
े 5 काय बताय ]
Ans.
1. Cell membrane protects the cell from its environment and is responsible for cell integrity.
[cell membrane cell को उसक
े वातावरण से सुर त रखती है और cell क अखंडता को बनाए रखने क
े लए
िज़ मेदार होती हैI]
2. It acts as a selective barrier between cells and their environment regulating the entry and exit
of molecules in the cells.
[यह अणुओं क
े cell क
े अंदर जाने और बाहर नकलने क या को नयं त करती है और इस कार cell और
उसक
े वातावरण क
े बीच एक चयना मक अवरोध का काय करती है I]
3. It acts as energy transducer such as the membranes of mitochondria and chloroplasts.
[mitochondria और chloroplasts क membranes ऊजा ांस यूसर का काय करती ह ]
4. The cell surface receptors recognise specific molecules such as hormones and other second
messengers and thus help in cell-cell recognition and communication.
[cell membrane surface receptors hormones और अ य messengers जैसे वशेष molecules को
पहचान कर cell-cell recognition और communication म मदद करते ह ]
3
Q.4(A). Give two main functions each of the nucleus, endoplasmic reticulum, Golgi
bodies, lysosomes and mitochondria.[nucleus, endoplasmic reticulum, Golgi bodies,
lysosomes और mitochondria क
े दो -दो मु य काय लख]
Ans.
Nucleus:
1. It is the " control center " of the cell. It contains DNA containing all the genetic information.
[यह cell का " नयं ण क " होता है I इसम DNA होता है िजसम सार genetic information होती है I]
2. It controls cellular metabolism, DNA synthesis and repair.
[यह cellular metabolism, DNA synthesis और repair को नयं त करता है I]
Endoplasmic reticulum:
1. It is responsible for the synthesis of different proteins and lipids.
[यह व भ न कार क proteins और lipids क
े सं लेषण क
े लए िज़ मेदार होता है I]
2. Peroxisomes are formed from smooth endoplasmic reticulum by the process of budding.
[peroxisomes smooth endoplasmic reticulum से budding process वारा बनते ह I]
Golgi bodies:
1. Modification and sorting of proteins for incorporation into organelles and for export.
[इनक
े वारा proteins क छँटाई और संशोधन कया जाता है ता क उनका व भ न organelles म नगमन या
समावेश कया जा सक
े या उनका नयात कया जा सक
े I]
2. Secretion of hormones into the blood is accomplished by Golgi bodies.
[hormones का blood म secretion Golgi bodies वारा ह संप न होता है I]
Mitochondria:
1. Energy conservation: The energy released by oxidation of nutrients is transformed into the
energy currency of the cell, ATP.
[ऊजा का संर ण : nutrients क
े oxidation से release हुई ऊजा mitochondria वारा ATP क
े प म प रव तत
हो जाती है, िजसे 'energy currency' भी कहते ह I]
2. Cellular respiration: Oxidation of fatty acids and carbohydrates oxidation products.
[cellular respiration: fatty acids और carbohydrates क
े oxidation products का oxidation भी
mitochondria वारा होता है I]
Lysosomes:
1. Cellular digestion: Hydrolysis of proteins, carbohydrates, fats and toxins.
[cellular digestion: proteins, carbohydrates, fats और toxins क hydrolysis lysosomes वारा होती है]
2. Scavenging of aged and damaged cells.
[वृ ध और मृत को शकाओं क सफाई करना I]
Q.4(B). Draw a labeled diagram of mitochondria. [Mitochondria का labeled diagram बनाए ]
Ans.
4
Q.5. Differentiate between glyoxysomes and peroxisomes.[Glyoxysomes और
peroxisomes म अंतर बताय]
Ans.
1.Glyoxysomes are single membrane microbodies found in plant cells whereas Peroxisomes,
also single membrane microbodies, are found in both plant and animal cells.
[Glyoxysomes plant cells म पाई जाने वाल single membrane microbodies ह जब क peroxisomes भी
single membrane microbodies ह क तु ये plant और animal cells दोन म पाई जाती ह I]
2. Glyoxysomes contain enzymes of glyoxylate cycle viz. Isocitrate lyase, malate synthetase
and glycolate oxidase etc. whereas Peroxisomes contain enzymes like peroxidase, oxidases
and catalase.
[glyoxysomes म glyoxylate cycle क
े enzymes जैसे - Isocitrate lyase, malate synthetase and
glycolate oxidase आ द होते ह, जब क peroxisomes म peroxidase, oxidases और catalase enzymes
होते ह I]
3. Glyoxysomes are involved in photorespiration and conversion of fats into carbohydrates
whereas Peroxisomes are involved in formation and degradation of hydrogen peroxide and
detoxification of poisons in the cells.
[Glyoxysomes photorespiration और fats क
े carbohydrates म प रवतन म शा मल होते ह, जब क
peroxisomes cells म hydrogen peroxide क
े formation और degradation एवं poisons क
े
detoxification म शा मल होते ह I]
Q.6. Differentiate between microtubules and microfilaments.[microtubules और
microfilaments म अंतर लख]
Ans.
1. Microtubules comprise of proteins alpha and beta tubulins whereas microfilaments comprise
of proteins actin and myosin.
[microtubules alpha और beta tubulins proteins से यु त होते ह, जब क microfilaments actin और
myosin proteins से यु त होते ह I]
2. Microtubules play important role in cell division whereas microfilaments play role in
intracellular movement of cell organelles.
[microtubules cell division म मह वपूण भू मका नभाते ह, जब क microfilaments cell क
े अंदर cell
organelles क
े movement म भू मका नभाते ह I]
3. Microtubules are the largest elements of the cytoskeleton whereas microfilaments are smaller
elements.
[microtubules cytoskeleton क
े सबसे बड़े त व ह, जब क microfilaments छोटे त व ह I]
4. Microtubules have shorter half life as compared to microfilaments.
[microtubules क अ ध -आयु microfilaments क अपे ा कम होती है I]
Q.7. Draw a labeled diagram of chloroplast. Write the functions of chloroplasts.
[Chloroplast का labeled च बनाएं I Chloroplast क
े काय लख ]
Ans.
Functions of chloroplasts -
1. Chloroplasts are the site of photosynthesis.
5
[photosynthesis chloroplasts म होती है I]
2. Chloroplasts are light harvesting organelles. They convert light energy into chemical energy.
[chloroplasts काश का संचयन करने वाले organelles ह जो light energy को chemical energy म
प रव तत करते ह I]
3. Their function is synthesis of ATP and generation of NADPH in light reaction.
[इनका काम photosynthesis क
े light reaction म ATP का सं लेषण और NADPH उ प न करना है I]
4. Their function is synthesis of carbohydrates in the dark reaction.
[chloroplasts dark reaction वारा carbohydrates क synthesis करते ह I]
5. Chloroplasts impart green colour and other colours to the plants.
[chloroplasts पौध को green और अ य colours दान करते ह I]
Q.8. What will happen if peroxisomes are absent in the cells?[य द cells म peroxisomes
नह ं ह तो या होगा?]
Ans. Since peroxisomes are important for the oxidation of various toxic chemicals such as
hydrogen peroxide, their absence would result in accumulation of these toxic chemicals that
could prove fatal to the cells.
[चूं क व भ न toxic chemicals जैसे - hydrogen peroxide, क
े oxidation क
े लए peroxisomes मह वपूण
होते ह, इस लए peroxisomes क अनुपि थ त म ये toxic chemicals cells म एक होने लगगे जो cells क
े
लए घातक हो सकते ह ]
Q.9. What are Lysosomes? Mention their functions. Name two enzymes present in
lysosomes. What will happen if some lysosomal enzymes are missing or
deficient.[lysosomes या होते ह? Lysosomes म उपि थत दो enzymes क
े नाम बताय I इन
lysosomal enzymes क अनुपि थ त म या होगा?]
Ans. Lysosomes are specialized membrane bound vesicles formed by budding from the Golgi
bodies. They contain some 40 enzymes.
Their function is hydrolysis of proteins, carbohydrates, lipids and toxins. They are also involved
in the scavenging of aged and damaged cells.
The two lysosomal enzymes are acid phosphatase and cathepsins.
The absence of some lysosomal enzymes may result in intracellular accumulation of some
macromolecules. For example: In genetic disorders like 'glycogen storage disorder' and 'Hurler's
disease' the lysosomal enzymes associated with the breakdown of glycogen and
mucopolysaccharides respectively, are missing or deficient. This results in accumulation of
these polysaccharides in the cells, leading to severe consequences. Some disorders associated
with lysosomal enzymes deficiencies may also lead to severe mental disorders.
[Lysosomes एक व श ट कार क
े membrane bound vesicles ह जो Golgi bodies से budding वारा
बनते ह I इनम लगभग 40 enzymes पाये जाते ह I इनका काय carbohydrates, proteins, lipids और toxins
क hydrolysis करना होता है I
दो lysosomal enzymes ह - acid phosphatase और cathepsins.
क
ु छ lysosomal enzymes क अनुपि थ त क
े कारण cells क
े अंदर क
ु छ macromolecules का एक ण हो
सकता है I उदाहरण - 'glycogen storage disorder' और 'Hurler's disease' जैसे genetic disorders म
मशः glycogen और mucopolysaccharides को break करने वाले lysosomal enzymes कम या
अनुपि थत होते ह I िजसक
े प रणाम व प cells क
े अंदर इन polysaccharides का एक ण हो जाता है और
इसक
े गंभीर प रणाम हो सकते ह I क
ु छ lysosomal enzymes क कमी से गंभीर मान सक वकार भी हो सकते
ह I]
6
Q.10. What are the various constituents of cell membranes? Describe the modes by
which cell membrane controls the transport of ingoing and outgoing molecules. [Cell
membranes क
े या - या अवयव होते ह? Cell membrane कन तर क से molecules क
े cell क
े अंदर
जाने और बाहर नकलने क या को नयं त करती है?]
Ans. The main components of most of the cell membrane are lipids and proteins which are
present in approximately equal amounts. However, their ratio varies from tissues to organelles.
Among the lipids, phospholipids are the most abundant lipids and these are phosphatidyl
choline , phosphatidyl ethanolamine, phosphatidyl serine and sphingomyelins. In addition, small
amounts of cholesterol and glycolipids are also present. Apart from lipids and proteins the
membranes contain about 2-5% carbohydrates.
The three modes of transport of ingoing and outgoing molecules across the cell membrane are :
1. Facilitated diffusion - In this mode of transport the diffusion of ions and molecules across the
membrane is driven by a concentration difference on the two sides of membrane (from higher to
lower concentration) with the help of specific carrier proteins present in the membrane.
Example: transport of sodium and potassium ions and glucose molecules.
2. Passive diffusion - The molecules like water, simply diffuse across the membrane depending
on the concentration gradient across the membrane(from higher to lower concentration ).
3. Active transport - Most biomolecules are transported into and out of the cell by this process
which is similar to facilitated diffusion except that it works against concentration gradient and
this process requires expenditure or input of energy.
[अ धकतर Cell membrane क
े मु य अवयव लगभग बराबर मा ा म lipids और proteins ह, हालां क इनका
अनुपात व भ न tissues और organelles म अलग - अलग हो सकता है I lipids म सबसे अ धक मा ा म
phospholipids जैसे - phosphatidylcholine , phosphatidylethanolamine, phosphatidylserine और
sphingomyelins होती ह I इसक
े अलावा कम मा ा म cholesterol और glycolipids भी होते ह I proteins और
lipids क
े अ त र त लगभग 2-5% carbohydrates भी होते ह I
व भ न molecules क
े membrane क
े आर - पार जाने हेतु तीन कार क transport याय ह :
1.Facilitated diffusion - इस transport या म ions और molecules का membrane क
े आर - पार
diffusion higher concentration से lower concentration क ओर membrane म ह उपि थत एक व श ट
carrier protein क मदद से होता है I
2. Passive diffusion - Water जैसे molecules membrane क
े आर -पार आसानी से concentration
gradient क
े आधार पर diffuse हो जाते ह (higher concentration से lower concentration क ओर) I
3. Active transport - अ धकतर biomolecules इसी या वारा ह cell क
े अंदर - बाहर transport होते ह I
यह facilitated diffusion क
े समान ह होता है क तु यह concentration gradient क
े वपर त काय करता है
और इसक
े लए energy क
े खच या आगत क आव यकता होती है I]
Q. 11(A). Describe the method for separation of subcellular organelles. [Subcellular
organelles क
े पृथ करण क व ध लख]
Ans. This can be done by the technique of ' Differential Centrifugation' which is based on the
principle that when the mixture containing different organelles (homogenate) is centrifuged at
different speeds (different centrifugal force; g), the cell organelles get separated on the basis of
their size and weight.
In this technique, first the tissue (from which the subcellular organelles are to be separated) is
homogenized in a medium (e.g. isotonic sucrose, 0.25 M) at 277 K (4 °C) using a homogenizer.
The resulting homogenate is centrifuged at 600×g for 10 minutes. This results in sedimentation
of nuclei (being the heaviest) in the form of a pellet. The supernatant containing other organelles

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Cell structure & function | IGNOU Biochemitry • CHE9 (English/Hinglish)

  • 1. 1 1. SOME IMPORTANT QUESTION - ANSWER FOR IGNOU BIOCHEMISTRY [CHE 9] CELL STRUCTURE AND FUNCTION Q. 1. What is cell theory? Who proposed it? [Cell theory या है और इसे कसने ता वत कया था?] Ans. The cell theory states that all living things are made of cells (unicellular or multicellular) and cells are the basic structural and functional units of life and all cells come from pre-existing cells. This concept was proposed by Schleiden and Schwann. [Cell theory क े अनुसार सभी जीव को शकाओं से बने ह और ये को शकाएं जीव क संरचना मक और या मक इकाई ह I इन को शकाओं क उ प पूव पि थत को शकाओं से होती है। यह संक पना लाइडन और वान (Schleiden and Schwann) वारा ता वत क गई थी I] Q.2. (i) What are similarities and dissimilarities between prokaryotic and eukaryotic cells? Give any three similarities and dissimilarities.(ii) Give three differences between plant cell and animal cell. (iii) What is peptidoglycan?[(i) Prokaryotic और eukaryotic cells क े बीच या समानताय और अंतर ह, कोई तीन समानताय और अंतर बताय I (ii) Plant cell और animal cell क े बीच तीन अंतर बताय I (iii) Peptidoglycan या है? Ans. (i) Similarities between prokaryotic and eukaryotic cells: 1.Both prokaryotic and eukaryotic cells store information in genes. [Prokaryotic और eukaryotic cells दोन म genetic information genes म store रहती है I] 2. Ribosomes are the centre of protein synthesis in both prokaryotic and eukaryotic cell [दोन कार क cells म protein synthesis का क ribosomes होते ह I] 3. In both prokaryotes and eukaryotes proteins control the structure and functions in all cells. [दोन कार क cells म proteins ह cell structure और functions को नयं त करती ह I] Dissimilarities between prokaryotic and eukaryotic cells: 1. Prokaryotic cells have simple internal organisation whereas eukaryotic cells have complex internal organisation. [Prokaryotic cells का अ तःसंघठन (internal organization) simple होता है जब क eukaryotic cells का अ तःसंघठन ज टल होता है I] 2. DNA is naked (no nuclear membrane) in prokaryotes while in eukaryotes DNA is covered by nuclear membrane. [Eukaryotic cell का DNA nuclear membrane से cover रहता है क तु Prokaryotic cell म DNA को घेरने हेतु कोई nuclear nuclear membrane नह ं होती I] 3. Prokaryotic cells have no membrane bound organelles whereas eukaryotic cells have distinct membrane bound organelles. [Eukaryotic cells क े अंदर membrane bound organelles होते ह जब क prokaryotic cells क े अंदर ऐसे कोई membrane bound organelles नह ं होते ह I] (ii) Differences between plant cell and animal cell: A. Plant cells have cell membrane surrounded by cell wall but animal cells have only cell membrane. [plant cell क cell membrane एक cell wall वारा घर रहती है जब क animal cell म क े वल cell membrane होती है, cell wall नह ं] B. Plant cells have chloroplasts which are absent in animal cells.
  • 2. 2 [plant cell म chloroplast होता है जब क animal cell म chloroplast नह ं होता ] C. Animal cells and plant cells both have peroxisomes whereas in plants only glyoxysomes are present. [animal cells और plant cells दोन म peroxisomes होते ह जब क plant cells म peroxisomes क े अनु प क े वल glyoxysomes होते ह] (iii) Peptidoglycan (murein) - The bacterial cell wall found on the outside of almost all bacteria's cytoplasmic membrane is composed of peptidoglycan. Its primary role is to maintain cell integrity by resisting turgor. Peptidoglycan is made up of linear polysaccharide strands that are connected together by short peptides. The polysaccharide strands consist of alternating N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc) residues linked by β1→4 glycosidic bonds. These polysaccharide strands are crosslinked in the cell wall by short peptides. [Peptidoglycan (murein) - Bacterial cell wall peptidoglycan क बनी होती है िजसका मुख काय cell integrity को बनाए रखना होता है I Peptidoglycan linear polysaccharide strands का बना होता है जो आपस म short peptides वारा जुड़े होते ह I ये polysaccharide strands N-acetylglucosamine (GlcNAc) और N-acetylmuramic acid (MurNAc) क े alternating residues (जो एक दूसरे से β1→4 glycosidic bonds वारा जुड़े होते ह) क े बने होते ह और ये polysaccharide strands short peptides वारा आपस म cross linked होते ह I] Q.3. Mention five functions of cell membrane in eukaryotic cells. [एक eukaryotic cell क cell membrane क े 5 काय बताय ] Ans. 1. Cell membrane protects the cell from its environment and is responsible for cell integrity. [cell membrane cell को उसक े वातावरण से सुर त रखती है और cell क अखंडता को बनाए रखने क े लए िज़ मेदार होती हैI] 2. It acts as a selective barrier between cells and their environment regulating the entry and exit of molecules in the cells. [यह अणुओं क े cell क े अंदर जाने और बाहर नकलने क या को नयं त करती है और इस कार cell और उसक े वातावरण क े बीच एक चयना मक अवरोध का काय करती है I] 3. It acts as energy transducer such as the membranes of mitochondria and chloroplasts. [mitochondria और chloroplasts क membranes ऊजा ांस यूसर का काय करती ह ] 4. The cell surface receptors recognise specific molecules such as hormones and other second messengers and thus help in cell-cell recognition and communication. [cell membrane surface receptors hormones और अ य messengers जैसे वशेष molecules को पहचान कर cell-cell recognition और communication म मदद करते ह ]
  • 3. 3 Q.4(A). Give two main functions each of the nucleus, endoplasmic reticulum, Golgi bodies, lysosomes and mitochondria.[nucleus, endoplasmic reticulum, Golgi bodies, lysosomes और mitochondria क े दो -दो मु य काय लख] Ans. Nucleus: 1. It is the " control center " of the cell. It contains DNA containing all the genetic information. [यह cell का " नयं ण क " होता है I इसम DNA होता है िजसम सार genetic information होती है I] 2. It controls cellular metabolism, DNA synthesis and repair. [यह cellular metabolism, DNA synthesis और repair को नयं त करता है I] Endoplasmic reticulum: 1. It is responsible for the synthesis of different proteins and lipids. [यह व भ न कार क proteins और lipids क े सं लेषण क े लए िज़ मेदार होता है I] 2. Peroxisomes are formed from smooth endoplasmic reticulum by the process of budding. [peroxisomes smooth endoplasmic reticulum से budding process वारा बनते ह I] Golgi bodies: 1. Modification and sorting of proteins for incorporation into organelles and for export. [इनक े वारा proteins क छँटाई और संशोधन कया जाता है ता क उनका व भ न organelles म नगमन या समावेश कया जा सक े या उनका नयात कया जा सक े I] 2. Secretion of hormones into the blood is accomplished by Golgi bodies. [hormones का blood म secretion Golgi bodies वारा ह संप न होता है I] Mitochondria: 1. Energy conservation: The energy released by oxidation of nutrients is transformed into the energy currency of the cell, ATP. [ऊजा का संर ण : nutrients क े oxidation से release हुई ऊजा mitochondria वारा ATP क े प म प रव तत हो जाती है, िजसे 'energy currency' भी कहते ह I] 2. Cellular respiration: Oxidation of fatty acids and carbohydrates oxidation products. [cellular respiration: fatty acids और carbohydrates क े oxidation products का oxidation भी mitochondria वारा होता है I] Lysosomes: 1. Cellular digestion: Hydrolysis of proteins, carbohydrates, fats and toxins. [cellular digestion: proteins, carbohydrates, fats और toxins क hydrolysis lysosomes वारा होती है] 2. Scavenging of aged and damaged cells. [वृ ध और मृत को शकाओं क सफाई करना I] Q.4(B). Draw a labeled diagram of mitochondria. [Mitochondria का labeled diagram बनाए ] Ans.
  • 4. 4 Q.5. Differentiate between glyoxysomes and peroxisomes.[Glyoxysomes और peroxisomes म अंतर बताय] Ans. 1.Glyoxysomes are single membrane microbodies found in plant cells whereas Peroxisomes, also single membrane microbodies, are found in both plant and animal cells. [Glyoxysomes plant cells म पाई जाने वाल single membrane microbodies ह जब क peroxisomes भी single membrane microbodies ह क तु ये plant और animal cells दोन म पाई जाती ह I] 2. Glyoxysomes contain enzymes of glyoxylate cycle viz. Isocitrate lyase, malate synthetase and glycolate oxidase etc. whereas Peroxisomes contain enzymes like peroxidase, oxidases and catalase. [glyoxysomes म glyoxylate cycle क े enzymes जैसे - Isocitrate lyase, malate synthetase and glycolate oxidase आ द होते ह, जब क peroxisomes म peroxidase, oxidases और catalase enzymes होते ह I] 3. Glyoxysomes are involved in photorespiration and conversion of fats into carbohydrates whereas Peroxisomes are involved in formation and degradation of hydrogen peroxide and detoxification of poisons in the cells. [Glyoxysomes photorespiration और fats क े carbohydrates म प रवतन म शा मल होते ह, जब क peroxisomes cells म hydrogen peroxide क े formation और degradation एवं poisons क े detoxification म शा मल होते ह I] Q.6. Differentiate between microtubules and microfilaments.[microtubules और microfilaments म अंतर लख] Ans. 1. Microtubules comprise of proteins alpha and beta tubulins whereas microfilaments comprise of proteins actin and myosin. [microtubules alpha और beta tubulins proteins से यु त होते ह, जब क microfilaments actin और myosin proteins से यु त होते ह I] 2. Microtubules play important role in cell division whereas microfilaments play role in intracellular movement of cell organelles. [microtubules cell division म मह वपूण भू मका नभाते ह, जब क microfilaments cell क े अंदर cell organelles क े movement म भू मका नभाते ह I] 3. Microtubules are the largest elements of the cytoskeleton whereas microfilaments are smaller elements. [microtubules cytoskeleton क े सबसे बड़े त व ह, जब क microfilaments छोटे त व ह I] 4. Microtubules have shorter half life as compared to microfilaments. [microtubules क अ ध -आयु microfilaments क अपे ा कम होती है I] Q.7. Draw a labeled diagram of chloroplast. Write the functions of chloroplasts. [Chloroplast का labeled च बनाएं I Chloroplast क े काय लख ] Ans. Functions of chloroplasts - 1. Chloroplasts are the site of photosynthesis.
  • 5. 5 [photosynthesis chloroplasts म होती है I] 2. Chloroplasts are light harvesting organelles. They convert light energy into chemical energy. [chloroplasts काश का संचयन करने वाले organelles ह जो light energy को chemical energy म प रव तत करते ह I] 3. Their function is synthesis of ATP and generation of NADPH in light reaction. [इनका काम photosynthesis क े light reaction म ATP का सं लेषण और NADPH उ प न करना है I] 4. Their function is synthesis of carbohydrates in the dark reaction. [chloroplasts dark reaction वारा carbohydrates क synthesis करते ह I] 5. Chloroplasts impart green colour and other colours to the plants. [chloroplasts पौध को green और अ य colours दान करते ह I] Q.8. What will happen if peroxisomes are absent in the cells?[य द cells म peroxisomes नह ं ह तो या होगा?] Ans. Since peroxisomes are important for the oxidation of various toxic chemicals such as hydrogen peroxide, their absence would result in accumulation of these toxic chemicals that could prove fatal to the cells. [चूं क व भ न toxic chemicals जैसे - hydrogen peroxide, क े oxidation क े लए peroxisomes मह वपूण होते ह, इस लए peroxisomes क अनुपि थ त म ये toxic chemicals cells म एक होने लगगे जो cells क े लए घातक हो सकते ह ] Q.9. What are Lysosomes? Mention their functions. Name two enzymes present in lysosomes. What will happen if some lysosomal enzymes are missing or deficient.[lysosomes या होते ह? Lysosomes म उपि थत दो enzymes क े नाम बताय I इन lysosomal enzymes क अनुपि थ त म या होगा?] Ans. Lysosomes are specialized membrane bound vesicles formed by budding from the Golgi bodies. They contain some 40 enzymes. Their function is hydrolysis of proteins, carbohydrates, lipids and toxins. They are also involved in the scavenging of aged and damaged cells. The two lysosomal enzymes are acid phosphatase and cathepsins. The absence of some lysosomal enzymes may result in intracellular accumulation of some macromolecules. For example: In genetic disorders like 'glycogen storage disorder' and 'Hurler's disease' the lysosomal enzymes associated with the breakdown of glycogen and mucopolysaccharides respectively, are missing or deficient. This results in accumulation of these polysaccharides in the cells, leading to severe consequences. Some disorders associated with lysosomal enzymes deficiencies may also lead to severe mental disorders. [Lysosomes एक व श ट कार क े membrane bound vesicles ह जो Golgi bodies से budding वारा बनते ह I इनम लगभग 40 enzymes पाये जाते ह I इनका काय carbohydrates, proteins, lipids और toxins क hydrolysis करना होता है I दो lysosomal enzymes ह - acid phosphatase और cathepsins. क ु छ lysosomal enzymes क अनुपि थ त क े कारण cells क े अंदर क ु छ macromolecules का एक ण हो सकता है I उदाहरण - 'glycogen storage disorder' और 'Hurler's disease' जैसे genetic disorders म मशः glycogen और mucopolysaccharides को break करने वाले lysosomal enzymes कम या अनुपि थत होते ह I िजसक े प रणाम व प cells क े अंदर इन polysaccharides का एक ण हो जाता है और इसक े गंभीर प रणाम हो सकते ह I क ु छ lysosomal enzymes क कमी से गंभीर मान सक वकार भी हो सकते ह I]
  • 6. 6 Q.10. What are the various constituents of cell membranes? Describe the modes by which cell membrane controls the transport of ingoing and outgoing molecules. [Cell membranes क े या - या अवयव होते ह? Cell membrane कन तर क से molecules क े cell क े अंदर जाने और बाहर नकलने क या को नयं त करती है?] Ans. The main components of most of the cell membrane are lipids and proteins which are present in approximately equal amounts. However, their ratio varies from tissues to organelles. Among the lipids, phospholipids are the most abundant lipids and these are phosphatidyl choline , phosphatidyl ethanolamine, phosphatidyl serine and sphingomyelins. In addition, small amounts of cholesterol and glycolipids are also present. Apart from lipids and proteins the membranes contain about 2-5% carbohydrates. The three modes of transport of ingoing and outgoing molecules across the cell membrane are : 1. Facilitated diffusion - In this mode of transport the diffusion of ions and molecules across the membrane is driven by a concentration difference on the two sides of membrane (from higher to lower concentration) with the help of specific carrier proteins present in the membrane. Example: transport of sodium and potassium ions and glucose molecules. 2. Passive diffusion - The molecules like water, simply diffuse across the membrane depending on the concentration gradient across the membrane(from higher to lower concentration ). 3. Active transport - Most biomolecules are transported into and out of the cell by this process which is similar to facilitated diffusion except that it works against concentration gradient and this process requires expenditure or input of energy. [अ धकतर Cell membrane क े मु य अवयव लगभग बराबर मा ा म lipids और proteins ह, हालां क इनका अनुपात व भ न tissues और organelles म अलग - अलग हो सकता है I lipids म सबसे अ धक मा ा म phospholipids जैसे - phosphatidylcholine , phosphatidylethanolamine, phosphatidylserine और sphingomyelins होती ह I इसक े अलावा कम मा ा म cholesterol और glycolipids भी होते ह I proteins और lipids क े अ त र त लगभग 2-5% carbohydrates भी होते ह I व भ न molecules क े membrane क े आर - पार जाने हेतु तीन कार क transport याय ह : 1.Facilitated diffusion - इस transport या म ions और molecules का membrane क े आर - पार diffusion higher concentration से lower concentration क ओर membrane म ह उपि थत एक व श ट carrier protein क मदद से होता है I 2. Passive diffusion - Water जैसे molecules membrane क े आर -पार आसानी से concentration gradient क े आधार पर diffuse हो जाते ह (higher concentration से lower concentration क ओर) I 3. Active transport - अ धकतर biomolecules इसी या वारा ह cell क े अंदर - बाहर transport होते ह I यह facilitated diffusion क े समान ह होता है क तु यह concentration gradient क े वपर त काय करता है और इसक े लए energy क े खच या आगत क आव यकता होती है I] Q. 11(A). Describe the method for separation of subcellular organelles. [Subcellular organelles क े पृथ करण क व ध लख] Ans. This can be done by the technique of ' Differential Centrifugation' which is based on the principle that when the mixture containing different organelles (homogenate) is centrifuged at different speeds (different centrifugal force; g), the cell organelles get separated on the basis of their size and weight. In this technique, first the tissue (from which the subcellular organelles are to be separated) is homogenized in a medium (e.g. isotonic sucrose, 0.25 M) at 277 K (4 °C) using a homogenizer. The resulting homogenate is centrifuged at 600×g for 10 minutes. This results in sedimentation of nuclei (being the heaviest) in the form of a pellet. The supernatant containing other organelles
  • 7. 7 is then centrifuged at 15000×g for 5 minutes. Now, mitochondria can be obtained in the form of a pellet and the supernatant is again centrifuged at 100000×g for 60 minutes which results in sedimentation of microsomal fraction (ribosomes, endoplasmic reticulum) in the form of a pellet and the supernatant will be without any cell organelles and is called 'cytosol'. This way the subcellular organelles fractionation is done. [इस पृथ करण हेतु 'Differential centrifugation' तकनीक का इ तेमाल करते ह िजसका स धांत यह है क जब व भ न cell organelles क े एक म ण (homogenate) को व भ न speeds या centrifugal force (g) पर centrifuge कया जाता है तो cell organelles उनक े size और weight क े आधार पर पृथक हो जाते ह I इस तकनीक म, िजस tissue से cell organelles पृथक करने होते ह, सव थम उसको एक medium (जैसे - isotonic sucrose, 0.25 M) म 277 K (4°C) पर एक homogenizer म homogenize करते ह I इस तरह ा त homogenate को 600×g पर 10 मनट क े लए centrifuge करते ह िजससे nuclei (सब organelles से भार होने क े कारण) एक pellet क े प म नीचे बैठ जाते ह I अब ा त supernatant, िजसम अ य organelles ह, को 15000×g पर 5 मनट क े लए centrifuge करते ह, िजससे mitochondria pellet क े प म ा त होते ह I फर ा त हुए supernatant को 100000×g पर 60 मनट क े लए centrifuge करते ह तो pellet क े प म microsomal fraction (ribosomes, endoplasmic reticulum) ा त होता है और बना कोई organelles वाला supernatant (cytosol) ा त होता है I इस कार subcellular fractionation कया जाता है I] Q.11(B). How will you separate mitochondria and endoplasmic reticulum from a mixture of mitochondria and rough endoplasmic reticulum?[mitochondria और endoplasmic reticulum क े एक म ण से mitochondria और endoplasmic reticulum को कस कार पृथक करगे?] Ans. This can be done by the technique of ' Differential Centrifugation' which is based on the principle that when the mixture containing different organelles (homogenate) is centrifuged at different speeds (different centrifugal force; g), the cell organelles get separated on the basis of their size and weight. When the mixture of mitochondria and rough endoplasmic reticulum is centrifuged at 15000 xg for 5 minutes, the mitochondria would sediment and the endoplasmic reticulum would remain in the supernatant. The supernatant can be decanted and the pellet containing mitochondria can be obtained. To separate endoplasmic reticulum from the supernatant, the supernatant is centrifuged at 100000 xg for 60 minutes which would sediment endoplasmic reticulum and can be separated by decantation of the supernatant. [इस पृथ करण हेतु 'Differential centrifugation' तकनीक का इ तेमाल करते ह िजसका आधार यह है क जब व भ न cell organelles क े एक म ण (homogenate) को व भ न speeds या centrifugal force (g) पर centrifuge कया जाता है तो cell organelles उनक े size और weight क े आधार पर पृथक हो जाते ह I जब mitochondria और endoplasmic reticulum क े म ण को 15000 ×g पर 5 मनट क े लए centrifuge करगे तो mitochondria नीचे बैठ जायगे और endoplasmic reticulum ऊपर क े liquid (supernatant) म ह गे I अब
  • 8. 8 जब इस supernatant को अलग करक े इसे 100000 ×g पर 60 मनट पुनः centrifuge करगे तो endoplasmic reticulum नीचे बैठ जायगे िज ह हम supernatant को अलग करक े ा त कर लगे I] Q.12. Give the salient features of a typical prokaryotic cell. Ans. Escherichia coli, a typical prokaryotic cell, is extensively studied. It has a cell wall made of a structural polysaccharide peptidoglycan. Some E. coli cells have pili which are small thin filamentous extensions of the cell wall. In addition, they have flagella which are long, slender, whips of protoplasm which help the bacteria propel rapidly. The inner surface of the cell wall has a cell membrane made up of phospholipids and proteins. The cell membrane encloses the cytoplasm. In the cytoplasm there is a single molecule of double stranded circular DNA in the form of a tightly coiled endless loop (nucleoid or genophore). Some small circular fragments of DNA (plasmids) may also be present. Cytoplasm also contains ribosomes, certain storage granules consisting of fats, starch and other nutrients and all the enzymes required for the bacterial metabolism. There are some polysomes also which are two are more ribosomes bound together and these are involved in translation of a single mRNA. [Escherichia coli एक typical prokaryotic cell है और इसका यापक प से अ ययन कया गया है I इसक cell wall एक structural polysaccharide peptidoglycan क बनी होती है I क ु छ E. coli cells म cell wall क े ह छोटे और पतले filamentous extensions होते ह िज हे pili कहते ह I इसक े अ त र त पतले और कोड़े क तरह क े flagella भी होते ह जो protoplasm क े ह extensions होते ह और ये bacteria को तेजी से move करने म मदद करते ह I इस cell wall क आतं रक सतह पर phospholipids और proteins से बनी एक cell membrane होती है जो cytoplasm को घेरे रहती है I cytoplasm म अंतह न फ दे क े प म एक tightly coiled double stranded circular DNA (nucleoid या genophore) होता है I इसक े अ त र त क ु छ छोटे circular DNA fragments भी हो सकते ह िज हे plasmids कहते ह I cytoplasm म fats, starch और अ य nutrients से बने क ु छ storage granules, ribosomes तथा bacterial metabolism क े लए आव यक enzymes भी होते ह I इसक े अलावा cell म polysomes भी होते ह जो दो या अ धक ribosomes से मलकर बने होते ह और ये mRNA क े translation म शा मल होते ह ] E. coli Q. 13. Fill in the blanks - 1.The 'cell theory' was proposed by ______ and ________. 2. In ________ cells the genetic material is without any nuclear membrane. 3. Nucleolus is absent in ______ cells and present in ________ cells. 4. Chloroplast is found in _______ cells. 5. Mitochondria are absent in _______ cells. 6. The cell wall of E. coli is made of a rigid framework called the ___________. 7. The extrachromosomal small circular fragment of DNA found in prokaryotic cells is called _______. 8. Cell is the basic structural and ______ unit of life forms. 9. The cell wall of fungi is made of ______. 10. Singer and Nicolson proposed _______ ______ model for plasma membrane. 11. Active transport of molecules across a cell membrane requires _______.
  • 9. 9 12. The passage of solvent across a selectively permeable membrane from higher concentration to lower concentration is called _______. 13. Nucleus of eukaryotic cells contains chromatin is composed of DNA which is associated with a set of five basic proteins called _______. 14. The DNA which does not code for proteins in eukaryotic cells is called ______ DNA. 15. The human cell has ____ pairs of chromosomes. 16. A roughly spherical body in the nucleus where RNA component of ribosomes is synthesized is called ______. 17. The smooth endoplasmic reticulum is mainly involved in the synthesis of ______. 18. _________ associated with the rough endoplasmic reticulum are involved in the synthesis of proteins. 19. Glycosylation of proteins takes place in ____ ______. 20. Scavenging of aged and damaged cells is done by ______. 21. Glyoxysomes are found in _____ cells. 22. Peroxisomes are found in both ______ and _____. 23. "Bone and muscles" of eukaryotic cells is ___________. 24. The two major types of protein filaments of cytoskeleton are called ______`and _____`. 25. The power houses of the cell are ______. 26. ATP synthesis takes place in the _______ factors of cristae of mitochondria. 27. The light harvesting cell organelles are called _______. 28. Photosynthesis takes place in _______. 29. The green colour of plants is due to the presence of pigment called _______. 30. The organelles of a cell can be separated by the technique of _________ centrifugation. 31. The subcellular organelle rich in hydrolytic enzymes is ________. 32. Golgi bodies are found only in ______ cells. 33. The transport of molecules and ions across cell membranes against a concentration gradient is called ________ diffusion. 34. The mitotic spindle is made up of _______. 35. Golgi bodies modify proteins by the process called ________. 36. Hydrogen peroxide is decomposed by enzyme _____. 37. The chlorophyll pigments of thylacoid membrane are organized into two photosystems called photosystems ____ & ___. 38. Chloroplasts need _______ energy for photosynthesis. 39. Vacuoles are filled with cell _____ and vacuoles are separated from rest of the cytoplasm by a thin membrane called __________. 40. The coupling factors of mitochondria are also called ________. Ans. 1- Schneiden, Schwann, 2- Prokaryotic, 3- prokaryotic, eukaryotic, 4- plant, 5- prokaryotic, 6- peptidoglycan, 7- plasmid, 8- functional, 9- chitin, 10- mosaic, 11- energy, 12- osmosis, 13. Histone, 14- junk, 15- 23, 16- nucleolus, 17- lipids, 18- Ribosomes, 19- Golgi bodies, 20- lysosomes, 21- plant, 22- animal, plant, 23- cytoskeleton, 24- microfilaments, microtubules, 25- mitochondria, 26- coupling, 27- chloroplast, 28- chloroplast, 29- chlorophyll, 30- differential, 31- Lysosomes, 32- Eukaryotic, 33- Passive, 34- Microtubules, 35- Glycosylation, 36- Catalase, 37- I, II, 38-light, 39-sap, tonoplast, 40- F1ATPase
  • 10. 10 Q. 14. Match the following : (i) The term cell a. Schleiden & Shwann (ii) Cell theory b. Robert Hooke (iii) Fluid mosaic model c. Camillio Golgi (iv) Golgi bodies d. Singer & Nicolson Ans. (i)- b, (ii)- a, (iii)-d, (iv)-c REFERENCES: 1. IGNOU, CHE - 9 Biochemistry, Block 1 2. Lehninger Principles of biochemistry, seventh edition ; David L. Nelson & Michael M. Cox. Disclaimer : The picture given in the text has been downloaded from Google image and I am thankful to the person who has uploaded this picture. Dr. P. K. Nigam Ph. D. (Retired Biochemist)