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Questions and Answers
What is a deletion error in chromosome structure?
Which genetic disorder is caused by a deletion error?
What characterizes duplication errors in chromosomes?
Which of the following is a symptom of Charcot-Marie-Tooth Disease?
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What type of genetic alteration does inversion refer to?
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Which disorder is associated with an inversion error?
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Which of the following does NOT describe a feature of Cri du Chat?
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What is a characteristic common to genetic disorders described from chromosomal errors?
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What is a common genetic disorder caused by a translocation error?
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During which stage of meiosis does nondisjunction occur in homologous chromosomes?
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What term describes the condition of having one or more extra or missing chromosomes?
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Which disorder is characterized by an additional copy of chromosome 21?
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What is the result of monosomy during meiosis?
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What factor could potentially increase the risk of chromosome abnormalities?
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What happens during Anaphase 2 of meiosis?
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Which of the following is NOT a type of genetic disorder associated with chromosome number?
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What are the two primary processes that produce genetic variation during meiosis?
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How does sexual reproduction benefit genetic diversity compared to asexual reproduction?
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Which type of chromosomal error involves a piece of chromosome being removed?
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What can result from errors during the crossing over process in meiosis?
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What is a major drawback of sexual reproduction?
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Which of the following errors results in a section of a chromosome repeating multiple times?
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What is the role of independent assortment in genetic variation?
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What happens if a surviving gamete with a chromosomal error participates in fertilization?
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What is a significant risk factor for older women regarding childbirth?
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What percentage of babies is born with cystic fibrosis?
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Which type of genetic screening is performed directly on the fetus?
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What does prenatal genetic testing evaluate in a fetus?
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Which of the following is a non-invasive test in genetic screening?
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What represents a significant ethical consideration in prenatal genetic testing?
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What material is collected during amniocentesis?
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Which factor can influence the likelihood of certain genetic disorders?
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Study Notes
Errors in meiosis
- Crossing over and independent assortment, while increasing genetic variability, can lead to chromosomal abnormalities
- Many errors in meiosis lead to gametes that cannot survive
- If a gamete with an error survives it will produce a zygote with that error
- Every cell in offspring will contain the error
Types of chromosomal errors
- Errors can occur in chromosome structure or chromosome number
- Errors in structure include: deletion, duplication, inversion, and translocation
- Errors in chromosome number occur when chromosomes fail to separate during meiosis (nondisjunction) and result in aneuploidy (a gain or loss of chromosomes)
Deletion
- A piece of a chromosome is removed
- Cri du Chat syndrome is caused by a deletion in chromosome 5
- Symptoms include high-pitched cries, low birth weight, widely spaced eyes, recessed chin, and developmental and cognitive delays.
Duplication
- A segment of a chromosome is duplicated - occurs 2 or more times
- Charcot-Marie-Tooth disease is caused by a duplication of a gene on chromosome 17
- Symptoms include muscle weakness and loss of sensation in legs, feet, and hands, and a high foot arch with flexed toes
Inversion
- A segment of a chromosome is inverted or reversed
- FG Syndrome is caused by an inversion in the X chromosome
- Symptoms include intellectual disabilities, delayed motor development, and low muscle tone, and occurs almost exclusively in males
- No cure
Translocation
- A segment of one chromosome attaches to another
- Chronic Myelogenous Leukemia (CML) is a cancer caused by a translocation between chromosome 9 and chromosome 22.
- A translocation produces an abnormal gene that leads to an increase in white blood cell production
- CML is treatable with a drug that stops the production of white blood cells
Nondisjunction
- A failure of homologous chromosomes or sister chromatids to separate during meiosis (Anaphase 1 or 2)
- Causes aneuploidy (when gametes have too many or too few chromosomes)
- Trisomy involves the gain of an extra chromosome, for example: Down Syndrome, which is caused by an extra copy of chromosome 21
- Down Syndrome results in intellectual disabilities, a flattened face, short stature and more
- Monosomy involves the loss of a chromosome, for example: Turner Syndrome, (missing X chromosome), which results in underdeveloped female sexual characteristics.
- Turner Syndrome occurs almost only in females
Other factors that may increase the risk of chromosomal abnormalities
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Maternal age: older women are at a higher risk of giving birth to infants with chromosomal abnormalities
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Environmental factors may also play a role in chromosomal abnormalities
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Key Concepts*
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Errors in Meiosis can lead to genetic disorders
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Genetic disorders can result from changes in chromosome structure and chromosome number
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Nondisjunction leads to aneuploidy, which describes a change in the number of chromosomes.
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Description
This quiz covers the key concepts related to errors in meiosis, including chromosomal abnormalities caused by crossing over and independent assortment. It explores types of structural and numerical chromosomal errors, as well as specific conditions such as Cri du Chat syndrome resulting from deletion. Test your understanding of how these errors affect genetic variability and offspring development.
