Differences Between Mitosis and Meiosis?



 Mitosis 

1): It occurs in all kinds of cells and may continue throughout life.

2): In involves a single division, resulting in two daughter cells only.

3): A cell can repeat mitosis almost indefinitely. 

4): All mitotic  divisions are alike.

5): Each mitotic division is preceded by an interphase.

6): Chromosomes replicate before each mitotic division. 

7): Prophase is relatively short and simple.

8): Prophase chromosomes appear double from the very start.

9): There is no pairing of homologous chromosomes, hence no chance of crossing  over.

10): No chiasmata  are formed.

11): Chromatids are genetically similar to chromosomes they arise from.

12): No synaptinemal complex forms between chromosomes. 

13): Chromosomes  do not unfold, and no transcription and protein synthesis occur in prophase.

14):All  Chromosomes  form a single plate in metaphase.

15): The kinetochores of a chromosome connect to both the poles of the spindle.

16): Anaphase involves separation of chromatids of each chromosome.

17): Telophase occurs in all cases.

18): Daughter  cells have diploid number of chromosomes like the parent cell.

19): Daughter  cells have 2n amount of  DNA unlike the 4n amount in  the  parent cell.

20): Daughter  cells divide again after interphase.

21): Mitosis brings about growth, repair and  healing. 

22): Mitosis is much shorter than meiosis in the same  animal. 

23): Cytokinesis usually follows karyokinesis. 

24): Mitosis may occur in haploid or diploid cells.

25): Chromosomes do not show chromomeres.

Meiosis 

1): It   occurs  only  in special cells ( gamete mother  cells or spore  mother cells) and at specific  times.

2): It involves two  successive divisions, resulting  in four daughter cells.

3): Meiosis takes place only once. 

4): Two meiotic divisions  are dissimilar, first  is reductional  and second equational.

5): The second meiotic division is generally  not preceded by an interphase.

6): Chromosomes do not replicate before second meiotic division. 

7): Prophase__ 1 is very long and elaborate, comprising 5 subphases.

8): Prophase __ 1  chromosomes do not look double in  the beginning. 

9): Homologous chromosomes pair and often undergo  crossing over in prophase __ 1.

10): Chiasmata form temporarily where crossing  over occurs. 

11): Chromatids may differ generically from the chromosomes they arise from due to crossing over.

12): Synaptonemal complex forms between  synapsed homologous chromosomes. 

13): Chromosomes unfold, and transcription and protein synthesis may occur in diplotene of prophase __ 1 ( oocytes  of certain animals).

14): Chromosomes  form two parallel  plates in metaphase __ 1 and  one plate in metaphase__ 2.

15): The kinetochores of a chromosome connect to the same spindle pipe in metaphase __ 1 and to both the poles in metaphase __ 2.

16): Anaphase__ 1 involves  separation of homologous  chromosomes. The chromatids move apart  in anaphase __2.

17): Telophase __ 1 is eliminated in some cases.

18): Daughter cells have haploid  number of chromosomes unlike the parent cell.

19): Daughter cells have in amount of DNA unlike the 4n amount in the parent cell.

20): Daughter cells, if gametes , do not divide further.

21): Meiosis forms gametes or spores, helps maintain the number of chromosomes constant from generation to generation, and introduces variation.

22): Meiosis is much longer than mitosis in the same animal. 

23): Cytokinesis often does not occur after meiosis _1 , but always occurs  after meiosis _ II, forming 4 cells simultaneously. 

24): Meiosis  always occurs in the diploid cells.

25): Chromosomes  may show chromomeres.

Differences between Diplontic  and Haplontic Life Cycles 

1): Occurs in all animals, many protozoans and some lower plants.

2): Meiosis precedes fertilization. 

3): Meiosis  takes place in the gametocytes and produces gametes ( gemetic  or terminal meiosis).

4): Adult is diploid,  having developed by mitotic divisions  of a zygot.

5): Haploid  stage is very short, represented  by gametes only.

6): Gametes arise by meiosis. 

7): Varitions appear at the time of gamete formation  as well as at the time of fertilization. 

Haplontic Life Cycles :

1): Occurs in fungi, certain protozoans and some algae.

2): Meiosis follows fertilization. 

3): Meiosis take place in the zygot and produces spores ( zygotic or initial  meiosis).

4): Adult  is haploid having  developed  by mitotic divisions  of a spore.

5): Diploid stage is very short, represented by zygote only.

6) Gametes arise by mitosis.

7): Variation  appear only  at the time of spore formation. 


Differences between Animal  and plant Cells  Regarding  Mitosis ?

Animal Cells

1): Centrioles present  at spindle poles.

2): Asters are formed ( amphiastral).

3): Cytokinesis by furrowing of cytoplasm. 

4): Furrow extends centripetally. 

5): Microfilaments  ring brings about cleavage. 

6):  Occurs nearly in a tissues. 

7): Cell does not change form or nature at the time of at the time of mitosis .

8): Midbody is formed at  the equator  of the spindle.

9): Intercellular spaces appear between  the daughter  lamella. 

10): Animals  mitosis is controlled  by certain mitogens. 


Plant  Cells 

1): Centrioles lacking at spindle poles.

2): No asters are formed ( anastral).

3): Cytokinesis  mostly by cell plate formation. 

4): Cell plate grows centeifugally. 

5): Microfilaments have no role in cytokinesis .

6):  Occurs  mainly at meristems.

7): Cell becomes rounded and its cytoplasm more viscous mitosis. 

8):Equator of the spindle changes into phragmoplast. 

9): Daughter  cells remain adhered together  by middle lamella. 

10): Plant mitosis is usually  controlled by a hormone  cytokinine.


Short Questions  and Answers:

Why is mitosis called equational  Division?

It is so because mitosis is the division  of parent cell into two identical  daughter  cells, each with a nucleus having the same amount  of DNA, the same number  and kind of chromosomes,  and the same hereditary  instructions as the parent cell.

Why is mitosis  also known as the equational division  ? 

Mitosis is the division  of a parent cell into two identical  daughter cells, each with a nucleus having the same amount of DNA, the same number  and kind of chromosomes,  an dthe same hereditary  instructions as the parent cell. Hence, it is also known as the equational division. 

Where do mitosis and meiosis occur in animals and plants?


In animals mitosis  occurs in somatic cells and  meiosis in germ cells during gamete formation, in plants mitosis occurs in all cells except those which produce spore by meiosis. 

What is endomitosis ( endoduplication)?

Replication of DNA and chromosomes without nuclear division. 

Give an alternative term for meiosis?

An alternative term for meiosis is "reduction division."

What is amphiastral  mitosis?


Amphiastral mitosis refers to a type of cell division that occurs in certain organisms, such as some species of algae and fungi. In amphiastral mitosis, nuclear division takes place with the formation of two spindle poles, or asters, which are responsible for separating the chromosomes in the nucleus. This type of mitosis is distinct from the usual bipolar mitosis, where two spindle poles are formed. In amphiastral mitosis, the spindle poles are formed on both ends of the cell, and each pole contributes to the separation of chromosomes during cell division.


Q: You  are viewing a dividing cell under a microscope.How can you determine  whether  it is an animal cell or a plant cell ?


Ans: In the animal cells, centrioles are present . Hence, the spindle has an aster at each pole in the dividing  cell. On the other hand, there are no centrioles in plant  cells and no asters are formed. 


QN: Differentiate between  intranuclear and extranuclear mitosis. In which organisms  such types occur?

Intranuclear mitosis occurs within the nucleus of a cell, while extranuclear mitosis occurs outside of the nucleus in the cytoplasm. 

Intranuclear mitosis occurs in eukaryotic organisms with a nuclear envelope, such as animals, plants, and fungi. It involves the division of the nucleus and separation of the chromosomes.

Extranuclear mitosis occurs in prokaryotic organisms, such as bacteria, which do not have a nucleus. It involves the separation of the genetic material through various mechanisms, such as binary fission or budding.

In unicellular organisms ( e.g., Amoeb and yeast) mitotic events usually  occur  within the nuclear  envelope,  which remains intact, and the nucleus divides by furrowing  along with the cytoplasm .Such a mitosis is called  intranuclear mitosis. 

In multicellular organisms ( e.g., man), the nuclear  envelope breakdown and the mitosis is termed extranuclear mitosis.

What are mitosis and meiosis called?


Mitosis and meiosis are both types of cell division. Mitosis is a process where a single cell divides into two identical daughter cells, while meiosis is a type of cell division that produces four genetically diverse daughter cells. Mitosis is typically used for growth and repair of body tissues, while meiosis is important for sexual reproduction in eukaryotic organisms.

What is haploid and diploid?

Haploid and diploid are terms used to describe the number of sets of chromosomes in a cell or organism.

- Haploid (n): Haploid cells or organisms have only one set of chromosomes. In humans, haploid cells are the sperm and egg cells, also known as gametes. These cells contain half the number of chromosomes (23 in humans) compared to diploid cells.

- Diploid (2n): Diploid cells or organisms have two sets of chromosomes. In humans, diploid cells are most of the cells in our body, excluding the gametes. They contain a total of 46 chromosomes, with 23 chromosomes inherited from each parent. When a sperm and an egg fuse during fertilization, the resulting zygote also becomes diploid.

The difference between haploid and diploid is important for sexual reproduction. During fertilization, the haploid sperm and egg cells fuse, resulting in a diploid zygote. This ensures that the offspring inherit genetic material from both parents.

Which of  the following  will undergo meiosis  and mitosis  both ? 


All sexually reproducing organisms undergo meiosis to produce gametes, and then the fusion of gametes during fertilization leads to the formation of a zygote that undergoes mitosis for growth and development. Therefore, all sexually reproducing organisms undergo both meiosis and mitosis.

MCQ

1):The cell division  in plant  cells was first studied by

 (1) Strasburger

 (2) W.Flemming 

3): Wini water 

4): Frmer & Moore

Ans  (1)

2) One of the basis of variation  is 

1): Crossing over 

2): Segregation of chromosomes at anaphase

3): Disjunction of chromosomes 

4): Non_ disjunction of chromosomes at telophase. 

Ans  (1)

3)  The type of meiosis   occurring before fertilization is called 

(a) Zygotic       (c)   gametic 

(b)  Sporic        (d)   azygotic 

Ans (c) 

QNo4 : E.coli / Bacteria does not show alternation of generation  because of absence of 

(a) nucleus     (b)  chromosomes 

(c) Reduction division   (c) Syngamy 


Ans (c)

Qno5 : The decision of cell division occurs in 

(a)   G1    (b)   S    (c) G2  (d)  Not known

Ans   (a)

Qno6 : Spindle formation occurs in 

(a) Prophase     (b) Anaphase 

(c) Telophase   (d)   Metaphse 

Ans (a)

QNo 7 : In cell cycle, DNA/ chromosomes doubles in its amount due to its synthesis  ( replication or duplication). It occurs in 

( a) G1_ phase / Post mitotic phase 

(b) G2_ phase/ Pre mitotic phase 

(c) Synthetic (s) _ phase

(d) I_ phase 

Ans (c)

QNo 8 : The active phase, also called metabolic or energetic phase most cytogenetic activity is 

(a) Interphase  (b) M_ Phase 

(c) Meiosis     (c) Pachytene 

Ans (a) 
QNo 9: Which among the following is most active and of longest duration in animals?

(a) Laptotene    (b) Zygotene 

(c) Pachytene    (d) Diplotene 

Ans (d) 

QNo 10 : Where will you not get cell division on man? 

(a) Gonads        

(b) Epithelial tissue 

(c) Connective  tissue 

(d) Nervous and muscular  tissue 

Ans (d) 

QNo 11: Which of  the following  will undergo meiosis  and mitosis  both ? 

( a) Oocytes  (b) Spermatids 

(c) Interstitial   (d) Gonads 

Ans (d) 

 QNo 12 :  A cell will proceed to mitosis if entered in 

(a) G1 Phase  ( b)  S_ Phase 

(c) G2 _ Phase   (d) M_ Phase 

Ans (b) 

QNo 13 : Which substage of I_ phase is of shortest duration?

(a) G1            

 ( b) G2  

(c) S   

(d) All are of almost equal duration 

Ans (b)      

QNo 14: A bipolar  mass of fibrils arising from  poles to distribute chromosomes in cell division  is 

(a) aster   ( b) Centriole

(c) Spindle   (d) Cell plate 

Ans (c) 

QNo 15 : Bouquet stage shows convergence of chromosomal  ends towards centriole during

(a) zygotene  (b) Lepotene 

(c) Pachytene   (d) Diplotene

Ans  (b) 

QNo 16 : Number of meiotic divisions  required  to produce 10p microspores  (pollens) in an angiogram  is 

(a) 125     ( b) 100     (c) 50     (d) 25 

Ans  (d) 

QNo 17 : Number of meiotic divisions required to produce 100 macrospores in angiosperm/ egg is 

(a) 125     ( b) 100     (c) 50   ( d)  25 

Ans (b) 

QNo 18: Longest stage in M _ phase of cell cycle is 

(a) Interphase ( b) Metaphase  

(c) Prophase  (d) Telophase 

Ans (c)

QNo19 : Quiescent cells in the  root tip cells are in which phase of cell cycle of mitosis ?

(a)  G1   (b) G0   (c)  G2  (d)   M

Ans (b) 

QNo 20: Specific number of chromosomes  is restored in the  individual  by the process of 

(a) Regeneration    (b) Reduction  division 

(c) Fertilization   (d) Parthenogenesis 

Ans (c) 

QNo 21 : A temporary  suppression  of cell division  activity in cell can be brought  about by 

(a) Colchicine   (b) UV Rays 

(c) Reducing nitrogen supply 

(d) Reacting cell with Auxin 

Ans (a) 

QNo 22 :  Anastral mitosis is  found in 

(a) Plants        (b) Animals 

(c) All living  cells    (d) Chordates 

Ans (a)  

QNo 23 : Where would  you look for active cell division  in plant ? 

(a) Shoot Apex    (b) Pith 

(c) Cortex           (d)   Internodal region 

Ans  ( a) 

QNo 24 : In plant cell, spindle is formed from 

(a) Cytoplasm       (b) ER

(c) Nucleat membrane  (d) Centrosome 

Ans (a) 

QNo25 : When  a chromosome duplicates, it forms a pair of 

(a) chromatids  (b) Centrosomes 

(c) Spindle    (d) Metaphasic plate 

Ans (a) 

QNo 26 : Nuclear membrane disappears at 

(a) Anaphase   (b) Early telophase 

(c) Late prophase (d) Early prophase 

Ans (c)

QNo27 : A diploid somatic cell can divide by 

(a) Mitosis but not meiosis 

(b) meiosis  but not mitosis

(c) Meiosis  or mitosis 

(d) Amitosis only 

Ans (a) 

QNo28 : In eggs ( oocytes), most active period of growth and  metabolism  is 

(a) Leptotene      (b) Zygotene 

(c) Pachytene       (d) Diplotene 

Ans (d)

QNo29 : To observe chiasmata, the most appropriate stage of meiosis  would be 

(a) Metaphase_II   (b) Diakinesis 

(c) Diplotene   (d) Pachytene 

Ans (c)

QNo30 : The number of chromatids in a chromosome at metaphase  is 

(a) Two in mitosis and one in meiosis 

(b) One  in  mitosis and two in meiosis

(c) two in mitosis and two in meiosis 

(d) Two in mitosis and four in meiosis 

Ans  (c)


QNo31: In the pachynema , each bivalent, chromosome contains __ chromatids.

(a) Two         (b) Four   

 (c) Eight        (d) Many 

Ans (b)


QNo32 The best stage to view structure, size and to count the  number of chromosomes is 

(a) Metaphase    (b) Late Prophase 

(c) Telophase    (d) I_ phase

Ans (a)

QNo 33: Meiosis  occurs  in 

(a) Getmplasm  (b) Somatoplasm 

(c) Both (a) and (b) 

(d) All body parts 

Ans (a)

QNo 34 : G0 phase is 

(a) Arrest of cell cycle and onset of differentiation 

(b) Phase after G2 

(c) phase after M phase in which daughter   calls enter new cell cycle.

(d) All of  the above.

Ans (a) 

QNo35 : For studying meiosis which is most suitable material?

(a) Root tips/ shoot tips 

(b) Mature leaves 

(c) Young  floral  buds 

(d) Young  anthers/ Testes  of Grasshopper.

Ans (d)

QNo36 : In which  stage of cell division  the nucleus  looks like a ball of wool ( spireme stage )? 

(a) Prophase    (b) Prophase  _ I 

(c) Anaphase   ( d) Cytokinesis 

Ans ( a) 

QNo37 : In which stage size of nucleus increase?

(a) I_ phase       (b) Prophase 

(c) Early Prophase   (d) Mid Prophase 

Ans  (a) 

QNo 38 : In Meiosis , how many times nucleus  divides ?

(a) Once       (b) Twice 

(c) Does not divide      (d) Four times.

Ans  

QNo39 : Chromosomes at anaphase  are of various shapes  depending  upon position  of centromere. It is J shaped  when centromere  is 

(a)    Metacentric     (b)  Telocentric 

(c)  Acrocentric    (d) Submetacentric 

Ans  (c). 


QNo40 :  During  metaphase, each chromosome becomes connected to the spindle fibre at a point called 

(a) Centrosome     (b) chromosome  

(c) Kinetochore    (d) Aster 

Ans (c) 


















































Comments

Popular posts from this blog

Proteins

Cytoplasm

Nucleic Acids