Tag: mitosis

Questions Related to mitosis

The cell is not allowed to past the cell cycle restriction point, DNA damage is detected. Which of the following proteins are involved in detection of DNA damage and inhibition of cycle at the restriction point?

biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. Replication protein A (RPA)

  2. ATM (ataxia telangiectasia mutated ) protein

  3. Cyclin D

  4. PSS

Show answer
Correct Option: A
Explanation:

A. Replication protein (RPA) - is the major protein that binds to single-stranded DNA (ssDNA) in eukaryotic cells. ... During DNA replication, RPA prevents single-stranded DNA (ssDNA) from winding back on itself or from forming secondary structures.

B. ATM (ataxia telangiectasia mutated ) protein

 It activates checkpoint signalling upon genotoxic stresses such as ionizing radiation (IR), ultraviolet light (UV), or DNA replication stalling, thereby acting as a DNA damage sensor.

C.Cyclin D - a member of the cyclin protein family that is involved in regulating cell cycle progression. 

D.PSS - an autoimmune disease of the connective tissue. It is characterized by thickening of the skin caused by the accumulation of collagen, and by injuries to small arteries.

So, the correct option is ‘Replication protein A (RPA)’.

In order to enter cell cycle a cell must be stimulated from outside. What type of molecule provides this stimulation?

biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. cyclin

  2. colk

  3. cytokines and growth factor

  4. tyrosine kinases

Show answer
Correct Option: A
Explanation:

  • Cyclin-dependent kinases, through phosphorylation,  signal the cell that it is ready to pass into the next stage of the cell cycle. As their name suggests, Cyclin-Dependent Protein Kinases are dependent on cyclins, another class of regulatory proteins. Cyclins bind to Cdks, activating the Cdks to phosphorylate other molecules.

So, the correct option is 'cyclin'.

Select the correct option:

A cell cycle includes

biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. Interphase and M phase

  2. Prophase, metaphase, anaphase and telophase

  3. $G _1$, S and $G _2$ phases

  4. Karyokinesis and cytokinesis

Show answer
Correct Option: A
Explanation:

The cell cycle starts from interphase . Interphase is the phase in the cell cycle that prepare a cell and its nucleus for division. It has three stages- $G _1,S $ and $G _2$.M- phase is the final phase of cell cycle..It represent the phase of actual division. It consists of karyokinesis (division of nucleus ) and cytokinesis (division of cell protoplast).

Select the correct option:

Which one is the correct sequence of a cell cycle?

biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. $G _2 \rightarrow M \rightarrow G _1 \rightarrow S$

  2. $S \rightarrow G _2 \rightarrow M \rightarrow G _1$

  3. $G _1 \rightarrow S \rightarrow G _2 \rightarrow M$

  4. $M \rightarrow G _1 \rightarrow S \rightarrow G _2$

Show answer
Correct Option: C
Explanation:

The cell cycle starts from interphase . Interphase is the phase in the cell cycle that prepare a cell and its nucleus for division. It has three stages- $G _1,S $ and $G _2$.M- phase is the final phase of cell cycle..It represent the phase of actual division. It consists of karyokinesis (division of nucleus ) and cytokinesis (division of cell protoplast).

So, the correct answer is 'G1→S→G2→M'.

Select the correct option:

Synthesis of histone proteins occurs in 

biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. $G _1$ phase

  2. Interphase

  3. Anaphase

  4. $G _0$ phase

Show answer
Correct Option: B
Explanation:

The cell cycle is a sequence of event which occurs during cell growth and cell division. It has two phases; interphase and the M phase. Interphase is the period between the end of 1 division and the beginning of next cell division. It is also known as resting phase or the non-dividing stage.

It has three phases G₁ phase which is the post-mitotic phase, the synthetic phase which is the S phase and the G₂ phase. During the S phase, DNA replication takes place and the amount becomes double. Here the synthesis of histone protein and non-histone chromosomal proteins also takes place.
So, the correct option is 'Interphase'

Human cells in culture show a cell cycle to be completed in approximately 
biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. 42 hours

  2. 24 hours

  3. 24 minutes

  4. 24 seconds

Show answer
Correct Option: B
Explanation:

Cell division is the process by which a cell divides to form to nearly equal daughter cell which resembles the parent. The cell cycle is the sequence of events which occur during the cell growth and cell division. It is completed into two steps interphase and M-phase.

In the cell cycle interphase is the period between the end of one division to the beginning of next cell division. It is known as the resting phase. In the case of human beings it is around 24 hours then the M phase takes place.

So, the correct option is '24 hours'

________ is characterised by all the chromosomes coming to lie at the equator, with one chromatid connected by its kinetochore to spindle fibres from one pole and its sister chromatid connected by its kinetochore to spindle fibres from the opposite pole.
biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

Show answer
Correct Option: B
Explanation:

During the cellular division phase, metaphase is a stage where all the chromosome arranges themselves on the metaphase plate.

On this equatorial plate, these are aligned and appear as two threaded chromosomes. These are attached to the pole by spindle fibre.
So, the correct option is 'Metaphase'

Select the correct option:

Read the following statements about cell division and select the correct ones.
(i) M phase represents the phase when actual cell division occurs and I phase represents the phase between two successive M phases.
(ii) In the 24 hours average duration of cell cycle of a human cell, cell division proper lasts for only about an hour.
(iii) M phase constitutes more than 95% of the duration of cell cycle.

biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. (i) and (ii)

  2. (ii) and (iii)

  3. (i) and (iii)

  4. (i), (ii) and (iii)

Show answer
Correct Option: A
Explanation:

Cell cycle consists of two basic phases, long nondividing I phase and a short dividing M phase . In the average duration of 24 hours in the cell cycle of dividing human cell , M phase lasts for one hour (less than $5\%$ of total) while I phase or interphase occupies $75-95\%$ of total generation time.

So, the correct answer is '(i) and (ii)'.

Before cell division, copying of DNA is not essential.
biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. True

  2. False

Show answer
Correct Option: B
Explanation:
  • DNA replication must occur before cell division. So, that all newly produced cells have all the DNA of the original cell (except gametes of course). If DNA did not replicate (make exact copies), then new cells would not receive all the chromosomes and genes necessary for life processes.
  •  Each new cell would only have half the needed chromosome. If it could survive each successive generation of cells would have fewer chromosomes and of course after a few divisions cells would receive none at all.

How many following statements are correct?
(A) Nucleus as a cell organelle was first described by Robert Brown as early as 1651.
(B) The interphase nucleus has highly condensed nucleoprotein fibres called chromatin.
(C) During different stages of cell division, cells show structured chromatin in place of the nucleus.
(D) Every chromosome essentially has a primary constriction which is also known as NOR.
(E) Many membrane-bound minute vesicles called microbodies that contain various enzymes are present in both plant and animal cells.

biology division for growth and reproduction cell division in embryo development structure of chromosome, cell cycle and cell division component of the cell different types of reproduction reproductive health of humans need of family planning tissues of animals mitosis reproductive health

  1. One

  2. Two

  3. Three

  4. Four

Show answer
Correct Option: B
Explanation:

Answer is option B i.e. "Two"

  • Correct statements are statements C and E because-
During cell division stages of eukaryotes instead of nucleus, DNA associated with histone proteins in a highly condensed nucleoprotein complex is called chromatin.
Microbodies are membrane-bound minute vesicular organelles. They are found in both plant and animal cells. They contain various enzymes and proteins.
  • While, Nucleus was discovered by  Robert Brown in 1831 and published in 1833.
  • During interphase chromatin is distributed throughout the nucleus.
  • Every chromosome essentially has a primary constriction which is also known as kinetochores. Nucleolus organiser regions (NORs) are chromosomal regions crucial for the formation of the nucleolus.