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Questions and Answers
What is the basic unit of inheritance?
What is the basic unit of inheritance?
What does a telomere do?
What does a telomere do?
Which type of chromosomal abnormality involves a loss of a chromosomal segment?
Which type of chromosomal abnormality involves a loss of a chromosomal segment?
What term describes when a chromosomal segment breaks, reorients, and reinserts itself?
What term describes when a chromosomal segment breaks, reorients, and reinserts itself?
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What is the effect of old age on the risk of chromosomal abnormalities in pregnant women?
What is the effect of old age on the risk of chromosomal abnormalities in pregnant women?
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What structure is formed when both arms of a chromosome are lost and reunite in a ring formation?
What structure is formed when both arms of a chromosome are lost and reunite in a ring formation?
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What are somatic cells characterized by regarding chromosome number?
What are somatic cells characterized by regarding chromosome number?
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What causes numerical chromosomal abnormalities?
What causes numerical chromosomal abnormalities?
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What is polyploidy?
What is polyploidy?
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Which of the following is NOT a mechanism of polyploidy?
Which of the following is NOT a mechanism of polyploidy?
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What does aneuploidy refer to?
What does aneuploidy refer to?
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Which trisomy is associated with Down syndrome?
Which trisomy is associated with Down syndrome?
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Which syndrome is characterized by the presence of 47 chromosomes, XXY?
Which syndrome is characterized by the presence of 47 chromosomes, XXY?
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What is a characteristic of Turner syndrome?
What is a characteristic of Turner syndrome?
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Which of the following describes the term 'Barr body'?
Which of the following describes the term 'Barr body'?
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What is the result of monosomy in autosomes?
What is the result of monosomy in autosomes?
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Study Notes
Chromosomal Abnormalities
- Genetics is the study of heredity and its variations.
- A gene is the basic unit of inheritance, formed of DNA, and responsible for protein formation.
- A chromosome is a thread-like structure of DNA that carries genes for hereditary information.
- Each chromosome is formed of two chromatids.
- Each chromatid has a short arm (p arm) and a long arm (q arm).
- The two chromatids are attached at a point called the centromere.
- Kinetochores are points on the centromere, where spindle fibers attach.
- A diploid state signifies the presence of two copies of each chromosome.
- A haploid state signifies a single copy of each chromosome.
- Somatic cells have a diploid number of chromosomes.
- Gametes (ova and testes) have a haploid number of chromosomes.
- Telomeres are repetitive DNA sequences at each chromosome end, protecting from deterioration or fusion with adjacent chromosomes.
Types of Chromosomal Abnormalities
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Structural abnormalities:
- Deletions (del): Loss of a chromosomal segment.
- Ring chromosomes (r): The ends of chromosome arms fuse to form a ring.
- Inversions (inv): A chromosomal segment breaks, reorients 180 degrees, and rejoins.
- Translocation: Transfer of segments between chromosomes.
- Isochromosomes: Abnormal transverse division of the centromere, separating the two arms instead of longitudinally dividing the two chromatids.
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Numerical abnormalities:
- Polyploidy: Abnormal duplication of the haploid chromosome number (e.g., 3n, 4n).
- Aneuploidy: Abnormal number of chromosomes.
- Trisomy: Extra chromosome (e.g., Down syndrome - trisomy 21, Patau syndrome - trisomy 13, Edward syndrome - trisomy 18 ).
- Monosomy: Missing chromosome.
- Monosomy of autosomes is lethal.
- Aneuploidy of sex chromosomes (e.g., Klinefelter syndrome - 47, XXY, Turner syndrome - 45, X).
Causes of Chromosomal Abnormalities
- Hereditary factors
- Advanced maternal age
- Infections during pregnancy (e.g., German measles).
- Exposure to radiation or autoimmune diseases during pregnancy.
Sex Chromatin (Barr Body)
- Sex chromatin is an inactive X chromosome in female cells during interphase.
- Stained with basic dyes (Feulgen positive).
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Description
This quiz explores the fundamental concepts of chromosomal abnormalities and genetic inheritance. It covers the structure of chromosomes, types of chromosomal variations, and the significance of genes and DNA. Test your knowledge on the genetic principles that govern hereditary information and the role of chromosomes in biological functions.
