Cell Cycle Cell Division

Question 1

What is cell cycle?

Answer 1

Events in which cell duplicates its genome and other contents and eventually divides into daughter cells.

Question 2

Duration of cell cycle in
1️⃣Bacteria
2️⃣Yeast
3️⃣Human cells

Answer 2

Bacteria = 20min
Yeast =90min
Human cell = 24hrs

Question 3

Duration of interphase is

Answer 3

Almost 95% of the total duration of cell cycle.

Question 4

Which is the intense phase related to growth

Answer 4

Interphase.

Question 5

Events that occur in G1 phase are:

Answer 5

Most Organelles duplicate.

Cell is metabolically active and grows continuously.

Question 6

Events that occur in S phase are

Answer 6

DNA 🧬 replication .
Histone protein synthesis
Centriole replication
Sub-units for kinetochore are synthesized.

Question 7

Duration of G1 phase in humans is ______, S phase is _____ and G2 phase is

Answer 7

G1 phase= 10hrs
S phase= 9hrs
G2 phase= 4hrs

Question 8

Events that occur in G2 phase are

Answer 8

Proteins and RNA synthesis continues.
Tubulin protein is synthesized.
Final preparation for M-phase occurs.

Question 9

Events in Go- phase are

Answer 9

Cell is metabolically active but no longer proliferates.

Cell decides to enter Go phase in M-phase.

Question 10

Name the 4 stages of karyokinesis?

Answer 10

Prophase
Metaphase
Anaphase
Telophase
(Prof. Mehmood ah. Tak)

Question 11

Events of early prophase are

Answer 11

Chromatin condensation occurs
Centriole pair start separating
Chromosome ends are not clearly visible.[spireme stage]
Viscosity increases.

Question 12

Events in mid prophase

Answer 12

Centriole pair moves farther apart.
Chromatin condensation occurs.
# Aster formation starts.

Question 13

Events in late prophase are

Answer 13

Spindle formation is ‘almost’ completed.
Aster formation ‘almost’ complete.
Chromosomes are fully condensed.

Question 14

Events that occur in pro-metaphase

Answer 14

Aka 5th phase
Aster formation completed.
Spindle formation completed.
Mitotic apparatus (spindle & aster) is formed.

Question 15

Events in metaphase are

Answer 15

▪️Congression metakinesis ( process of bringing of chromosomes from different locations towards equator).
▪️Chromosomes are fully condensed.
▪️Only metaphasic plate or equatorial plate is formed.

Question 16

Chromosomes are attached with spindle fibres with the help of ___________

Answer 16

Kinetochores.

Question 17

Events of anaphase are

Answer 17

Centromeric division occurs = Separation of sister chromatids = now called Chromosomes
DOUBLING OF CHROMOSOME NUMBER.

Question 18

Best stage to study the shape of chromosomes are

Answer 18

Anaphase

Question 19

Best stage for studying chromosome morphology is

Answer 19

Metaphase.

Question 20

Match the following:
1️⃣Metacentric             I 
2️⃣Sub-metacentric.     J
3️⃣Acrocentric       L 
4️⃣Telocentric        V

Answer 20

Metacentric = V shaped
Sub metacentric = L shaped
Acrocentric = J shaped
Telocentric = I shaped

Question 21

Rate of anaphasic movt. Of chromosomes is

Answer 21

0.2 - 5 μm/min

Question 22

Number of ATP molecules used by a chromosome to reach the pole is

Answer 22

25ATP

Question 23

Events that occur in telophase are

Answer 23

Chromosomes start de condensation .
Spindle and aster disappear.
Viscosity dcereases.
At the end, 2 nuclei are present in the same cell.

Question 24

In animal cells cytokinesis occurs by ______method.

Answer 24

Cleavage forrow method.

To explain this method contractile ring theory was given by Dauglas Marshland.

Question 25

Invagination in contractile ring theory is ________.(centripetal/centrifugal type)

Answer 25

Centripetal type( towards centre).

Question 26

Cytokinesis in plants occurs by ________ method.

Answer 26

Cell plate method.

Question 27

Cell plate method is a) Centripetal type b) Centrifugal type c) Niether a) nor b)

Answer 27

Centrifugal type.

Question 28

Initial signs for cytokinesis are observed in _______ phase

Answer 28

Late anaphase.

Question 29

_______ gives rise to middle lamella formation (by cell plate method).

Answer 29

Mainly Golgi apparatus. | Sometimes ER.

Question 30

What is phragmoplast?

Answer 30

In cell plate method, vesicles sent by golgi are trapped at the centre by spindle and the complex thus formed is called phragmoplast.

Question 31

``` Which of them is/are mitotic poison: 1️⃣Ribonuclease 2️⃣Azide & cyanide 3️⃣Mustard gas 4️⃣Chalones ```

Answer 31

``` All of them. ▪️Ribonuclease = inh. at prophase ▪️Azide & cyanide = inh. at prophase ▪️Mustard gas = agglutination of chromosomes ▪️Chalones = these are glycoproteins. ```

Question 32

Match the following: ▪️Ribonuclease agglutination of chromosomes ▪️Azide & cyanide these are glycoproteins ▪️Mustard gas inh. at prophase ▪️Chalones inh. at prophase

Answer 32

▪️Ribonuclease = inh. at prophase ▪️Azide & cyanide = inh. at prophase ▪️Mustard gas = agglutination of chromosomes ▪️Chalones = these are glycoproteins.

Question 33

Which of them is correct: 1) Meiosis always occurs in diploid cell. 2) Meiosis always occurs in haploid cell. 3) Meiosis can occur in either haploid or diploid cell.

Answer 33

Only statement 1) is correct. | Meiosis always occurs in diploid cell but not in haploid cell.

Question 34

Which cells undergo meiosis?

Answer 34

Only cells of sexually reproducing organisms undergo meiosis. * Some special cells (gonad cells) switch rom mitosis to meiosis in certain stage of their life.

Question 35

Meiosis involves ______ cycles of karyokinesis and _______ cycles of DNA replication.

Answer 35

2 cycles of karyokinesis | 1 round/ cycle of DNA replication

Question 36

``` Interphase of meiosis has longer ____phase and short or no _____phase. 1️⃣s phase , G2 phase 2️⃣M phase , S phase. 3️⃣G1 phase ,M phase 4️⃣G2 phase, S phase ```

Answer 36

Opt 1 | Longer s phase and short or no G2 phase.

Question 37

Chromatin condensation starts in

Answer 37

Leptotene or leptonema aka Bouquet stage.

Question 38

Synapsis occurs in

Answer 38

Zygotene or synaptotene or zygoneme.

Question 39

What is synapsis or syndesis?

Answer 39

Pairing of homologous or maternal and paternal chromosomes is c/d synapsis or syndesis.

Question 40

Formation of tetrad or bivalent occurs in

Answer 40

Zygotene.

Question 41

Synaptonemal complex is formed due to

Answer 41

``` Involvement of nuclei proteins or synaptonemal complex proteins(SCP) e.g, SCP-1, SCP-2, SCP-3. # it was first observed by Moses. ```

Question 42

Crossing over or recombination occurs in

Answer 42

Pachytene

Question 43

What’s crossing over or recombination?

Answer 43

``` Exchange of chromatin segments b/w non-sister chromatids of homologous chromosomes is c/d crossing over. # first observed by Morgan in Drosophila. ```

Question 44

Chiasma is observed in

Answer 44

Diplotene.

Question 45

What is chiasma or chiasmata?

Answer 45

Homologous chromosomes start separating from each other except at cross- over point c/d chiasma.

Question 46

What is dictyotene?

Answer 46

``` In vertebrates and invertebrates, diplotene is metabolically active and is extended (duration very high), and is called dictyotene. # extending cell can range from months upto years. # observed in primary oocytes. ```

Question 47

Separation of homologous Chromosomes is called

Answer 47

``` De-synapsis. #occurs in diplotene. ```

Question 48

Terminalisation of chiasma occurs in

Answer 48

Diakinesis

Question 49

Events in diakinesis are

Answer 49

Terminalisation of chiasma. At the end, chromosomes are fully condensed. Spindle and aster formation is completed.

Question 50

What is dyad?

Answer 50

Two cells formed after meiosis-1 are called dyad.

Question 52

What is disjunction?

Answer 52

The separation of homologous chromosomes is called disjunction.

Question 53

Why is meiosis-1 called as reductional division?

Answer 53

Meiosis 1 is called as reductional division because chromosomes are reduced to half in dyad cell.

Question 54

Events that occur in metaphase-1 are

Answer 54

Bivalents are arranged at equator. 2 metaphasic plate are formed. Maternal and paternal chromosomes are arranged randomly on equator.

Question 56

Stages of prophase-1, in order, are

Answer 56

1. Leptotene 2. Zygotene 3. Pachytene 4. Diplotene 5. Diakinesis