cell cycle and division Flashcards
(9 cards)
Cell cycle and mitosis
interphase:
G1phase : cell growth
S phase: DNA replication
G2: Preparation for mitosis
mitosis phases:
prophase: Chromatin condenses and spindles form
Metaphase: chromosomes align at the metaphase state
Anaphase: sibling chromatids separate
telophase: nuclear envelope reforms
cytokinesis: Division of cytoplasm
Cell cycle regualtion and cancer
chedck points G1, G2, M) : ensure proper division ; mutation can lead to cancer
camcer: unregulated cell growtj ( benign = localized, malignant = spreads)
metastasis: cancer cells breal from the original state and spread
angiosgensisis: Formation of new blood vessles to supply tumors
Meiosis and genetic variation
Meiosis I and II:
crossing over ( prophase II) -> genetic recombonation
independant accortment ( metaphase I) -> random chromosome distribution
Haploid vs Diploid : meiosis produces haploid gametes, while mitosis maintains diploidy
mitosis vs meiosis
mitosis : produces 2 identical diploid cells ( growth and repair)
meiosis: production)
Nondisjunction and chromosomal disorders
nondisjunction: failure of chromosomes to separate during meiosis
Trisomy 21 ( down syndrome), Klinefelter syndrom (XXY), Turner syndrome (XO)
describe the stages of the cell cycle and explain what happens in each stage
The cell cycle consists of Interphase (comprising G1, S, and G2 phases) and M phase (mitosis and cytokinesis). During G1, the cell grows and performs normal functions, while in S phase, DNA is replicated. In G2, the cell prepares for division, and during M phase, the cell undergoes mitosis, dividing its nucleus, followed by cytokinesis, which splits the cytoplasm and results in two daughter cells.
outline the four stages of mitosis, describing the key events in each
Prophase: Chromosomes condense into visible structures, and the nuclear envelope begins to break down. The mitotic spindle, made of microtubules, starts to form, and centrosomes move to opposite poles of the cell.
Metaphase: Chromosomes align along the equatorial plane (metaphase plate) of the cell. The spindle fibers attach to the centromeres of the chromosomes through the kinetochores.
Anaphase: Sister chromatids are pulled apart toward opposite poles of the cell as the spindle fibers shorten. This ensures that each daughter cell will receive an identical set of chromosomes.
Telophase: The chromatids reach the poles, and a new nuclear envelope forms around each set of chromosomes. The chromosomes begin to de-condense back into chromatin, preparing for the final step of cytokinesis.
explain how cancer cells bypass desnity-dependant inhibition and apoptosis
Cancer cells bypass density-dependent inhibition by continuing to divide and grow even when they are crowded, ignoring signals that typically halt cell division when the tissue becomes too dense. They also evade apoptosis by acquiring mutations that disable the cell’s ability to undergo programmed cell death, allowing damaged or abnormal cells to survive. This abnormal behavior is often due to mutations in genes regulating the cell cycle and survival, such as tumor suppressor genes and proto-oncogenes.
how does the presence of extra or missing sex chromosomes affect human development?
The presence of extra or missing sex chromosomes can lead to developmental differences, including physical, hormonal, and cognitive effects. For example, Turner Syndrome (XO) results in short stature, infertility, and heart defects, while Klinefelter Syndrome (XXY) can cause reduced testosterone, infertility, and learning difficulties.
