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Questions and Answers
What may occur if meiosis does not proceed normally?
Miscarriages, genetic errors, and birth defects
What is a mutation?
A harmful change to a gene
Which of the following are causes of mutations? (Select all that apply)
Match the types of mutations with their descriptions:
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What is meiotic nondisjunction?
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What condition is a common cause of genetic disorders?
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What is Trisomy 21 also known as?
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Which of the following is a sign of Down syndrome? (Select all that apply)
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What is Cri-du-chat syndrome caused by?
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What is Turner syndrome?
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Study Notes
Chromosomal Genetic Disorders
- Result from mutations affecting genes or an incorrect amount of genetic material.
- Mutations are harmful changes to a gene, often caused by errors during cell division or exposure to DNA-damaging agents like chemicals, radiation, and UV light.
Types of Mutations
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Point mutations involve a single base change in DNA.
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Substitution: One base is replaced with another.
- Example: Sickle cell anemia results from a substitution mutation in the gene for hemoglobin.
- Insertion: Extra nucleotides are added to the DNA sequence.
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Deletion: One or more nucleotides are removed from the DNA sequence.
- Example: Cystic fibrosis is caused by a deletion mutation in the CFTR gene.
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Substitution: One base is replaced with another.
Chromosomal Mutations
- Affect the structure or number of chromosomes.
- Deletion: A part of a chromosome is lost, removing all genes in that segment.
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Duplication: A segment of a chromosome is repeated, increasing the concentration of genes in that area.
- Example: Duplication of genes can contribute to cancer development.
Meiosis and Chromosomal Disorders
- Meiosis is the process of cell division that creates gametes (sperm and egg).
- Meiotic nondisjunction occurs when homologous chromosomes fail to separate properly during meiosis, resulting in gametes with an incorrect number of chromosomes.
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Aneuploidy refers to an abnormal number of chromosomes.
- Trisomy: Presence of an extra chromosome.
- Monosomy: Absence of one chromosome.
- Deletions: Missing pieces of chromosomes or genetic material.
- Translocations: Pieces of chromosomes break off and reattach to another chromosome.
Trisomy 21/Down Syndrome
- Caused by the presence of an extra copy of chromosome 21.
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Signs and symptoms:
- Distinctive facial features (slanted eyes, flat nasal bridge, small mouth).
- Flexible joints and weak muscles.
- Inwardly curved little finger (clinodactyly).
- Wide space between big and second toe.
- Short stature.
- Small hands and feet.
- Single, deep crease across palm (simian crease).
Cri-du-chat Syndrome
- Also known as 5p- Syndrome, it results from deletion of a piece of chromosome 5.
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Signs and symptoms:
- High-pitched cry resembling a cat's meow.
- Mental retardation.
- Delayed development.
- Distinctive facial features (small head, widely spaced eyes).
- Low birth weight and weak muscle tone.
Turner Syndrome
- Genetic condition affecting females where one X chromosome is missing or partly missing.
- Affects physical development and reproductive system.
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Signs and symptoms:
- Short stature.
- Webbed neck.
- Infertility.
- Heart defects.
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Description
Test your knowledge on chromosomal genetic disorders and mutations. This quiz covers various types of mutations like point mutations, chromosomal mutations, and their effects on health. Understand how alterations in DNA can lead to conditions like sickle cell anemia and cystic fibrosis.
