Aneuploidy and Miscarriage Risk Factors
48 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following is NOT a factor linked to pregnancy loss?

  • Obesity
  • Smoking
  • Allergies (correct)
  • Maternal age

    • What is the estimated percentage of spontaneous abortions that have an abnormal chromosome complement?

  • 10%
  • 75%
  • 50% (correct)
  • 20%

    • What is the approximate percentage of pregnancies that result in miscarriage for women aged between 35 to 39?

  • 20% (correct)
  • 10%
  • 50%
  • 30%

    • What is the main process that reduces the diploid complement of chromosomes in humans?

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

    In which stage of the cell cycle does DNA replication occur during meiosis?

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

    How many rounds of chromosome segregation occur in meiosis?

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

    Which of the following is NOT a chronic health condition mentioned as a risk factor for pregnancy loss?

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

    What is the term used for an abnormal complement of chromosomes in a cell?

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

    What happens to the sister chromatids during anaphase I?

    <p>They are separated and move to opposite poles of the cell. (A)</p> Signup and view all the answers

    Which of the following is NOT a stage of prophase I in meiosis?

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

    What is the name of the protein complex that holds sister chromatids together?

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

    What is the difference between meiotic cohesin complexes and mitotic cohesin complexes?

    <p>Meiotic complexes have Rec8 instead of Scc1. (A)</p> Signup and view all the answers

    What is the role of Spo11 in meiosis?

    <p>It is recruited to sites of replication to initiate recombination. (B)</p> Signup and view all the answers

    What is the significance of the G-banded metaphase cell shown in the slide?

    <p>It shows the chromosomes of a person with a genetic disorder. (D)</p> Signup and view all the answers

    What is the function of the spindle complex in meiosis?

    <p>It helps to separate homologous chromosomes. (B)</p> Signup and view all the answers

    How are sister chromatids created?

    <p>They are created during the process of DNA replication. (B)</p> Signup and view all the answers

    Which of the following statements is TRUE regarding the effects of aneuploidy on sex chromosomes compared to autosomal chromosomes?

    <p>Aneuploidy of sex chromosomes is more tolerable than aneuploidy of autosomal chromosomes. (C)</p> Signup and view all the answers

    Which of the following syndromes is linked to trisomy of the 13th chromosome and is known to significantly limit the life expectancy of affected individuals?

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

    What is the approximate percentage of pregnancies affected by trisomy 13 that result in spontaneous abortion?

    <p>99% (B)</p> Signup and view all the answers

    Which of the following accurately describes the combined test used for aneuploidy screening in pregnancy?

    <p>A combination of ultrasound scans and blood tests. (B)</p> Signup and view all the answers

    What is the median life expectancy of individuals with Edwards' Syndrome?

    <p>Approximately 24 hours (D)</p> Signup and view all the answers

    What is the primary reason for the relatively high tolerance of sex chromosome aneuploidy compared to autosomal aneuploidy?

    <p>The process of X chromosome inactivation in females. (C)</p> Signup and view all the answers

    What is the name of the disease associated with a 45,X karyotype, meaning one missing X chromosome?

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

    Which of the following is NOT a common aneuploidy screened for in the combined test?

    <p>Trisomy 16 (D)</p> Signup and view all the answers

    What is the most common viable human aneuploidy?

    <p>Trisomy for chromosome 21 (A)</p> Signup and view all the answers

    What percentage of Down syndrome cases are attributed to trisomy 21?

    <p>95% (B)</p> Signup and view all the answers

    Which factor does NOT contribute to faithful chromosome segregation in meiosis II?

    <p>Chromosomal duplication in the S phase (A)</p> Signup and view all the answers

    What morphological feature is commonly seen in Down syndrome?

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

    Which chromosome is considered the smallest human autosome?

    <p>Chromosome 21 (D)</p> Signup and view all the answers

    What serious physiological complication is associated with Down syndrome?

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

    How has Down syndrome been linked to acute myeloid leukaemia?

    <p>A specific subtype of leukaemia is more common in Down syndrome (C)</p> Signup and view all the answers

    What is the expected outcome for most conceptions affected by trisomy 18?

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

    What role does a crossover play during meiosis I?

    <p>It holds homologs together to ensure proper segregation. (D)</p> Signup and view all the answers

    What happens to the centromeres of homologous chromosomes during tension build-up in meiosis?

    <p>They move apart until opposing forces are equal. (C)</p> Signup and view all the answers

    How does a single distal crossover affect sister chromatid cohesion?

    <p>It reduces the cohesion between sister chromatids. (B)</p> Signup and view all the answers

    What is a likely consequence of extended arrest in oocytes during female gametogenesis?

    <p>Increased incidence of chromosomal mal segregation. (C)</p> Signup and view all the answers

    In comparison to males, when does meiosis in females begin?

    <p>During fetal development. (A)</p> Signup and view all the answers

    What leads to a 50% chance of both homologs segregating to the same pole?

    <p>Absence of chiasmata. (C)</p> Signup and view all the answers

    What structural factors are involved in maintaining bivalents during meiosis?

    <p>Chiasmata and sister chromatid cohesion. (D)</p> Signup and view all the answers

    Why is advanced maternal age associated with aneuploidy?

    <p>Chromosomes are likely to sustain damage during long periods of arrest. (C)</p> Signup and view all the answers

    What is the main function of Spo11 in the process of homologous recombination?

    <p>Spo11 initiates the process of DNA end resection, creating single-stranded DNA tracts that can invade homologous duplexes. (A)</p> Signup and view all the answers

    Why is the synaptonemal complex crucial for homologous recombination?

    <p>The synaptonemal complex provides a physical scaffold that holds homologous chromosomes together during recombination. (A)</p> Signup and view all the answers

    Which of the following is NOT a potential target for invasion by a single-stranded DNA tract during homologous recombination?

    <p>A non-homologous chromosome. (D)</p> Signup and view all the answers

    What is the main consequence of the repair pathway that results in a crossover?

    <p>The two homologous chromosomes are physically linked together, creating genetic diversity. (C)</p> Signup and view all the answers

    Why is it crucial for the DNA damage caused by Spo11 to be repaired?

    <p>Repair is essential for the viability of the cell as a double-strand break is a lethal genetic insult. (A)</p> Signup and view all the answers

    What is the main difference between the two repair pathways that occur after strand invasion?

    <p>One pathway generates a crossover while the other does not. (D)</p> Signup and view all the answers

    Why is homologous recombination considered an important process during meiosis?

    <p>It allows for the exchange of genetic material between homologous chromosomes, increasing genetic diversity. (C)</p> Signup and view all the answers

    What is the significance of the 'strand invasion intermediate' in homologous recombination?

    <p>It is a crucial point where the single-stranded DNA tract invades a homologous duplex. (A)</p> Signup and view all the answers

    Flashcards

    Aneuploidy

    A genetic condition where there is an abnormal number of chromosomes.

    Miscarriage Rates

    Percentage of pregnancies that result in spontaneous abortion.

    Chromosome Segregation

    The process of separating chromosomes during meiosis.

    Meiosis

    Specialized cell division that reduces chromosome number by half.

    Signup and view all the flashcards

    Factors Influencing Miscarriage

    Environmental and health conditions linked to pregnancy loss.

    Signup and view all the flashcards

    Chromosome Abnormalities

    Irregularities in the number or structure of chromosomes.

    Signup and view all the flashcards

    Advanced Maternal Age

    Maternal age over 35 which increases miscarriage risk.

    Signup and view all the flashcards

    Spontaneous Abortion

    Natural termination of pregnancy, often due to chromosome issues.

    Signup and view all the flashcards

    Prophase I

    The first phase of Meiosis I, where chromosomes condense and pair up.

    Signup and view all the flashcards

    Sister chromatids

    Identical copies of a chromosome formed after DNA replication.

    Signup and view all the flashcards

    Sister chromatid cohesion

    The process that holds sister chromatids together during cell division.

    Signup and view all the flashcards

    Cohesin

    A protein complex that maintains sister chromatid cohesion.

    Signup and view all the flashcards

    Spo11

    A protein recruited during replication in meiosis.

    Signup and view all the flashcards

    Anaphase I

    The stage of meiosis where homologous chromosomes are pulled apart.

    Signup and view all the flashcards

    G-banding

    A technique used to visualize chromosomes and sister chromatids.

    Signup and view all the flashcards

    Meiosis II

    The second stage of meiosis where sister chromatids separate.

    Signup and view all the flashcards

    Crossover Events

    Exchanges of genetic material between homologous chromosomes during meiosis I.

    Signup and view all the flashcards

    Trisomy 21

    Condition of having three copies of chromosome 21, associated with Down Syndrome.

    Signup and view all the flashcards

    Down Syndrome Characteristics

    A developmental disorder with distinct physical and cognitive features.

    Signup and view all the flashcards

    Mosaicism

    Presence of two or more genetically different cell lines in an individual.

    Signup and view all the flashcards

    Aneuploidy Viability

    The likelihood of surviving with an abnormal number of chromosomes.

    Signup and view all the flashcards

    Chromosome 21

    The smallest human autosome, often implicated in trisomies.

    Signup and view all the flashcards

    Topoisomerase

    An enzyme that alters DNA supercoiling and can create double strand breaks.

    Signup and view all the flashcards

    Double Strand Breaks

    Damages in DNA where both strands are severed, initiating repair processes.

    Signup and view all the flashcards

    Homologous Recombination

    A process where DNA strands exchange genetic information for repair.

    Signup and view all the flashcards

    Synaptonemal Complex

    A protein structure that holds homologous chromosomes together during meiosis.

    Signup and view all the flashcards

    Strand Invasion

    The step in homologous recombination where single-stranded DNA enters a homologous duplex.

    Signup and view all the flashcards

    Crossover

    A process in homologous recombination where homologous chromosomes exchange segments.

    Signup and view all the flashcards

    Bivalent

    A paired structure of two homologous chromosomes during meiosis.

    Signup and view all the flashcards

    Mitotic spindle

    A structure that segregates chromosomes during cell division.

    Signup and view all the flashcards

    Disomic gamete

    A gamete with two copies of a particular chromosome instead of one.

    Signup and view all the flashcards

    Non-disjunction

    The failure of homologous chromosomes to separate properly during meiosis.

    Signup and view all the flashcards

    Chiasmata

    Points where homologous chromosomes exchange genetic material during crossover.

    Signup and view all the flashcards

    Meiotic arrest

    A temporary stoppage of meiosis observed in oocytes during fetal development.

    Signup and view all the flashcards

    Aneuploidy and maternal age

    Increased risk of aneuploidy associated with older maternal age.

    Signup and view all the flashcards

    Patau Syndrome

    A genetic disorder caused by trisomy of chromosome 13, leading to severe developmental issues and low life expectancy.

    Signup and view all the flashcards

    Edwards' Syndrome

    A genetic disorder resulting from trisomy 18, where newborns typically survive only a short time post-birth.

    Signup and view all the flashcards

    Turner Syndrome

    A condition in females where one X chromosome is missing or partially missing, occurring in about 1 in 2,000 births.

    Signup and view all the flashcards

    Klinefelter Syndrome

    A genetic condition in males caused by an extra X chromosome, leading to physical and reproductive issues.

    Signup and view all the flashcards

    Triple X Syndrome

    A condition in females due to an extra X chromosome, usually mild and associated with normal life expectancy.

    Signup and view all the flashcards

    Combined Test

    A screening test during pregnancy to assess the risk of chromosomal abnormalities, conducted between 10-14 weeks.

    Signup and view all the flashcards

    Nuchal Translucency

    A measurement of fluid at the back of a fetus's neck used in pregnancy screening for chromosomal disorders.

    Signup and view all the flashcards

    Pregnancy Associated Plasma Protein A (PAPP-A)

    A hormone measured during pregnancy screening; low levels may indicate an increased risk for chromosomal abnormalities.

    Signup and view all the flashcards

    Study Notes

    Aneuploidy: Miscarriage Rates and Risk Factors

    • Spontaneous abortion occurs in ~15% of pregnancies.
    • Women under 30: ~10%
    • Women aged 35-39: ~20%
    • Women over 45: ~50%
    • Environmental factors: Smoking, drug abuse, obesity
    • Health conditions: Diabetes, hypertension, infections
    • Genetic factors: ~50% of first-trimester miscarriages are linked to abnormal chromosome complements.

    Chromosome Abnormalities and Miscarriage

    • Abnormal chromosome segregation during meiosis is a leading cause of miscarriage.
    • Understanding meiosis is key to examining chromosome inheritance errors.

    Meiosis and Chromosome Segregation

    • Meiosis reduces chromosomes from diploid (2n) to haploid (1n) through one DNA replication and two segregation rounds.
    • Stages of meiosis I: Leptotene, zygotene, pachytene, dictyotene
    • Metaphase I and Anaphase I: Homologous chromosomes are separated.

    Molecular Mechanisms in Meiosis

    • Sister chromatid cohesion: Proteins like cohesin link sister chromatids.
    • Rec8 replaces Scc1 in meiosis-specific cohesin.
    • Homologous recombination: Spo11 creates DNA double-strand breaks.
    • Repairs lead to crossover events, essential for correct segregation and genetic diversity.

    Errors in Chromosome Segregation

    • Faithful segregation requires proper crossover number and positioning.
    • Errors can result in aneuploidy (abnormal chromosome number) examples are Down Syndrome.
    • Advanced maternal age is strongly linked to increased aneuploidy risk.
    • Decreased or incorrect crossovers increase meiotic segregation errors.

    Aneuploidy and Associated Syndromes

    • Trisomy 21 (Down Syndrome): Intellectual disability, distinct physical features (~1 in 700 births).
    • Trisomy 18 (Edwards' Syndrome): Low survival rate (<24 hours).
    • Trisomy 13 (Patau Syndrome): Low survival rate (days).
    • Sex chromosome aneuploidies: Turner Syndrome (45,X), Klinefelter Syndrome (47,XXY), Triple X Syndrome (47,XXX).

    Mechanisms Underlying Aneuploidy

    • Parental origin: Most instances of trisomy arise during maternal meiosis errors.
    • Crossover deficiency: Reduced or misplaced crossovers contribute to non-disjunction, especially near telomeres in meiosis I and near centromeres in meiosis II.

    Advanced Maternal Age and Aneuploidy

    • Trisomy rates increase with age: ~2% under 25, ~30% over 40

    Prenatal Screening and Detection

    • Screening programs (e.g., combined test) assess nuchal translucency and hormone levels (PAPP-A, free β-hCG).
    • Risk thresholds for further testing (e.g., qPCR, FISH, karyotyping).
    • Ultrasound markers for aneuploidy: Short limbs, facial anomalies, heart/kidney defects (e.g., Trisomy 18 - clenched fists, rocker-bottom feet; Trisomy 13 - cyclopia, polydactyly; Trisomy 21 - short nasal bones).

    Meiosis in Male and Female Development

    • Male meiosis occurs continuously.
    • Female meiosis pauses at prophase I, potentially increasing segregation errors over time.

    ###Additional Information

    • Approximately 15% of pregnancies spontaneously abort.
    • Miscarriage rates are lower in women under 30, slightly higher in women between 35–39, and higher still in women over 45.
    • Many factors are linked to pregnancy loss, including environmental factors (smoking, drug abuse, obesity) and maternal health conditions (diabetes, hypertension, infections).

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Aneuploidy PDF

    Description

    Explore the connection between aneuploidy and miscarriage rates across different age groups. This quiz also delves into the environmental, health, and genetic factors influencing spontaneous abortion, as well as the molecular mechanisms involved in meiosis. Test your understanding of chromosome abnormalities and their impact on pregnancy outcomes.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser