Anatomy of a Chromosome
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Anatomy of a Chromosome

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Questions and Answers

What are sister chromatids?

  • The two halves of a replicated chromosome (correct)
  • Segments at the ends of chromosomes
  • Unreplicated chromosomes
  • The pinched center of a chromosome

    • What role do telomeres play at the ends of chromosomes?

  • They connect sister chromatids
  • They protect chromosome ends from degradation (correct)
  • They assist in the alignment of chromosomes during mitosis
  • They facilitate chromosome replication

    • How are telomeres related to aging?

  • They have no known impact on aging
  • They remain constant throughout life
  • They grow longer as we age
  • They shorten with age and lead to cell death (correct)

    • What is the outcome of mitosis?

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

    What is the significance of crossing over during meiosis?

    <p>It allows for recombination between homologous chromosomes</p> Signup and view all the answers

    What characterizes meiosis I?

    <p>It segregates homologous chromosomes</p> Signup and view all the answers

    What happens to DNA between meiosis I and meiosis II?

    <p>There is no DNA replication</p> Signup and view all the answers

    Why is it necessary for gametes to have half the number of chromosomes?

    <p>To ensure proper fertilization and avoid extra chromosomes</p> Signup and view all the answers

    What can lead to shortened telomeres?

    <p>Aging and lifestyle choices like smoking</p> Signup and view all the answers

    What is the function of the kinetochore?

    <p>To attach the mitotic spindle during cell division</p> Signup and view all the answers

    Which functional group is part of thiols and contributes to hydrophilicity?

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

    At body pH, carboxyl groups are positively charged.

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

    What is the significance of phosphate groups in organic compounds?

    <p>They are part of ATP and nucleic acids, and are negatively charged and very hydrophilic.</p> Signup and view all the answers

    The structural formula of an alcohol features the functional group known as the ______ group.

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

    Match the following functional groups with their significance:

    <p>Ester = Part of dietary fats and oils Amino = Part of amino acids Carbonyl = Part of ketones and aldehydes Carboxyl = Part of carboxylic acids</p> Signup and view all the answers

    Which functional group is part of amino acids and is typically positively charged at body pH?

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

    At body pH, carboxyl groups are negatively charged.

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

    What part of organic compounds do functional groups represent?

    <p>Other atoms or molecules attached to the carbon skeleton</p> Signup and view all the answers

    The __________ group is found in fats and oils and contributes to their structure.

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

    Match the following functional groups with their significance:

    <p>Hydroxyl = Provides hydrophilicity Sulfhydryl = Part of thiols including amino acids Phosphate = Part of ATP and nucleic acids Carbonyl = Present in ketones and aldehydes</p> Signup and view all the answers

    Study Notes

    Anatomy of a Chromosome

    • An unreplicated chromosome is referred to simply as a chromosome.
    • A replicated chromosome remains classified as a chromosome.
    • The two identical halves of a replicated chromosome are called sister chromatids.
    • The centromere is the pinched center of a chromosome.
    • The kinetochore, a protein complex around the centromere, attaches to the mitotic spindle during mitosis.

    Telomeres

    • Telomeres are protective DNA sequences located at the ends of chromosomes, preventing shortening.
    • Human chromosomes are linear, exposing free DNA ends to nucleases that can degrade them.
    • Telomeres "cap" chromosome ends to safeguard against nucleolytic degradation and are added by telomerase.
    • One aging hypothesis suggests that telomeres shorten over time, leading to cell death when they reach a critical length.
    • Lifestyle choices like smoking and obesity are linked to shortened telomeres.
    • Cancer cells often exhibit overactive telomerase, which prolongs telomeres and promotes rapid cell division, contributing to tumor growth.

    Mitosis

    • Mitosis produces two identical diploid daughter cells.

    Reproductive Cell Division

    • Fertilization poses a challenge where an egg and sperm fuse; both having a full chromosome set would double the DNA.
    • Gametes (eggs and sperm) must have half the DNA, achieved through meiosis.
    • Meiosis involves two consecutive divisions and starts with diploid reproductive cells.

    Meiosis I

    • During Meiosis I, homologous chromosomes are segregated.
    • Crossing over occurs early in Meiosis I, allowing genetic recombination between homologous chromosomes.
    • Homologous chromosomes align at the equatorial plate during meiosis.
    • The meiotic spindle partitions homologous chromosomes into two nonidentical daughter cells, each with a haploid set of chromosomes.

    Meiosis II

    • No DNA replication occurs between Meiosis I and Meiosis II.
    • Meiosis II involves the segregation of sister chromatids.
    • Replicated chromosomes align along the equatorial plate in Meiosis II.
    • The meiotic spindle partitions sister chromatids into separate daughter cells, resulting in four nonidentical daughter cells, each with a haploid chromosome set.

    Functional Groups of Organic Compounds

    • Hydroxyl (R-O-H)

      • Characterizes alcohols
      • Provides a polar group, contributing to hydrophilicity in various compounds

    • Sulfhydryl (R-S-H)

      • Integral to thiols, including amino acids like cysteine and methionine
      • Exhibits polarity and contributes to hydrophilicity

    • Carbonyl

      • Part of ketones (structure on the left) and aldehydes (structure on the right)
      • Exhibits polar characteristics and is hydrophilic

    • Carboxyl

      • Found in carboxylic acids and amino acids
      • At physiological pH, carboxyl groups carry a negative charge, enhancing hydrophilicity

    • Ester

      • Common in dietary fats, oils, and triglycerides
      • Some medications, including aspirin, are classified as esters

    • Phosphate

      • Essential part of ATP and nucleic acids
      • Negatively charged and exhibits strong hydrophilicity

    • Amino

      • Key component of amino acids
      • At body pH, most amino groups are positively charged, contributing to hydrophilicity

    Functional Groups of Organic Compounds

    • Hydroxyl (R-O-H)

      • Characterizes alcohols
      • Provides a polar group, contributing to hydrophilicity in various compounds

    • Sulfhydryl (R-S-H)

      • Integral to thiols, including amino acids like cysteine and methionine
      • Exhibits polarity and contributes to hydrophilicity

    • Carbonyl

      • Part of ketones (structure on the left) and aldehydes (structure on the right)
      • Exhibits polar characteristics and is hydrophilic

    • Carboxyl

      • Found in carboxylic acids and amino acids
      • At physiological pH, carboxyl groups carry a negative charge, enhancing hydrophilicity

    • Ester

      • Common in dietary fats, oils, and triglycerides
      • Some medications, including aspirin, are classified as esters

    • Phosphate

      • Essential part of ATP and nucleic acids
      • Negatively charged and exhibits strong hydrophilicity

    • Amino

      • Key component of amino acids
      • At body pH, most amino groups are positively charged, contributing to hydrophilicity

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    Description

    This quiz delves into the structure and components of chromosomes, including unreplicated and replicated forms. It covers essential terms such as sister chromatids, centromeres, kinetochores, and telomeres. Test your understanding of these fundamental concepts in cell biology!

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