Biology Chapter 2 summary
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Questions and Answers

What is the outcome of meiosis?

  • One haploid cell
  • Four nonidentical haploid sex cells (correct)
  • Four identical diploid cells
  • Two diploid cells

    • Crossing over occurs in anaphase I of meiosis.

    False

    What is the role of Sertoli cells in the male reproductive system?

    To nourish developing sperm.

    The main hormone responsible for the maintenance and development of male secondary sex characteristics is __________.

    <p>testosterone</p> Signup and view all the answers

    What triggers ovulation in the menstrual cycle?

    <p>A surge in LH</p> Signup and view all the answers

    Match the hormone with its function:

    <p>FSH = Stimulates development of ovarian follicles LH = Triggers ovulation GnRH = Stimulates release of FSH and LH Testosterone = Maintains male secondary sex characteristics</p> Signup and view all the answers

    During which stage of meiosis are homologous chromosomes separated?

    <p>Anaphase I</p> Signup and view all the answers

    The corpus luteum produces estrogen and progesterone mainly during the follicular phase.

    <p>False</p> Signup and view all the answers

    In oogenesis, the oocyte undergoes cytokinesis evenly.

    <p>False</p> Signup and view all the answers

    What hormone does the blastula produce to maintain the corpus luteum after fertilization?

    <p>human chorionic gonadotropin (hCG)</p> Signup and view all the answers

    What triggers the release of testosterone in males?

    <p>Luteinizing hormone (LH)</p> Signup and view all the answers

    During menopause, the ovaries stop producing __________ and __________.

    <p>estrogen, progesterone</p> Signup and view all the answers

    The __________ is the site where sperm are deposited during intercourse.

    <p>vaginal canal</p> Signup and view all the answers

    Match the following phases of the menstrual cycle with their key characteristics:

    <p>Follicular Phase = Follicle development and ovulation Luteal Phase = Corpus luteum formation and maintenance of the uterine lining Menstruation = Sloughing off of the endometrial lining Menopause = Stop in ovarian hormone production</p> Signup and view all the answers

    Which hormone is primarily responsible for maintaining the uterine lining during the luteal phase?

    <p>Progesterone</p> Signup and view all the answers

    What type of cells are produced during spermatogenesis?

    <p>Spermatids</p> Signup and view all the answers

    High levels of estrogen and progesterone have a negative feedback effect on GnRH, LH, and FSH.

    <p>True</p> Signup and view all the answers

    What are common physical changes accompanying menopause?

    <p>Flushing, hot flashes, bloating, headaches, irritability</p> Signup and view all the answers

    The decidua undergoes __________ and __________ during the follicular phase due to estrogen stimulation.

    <p>vascularization, glandularization</p> Signup and view all the answers

    At what age range does menopause typically occur?

    <p>45 to 55</p> Signup and view all the answers

    What is the main difference between diploid and haploid cells?

    <p>Diploid cells have two copies of each chromosome.</p> Signup and view all the answers

    The G1 stage of the cell cycle is where DNA replication occurs.

    <p>False</p> Signup and view all the answers

    What does p53 do in the cell cycle?

    <p>It plays a role in checking the quality of DNA at major checkpoints.</p> Signup and view all the answers

    During the S stage, the strands of DNA are held together at the __________.

    <p>centromere</p> Signup and view all the answers

    Match the following cell cycle stages with their functions:

    <p>G1 = Cell growth and organelle production S = DNA replication G2 = Preparation for mitosis M = Mitosis and cytokinesis</p> Signup and view all the answers

    What phase follows metaphase in mitosis?

    <p>Anaphase</p> Signup and view all the answers

    Cancer occurs when cell cycle control is functioning properly.

    <p>False</p> Signup and view all the answers

    What is produced at the end of mitosis?

    <p>Two genetically identical diploid daughter cells.</p> Signup and view all the answers

    Cells in the G0 stage perform their functions without preparing for __________.

    <p>division</p> Signup and view all the answers

    What role do cyclins play in the cell cycle?

    <p>They bind to CDKs and activate transcription factors.</p> Signup and view all the answers

    Study Notes

    Cell Types and Cycle

    • Diploid (2n) cells contain two copies of each chromosome; haploid (n) cells have one copy.
    • The cell cycle comprises five stages: G1, S, G2, M, and G0.
    • G1 stage involves cell growth and organelle production, preparing for DNA synthesis.
    • S stage is where DNA replication occurs, forming sister chromatids held at the centromere.
    • G2 stage includes further cell growth and organelle replication, with quality control before mitosis.
    • M stage encompasses mitosis and cytokinesis, resulting in two identical diploid daughter cells.
    • G0 stage is a non-dividing phase where cells perform regular functions.
    • p53 plays a critical role in cell cycle checkpoints, particularly G1 to S and G2 to M.
    • Cyclins and cyclin-dependent kinases (CDKs) regulate progression through the cell cycle.

    Mitosis

    • Mitosis consists of four phases: prophase, metaphase, anaphase, and telophase.
    • In prophase, chromosomes condense, the nuclear membrane dissolves, and centriole migration occurs.
    • Metaphase features chromosomes aligning along the metaphase plate.
    • Anaphase involves separation of sister chromatids to opposite poles.
    • Telophase sees the reformation of the nuclear membrane and division of cytosol and organelles during cytokinesis.

    Meiosis

    • Meiosis occurs in gametocytes and results in four haploid gametes.
    • It involves one round of replication followed by two divisions: meiosis I and II.
    • Prophase I features synapsis, where homologues intertwine, forming tetrads.
    • Crossing over during prophase I provides genetic diversity, following Mendel’s second law.
    • In metaphase I, homologous chromosomes align on the metaphase plate; in anaphase I, they are pulled apart.
    • Meiosis II resembles mitosis, separating sister chromatids.

    Reproductive System

    • Human biological sex is determined by the 23rd chromosome pair: XX for females, XY for males.
    • X-linked mutations can lead to sex-linked disorders, more commonly affecting males due to hemizygosity.
    • The Y chromosome contains the SRY gene, which differentiates gonads into testes.
    • Sperm develop in the seminiferous tubules of the testes, nourished by Sertoli cells.
    • Leydig cells produce testosterone, essential for male secondary sex characteristics.
    • Sperm mature in the epididymis and are transported through the reproductive tract during ejaculation.
    • Seminal vesicles and the prostate gland contribute fluids that nourish and alkalinize semen during ejaculation.

    Spermatogenesis

    • In spermatogenesis, a spermatogonium yields four haploid sperm.
    • Germ cells transition from primary spermatocytes to secondary spermatocytes after meiosis I, and to spermatids after meiosis II.
    • After maturation, spermatozoa have a head (containing genetic material and acrosome), midpiece (ATP generation), and flagellum (motility).

    Oogenesis

    • Oogenesis occurs in the ovaries, producing one ovum and polar bodies from an oogonium.
    • At birth, primary oocytes are arrested in prophase I and later mature into secondary oocytes, halted at metaphase II until fertilization.
    • Zona pellucida and corona radiata protect and support the oocyte during fertilization.
    • Hormones regulating the reproductive cycle include GnRH, FSH, and LH, influencing both male and female reproductive functions.

    Menstrual Cycle

    • The menstrual cycle involves a periodic endometrial lining growth and shedding.
    • Follicular phase stimulated by GnRH leads to FSH and LH secretion, promoting follicle development.
    • Ovulation occurs due to an LH surge triggered by elevated estrogen levels.
    • In the luteal phase, the corpus luteum secretes progesterone, sustaining the uterine lining.
    • Menstruation happens if fertilization does not occur, leading to a drop in estrogen and progesterone.

    Menopause

    • Menopause typically occurs between ages 45 and 55, signifying the end of reproductive capability.
    • Ovarian hormone production ceases, leading to an increase in FSH and LH levels.
    • Accompanying changes include hot flashes, bloating, headaches, and mood swings.

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    Description

    Explore the fundamental concepts of the cell cycle, including diploid and haploid cells, interphase stages such as G1, S, and G2, and the crucial processes that take place during each phase. Understand how cells prepare for division and the importance of the restriction point in maintaining DNA integrity.

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