Biology Meiosis and Cell Cycle Quiz
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Questions and Answers

What is the primary purpose of meiosis?

  • To produce somatic cells
  • To maintain chromosome number
  • To replicate DNA
  • To generate non-identical daughter cells (correct)

    • Which term refers to the study of heredity and variation?

  • Biochemistry
  • Genomics
  • Genetics (correct)
  • Epigenetics

    • What are genes primarily made up of?

  • Nucleic acid segments (correct)
  • Proteins
  • Lipids
  • Carbohydrates

    • What is the term for a gene's specific position along a chromosome?

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

    How many pairs of chromosomes are present in human somatic cells?

    <p>23</p> Signup and view all the answers

    What term describes a display of pairs of chromosomes from a cell?

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

    What are gametes?

    <p>Reproductive cells</p> Signup and view all the answers

    What is heredity?

    <p>The transmission of traits between generations</p> Signup and view all the answers

    What state does a cell enter if it does not receive the go-ahead signal at a checkpoint?

    <p>G0 phase</p> Signup and view all the answers

    Which cells divide frequently?

    <p>Intestinal cells</p> Signup and view all the answers

    What drives the cell cycle according to the content?

    <p>Chemical signals in the cytoplasm</p> Signup and view all the answers

    What happens at the checkpoints in the cell cycle?

    <p>Cells can exit the cell cycle</p> Signup and view all the answers

    What is a characteristic of cancer cells regarding the cell cycle?

    <p>They have lost their cell cycle checkpoints</p> Signup and view all the answers

    What are HeLa cells known for?

    <p>They are harvested from a woman named Henrietta Lacks</p> Signup and view all the answers

    Which phases contain important checkpoints in the cell cycle?

    <p>G1, G2, and M</p> Signup and view all the answers

    What is a common trait of cancerous cells compared to normal cells?

    <p>They can become immortal under certain conditions</p> Signup and view all the answers

    What is the primary function of mitosis in multicellular eukaryotes?

    <p>To facilitate cell repair and growth</p> Signup and view all the answers

    Which structure is responsible for the movement of chromosomes during mitosis?

    <p>Mitotic spindle</p> Signup and view all the answers

    What type of cellular division results in the formation of gametes?

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

    What is meant by the term 'chromatin' in eukaryotic cells?

    <p>DNA that is packaged into chromosomes</p> Signup and view all the answers

    How do haploid cells differ from diploid cells?

    <p>Haploid cells have one set of chromosomes, while diploid cells have two sets</p> Signup and view all the answers

    What occurs during cellular checkpoints in the cell cycle?

    <p>The cell assesses its readiness for division</p> Signup and view all the answers

    Which phase of the cell cycle is directly responsible for the DNA replication?

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

    What is a significant difference between asexual and sexual reproduction?

    <p>Asexual reproduction results in genetically identical organisms, while sexual reproduction does not</p> Signup and view all the answers

    In what way does meiosis contribute to genetic diversity?

    <p>By crossing over and independent assortment of chromosomes</p> Signup and view all the answers

    Why is it important for cells to maintain a characteristic number of chromosomes?

    <p>To maintain proper cellular function and genetic integrity</p> Signup and view all the answers

    What is the role of cohesins during cell division?

    <p>To attach sister chromatids along their lengths</p> Signup and view all the answers

    Which phase of the cell cycle includes DNA replication?

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

    What happens to sister chromatids during anaphase?

    <p>They become individual chromosomes</p> Signup and view all the answers

    Which structure forms during prometaphase to assist in chromosome movement?

    <p>Mitotic spindle</p> Signup and view all the answers

    What characterizes the metaphase stage of mitosis?

    <p>Chromosomes align at the metaphase plate</p> Signup and view all the answers

    What is the primary function of the centromere?

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

    Which phase of the cell cycle is primarily for cell growth and preparation for mitosis?

    <p>G2 phase</p> Signup and view all the answers

    In animal cells, what mechanism is used during cytokinesis?

    <p>Cleavage furrow formation</p> Signup and view all the answers

    Which major phase of the cell cycle includes mitosis?

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

    What is the main role of the mitotic spindle during mitosis?

    <p>To control chromosome movement</p> Signup and view all the answers

    What leads to the separation of sister chromatids during anaphase?

    <p>Cleavage of cohesins by separase</p> Signup and view all the answers

    What happens to chromosomes during telophase?

    <p>Chromosomes start to decondense</p> Signup and view all the answers

    What occurs during G1 phase of the cell cycle?

    <p>Cell growth and preparation for DNA synthesis</p> Signup and view all the answers

    During which phase do centrosomes replicate and migrate to opposite ends of the cell?

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

    What type of reproduction involves only one parent that passes all genes to offspring?

    <p>Asexual reproduction</p> Signup and view all the answers

    How many sets of chromosomes are present in diploid human somatic cells?

    <p>46</p> Signup and view all the answers

    What is the primary difference between gametes and somatic cells?

    <p>Gametes are haploid, while somatic cells are diploid</p> Signup and view all the answers

    Which process produces genetic variation through the exchange of genetic material between homologous chromosomes?

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

    In human males, which sex chromosome is present along with the X chromosome?

    <p>Y chromosome</p> Signup and view all the answers

    What term describes an abnormal number of chromosomes?

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

    During which phase of meiosis do homologous chromosomes separate?

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

    What is produced as the final outcome of meiosis?

    <p>Four haploid daughter cells</p> Signup and view all the answers

    What process alternates with fertilization in sexual life cycles to maintain chromosome number?

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

    What is the process called where homologous chromosomes connect and exchange genetic information?

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

    What type of cells are produced by meiosis in humans?

    <p>Haploid gametes</p> Signup and view all the answers

    In mitosis, how many daughter cells are produced?

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

    What occurs during telophase II of meiosis?

    <p>Nuclear envelopes reform</p> Signup and view all the answers

    What do homologous chromosomes share?

    <p>Same lengths and shapes, but not identical genes</p> Signup and view all the answers

    Study Notes

    Chapter Overview

    • This course covers cell division (mitosis and meiosis), the cell cycle, and the organization of genetic material.

    Learning Objectives

    • Understand the functions of cellular division and the organization of genetic material in chromatin and chromosomes.
    • Define key chromosomal and genetic material terminology.
    • Understand the major phases and processes occurring in the cell cycle during mitosis.
    • Explain how the mitotic spindle contributes to chromosomal movement in all phases of mitosis.
    • Understand the difference between animal and plant cell cytokinesis.
    • Understand why cellular checkpoints are important and what happens when they malfunction.
    • Explain how genetic material is passed through generations.
    • Understand chromosomal numbers in humans, haploid vs diploid cells, and the human life cycle.
    • Describe differences between asexual and sexual reproduction.
    • Explain the major outcomes of meiosis, major phases of meiosis I and meiosis II.
    • Explain how genetic diversity occurs.
    • Compare and contrast mitosis and meiosis.

    Cellular Division

    • The ability of organisms to produce more of their own kind.
    • The continuity of life is based on the reproduction of cells, or cell division.
    • Mitosis and meiosis

    Functions of Cellular Division

    • In unicellular organisms, cell division reproduces the entire organism.
    • Multicellular eukaryotes depend on cell division for development from a fertilized egg, growth, and repair.

    Introducing the Cell Cycle

    • Cell division is an integral part of the cell cycle.
    • The cell cycle is the life of a cell from formation to its own division.
    • Most cell division results in two daughter cells with identical genetic information.
    • The exception is meiosis, a special type of division that can produce sperm and egg cells (gametes).
    • Meiosis produces non-identical daughter cells.

    Cellular Organization of the Genetic Material

    • Genome: all the DNA in a cell.
    • A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells).
    • DNA molecules in a cell are packaged into chromosomes.
    • Eukaryotic chromosomes consist of chromatin which is a complex of DNA and protein (histones) that condenses during cell division.
    • Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus.

    Distribution of Chromosomes During Eukaryotic Cell Division

    • In preparation for cell division, DNA is replicated, and the chromosomes condense.
    • Each duplicated chromosome has two sister chromatids.
    • Sister chromatids: joined copies of the original chromosome, attached along their lengths by cohesins.
    • Cohesins : protein complexes that attach sister chromatids.
    • The centromere is the narrow "waist" of the duplicated chromosome, where the two chromatids are most closely attached.

    The Two Major Phases of the Cell Cycle

    • Interphase (G1, S, and G2): Cell growth and copying of chromosomes in preparation for cell division.
    • Mitotic phase (Mitosis and Cytokinesis): Mitosis is the division of the genetic material in the nucleus, and Cytokinesis is the division of the cytoplasm.

    Interphase: G1, S, and G2

    • Cell growth and copying of chromosomes in preparation for cell division.
    • About 90% of the cell cycle.
    • G1 phase: Cells increase in size and get ready for S phase.
    • S phase: DNA replication occurs.
    • G2 phase: Cells continue to grow, and get ready for Mitosis

    Mitosis consists of Stages

    • Prophase
    • Prometaphase
    • Metaphase
    • Anaphase
    • Telophase and Cytokinesis

    G2 of Interphase

    • A nuclear envelope encloses the Nucleus
    • Two centrosomes have formed and are Regions that organize microtubules.
    • Chromosomes duplicated in S phase cannot be seen because they have not condensed.

    Prophase

    • Chromatin fibers tightly coil into discrete chromosomes becoming visible.
    • Duplicated chromosomes appear as two sister chromatids.
    • Mitotic spindle begins to form.
    • Centrosomes and the microtubules extending from centrosomes.
    • Centrosomes move away from each other.

    Prometaphase

    • Nuclear envelope fragments, chromosomes are even more condensed.
    • Microtubules from each centrosome invade nuclear area.
    • Kinetochore: protein structure at the centromere on each sister chromatid.
    • Some microtubule become kinetochore microtubules jerking chromosomes back and forth.
    • Any non-kinetochore microtubules elongate the cell.

    Metaphase

    • Centrosomes are now at opposite poles of the cell.
    • Chromosomes have arrived at the metaphase plate, an imaginary plane in the middle of the cell.
    • Centromeres lie at the metaphase plate.
    • Kinetochore of each sister chromatid attaches to kinetochore microtubules.

    Anaphase

    • Shortest phase of mitosis.
    • Cohesins between chromatids are cleaved, allowing each pair to separate (becoming an independent chromosome).
    • Two new daughter chromosomes move towards opposite poles.
    • Centromeres lead, because microtubules attached to kinetochore.

    Telophase and Cytokinesis

    • Two daughter nuclei form.
    • Nuclear envelope reappears.
    • Chromosomes start to decondense.
    • Mitosis is now complete, creating two genetically identical nuclei.
    • Cytokinesis: Division of the cytoplasm.
    • Involves formation of a cleavage furrow, pinching the cell in two (animal cells).

    Animal and Plant Cell Cytokinesis

    • Plant Cells: Vesicles contain cell wall material derived from Golgi apparatus. A cell plate forms during cytokinesis.
    • Animal Cells: Contractile ring of microfilaments. A cleavage furrow forms during cytokinesis.

    ###How do Cells Know When to Divide?

    • Cell Cycle is tightly regulated.
    • Some cells divide frequently (intestinal cells) and others rarely divide (neuronal cells).
    • Cancerous cells can escape the usual controls and proliferate.
    • Molecular clocks drive the cell cycle
    • Cell cycle control system has checkpoints where the cell cycle stops until go ahead signal has been issued.
    • Regulatory proteins drive the cell cycle

    Cellular Checkpoints

    • Regulatory proteins drive the cell cycle.
    • Three important checkpoints are those in the G1, G2, and M phases
    • If the cell does not receive the go-ahead signal, it will exit the cycle and enter the G0 phase, a non-dividing state.

    Cancer Cells

    • Have lost their cell cycle checkpoints (due to internal and external factors)
    • Can become immortal, continuously divide, provided they have enough nutrients.
    • HeLa cells: Harvested from a women named Henrietta Lacks (in 1951).

    Meiosis

    • A special type of cell division that can produce sperm and egg cells (gametes).
    • Produces non-identical daughter cells.
    • Heredity: Transmission of traits from one generation to the next.
    • Variation: Differences in appearance offspring show from parents and siblings
    • Genetics is the scientific study of heredity and variation

    Inheritance of Genetic Material

    • Offspring inherit genetic material from parents.
    • Genes are the units of heredity and are made up of segments of DNA.
    • Locus: A gene's specific position along a chromosome.
    • Genes are passed to the next generation via reproductive cells called gametes (sperm and eggs).
    • Offspring acquire genes from parents by inheriting chromosomes.
    • Human somatic cells have 23 pairs of chromosomes (total of 46)
    • Karyotype: an ordered display of the pairs of chromosomes from a cell.
    • Diploid cells have 2 sets of chromosomes and haploid cells have one.

    Comparison of Asexual and Sexual Reproduction

    • Asexual: A single individual passes all of its genes to its offspring without the fusion of gametes. A clone is genetically identical to individuals from the same parent.
    • Sexual: Two parents give rise to offspring that have unique combinations of genes from the two parents.

    Cellular Organization of the Genetic Material (Somatic and Gametes)

    • Somatic cells (Non-reproductive cells) have two sets of chromosomes (diploid).
    • Gametes (Reproductive cells: sperm and eggs) have half the number of chromosomes as somatic cells (haploid).
    • In an unfertilized egg, the sex chromosome is X.
    • In a sperm cell, the sex chromosome may be either X or Y.
    • Sex chromosomes are X and Y.
    • Females have XX chromosomes and males have XY chromosomes.
    • Autosomes are the 22 pairs of chromosomes that are not involved in determining sex.
    • Aneuploidy: abnormal number of chromosomes.

    Sets of Chromosomes in Human Cells, Cell

    • Humans have 23 pairs of chromosomes.
    • The sex chromosomes are called X and Y.
    • Human females have a homologous pair of X chromosome (XX).
    • Human males have one X and one Y chromosome.
    • The remaining 22 pairs of chromosomes are called autosomes.

    Sets of Chromosomes in a Cell (Homologous)

    • The two chromosomes in each pair are called homologous chromosomes or homologs.
    • Chromosomes in a homologous pair have the same length and shape and carry similar genes
    • Each pair of homologous chromosomes includes one chromosome from each parent.
    • Non sister chromatids are chromatids in a homologous pair, one from each parent.

    Behavior of Chromosome Sets in the Human Life Cycle

    • A life cycle is the generation-to-generation sequence of stages in the reproductive history of an organism
    • Fertilization: The union of gametes
    • Zygote: The fertilized egg. Has one set of chromosomes from each parent.
    • The zygote produces somatic cells by mitosis and develops into an adult.

    Animal Life Cycles

    • Gametes are the only haploid cells in animals.
    • Produced by meiosis and undergo no further cell division before fertilization.
    • Gametes fuse to form a diploid zygote that divides by mitosis.
    • Only diploid cells can undergo meiosis.

    Meiosis

    • Meiosis reduces chromosome sets from diploid to haploid cells.
    • Meiosis is preceded by chromosome replication.
    • Meiosis takes place in two consecutive cell divisions called meiosis I and meiosis II.
    • Each daughter cell has half as many chromosomes as the parent cell.
    • Meiosis produces four haploid daughter cells.
    • Crossover allows for genetic recombination.
    • The two cell divisions result in four daughter cells rather than the two daughter cells in mitosis.

    Comparing Mitosis and Meiosis

    • Mitosis: Conserves the number of chromosome sets, and produces cells that are genetically identical to the parent cell.
    • Meiosis: Reduces the number of chromosome sets from two to one (haploid), and produces cells that differ genetically from each other and from the parent cell.

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    Description

    Test your knowledge on meiosis, heredity, and the cell cycle. This quiz covers essential concepts like the structure of genes, gametes, and the characteristics of cancer cells. Dive into the intricate details of cellular processes and their implications for heredity and variation.

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