Cellular Basis of Inheritance: Mitosis and Meiosis
45 Questions
3 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What event marks the formation of tetrads during meiosis?

  • Anaphase I
  • Metaphase I
  • Telophase I
  • Prophase I (correct)

    • During which phase of meiosis does independent assortment occur?

  • Prophase II
  • Metaphase I (correct)
  • Anaphase II
  • Telophase II

    • What is a key distinction between mitotic anaphase and meiotic anaphase I?

  • Centromeres do not separate during meiotic anaphase I (correct)
  • Homologous chromosomes separate in mitotic anaphase
  • Centromeres divide in both processes
  • Chromatids separate in mitotic anaphase I

    • What happens during Telophase I of meiosis?

    <p>The nuclear membrane reforms and cytokinesis occurs</p> Signup and view all the answers

    Which of the following statements about interkinesis is true?

    <p>It is brief or may be absent altogether</p> Signup and view all the answers

    Which phase involves the separation of sister chromatids?

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

    What type of cells are considered haploid?

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

    Which term describes the number of chromosomes in somatic cells for a given species?

    <p>Diploid number</p> Signup and view all the answers

    What is the primary function of histones in chromatin?

    <p>Organize DNA into nucleosomes</p> Signup and view all the answers

    In terms of chromosome morphology, what distinguishes the p arm from the q arm?

    <p>Relative length of the chromosome</p> Signup and view all the answers

    What characterizes a chromosome as an autosome?

    <p>Chromosomes that do not determine sex</p> Signup and view all the answers

    What is the outcome of mitosis?

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

    Which of the following processes is essential for sexual reproduction and genetic variation?

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

    What key role do chromosomes play in the inheritance of traits?

    <p>They carry genetic information</p> Signup and view all the answers

    Which of the following is NOT associated with chromosome morphology?

    <p>Type of nucleic acid present</p> Signup and view all the answers

    What is absent in plant cells during mitosis?

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

    During which phase do sister chromatids become visible as condensed structures?

    <p>Late Prophase</p> Signup and view all the answers

    What happens to the nuclear membrane during late prophase?

    <p>It disappears.</p> Signup and view all the answers

    What is the primary role of spindle fibers during mitosis?

    <p>To separate sister chromatids.</p> Signup and view all the answers

    At what stage of mitosis are chromosomes most easily studied and counted?

    <p>Late Prophase</p> Signup and view all the answers

    What happens to sister chromatids during anaphase?

    <p>They separate and move to opposite poles.</p> Signup and view all the answers

    What characteristic shape do metacentric chromosomes have during mitosis?

    <p>V-shaped</p> Signup and view all the answers

    What chemical can be used to arrest mitosis at late prophase?

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

    Which phase of mitosis concludes with the reformation of the nuclear membrane?

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

    How do chromosomes move to opposite poles during anaphase?

    <p>By microtubule contraction.</p> Signup and view all the answers

    What is the primary outcome of cytokinesis in animal cells?

    <p>Pinching of the cell into two daughter cells</p> Signup and view all the answers

    What occurs during the first meiotic division (meiosis I)?

    <p>Reduction of chromosome number from diploid to haploid</p> Signup and view all the answers

    What distinguishes metaphase I of meiosis from mitotic metaphase?

    <p>Presence of bivalents</p> Signup and view all the answers

    What is karyotyping used to determine?

    <p>Chromosome structure and number</p> Signup and view all the answers

    During which meiotic stage does crossing over occur?

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

    What are the diploid cells produced in meiosis I subsequently further divided in?

    <p>Meiosis II</p> Signup and view all the answers

    Which term refers to the pairing of homologous chromosomes during meiosis?

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

    What is formed as a result of fertilization in sexual reproduction?

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

    What happens to chromosomes at telophase of mitosis?

    <p>They relax into their extended phase</p> Signup and view all the answers

    Which process increases genetic variation during meiosis?

    <p>Crossing over and recombination</p> Signup and view all the answers

    What are chromatids?

    <p>The two identical copies of a chromosome</p> Signup and view all the answers

    During which phase of the cell cycle do chromosomes replicate?

    <p>S phase</p> Signup and view all the answers

    Which phase of the cell cycle is the longest?

    <p>G1 phase</p> Signup and view all the answers

    What structure is responsible for organizing spindle fibers during mitosis?

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

    What is the end result of mitosis?

    <p>Two identical sets of chromosomes distributed to daughter cells</p> Signup and view all the answers

    Which phase is NOT part of Interphase?

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

    What occurs during the G2 phase of the cell cycle?

    <p>Cell prepares for mitosis</p> Signup and view all the answers

    How long does mitosis typically take in an ideal animal cell?

    <p>1 hour</p> Signup and view all the answers

    What is a key characteristic of Interphase?

    <p>Cell produces proteins and organelles</p> Signup and view all the answers

    What initiates the formation of the mitotic apparatus during prophase?

    <p>Reproduction of centrioles</p> Signup and view all the answers

    Study Notes

    Cellular Basis of Inheritance: Mitosis and Meiosis

    • The study aims to observe chromosome morphology, understand mitosis and meiosis, and analyze the relationship between meiosis and Mendel's rule.

    Chromosome

    • A thread-like entity entirely composed of nucleic acid, carrying genetic information.
    • In eukaryotes (plants and animals), somatic cells contain one set of chromosomes inherited from the maternal parent and a comparable set (homologous chromosome) from the paternal parent.
    • The number of chromosomes in a dual set is called the diploid (2n) number.
    • Sex cells (gametes) have half the number of chromosomes (haploid, n) compared to somatic cells.
    • The number of chromosomes in somatic cells is consistent for all members of a species.
      • Example: Human somatic cells have 46 chromosomes, garden peas have 14, and cattle have 60.
    • Human chromosomes consist of 22 pairs of autosomes and one pair of sex chromosomes.

    Chromosome Morphology

    • Chromosomes are composed of DNA (nucleic acid) and associated proteins.
    • This complex of DNA and protein is called chromatin.
    • Histones organize DNA into structures called nucleosomes.
    • Chromosomes can be distinguished by:
      • Relative lengths
      • Position of the centromere (a condensed structure dividing the chromosome into arms of varying length).

    Centromere Positions

    • Telocentric: Rod-shaped.
    • Acrocentric: Short p arm and long q arm.
    • Submetacentric: Short p arm and long q arm, but not as extreme as acrocentric.
    • Metacentric: Equal-length arms.

    Mitosis

    • A non-reductional nuclear division resulting in two daughter cells identical to the parental cell.
    • Mitosis copies each chromosome and distributes an identical set to each daughter cell.
    • Mitosis is a continuous process, divided into four recognizable stages: prophase, metaphase, anaphase, telophase.
      • Early Prophase: Progeny centrioles move; thin replicated sister chromatids become coiled and condensed, visible as thin threads.
      • Late Prophase: Two chromatids per chromosome held together at centromere (spindle fiber attachment).
      • Nuclear membrane and nucleolus disappear during prophase, allowing for observation of chromosomes.
      • Colchicine halts mitosis at prophase by interfering with spindle fiber assembly.
      • Prophase: Spindle fibers form using centrioles, nuclear envelope and nucleolus break down; chromosomes condense.
      • Metaphase: Chromosome pairs align along the cell’s equator and spindle fibers attach.
      • Anaphase: Sister chromatids separate and move to opposite poles. Shape of the moving chromosome depends on the position of the centromere. - Metacentric = V-shaped - Submetacentric = J-shaped - Telocentric = Rod-shaped
      • Telophase: Nuclear envelope forms around each set of chromosomes, nucleolus reappear. Spindle disappears. Cytoplasm divides via cytokinesis. Formation of two new daughter cells.
    • Mitosis is just a small part of the cell cycle; most of the cell cycle is spent in interphase.
    • Interphase includes:
      • G1 (Gap 1): Cell grows and performs normal metabolic functions.
      • S (Synthesis): DNA replicates, creating identical DNA molecules (sister chromatids).
      • G2 (Gap 2): Cell grows more and prepares for mitosis.

    Meiosis

    • A specialized cell division with two consecutive divisions (meiosis I and II) reducing the chromosome number from diploid to haploid.
    • Meiosis involves one DNA replication followed by two divisions.
    • Meiosis I:
      • Prophase I: Chromosomes condense, homologous chromosomes pair up (synapsis), crossing over (exchange of genetic material) occurs.
      • Metaphase I: Homologous pairs align along the equator.
      • Anaphase I: Homologous chromosomes separate and move to opposite poles.
      • Telophase I: Chromosomes reach poles; cytokinesis occurs, two haploid cells are formed.
    • Meiosis II:
      • Interkinesis: Short interval between meiosis I and meiosis II. DNA does not replicate during interkinesis.
      • Prophase II: Chromosomes condense.
      • Metaphase II: Chromosomes align along the equator.
      • Anaphase II: Sister chromatids separate and move to opposite poles.
      • Telophase II: Chromosomes reach poles. Four haploid daughter cells are formed. -Nondisjunction during anaphase I can lead to genetic aberrations, where chromosomes fail to separate correctly.
    • Significance of Meiosis:
      • Maintains constant chromosome number across generations.
      • Recombines paternal and maternal traits.

    Review Questions

    • Stages of mitosis in chronological order with key characteristics.
    • Definition and differentiation methods for karyotypes.
    • How does meiosis differ from mitosis?
    • Events occurring during synaptonemal crossing-over.
    • Are human somatic and gamete-producing cells haploid/diploid?

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Mitosis and Meiosis PDF

    Description

    This quiz focuses on the cellular mechanisms of inheritance through mitosis and meiosis. Learners will explore chromosome structure, diploid and haploid numbers, and how these processes relate to Mendel's laws. Test your understanding of how chromosomes function in eukaryotic organisms.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser