Cell Cycle Overview Quiz

Cell Cycle

• Regular sequence of growth and division
• Consists of Interphase and M Phase (Cell Division)

Interphase

• Longest phase of the cell cycle
• Cell increases in size (G1 phase)
• DNA replication occurs, forming two sister chromatids (S phase)
• Organelles are duplicated (G2 phase)
• Non-dividing cells enter G0 phase (e.g., nerve cells)
• Checkpoint mechanism destroys abnormal cells during the cell cycle
• Nucleolus appears only during interphase

M Phase (Cell Division)

• Consists of Karyokinesis (nuclear division) and Cytokinesis (cytoplasmic division)

Karyokinesis (Nuclear Division)

• Occurs during the M phase
• Follows the PMAT stages: Prophase, Metaphase, Anaphase, Telophase

Prophase

• Nuclear membrane disappears
• Centrioles move to opposite poles of the cell
• Chromosomes become visible
• Spindle fibers begin to form

Metaphase

• Homologous chromosomes align at the equator of the cell

Anaphase

• Sister chromatids separate and move to opposite poles of the cell

Telophase

• Two identical nuclei form

Cytokinesis (Cytoplasmic Division)

• Occurs after karyokinesis
• Divides the cytoplasm and forms two new cells
• Each cell has 2n chromosomes

Cancer

• Uncontrolled cell division due to mutations
• Can be inherited or caused by environmental factors

Apoptosis

• Programmed cell death
• Plays a crucial role in embryonic development

Mitosis

• Occurs in somatic cells
• Produces two identical diploid (2n) cells
• Important for growth and regeneration
• One cell divides four times, resulting in 2^4 = 16 cells
• In plant cells, cytokinesis occurs through the formation of a cell plate

Meiosis

• Occurs in gonads (sex organs)
• Produces four haploid (n) cells
• Important for the formation of gametes (sex cells)
• Restores the original number of chromosomes in offspring
• Includes two cellular divisions: Meiosis I and Meiosis II

Meiosis I

• Starts with a diploid cell (2n)
• Divides into two non-identical haploid cells (n)

Meiosis II

• Similar to mitosis (except for interphase, which is present only in meiosis I)
• Produces four haploid cells (n)

Prophase I (Meiosis I)

• Centrioles move to opposite poles
• Spindle fibers begin to form
• Crossing over occurs between homologous chromosomes
  • Homologous chromosomes pair up and exchange genetic material
  • Leads to genetic variation
  • Synapsis forms a tetrad (four chromatids)

Spermatogenesis

• Formation of sperm cells
• Occurs in the testes

Cell Cycle

• Regular sequence of growth and division
• Consists of interphase and M phase

Interphase

• Longest phase of the cell cycle
• Cell increases in size (G1 phase)
• DNA replication occurs, forming two sister chromatids (S phase)
• Organelles are duplicated (G2 phase)
• Non-dividing cells enter G0 phase (e.g., nerve cells)
• Checkpoints ensure the destruction of abnormal cells during the cycle
• Nucleolus appears only during interphase

M Phase (Cell Division)

• Includes karyokinesis (nuclear division) and cytokinesis (cytoplasmic division)

Karyokinesis (Nuclear Division)

• Occurs in four stages: prophase, metaphase, anaphase, and telophase (PMAT)

Cytokinesis (Cytoplasmic Division)

• Division of the cytoplasm
• Formation of two new daughter cells

Cancer

• Uncontrolled cell division due to mutations
• Can be caused by inherited or environmental factors

Apoptosis

• Programmed cell death
• Important for embryonic development

Mitosis

• Occurs in somatic cells
• Produces two diploid (2n) daughter cells
• No variation in genetic material
• Important for growth, regeneration, and reproduction in unicellular organisms
• One cell dividing four times results in 2^4 = 16 cells
• No cytokinesis in plant cells, cell separation occurs through the formation of a central lamella

Meiosis

• Occurs in gonads (sex organs)
• Produces four haploid (n) daughter cells
• Important for the formation of gametes and restoring the original chromosome number
• Consists of two cell divisions: meiosis I and meiosis II
• Interphase is present only in meiosis I
• Diploid cell divides to produce two non-identical cells (2n)

Prophase I (Meiosis I)

• Homologous chromosomes synapse to form tetrads
• Crossing over occurs, exchanging genetic material between homologous chromosomes
• This leads to variations in the offspring

Spermatogenesis

• Process of sperm cell formation
• Begins with a diploid spermatogonium
• Proceeds through stages of spermatocyte formation and maturation
• Results in four haploid sperm cells