Genetics and Karyotype Analysis
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Questions and Answers

What is the main reason for X-chromosome inactivation in females?

  • To prevent the accumulation of harmful mutations on the X-chromosome.
  • To allow for greater genetic diversity in females.
  • To ensure equal gene expression between males and females. (correct)
  • To reduce the energy requirements of the cell by silencing one X-chromosome.
  • Which of the following is a characteristic of SSRs (Simple Sequence Repeats)?

  • They are less variable than VNTRs.
  • They consist of di, tri, or tetra nucleotides repeated tandemly. (correct)
  • They are found in only a few places in the genome.
  • They are typically larger than 1000 base pairs.
  • Which type of repeat is described as 'quite large' and found in only a few places in the genome?

  • SSR (Simple Sequence Repeat)
  • VNTR (Variable Number Tandem Repeat)
  • LCR (Low Copy Repeat) (correct)
  • None of the above
  • What is the relationship between the length of a repeat sequence and its variability?

    <p>Shorter repeat sequences are generally more variable. (C)</p> Signup and view all the answers

    Which of the following statements accurately describes the process of X-chromosome inactivation?

    <p>One X-chromosome is randomly chosen in each cell and completely silenced. (D)</p> Signup and view all the answers

    Based on the DNA analysis presented, which individual has the highest probability of being the father?

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

    What type of DNA polymorphism is primarily being analyzed in the DNA fingerprint provided?

    <p>Single Nucleotide Polymorphism (SNP) (C)</p> Signup and view all the answers

    Why are SSR polymorphisms useful for paternity testing?

    <p>They are highly variable, allowing for clear distinction between individuals. (D)</p> Signup and view all the answers

    What is the correct interpretation of the DNA analysis regarding the father?

    <p>Jerry is the most likely father of the child. (D)</p> Signup and view all the answers

    What is the significance of the 'polymorphic 14 bp tandem repeat' mentioned in the context of the genetic disorder?

    <p>It is linked to a gene potentially involved in the disorder. (C)</p> Signup and view all the answers

    Which of the following best describes a 'Copy Number Variant (CNV)'?

    <p>A variation in the number of copies of a specific DNA segment. (B)</p> Signup and view all the answers

    Which of the following best describes a 'VNTR'?

    <p>A tandem repeat of a short DNA sequence. (D)</p> Signup and view all the answers

    What is the primary function of LINEs (Long Interspersed Nuclear Elements) in the genome?

    <p>To create their own reverse transcriptase for replication. (C)</p> Signup and view all the answers

    Which genetic abnormality can be best diagnosed using standard G-banded karyotype analysis?

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

    What is a key feature of a human acrocentric chromosome?

    <p>It possesses repetitive rRNA sequences on one end. (B)</p> Signup and view all the answers

    Which regulatory element is likely removed by a mutation that deletes the 100 nucleotides before transcription start in β-globin genes?

    <p>CAAT &amp; TATA boxes (A)</p> Signup and view all the answers

    What is the most descriptive karyotype for a patient with Down syndrome?

    <p>47,XX (D)</p> Signup and view all the answers

    What is the name of the site where mitotic spindle fibers attach to chromosomes?

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

    Which part of the nuclear gene POLG is not transcribed during gene expression?

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

    What type of mutation was identified in the genetic testing of a 7-year-old boy with distal tubule acidosis?

    <p>A pathogenic mutation affecting splicing (C)</p> Signup and view all the answers

    Which of the following definitions best matches a frameshift mutation?

    <p>An insertion or deletion of nucleotides that alters the reading frame. (A)</p> Signup and view all the answers

    What would most likely cause an aberration if the mRNA for a gene is larger than normal?

    <p>Mutation of splice donor site of intron 1 (B), Mutation of the splice acceptor site of exon 2 (D)</p> Signup and view all the answers

    What best describes a 14 bp tandem repeat located near a gene involved in a genetic disorder?

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

    To maintain balanced gene expression between sexes, what happens to one of the X-chromosomes in females?

    <p>One X-chromosome is deactivated (A)</p> Signup and view all the answers

    What facilitates the export of RNA to the cytoplasm after it is processed in the nucleus?

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

    Which genetic abnormality is best established through standard G-banded karyotype analysis?

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

    What is the primary function of the specific amino acid sequence in mitochondrial proteins?

    <p>To direct the protein to the mitochondria (D)</p> Signup and view all the answers

    Which of the following mutations would have the least impact on mRNA size?

    <p>A non-sense mutation within exon 1 (D)</p> Signup and view all the answers

    What could be the consequence of a splice site mutation?

    <p>Alteration of mRNA size (A)</p> Signup and view all the answers

    Which mutation is most likely to cause an increased size of the mRNA transcript?

    <p>Mutation of splice donor site of an intron (A)</p> Signup and view all the answers

    What effect would a non-sense mutation within an exon likely have on mRNA?

    <p>No effect on mRNA length (C)</p> Signup and view all the answers

    Which type of mutation is characterized by a change in a single nucleotide that may lead to a premature stop codon?

    <p>Non-sense mutation (B)</p> Signup and view all the answers

    Which of the following would most likely cause a complete loss of mRNA function?

    <p>Frame-shift mutation (C)</p> Signup and view all the answers

    When discussing splicing, what does the term 'splice acceptor site' refer to?

    <p>Position correlating to the preceding exon (C)</p> Signup and view all the answers

    In the context of molecular biology, what term is used to describe the process of directing proteins to their specific cellular locations?

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

    Which choice would most likely lead to a smaller mRNA being produced?

    <p>Mutation of the splice acceptor site of an exon (A)</p> Signup and view all the answers

    What is the minimum size of a chromosomal abnormality detectable by G-band karyotype?

    <p>5 – 10 Mb (C)</p> Signup and view all the answers

    Which type of mutation typically creates a stop codon by chance?

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

    Which characteristic is true of acrocentric chromosomes?

    <p>They have very short p arms and long q arms (C)</p> Signup and view all the answers

    What is a dicentric chromosome?

    <p>A chromosome with two centromeres (C)</p> Signup and view all the answers

    What happens to a chromosome that lacks a centromere?

    <p>It is acentric and not stable (A)</p> Signup and view all the answers

    How are the repetitive rRNA sequences associated with acrocentric chromosomes?

    <p>They are found on the q arm, adjacent to the centromere (B)</p> Signup and view all the answers

    What describes the arm lengths of a submetacentric chromosome?

    <p>Both arms are of different lengths (C)</p> Signup and view all the answers

    Which of the following mutations is detectable by G-band karyotyping?

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

    Flashcards

    G-banded karyotype analysis

    A prenatal test that helps identify chromosomal abnormalities such as trisomy.

    Acrocentric chromosome

    A chromosome with the centromere located near one end, creating unequal arm lengths.

    β-thalassemia mutation

    A genetic condition resulting from mutations in β-globin genes, affecting hemoglobin production.

    Down syndrome karyotype

    A chromosomal condition characterized by an extra chromosome 21, represented as 47,XX.

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    Mitotic spindle fibers attachment

    The site where spindle fibers attach to chromosomes during cell division, located at the centromere.

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    NON-transcribed gene part

    Portions of a gene that are not translated into protein, including introns and promoters.

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    Pathogenic mutation

    A genetic change that has been proved or predicted to adversely affect an organism's function.

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    Splicing mutation prediction

    A genetic change affecting the proper splicing of RNA, potentially leading to dysfunctional proteins.

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    G-band karyotype

    A laboratory technique that stains chromosomes to reveal banding patterns for identification of abnormalities.

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    Chromosomal deletion

    The loss of a segment of DNA from a chromosome, affecting the banding pattern if over 5 Mb.

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    Trisomy

    A genetic condition where an individual has three copies of a chromosome instead of two.

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    Substitution mutation

    A type of mutation involving the replacement of one base pair with another.

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    Frameshift mutation

    A mutation resulting from the insertion or deletion of bases, changing the reading frame.

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    Gene duplication

    A mutation that results in a gene being copied, potentially visible on a karyotype in some cases.

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    Metacentric chromosome

    A chromosome with the centromere located in the middle, leading to arms of equal length.

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    Gene expression

    The process by which genes are turned on to produce RNA and proteins.

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    Protein trafficking

    The process of directing proteins to their specific cellular locations, like mitochondria.

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    Mitochondrial zip code

    A specific amino acid sequence in proteins that targets them to mitochondria.

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    Aberrant mRNA

    mRNA that has an abnormal size or sequence due to mutation or splicing errors.

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    Splice donor site

    The sequence at the start of an intron that signals where splicing begins.

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    Splice acceptor site

    The sequence at the end of an intron that indicates where splicing ends.

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    RNA editing

    The process of modifying RNA molecules after they are transcribed, altering their function.

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    Aberration in mRNA

    An abnormal size of mRNA transcript due to genetic mutations.

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    Splice donor site mutation

    A change at the beginning of an intron that affects mRNA splicing.

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    DNA fingerprinting

    A method used to analyze an individual's DNA characteristics.

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    Paternity analysis

    Studying DNA to determine the potential father of a child.

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    Tandem repeat sequence

    A short DNA sequence repeated multiple times in a row.

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    X-chromosome inactivation

    Process where one X-chromosome in females is turned off.

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    Simple Sequence Repeat (SSR)

    Highly polymorphic sequences of di, tri or tetra nucleotides repeated in tandem.

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    Variable Number Tandem Repeat (VNTR)

    Tandem repeats larger than SSR, consisting of repeat sequences up to several hundreds of nucleotides.

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    Low Copy Repeat (LCR)

    Large, highly similar repetitive sequences found in few places in the genome.

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    Gene Dosage Compensation

    Mechanism ensuring equal gene expression levels from X-chromosomes in males and females.

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    DNA Fingerprint

    A pattern of DNA bands that can identify individuals based on their unique genetic makeup.

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    SSR Polymorphisms

    Short Sequence Repeats that are inherited and can be tracked through co-dominance.

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    Paternity Probability

    The likelihood that an individual is the biological father based on DNA markers.

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    Polymorphic Loci

    Locations on DNA that contain variations, allowing for analysis of genetic diversity.

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    SNP

    Single Nucleotide Polymorphism, a common variation at a single nucleotide position in DNA.

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    CNV

    Copy Number Variant, indicating variations in the number of copies of a particular gene.

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    VNTR

    Variable Number Tandem Repeats, sequences in DNA where a short nucleotide motif is repeated multiple times.

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    Interspersed Nuclear Elements

    DNA sequences (LINE and SINE) that are repeated and scattered throughout the genome.

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    Study Notes

    Question 1

    • A pregnant 39-year-old woman is offered standard G-banded karyotype analysis.
    • This analysis is most helpful for diagnosing trisomy.
    • A 500,000 bp deletion is not visible on a G-band karyotype.
    • Gene substitutions and frameshift mutations are not easily diagnosed through G-banded karyotypes.
    • Gene duplications may or may not be visible.

    Question 2

    • An acrocentric chromosome has a centromere located near one end.
    • Repetitive rRNA sequences are found on one end.
    • The long and short arms are of different lengths.
    • A chromosome with two centromeres is called dicentric.

    Question 3

    • A teenage female with beta-thalassemia has a mutation removing 100 nucleotides before the start of transcription.
    • The CAAT and TATA boxes are most likely removed by this deletion.
    • These boxes are regulatory elements crucial for transcription initiation.

    Question 4

    • A 2-year-old female patient with Down syndrome has a karyotype of 47,XX+21.
    • This indicates an extra copy of chromosome 21.

    Question 5

    • The attachment site for mitotic spindle fibers on chromosomes is the centromere.

    Question 6

    • The POLG gene replicates the mitochondrial genome.
    • The 5' UTR (untranslated region) is transcribed.
    • The 3' UTR, exons, and introns are transcribed.

    Question 7

    • A 7-year-old boy with renal distal tubule acidosis has a splicing mutation.
    • The mutation results in a larger-than-normal mRNA.
    • A mutation in the splice donor site of intron 1 is the most likely cause.

    Question 8

    • Jessica gave birth to a baby boy, Billy.
    • Several men claim paternity.
    • A DNA analysis of multiple marker loci.
    • Jerry has the highest probability of being the father.

    Question 9

    • Linkage analysis is used to place a 14-bp tandem repeat.
    • The sequence is a variable number tandem repeat (VNTR).

    Question 10

    • The human X-chromosome has many protein-coding genes.
    • The Y-chromosome has fewer genes.
    • One X-chromosome is deactivated in females to balance gene expression.

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    Description

    This quiz focuses on key concepts related to genetics, particularly karyotype analysis and chromosomal abnormalities. You will be tested on topics such as trisomy, chromosome structure, and mutations affecting gene expression. Perfect for students in genetics or medical courses.

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