CR Biology A M4L3
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Questions and Answers

What is the main role of chromosomes during cell division?

  • They filter out unnecessary genetic material.
  • They ensure proper amounts of DNA are distributed to each cell. (correct)
  • They perform all cellular metabolic functions.
  • They produce proteins necessary for mitosis.

    • How many pairs of chromosomes do humans typically have?

  • 25 pairs
  • 23 pairs (correct)
  • 22 pairs
  • 24 pairs

    • What are autosomes?

  • Chromosomes that determine the genetic identity.
  • Chromosomes that are exclusively present in males.
  • Chromosomes specific to female characteristics.
  • Chromosomes that do not contain genes related to sex. (correct)

    • Which statement about the sex chromosomes is true?

    <p>Males have one X and one Y chromosome. (B)</p> Signup and view all the answers

    Why do females have only one active X chromosome in each cell?

    <p>One X chromosome is inactivated to form a Barr body. (C)</p> Signup and view all the answers

    What gene on the Y chromosome is crucial for male sex determination?

    <p>SRY gene (B)</p> Signup and view all the answers

    Which chromosome is larger and holds more genes?

    <p>X chromosome (D)</p> Signup and view all the answers

    Which of the following is considered the default sex of the human species?

    <p>Female (D)</p> Signup and view all the answers

    How many autosomes do humans have?

    <p>22 pairs (B)</p> Signup and view all the answers

    What is the total number of genes present on the Y chromosome?

    <p>Fewer than 100 (A)</p> Signup and view all the answers

    What is one reason the Y chromosome is smaller than the X chromosome?

    <p>The Y chromosome has fewer genes due to evolutionary pressures. (B)</p> Signup and view all the answers

    How do bees, wasps, and ants determine sex?

    <p>Based on the fertilization of eggs. (D)</p> Signup and view all the answers

    What percentage of the human genome consists of genes and their regulatory elements?

    <p>25 percent (B)</p> Signup and view all the answers

    What process allows human cells to produce multiple proteins from a single gene?

    <p>Splicing (B)</p> Signup and view all the answers

    What accounts for the considerable genetic variation among humans?

    <p>Differences in individual DNA bases within alleles (B)</p> Signup and view all the answers

    How many estimated genes do humans have?

    <p>20,000 to 22,000 (C)</p> Signup and view all the answers

    What is a feature of the majority of human genes?

    <p>They have two or more possible alleles. (B)</p> Signup and view all the answers

    Why might the total number of genes not be a reliable measure of complexity in organisms?

    <p>Simpler species sometimes have more genes than humans. (D)</p> Signup and view all the answers

    What is still unclear about a large portion of the base pairs in the human genome?

    <p>Their functions (A)</p> Signup and view all the answers

    Human beings typically possess 24 pairs of chromosomes.

    <p>False (B)</p> Signup and view all the answers

    All autosomes have genes related to sex characteristics.

    <p>False (B)</p> Signup and view all the answers

    Females have two X chromosomes, and males possess one X and one Y chromosome.

    <p>True (A)</p> Signup and view all the answers

    The Y chromosome has more genes than the X chromosome.

    <p>False (B)</p> Signup and view all the answers

    The SRY gene on the Y chromosome is essential for female development.

    <p>False (B)</p> Signup and view all the answers

    Humans have fewer than 20,000 genes.

    <p>False (B)</p> Signup and view all the answers

    The majority of human genetic variation is due to differences in alleles.

    <p>True (A)</p> Signup and view all the answers

    Only 25 percent of the human genome is made up of genes and their regulatory elements.

    <p>True (A)</p> Signup and view all the answers

    Bees and wasps have distinct sex chromosomes for determining gender.

    <p>False (B)</p> Signup and view all the answers

    Human cells can produce multiple proteins from the instructions of a single gene.

    <p>True (A)</p> Signup and view all the answers

    Match the following pairs of chromosomes with their characteristics:

    <p>Autosomes = Chromosomes that contain genes unrelated to sex Sex Chromosomes = Chromosomes that determine an individual's sex X Chromosome = Larger chromosome with about 2,000 genes Y Chromosome = Smaller chromosome containing fewer than 100 genes</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Barr Body = Inactivated X chromosome in females SRY Gene = Triggers male development Chromosome Pairs = Humans typically have 23 pairs Histones = Proteins that help coil DNA into chromosomes</p> Signup and view all the answers

    Match the following characteristics of chromosomes with their specific type:

    <p>Autosomes = 22 pairs in humans Sex Chromosomes = 1 pair in humans consisting of X and Y X Chromosome = Present in both sexes, with an active role in females Y Chromosome = Contains genes for male determination</p> Signup and view all the answers

    Match the following statements about cell division with their relevance:

    <p>Function of Chromosomes = Ensures proper DNA distribution during cell division Human Chromosome Count = 46 chromosomes total, 23 from each parent Chromosomal Structure = Coiled DNA and proteins called histones Autosome Dominance = Great majority of human genes located here</p> Signup and view all the answers

    Match the following features with their corresponding categories:

    <p>X Chromosome = Much larger chromosome Y Chromosome = Contains the SRY gene for sex determination Human Default Sex = Female is the default without Y chromosome Chromosome 22 = Smallest autosome with over 500 genes</p> Signup and view all the answers

    Study Notes

    Chromosomes

    • Coiled bundles of DNA and proteins, essential for cell division.
    • Humans typically have 46 chromosomes, organized into 23 pairs (23 from each parent).
    • Each species has a specific number of chromosomes, with humans having 23 pairs.

    Autosomes

    • Out of 23 pairs, 22 pairs are autosomes (numbered 1-22).
    • Autosomes carry genes unrelated to sex, identical in males and females.
    • Most human genes are found on autosomes.

    Sex Chromosomes

    • The 23rd pair consists of sex chromosomes: X and Y.
    • Females possess two X chromosomes; males have one X and one Y.
    • In females, one X chromosome is inactivated, forming a Barr body, ensuring one functional X per cell.
    • The X chromosome contains approximately 2,000 genes, while the Y chromosome has fewer than 100, none being essential for survival.

    Gene Distribution

    • The SRY gene on the Y chromosome triggers male development; absence of the Y results in female development.
    • The X chromosome has a vast number of genes unrelated to sex; only the Y is sex-specific.

    Human Genes

    • Estimated 20,000 to 22,000 genes in humans.
    • Despite seeming abundant, simpler species have nearly similar gene counts.
    • Human cells utilize splicing to produce multiple proteins from a single gene.
    • Approximately 25% of the 3 billion base pairs in the human genome are involved in gene coding and regulation; functions of many remaining base pairs are unclear.
    • Majority of human genes have two or more alleles, contributing to genetic diversity.
    • Most genetic variation among humans arises from differences in DNA bases within alleles.

    Interesting Fact

    • In species like bees, wasps, and ants, sex determination occurs via fertilization rather than sex chromosomes. Fertilized eggs develop into females, while unfertilized eggs become males.

    Chromosomes

    • Coiled bundles of DNA and proteins, essential for cell division.
    • Humans typically have 46 chromosomes, organized into 23 pairs (23 from each parent).
    • Each species has a specific number of chromosomes, with humans having 23 pairs.

    Autosomes

    • Out of 23 pairs, 22 pairs are autosomes (numbered 1-22).
    • Autosomes carry genes unrelated to sex, identical in males and females.
    • Most human genes are found on autosomes.

    Sex Chromosomes

    • The 23rd pair consists of sex chromosomes: X and Y.
    • Females possess two X chromosomes; males have one X and one Y.
    • In females, one X chromosome is inactivated, forming a Barr body, ensuring one functional X per cell.
    • The X chromosome contains approximately 2,000 genes, while the Y chromosome has fewer than 100, none being essential for survival.

    Gene Distribution

    • The SRY gene on the Y chromosome triggers male development; absence of the Y results in female development.
    • The X chromosome has a vast number of genes unrelated to sex; only the Y is sex-specific.

    Human Genes

    • Estimated 20,000 to 22,000 genes in humans.
    • Despite seeming abundant, simpler species have nearly similar gene counts.
    • Human cells utilize splicing to produce multiple proteins from a single gene.
    • Approximately 25% of the 3 billion base pairs in the human genome are involved in gene coding and regulation; functions of many remaining base pairs are unclear.
    • Majority of human genes have two or more alleles, contributing to genetic diversity.
    • Most genetic variation among humans arises from differences in DNA bases within alleles.

    Interesting Fact

    • In species like bees, wasps, and ants, sex determination occurs via fertilization rather than sex chromosomes. Fertilized eggs develop into females, while unfertilized eggs become males.

    Chromosomes

    • Coiled bundles of DNA and proteins, essential for cell division.
    • Humans typically have 46 chromosomes, organized into 23 pairs (23 from each parent).
    • Each species has a specific number of chromosomes, with humans having 23 pairs.

    Autosomes

    • Out of 23 pairs, 22 pairs are autosomes (numbered 1-22).
    • Autosomes carry genes unrelated to sex, identical in males and females.
    • Most human genes are found on autosomes.

    Sex Chromosomes

    • The 23rd pair consists of sex chromosomes: X and Y.
    • Females possess two X chromosomes; males have one X and one Y.
    • In females, one X chromosome is inactivated, forming a Barr body, ensuring one functional X per cell.
    • The X chromosome contains approximately 2,000 genes, while the Y chromosome has fewer than 100, none being essential for survival.

    Gene Distribution

    • The SRY gene on the Y chromosome triggers male development; absence of the Y results in female development.
    • The X chromosome has a vast number of genes unrelated to sex; only the Y is sex-specific.

    Human Genes

    • Estimated 20,000 to 22,000 genes in humans.
    • Despite seeming abundant, simpler species have nearly similar gene counts.
    • Human cells utilize splicing to produce multiple proteins from a single gene.
    • Approximately 25% of the 3 billion base pairs in the human genome are involved in gene coding and regulation; functions of many remaining base pairs are unclear.
    • Majority of human genes have two or more alleles, contributing to genetic diversity.
    • Most genetic variation among humans arises from differences in DNA bases within alleles.

    Interesting Fact

    • In species like bees, wasps, and ants, sex determination occurs via fertilization rather than sex chromosomes. Fertilized eggs develop into females, while unfertilized eggs become males.

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    Description

    Explore the fundamental concepts of chromosomes and genes in this quiz. Discover how chromosomes play a vital role during cell division and how they ensure proper DNA distribution. Test your knowledge of the characteristics and functions of these essential genetic structures.

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