North 24 Parganas

Suparna Dan replied | 19 hrs ago

Interphase (Before cell division starts)

Interphase is the longest phase of the cell cycle, where the cell grows and prepares for division. It has three stages:

1️⃣ G₁ phase (Gap 1)

Cell grows in size.

Proteins and organelles are synthesized.

Cell performs its normal functions.

The cell decides whether to continue to divide or enter G₀ (resting phase).

2️⃣ S phase (Synthesis)

DNA replication occurs (each chromosome duplicates to form two sister chromatids).

Centrosome also duplicates.

3️⃣ G₂ phase (Gap 2)

Cell continues to grow.

More proteins and enzymes needed for division are produced.

Cell checks and repairs any DNA errors.

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🔬 Mitosis (Equational division)

Occurs in somatic (body) cells for growth and repair; daughter cells are genetically identical to parent.

1️⃣ Prophase

Chromatin condenses into visible chromosomes (each with two sister chromatids).

Nuclear envelope starts to break down.Nucleolous, golgi apparatus, endoplasmic reticulum disappears.

Centrosomes move to opposite poles and spindle fibers form.

2️⃣ Metaphase

Chromosomes line up along the equatorial (metaphase) plate.

Spindle fibers attach to centromeres (via kinetochores).

3️⃣ Anaphase

Sister chromatids separate and move to opposite poles, pulled by spindle fibers.

4️⃣ Telophase

Chromatids reach poles and decondense into chromatin.

Nuclear envelope reforms around each set.

Nucleolus,golgi apparatus, Endoplasmic reticulum reappears.

Cytokinesis: Cytoplasm divides, forming two identical daughter cells.

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🌾 Meiosis (Reductional division)

Occurs in germ cells (to produce gametes), results in four haploid cells.
It has two successive divisions: Meiosis I and Meiosis II.

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Interphase before meiosis

Same as mitotic interphase: G₁, S (DNA replication), and G₂ phases.

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🌀 Meiosis I (Reductional division)

Reduces chromosome number to half (diploid → haploid).

1️⃣ Prophase I (Longest, most complex)

It is divided into five stages:

Leptotene: Chromosomes start condensing.
Zygotene: Synapsis (homolog pairing), bivalents form.
Pachytene: Crossing over happens.
Diplotene :Chiasmata visible, homologs start separating.
Diakinesis: Chromosomes fully condensed, nuclear membrane breaks down.

2️⃣ Metaphase I

Homologous chromosome pairs align at equatorial plate.

Spindle fibers attach to centromeres.

3️⃣ Anaphase I

Homologous chromosomes separate (sister chromatids remain together) and move to opposite poles.

4️⃣ Telophase I

Chromosomes reach poles.

Nuclear membrane may reform (varies by species).

Cytokinesis occurs, forming two haploid cells.

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🌀 Meiosis II (Equational division)

Similar to mitosis, separates sister chromatids.

1️⃣ Prophase II

Chromosomes condense again (if decondensed).

New spindle forms.

Nuclear envelope breaks down (if reformed).

2️⃣ Metaphase II

Chromosomes align at equatorial plate.

3️⃣ Anaphase II

Sister chromatids finally separate and move to opposite poles.

4️⃣ Telophase II

Chromatids (now chromosomes) reach poles.

Nuclear envelope reforms.

Cytokinesis occurs, resulting in four haploid daughter cells.

Isha Verma replied | 13 hrs ago

The cell cycle consists of two main phases: interphase and M phase (mitosis). Interterphase and M phase (mitosis). Interphase is further divided into G1, S, and G2 phases, while M phase includes prophase, metaphase, anaphase, and telophase. 

Interphase:

G1 (Gap 1) Phase: The cell grows and carries out normal metabolic activities. It prepares for DNA replication.

S (Synthesis) Phase: DNA replication occurs, resulting in the duplication of each chromosome.

G2 (Gap 2) Phase: The cell continues to grow and produce proteins and other molecules needed for cell division. It also prepares for mitosis. 

M Phase (Mitosis):

Prophase:

Chromosomes condense and become visible, the nuclear envelope breaks down, and the mitotic spindle begins to form. 

Metaphase:

Chromosomes line up along the middle of the cell (metaphase plate), attached to the spindle fibers. 

Anaphase:

Sister chromatids of each chromosome separate and move towards opposite poles of the cell. 

Telophase:

The separated chromosomes reach the poles, new nuclear envelopes form around them, and the cell starts to divide. 

Mihir Desai replied | 2 days ago

The valency of carbon is four. The property of carbon that leads to forming long chain compounds is called catenation, which is the ability of carbon atoms to form bonds with other carbon atoms, allowing the formation of long chains and rings.

Suparna Dan replied | 20 hrs ago

1) The valency of carbon is 4, as it has 4 electrons in its outer shell/valence shell and needs 4 more to complete its octet(fully filled outer shell)
2) Its property of catenation (ability to form bonds with other carbon atoms) allows it to make long chains and complex structures.

Yogesh Yadav replied | 26 Jun

Corporate training is a program designed to improve employees' skills, knowledge, and performance to meet organizational goals.

Sadiq replied | 4 days ago

Corporate training encompasses organized development programs designed by companies to enhance employees' skills, knowledge, and competencies. It's a planned effort to improve employee performance, focusing on both technical and soft skills, and aligning with the company's strategic goals. Essentially, it's about providing employees with the tools and knowledge they need to succeed in their roles and contribute