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

What chromosomal alteration involves the Philadelphia chromosome?

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

What does karyotyping primarily involve?

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

What denotes a normal male karyotype?

<p>46, XY (B)</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 (D)</p> Signup and view all the answers

What is a chromosomal anomaly?

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

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

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

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

<p>46 (A)</p> Signup and view all the answers

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

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

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

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

What is the karyotype for Klinefelter’s syndrome?

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

Which of the following correctly describes the Philadelphia chromosome?

<p>Translocation of part of chromosome 22 (C)</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 (A)</p> Signup and view all the answers

What condition is associated with the karyotype 45, X0?

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

What is the primary function of telomeres on chromatid ends?

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

How is a homologous pair of chromosomes defined?

<p>One chromosome from each parent (D)</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 (B)</p> Signup and view all the answers

What constitutes a normal female karyotype?

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

Which of the following causes can lead to chromosomal abnormalities?

<p>Infection with German measles (C)</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 (B)</p> Signup and view all the answers

Which statement correctly describes a diploid cell?

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

Which chromosome pairs do NOT have a observable secondary constriction?

<p>Chromosome 20 (A)</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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