Genetic and Chromosomal Disorders Overview
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Questions and Answers

Which term describes a permanent change in the DNA sequence of a gene?

  • Mutation (correct)
  • Karyotype
  • Phenotype
  • Carrier

    • Which of the following is an example of an autosomal recessive disorder?

  • Huntington's Disease
  • Marfan Syndrome
  • Hemophilia
  • Sickle Cell Anemia (correct)

    • What does a karyotype represent?

  • The total number of genes in an organism
  • The genetic makeup affecting specific traits
  • The physical characteristics of an organism
  • A photographic representation of chromosomes (correct)

    • Nondisjunction during meiosis leads to which of the following?

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

    Which inheritance pattern requires one mutated gene from either parent to cause a disorder?

    <p>Autosomal Dominant (D)</p> Signup and view all the answers

    Which of the following best defines a genome?

    <p>The complete set of DNA in an organism (C)</p> Signup and view all the answers

    What is the primary factor in multifactorial inheritance disorders?

    <p>Interplay of genetic and environmental influences (B)</p> Signup and view all the answers

    A carrier for a genetic disorder is defined as an individual who:

    <p>Possesses one normal and one defective allele (A)</p> Signup and view all the answers

    Which chromosomal disorder is characterized by the presence of an extra chromosome leading to specific physical and intellectual disabilities?

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

    What major factor influences the severity of teratogenic effects during fetal development?

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

    Which of the following teratogens is specifically linked to causing microcephaly and congenital heart defects?

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

    In which of the following periods of fetal development would exposure to teratogens most likely result in organ-specific malformations?

    <p>During Organogenesis (18-60 days) (C)</p> Signup and view all the answers

    Which disorder results from a numerical chromosomal abnormality where one chromosome is missing?

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

    Which congenital anomaly is specifically described as a structural abnormality associated with neural tube defects?

    <p>Spina Bifida (D)</p> Signup and view all the answers

    Which of the following maternal factors is associated with the increased risk of congenital heart defects?

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

    Which condition is characterized by the accumulation of excess iron in the body leading to multiple health issues?

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

    What is the primary genetic mechanism by which mitochondrial inheritance disorders are transmitted?

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

    Which of the following conditions is a result of trisomy involving chromosome 13?

    <p>Patau Syndrome (D)</p> Signup and view all the answers

    Flashcards

    Gene

    A segment of DNA that codes for a specific protein or polypeptide. These are like instruction manuals for making proteins.

    DNA

    The molecule that carries genetic instructions for all living organisms. It's the blueprint for growth, development, and functioning.

    Genome

    The complete set of DNA, including all genes of an organism. It's essentially all the genetic material.

    Mutation

    A permanent change in the DNA sequence of a gene. This can lead to variations or disorders.

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    Nondisjunction

    An error during cell division when chromosomes fail to separate properly. This leads to abnormal chromosome numbers.

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    Carrier

    An individual with one normal and one defective gene for a specific trait, often without showing symptoms.

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    Autosomal Dominant

    A pattern of inheritance where one copy of a mutated gene from either parent causes a disorder.

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    Autosomal Recessive

    A pattern of inheritance where two copies of a mutated gene, one from each parent, are needed for a disorder.

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    Monosomy

    A chromosomal abnormality where a person is missing one copy of a chromosome.

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    Trisomy

    A chromosomal abnormality where a person has an extra copy of a chromosome.

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    Down Syndrome

    A genetic disorder caused by trisomy 21, resulting in intellectual disability, characteristic facial features, and developmental delays.

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    Teratogen

    Any environmental agent that can cause developmental abnormalities during fetal development.

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    Organogenesis

    The period of fetal development (18-60 days) when major organs are formed.

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    Alcohol as a teratogen

    Alcohol can cause fetal alcohol spectrum disorders (FASDs) which include microcephaly, heart defects, and facial anomalies.

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    Rubella as a teratogen

    Rubella infection during pregnancy can cause microcephaly, cataracts, and heart defects in the baby.

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    Congenital Anomaly

    A structural or functional abnormality present at birth due to prenatal developmental issues.

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    Cleft Lip/Palate

    A congenital anomaly characterized by an opening in the lip and/or roof of the mouth.

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    Hemochromatosis

    A genetic disorder where the body absorbs too much iron, leading to liver disease, heart failure, and diabetes.

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    Study Notes

    Genetic and Chromosomal Disorders

    • Genetic and chromosomal disorders stem from abnormalities in DNA structure or chromosome numbers.
    • The human genome comprises approximately 3 billion base pairs.
    • DNA errors can lead to developmental issues, disorders, and sometimes embryonic failure.

    Basic Genetic Terminology

    • Gene: A DNA segment encoding a specific protein.
    • DNA (Deoxyribonucleic Acid): The genetic material guiding all life processes.
    • Genome: The complete set of an organism's DNA.
    • Chromosome: A DNA-protein complex within the cell nucleus.
    • Karyotype: An organized chart of chromosomes by size and shape.
    • Phenotype: Observable characteristics resulting from genotype and environment.
    • Genotype: The complete set of genes influencing a specific trait.
    • Mutation: A permanent DNA change potentially causing disorders.
    • Nondisjunction: Chromosome separation failure during cell division.
    • Carrier: An individual carrying one normal and one defective gene allele.

    Types of Genetic Disorders

    • Single-Gene Inheritance Disorders: Caused by single-gene mutations.
      • Autosomal Dominant: One mutated gene from either parent is sufficient.
      • Autosomal Recessive: Requires two mutated gene copies, one from each parent.
      • X-Linked Inheritance: The gene mutation is on the X chromosome, more commonly affecting males. Examples include Cystic Fibrosis, Sickle Cell Anemia, and Marfan Syndrome.
    • Multifactorial Inheritance Disorders: Stem from interacting genetic and environmental factors. Examples include heart disease, diabetes, and cancer.
    • Chromosomal Abnormalities: Result from changes in chromosome numbers or structure.
      • Numerical Abnormalities:
        • Monosomy: Missing a chromosome. Example: Turner Syndrome.
        • Trisomy: Extra chromosome. Example: Down Syndrome (Trisomy 21).
    • Mitochondrial Inheritance Disorders: Mutations in mitochondrial DNA inherited solely from the mother. Examples include Leber's Hereditary Optic Neuropathy (LHON) and MELAS Syndrome.

    Common Chromosomal Disorders

    • Down Syndrome (Trisomy 21): Intellectual disability, facial features, developmental delays.
    • Edwards Syndrome (Trisomy 18): Severe intellectual disability, heart defects, physical abnormalities.
    • Patau Syndrome (Trisomy 13): Severe developmental issues, brain abnormalities, multiple birth defects.

    Teratogens, Congenital Abnormalities, and Abnormal Metal Absorption

    • Teratogen: An environmental factor causing developmental abnormalities in a fetus.
    • Factors Influencing Teratogenicity:
      • Genotype of the conceptus: Genetic makeup can affect susceptibility.
      • Timing of exposure: Before germ layer differentiation: potential embryonic death. During organogenesis: organ-specific malformations. Fetal period: growth retardation, impairments.
      • Dose and interactions: Higher doses, combined factors, result in heightened negative impact.
    • Common Teratogens and Effects:
      • Drugs: Alcohol (microcephaly, heart defects, facial anomalies), Phenytoin (cleft lip/heart defects), Vitamin A (spina bifida).
      • Infections: Rubella (microcephaly, cataracts, heart defects), Toxoplasma (hydrocephalus), Varicella (limb defects, skin scarring).
      • Maternal Factors: Diabetes (neural tube defects, congenital heart defects), Phenylketonuria (microcephaly, heart problems).
      • Physical Agents: Hyperthermia (neural tube defects), X-rays (microcephaly, developmental delays).
    • Congenital Anomalies: Structural or functional birth defects due to prenatal development problems.
      • External Anomalies: Cleft lip/palate, Spina bifida, Clubfoot.
      • Internal Anomalies: Heart defects (e.g., Tetralogy of Fallot, Pulmonary Valve Atresia).
    • Disorders of Metal Metabolism:
      • Hemochromatosis: Excess iron absorption leading to organ damage (liver, heart, pancreas).
      • Wilson's Disease: Copper buildup in organs (liver, brain, eyes) causing organ damage.
      • Alpha-1 Antitrypsin Deficiency: Abnormal protein buildup in the liver and lungs leading to lung and liver problems.

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    Description

    Explore the fundamentals of genetic and chromosomal disorders, including terminology, DNA structure, and implications of mutations. This quiz covers key concepts such as genes, mutations, and karyotypes, providing a comprehensive understanding of how these elements influence development and health.

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