أسئلة السادسة هستولوجي (قبل التعديل)
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Questions and Answers

What is Klinefelter's syndrome characterized by?

  • Three X chromosomes in males
  • An extra Y chromosome in males
  • Only one X chromosome in males
  • An extra X chromosome in males (correct)

    • Which of the following describes Turner’s syndrome?

  • Presence of an extra Y chromosome in females
  • Presence of multiple X chromosomes in females
  • Duplication of chromosome 21 in females
  • Missing one X chromosome in females (correct)

    • What is a common karyotype associated with Multiple X syndrome?

  • 46, XY
  • 48, XXXX
  • 45, XX
  • 47, XXX (correct)

    • What genetic anomaly is associated with Cri-du-chat syndrome?

    <p>Partial deletion of the short arm of chromosome 5</p> Signup and view all the answers

    What chromosomal alteration involves the Philadelphia chromosome?

    <p>Translocation involving chromosome 22 and chromosome 9</p> Signup and view all the answers

    What does karyotyping primarily involve?

    <p>Studying the number and morphology of chromosomes</p> Signup and view all the answers

    Which of the following correctly describes the components of a chromosome?

    <p>Each chromosome is made of two identical halves called sister chromatids</p> Signup and view all the answers

    What denotes a normal male karyotype?

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

    In a homologous pair of chromosomes, where does each chromosome originate from?

    <p>One from the maternal parent, one from the paternal parent</p> Signup and view all the answers

    What is a chromosomal anomaly?

    <p>Deviation from the normal number or morphology of chromosomes</p> Signup and view all the answers

    Which of the following is NOT a cause of chromosomal abnormalities?

    <p>Young maternal age</p> Signup and view all the answers

    How many chromosomes are present in a normal human diploid cell?

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

    Which condition is characterized by a numerical aberration of sex chromosomes?

    <p>Turner’s syndrome</p> Signup and view all the answers

    What condition is characterized by an extra chromosome 21 in each cell?

    <p>Down syndrome</p> Signup and view all the answers

    What is the karyotype for Klinefelter’s syndrome?

    <p>47, XXY</p> Signup and view all the answers

    Which of the following correctly describes the Philadelphia chromosome?

    <p>Translocation of part of chromosome 22</p> Signup and view all the answers

    Which chromosomal abnormality is characterized by a partial deletion of the short arm of chromosome 5?

    <p>Cri-du-chat syndrome</p> Signup and view all the answers

    What condition is associated with the karyotype 45, X0?

    <p>Turner’s syndrome</p> Signup and view all the answers

    What is the primary function of telomeres on chromatid ends?

    <p>To protect and stabilize chromosome ends</p> Signup and view all the answers

    How is a homologous pair of chromosomes defined?

    <p>One chromosome from each parent</p> Signup and view all the answers

    Which of the following conditions is NOT classified as a numerical chromosomal anomaly?

    <p>Cri-du-chat syndrome</p> Signup and view all the answers

    What constitutes a normal female karyotype?

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

    Which of the following causes can lead to chromosomal abnormalities?

    <p>Infection with German measles</p> Signup and view all the answers

    What is the primary structural feature of a metaphase chromosome?

    <p>Sister chromatids are connected at the centromere</p> Signup and view all the answers

    Which statement correctly describes a diploid cell?

    <p>Contains two copies of every chromosome</p> Signup and view all the answers

    Which chromosome pairs do NOT have a observable secondary constriction?

    <p>Chromosome 20</p> Signup and view all the answers

    What is the karyotype for a male with Klinefelter's syndrome?

    <p>The karyotype for a male with Klinefelter's syndrome is typically 47, XXY.</p> Signup and view all the answers

    Describe the chromosomal composition of a female with Turner’s syndrome.

    <p>A female with Turner’s syndrome has a karyotype of 45, XO.</p> Signup and view all the answers

    What is a significant characteristic of Wolf syndrome?

    <p>Wolf syndrome is marked by a partial deletion of the short arm of chromosome 4.</p> Signup and view all the answers

    What type of chromosomal alteration is represented by the Philadelphia chromosome?

    <p>The Philadelphia chromosome involves a translocation between chromosome 9 and chromosome 22.</p> Signup and view all the answers

    Identify the karyotype associated with Multiple X syndrome.

    <p>The karyotype associated with Multiple X syndrome can be 47, XXX.</p> Signup and view all the answers

    What is the role of telomerase in relation to telomeres?

    <p>Telomerase adds repeated DNA sequences to telomeres, protecting and stabilizing the ends of chromosomes.</p> Signup and view all the answers

    How many homologous pairs of chromosomes are found in normal human males and females?

    <p>Normal human males have 22 homologous pairs and one non-homologous pair, while females have 23 homologous pairs.</p> Signup and view all the answers

    Describe what is meant by a chromosomal anomaly.

    <p>A chromosomal anomaly refers to a deviation from the normal number or morphology of chromosomes.</p> Signup and view all the answers

    What are the two main types of chromosomal abnormalities?

    <p>The two main types are numerical abnormalities (wrong number of chromosomes) and structural abnormalities (abnormal shape of chromosomes).</p> Signup and view all the answers

    Explain how homologous chromosomes are inherited from parents.

    <p>One homologue of a homologous pair comes from the maternal parent, and the other comes from the paternal parent.</p> Signup and view all the answers

    What is the significance of the centromere in a chromosome?

    <p>The centromere is where sister chromatids are joined and plays a key role during cell division.</p> Signup and view all the answers

    Identify one possible cause of chromosomal abnormalities.

    <p>One possible cause of chromosomal abnormalities is advanced maternal age during pregnancy.</p> Signup and view all the answers

    What is the typical number of chromosomes in human diploid cells?

    <p>Human diploid cells typically contain 46 chromosomes.</p> Signup and view all the answers

    Study Notes

    Karyotyping

    • Study of the number and morphology (shape) of chromosomes in an individual.
    • A map of the complete set of chromosomes of an individual, arranged as homologous pairs according to their length.
    • A person's karyotype is written with the total number of chromosomes followed by the sex chromosomes.
      • Normal male karyotype: 46, XY.
      • Normal female karyotype: 46, XX.

    Chromosome Morphology

    • Each chromosome (d-chromosome) is made of two identical halves called sister chromatids, joined at the primary constriction (centromere).
    • Each chromatid consists of a tightly coiled molecule of DNA.
    • The terminal end of the chromatid is called the telomere, which:
      • Is a repeated DNA sequence added by the telomerase enzyme.
      • Protects and stabilizes the end of the chromosome.
    • Diploid cells contain two copies of every chromosome.
    • A pair of such chromosomes is called a homologous pair.
    • One homologue originates from the maternal parent, the other from the paternal parent.
    • Humans have 46 chromosomes (23 homologous pairs).
    • Males have 22 homologous pairs (autosomes) and one non-homologous pair - the sex chromosomes X and Y.
    • Some chromosomes have a secondary constriction on the upper arms (chromosomes 13, 14, 15, 21, and 22).
    • The terminal portion of this secondary constriction is called a satellite.

    Chromosomal Anomalies

    • Deviation from the normal number or morphology of chromosomes.
    • Can affect autosomes or sex chromosomes.
    • Types:
      • Numerical (abnormal number)
      • Structural (abnormal shape)
    • Examples:
      • Numerical:
        • Turner's Syndrome
        • Klinefelter's Syndrome
        • Down's Syndrome
        • Wolf Syndrome
        • Cri-du-chat Syndrome
        • Multiple X Syndrome
        • YY Syndrome
      • Structural:
        • Philadelphia chromosome
    • Causes:
      • Radiation
      • Infection with German measles
      • Pregnancy in old age
      • Autoimmune diseases
      • Family history of chromosomal abnormalities

    Numerical Aberrations of Sex Chromosomes

    • Klinefelter’s Syndrome:
      • A condition in which a male has an extra X chromosome (XXY).
      • Karyotype:
        • 47, XXY
        • 48, XXXY
        • 49, XXXXY
    • YY Syndrome:
      • A condition in which a male has an extra Y chromosome (XYY).
      • Karyotype:
        • 47, XYY
    • Turner’s Syndrome:
      • A condition in which a female has only one X chromosome (XO).
      • Karyotype:
        • 45, XO
    • Multiple X Syndrome:
      • A condition in which a female has an extra X chromosome (XXX).
      • Karyotype:
        • 47, XXX
        • 48, XXXX
        • 49, XXXXX

    Down's Syndrome

    • A condition in which there is an extra chromosome 21 in each cell (trisomy).
    • Most common chromosomal abnormality.
    • Karyotype:
      • 47, XY+21 (male)
      • 47, XX+21 (female)

    Structural Chromosomal Aberrations

    • Wolf Syndrome:
      • Cause: Partial deletion of the short arm of chromosome 4.
      • Karyotype:
        • Male: 46, XY, 4p-
        • Female: 46, XX, 4p-
    • Cri-du-Chat Syndrome:
      • Cause: Partial deletion of the short arm of chromosome 5.
      • Karyotype:
        • Male: 46, XY, 5p-
        • Female: 46, XX, 5p-
    • Philadelphia Chromosome:
      • Cause: Translocation of half of the long arm of chromosome 22 to chromosome 9.
      • Karyotype:
        • 46, XX/XY, t(9;22)

    Karyotyping

    • Karyotyping: Study of the number and morphology (shape) of chromosomes in an individual.
    • Karyotype: Map of the complete set of chromosomes of an individual, arranged as homologous pairs according to their length.

    How to Write a Karyotype

    • The karyotype is written as the total number of chromosomes, followed by the sex chromosomes.
      • Normal male karyotype: 46, XY
      • Normal female karyotype: 46, XX
    • The shorter arm of a chromosome is denoted as "p" and the longer arm as "q".

    Chromosome Morphology

    • Each chromosome (d-chromosome) is made of two identical halves called sister chromatids, joined at the primary constriction called the centromere.
    • Each chromatid consists of a tightly coiled molecule of DNA.
    • The terminal end of a chromatid is called a telomere:
      • It's a repeated DNA sequence added by telomerase enzyme.
      • It protects and stabilizes the end of the chromosome.
    • Diploid cells contain two copies of every chromosome.
    • A pair of such chromosomes is called a homologous pair.
      • One homologue originates from the maternal parent.
      • The other originates from the paternal parent.
    • Humans have 46 chromosomes (23 homologous pairs).
    • In males, there are 22 homologous pairs (autosomes) and one non-homologous pair - the sex chromosomes X and Y.
    • Some chromosomes have a secondary constriction on the upper arm (chromosomes 13, 14, 15, 21, and 22).
    • The terminal portion of the secondary constriction is called a satellite.

    Chromosomal Anomalies

    • Deviation from the normal number or morphology (shape) of chromosomes.
    • Can affect autosomes or sex chromosomes.
    • Types:
      • Numerical (abnormal number)
      • Structural (abnormal shape)
    • Examples:
      • Turner's syndrome
      • Klinefelter's syndrome
      • Down's syndrome
      • Wolf syndrome
      • Cri-du-chat syndrome
      • Multiple X syndrome
      • YY syndrome
      • Philadelphia chromosome

    Causes of Chromosomal Anomalies

    • Radiation
    • Infection with German measles
    • Pregnancy in old age
    • Autoimmune diseases
    • Family history of chromosomal abnormalities

    Numerical Aberrations of Sex Chromosomes

    • Klinefelter's syndrome: A condition where a male has an extra X chromosome (XXY).
      • Karyotype: 47, XXY; 48, XXXY; 49, XXXXY
    • YY Syndrome: A condition where a male has an extra Y chromosome (XYY).
      • Karyotype: 47, XYY
    • Turner's syndrome: A condition where a female has only one X chromosome (XO).
      • Karyotype: 45, XO
    • Multiple X syndrome: A condition where a female has an extra X chromosome (XXX).
      • Karyotype: 47, XXX; 48, XXXX; 49, XXXXX

    Down's Syndrome

    • A condition where there is an extra chromosome 21 in each cell (trisomy).
    • Most common chromosomal abnormality.
    • Karyotype: 47, XY + 21 (male); 47, XX + 21 (female)

    Structural Chromosomal Aberrations

    • Wolf Syndrome: Partial deletion of the short arm of chromosome 4.
    • Causes:
      • Male: 46, XY, 4p-
      • Female: 46, XX, 4p-
    • Cri-du-chat Syndrome: Partial deletion of the short arm of chromosome 5.
    • Causes:
      • Male: 46, XY, 5p-
      • Female: 46, XX, 5p-
    • Philadelphia Chromosome (PH): Translocation of half of the long arm of chromosome 22 to chromosome 9.
    • Karyotype: 46, XX (or XY), t(9;22)

    Karyotyping

    • Study of the number and morphology (shape) of chromosomes in an individual
    • A karyotype is a map of the complete set of chromosomes of an individual, arranged as homologous pairs according to their length
    • Normal male karyotype: 46, XY
    • Normal female karyotype: 46, XX

    Chromosome Morphology

    • Each chromosome (d-chromosome) consists of two identical halves called sister chromatids, joined at the primary constriction known as the centromere
    • Each chromatid consists of a tightly coiled molecule of DNA
    • The terminal end of the chromatid is called the telomere, which is a repeated DNA sequence added by the telomerase enzyme
    • The telomere protects and stabilizes the end of the chromosome
    • Diploid cells contain two copies of every chromosome
    • A pair of such chromosomes is called a homologous pair
    • In a homologous pair of chromosomes:
      • One homologue originates from the maternal parent
      • The other from the paternal parent
    • Humans have 46 chromosomes (23 homologous pairs)
    • Males have 22 homologous pairs (autosomes) and one non-homologous pair - the sex chromosomes of X and Y
    • Some chromosomes have a secondary constriction on the upper arms (chromosomes: 13, 14, 15, 21 & 22)
    • The terminal portion of this constriction is called a satellite

    Chromosomal Anomalies

    • Deviations from the normal number or morphology (shape) of chromosomes
    • Can affect autosomes or sex chromosomes
    • Types:
      • Numerical (abnormal number)
      • Structural (abnormal shape)
    • Examples:
      • Turner’s syndrome
      • Klinefelter’s syndrome
      • Wolf syndrome
      • Down’s syndrome
      • Cri-du-chat syndrome
      • Multiple X syndrome
      • YY syndrome
      • Philadelphia chromosome
    • Causes:
      • Radiation
      • Infection with German measles
      • Pregnancy in old age
      • Autoimmune diseases
      • Family history of chromosomal abnormalities

    Numerical Aberrations of Sex Chromosomes

    • Klinefelter’s syndrome:
      • Male has an extra X chromosome (XXY)
      • Karyotypes: 47, XXY; 48, XXXY; 49, XXXXY
    • YY syndrome:
      • Male has an extra Y chromosome (XYY)
      • Karyotype: 47, XYY
    • Turner’s syndrome:
      • Female has only one X instead of two (XO)
      • Karyotype: 45, XO
    • Multiple X Syndrome:
      • Female has an extra X chromosome (XXX or more)
      • Karyotypes: 47, XXX; 48, XXXX; 49, XXXXX

    Down Syndrome

    • Extra chromosome 21 in each cell (trisomy)
    • Most common chromosomal abnormality
    • Karyotypes: 47, XY+21 (male); 47, XX+21 (female)

    Structural Chromosomal Aberrations

    • Wolf syndrome:
      • Partial deletion of the short arm of chromosome no. 4
      • Karyotype: 46, XY, 4p- (male); 46, XX, 4p- (female)
    • Cri-du-chat syndrome:
      • Partial deletion of the short arm of chromosome no. 5
      • Karyotype: 46, XY, 5p- (male); 46, XX, 5p- (female)
    • Philadelphia chromosome (PH):
      • Translocation of half of the long arm of chromosome no. 22 to chromosome no. 9
      • Karyotype: 46, XX (or XY), t (9; 22)

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