Human Chromosomal Abnormalities Quiz
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Questions and Answers

What does the karyotype notation '47,XX,+21' indicate?

  • Normal chromosome count with an extra chromosome 21
  • Trisomy 21, also known as Down syndrome (correct)
  • A missing chromosome 21
  • Normal female with additional genetic variants

    • Klinefelter syndrome is represented by the karyotype '46,XY/47,XXY'.

    True

    What type of chromosomal abnormality is indicated by '46,XX,del(5)(p25)'?

    Chromosome 5 deletion

    In early miscarriages, approximately _____% of chromosomal changes are abnormal.

    <p>60</p> Signup and view all the answers

    Match the karyotype with its associated condition:

    <p>47,XXX = Triple X syndrome 69,XXY = Triploidy 46,XY,fra(X)(q27.3) = Fragile X syndrome 45,X = Turner syndrome</p> Signup and view all the answers

    How many chromosomes do human cells contain?

    <p>46</p> Signup and view all the answers

    The 23rd pair of chromosomes in humans is made up of autosomal chromosomes.

    <p>False</p> Signup and view all the answers

    Name one type of chromosomal aberration.

    <p>Sickle cell anemia or Cystic fibrosis</p> Signup and view all the answers

    Chromosomes are made up of _____ that are responsible for carrying genetic information.

    <p>DNA</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Autosomes = Chromosomes not involved in determining sex Sex chromosomes = Chromosomes involved in determining sex Karyotype = The number and appearance of chromosomes Alleles = Alternative forms of a gene</p> Signup and view all the answers

    What is the role of the centromere in a chromosome?

    <p>Holding sister chromatids together</p> Signup and view all the answers

    Dark (G) bands on chromosomes contain transcriptionally active genes.

    <p>False</p> Signup and view all the answers

    What is the significance of telomeres in chromosomes?

    <p>They protect the ends of chromosomes from deterioration.</p> Signup and view all the answers

    The first 22 pairs of chromosomes in humans are called _____ chromosomes.

    <p>autosomal</p> Signup and view all the answers

    Which chromosome is the cystic fibrosis gene located on?

    <p>Chromosome 7</p> Signup and view all the answers

    What type of mutation leads to the formation of an unstable protein?

    <p>Nonsense mutations</p> Signup and view all the answers

    Aneuploidy refers to the presence of an abnormal number of chromosomes due to a de novo error in mitosis.

    <p>False</p> Signup and view all the answers

    Name one condition associated with mitochondrial DNA mutations.

    <p>MERRF or MELAS</p> Signup and view all the answers

    The normal male karyotype is represented as _____

    <p>46,XY</p> Signup and view all the answers

    Match the following types of chromosomal aberrations with their definitions:

    <p>Aneuploidy = Abnormal number of chromosomes Translocation = Segment of a chromosome is transferred to another chromosome Deletion = Loss of a chromosome segment Duplication = Copy of a chromosome segment</p> Signup and view all the answers

    Which type of mutation leads to the creation of an abnormal genetic product?

    <p>Missense mutations</p> Signup and view all the answers

    Mutations that affect post-translational modifications of proteins do not cause genetic diseases.

    <p>False</p> Signup and view all the answers

    Which mutation type is characterized by the insertion or removal of nucleotides in the DNA sequence?

    <p>Deletions/insertions</p> Signup and view all the answers

    Chromosomal mosaicism occurs when there are different cell lines after fertilization.

    <p>True</p> Signup and view all the answers

    Name a disease caused by a defective receptor function related to mutant genes.

    <p>Hypercholesterolemia</p> Signup and view all the answers

    Deletions, insertions, and __________ mutations can lead to defective synthesis of a genetic product.

    <p>point</p> Signup and view all the answers

    What is the result of mitochondrial mutations accumulating with age?

    <p>Reduced oxidative phosphorylation</p> Signup and view all the answers

    Match the following diseases to their related mutations:

    <p>α-thalassemia = Mutations affecting mRNA maturation Duchenne muscular dystrophy = Mutations affecting transcription Retinitis pigmentosa = Defective photoreceptor function Hemophilia A = Nonsense mutations</p> Signup and view all the answers

    Which of the following is NOT a type of mutation that can lead to reduced or absent synthesis of a normal genetic product?

    <p>Mismatched base pairs</p> Signup and view all the answers

    Mutant forms of collagen can lead to skeletal deformities.

    <p>True</p> Signup and view all the answers

    What is a common result of mutations in the active site of lysosomal hydrolase?

    <p>Accumulation diseases</p> Signup and view all the answers

    ___ mutations result when the reading frame of codons is changed, causing a shift in the entire sequence.

    <p>Frameshift</p> Signup and view all the answers

    Which of the following diseases is related to insulin receptor dysfunction?

    <p>Diabetes</p> Signup and view all the answers

    Study Notes

    Chromosomes and Chromosomal Aberrations

    • Chromosomes are made up of DNA, with genes arranged linearly.
    • Human cells contain 46 chromosomes in 23 pairs.
    • One chromosome pair is inherited from each parent.
    • Chromosome pairs 1-22 are autosomal.
    • The 23rd pair are sex chromosomes (XX for females, XY for males).
    • Chromosomes are visible during metaphase during cell division.
    • Telomeres are DNA and protein caps enabling binding to the nuclear membrane.
    • Short arms are 'p'(petit).
    • Long arms are 'q'.
    • Light bands are replicated early, are lightly condensed, contain transcriptionally active genes and are rich in GC.
    • Centromeres bind to sister chromatids and are important for chromosomal segregation during cell division.
    • Dark (G) bands are replicated later, are condensed, are rich in AT and are chromosomally specific.
    • Different chromosome band resolutions reveal different parts of chromosomes.
    • A pair of homologous chromosomes (number 1) is viewed during metaphase.
    • Locus is the site of a gene or DNA marker.
    • Alleles are alternative forms of a gene or marker.
    • In chromosomal theory of inheritance, both parts of a homologous chromosome pair carry alleles for the same gene.
    • Genes are arranged in a linear order on a chromosome.
    • Centromeric position and arm length:
      • Metacentric: centromere in middle
      • Submetacentric: centromere slightly off-center
      • Acrocentric: centromere close to one end
      • Telocentric: centromere at very end

    Chromosome Staining Techniques

    • G-banding
    • Q-banding
    • C-banding
    • R-banding
    • T-banding
    • NOR-banding
    • High-resolution banding
    • Staining with restrictive endonucleases

    Karyotype

    • Karyotype displays chromosomes, revealing chromosome structure and number.
    • Normal human male karyotype is 46,XY.
    • Normal human female karyotype is 46,XX.
    • Karyotypes are used to identify chromosomal abnormalities.
    • International Cytogenetic Nomenclature system used for detailed description of karyotypes.

    Chromosomal Mutations

    • Numerical chromosomal aberrations:
      • Aneuploidy (e.g., trisomy 21 (Down syndrome), monosomy)
      • Polyploidy (e.g., triploidy, tetraploidy)
      • Mosaics
    • Structural chromosomal aberrations:
      • Translocations (reciprocal, Robertsonian)
      • Deletions
      • Duplications
      • Ring chromosomes
    • Factors inducing mutations include environmental chemicals and radiation.
    • Chromosomal changes are prominent in early miscarriages.

    Etiology of Genetic Diseases

    • DNA Mutations: abnormal genetic product, post-translational modifications of proteins, transcription, mRNA maturation, translation defects.
    • Reduced or absent synthesis of a normal genetic product (e.g., Reduced transcription or absence of the gene, Deletion or partial deletion of gene, Mutations in the promoter region/regulatory seq.).
    • Modifications of allosteric properties changing the structure of genetic product.
    • Defects in receptor function, enzyme active site modification examples.

    Examples of DNA Mutations

    • Mutations affecting transcription, mRNA maturation, translation.
    • Deletions, insertions, inversions, duplications, translocation.
    • Gene fusions & hybrid genes.
    • Point mutations and frameshift mutations are presented as examples.

    Mutations in Mitochondrial DNA

    • Mitochondria are involved in oxidative phosphorylation.
    • Point mutations, deletions, insertions.
    • Associated diseases include myoclonic epilepsy, mitochondrial encephalopathy, Kearns-Sayre syndrome.
    • Mutations can impact neurodegenerative diseases and aging.

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    Chromosomes and Chromosomal Aberrations PDF

    Description

    Test your knowledge on human chromosomal abnormalities, karyotype notations, and related genetic concepts. This quiz will cover a variety of essential topics including conditions like Down syndrome and Klinefelter syndrome, as well as the structural components of chromosomes and their functions.

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