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Questions and Answers
What is a gain-of-function mutation?
What is a gain-of-function mutation?
- A mutation resulting in a protein with a stronger effect (correct)
- A mutation that eliminates the function of a protein
- A mutation leading to weakened protein activation
- A mutation causing the protein to remain unchanged
What is a splice-site mutation?
What is a splice-site mutation?
- A mutation that affects only RNA splicing
- A mutation that occurs within an exon
- A mutation that does not impact protein sequence
- A change at the border of exon and intron (correct)
Which type of mutation can cause loss of exons or inclusion of introns?
Which type of mutation can cause loss of exons or inclusion of introns?
- Frameshift mutation - deletion (correct)
- Frameshift mutation - insertion
- Missense mutation
- Nonsense mutation
What is the significance of mutations that are advantageous to organisms?
What is the significance of mutations that are advantageous to organisms?
Which type of cell mutations are inherited by offspring?
Which type of cell mutations are inherited by offspring?
In which type of mutation do all cells in an organism have a changed genetic information?
In which type of mutation do all cells in an organism have a changed genetic information?
What is the term used to describe a state where a cell or organism has one or more sets of chromosomes beyond the basic set?
What is the term used to describe a state where a cell or organism has one or more sets of chromosomes beyond the basic set?
Which type of gene mutations involve changes in the nucleotide sequence in a fragment of DNA in one gene?
Which type of gene mutations involve changes in the nucleotide sequence in a fragment of DNA in one gene?
What term is used to describe an abnormal number of chromosomes in a cell, often seen in cancer cells?
What term is used to describe an abnormal number of chromosomes in a cell, often seen in cancer cells?
What type of mutations are caused by physical, chemical, or biological factors?
What type of mutations are caused by physical, chemical, or biological factors?
What is the term for gene and chromosomal mutations that lead to the death of the embryo, fetus, or offspring soon after birth?
What is the term for gene and chromosomal mutations that lead to the death of the embryo, fetus, or offspring soon after birth?
What are marker chromosomes / extra structurally abnormal chromosomes (ESACs)?
What are marker chromosomes / extra structurally abnormal chromosomes (ESACs)?
What is the term for the failure of homologous chromosomes to properly separate during meiosis?
What is the term for the failure of homologous chromosomes to properly separate during meiosis?
'Mutation' is best defined as:
'Mutation' is best defined as:
What is a key characteristic of Drosophila melanogaster that makes it convenient for genetic research?
What is a key characteristic of Drosophila melanogaster that makes it convenient for genetic research?
What is a unique feature of the chromosomes in the cells of the salivary glands of Drosophila melanogaster larvae?
What is a unique feature of the chromosomes in the cells of the salivary glands of Drosophila melanogaster larvae?
What is the significance of gene mutations in Drosophila melanogaster with respect to genetic studies?
What is the significance of gene mutations in Drosophila melanogaster with respect to genetic studies?
How are polytene (giant) chromosomes formed in Drosophila melanogaster?
How are polytene (giant) chromosomes formed in Drosophila melanogaster?
Where are genes predominantly located on polytene (giant) chromosomes in Drosophila melanogaster?
Where are genes predominantly located on polytene (giant) chromosomes in Drosophila melanogaster?
What is a common feature of Omphalocele (exomphalos)?
What is a common feature of Omphalocele (exomphalos)?
What happens when a specific gene is activated on a polytene chromosome in Drosophila melanogaster?
What happens when a specific gene is activated on a polytene chromosome in Drosophila melanogaster?
Which condition is defined by the absence of testes from the scrotum?
Which condition is defined by the absence of testes from the scrotum?
What role does gene amplification play in the gene expression of Drosophila melanogaster?
What role does gene amplification play in the gene expression of Drosophila melanogaster?
What does the term Palpebral fissure refer to?
What does the term Palpebral fissure refer to?
Why are polytene (giant) chromosomes considered advantageous for studying gene expression?
Why are polytene (giant) chromosomes considered advantageous for studying gene expression?
What is the main feature of Proboscis in teratology?
What is the main feature of Proboscis in teratology?
Where is Sella turcica commonly found?
Where is Sella turcica commonly found?
What is a Spermatozoon?
What is a Spermatozoon?
Who provided a significant contribution to the chromosomal theory of heredity through experiments on Drosophila melanogaster?
Who provided a significant contribution to the chromosomal theory of heredity through experiments on Drosophila melanogaster?
Which of these conditions involves eyes not properly aligning when focusing on an object?
Which of these conditions involves eyes not properly aligning when focusing on an object?
Which type of inversion includes a centromere?
Which type of inversion includes a centromere?
What is the structural rearrangement within a chromosome that leads to the formation of chromosomes with either two long or two short arms?
What is the structural rearrangement within a chromosome that leads to the formation of chromosomes with either two long or two short arms?
What is the structural aberration where a fragment of a chromosome is inserted into a different place of the same chromosome or another chromosome?
What is the structural aberration where a fragment of a chromosome is inserted into a different place of the same chromosome or another chromosome?
Which type of chromosome is usually formed as a result of translocation and contains two centromeres?
Which type of chromosome is usually formed as a result of translocation and contains two centromeres?
In which condition is part of the short arm of chromosome 5 deleted?
In which condition is part of the short arm of chromosome 5 deleted?
What is formed as a result of two breaks in the distal sections of both arms of a chromosome followed by their connection?
What is formed as a result of two breaks in the distal sections of both arms of a chromosome followed by their connection?
Which type of translocation results in a reciprocal exchange between the long arms of chromosomes 9 and 22?
Which type of translocation results in a reciprocal exchange between the long arms of chromosomes 9 and 22?
Which symptom is NOT associated with cri du chat syndrome?
Which symptom is NOT associated with cri du chat syndrome?
What chromosomal abnormality is typically associated with Turner syndrome?
What chromosomal abnormality is typically associated with Turner syndrome?
Which syndrome involves an individual having an extra X chromosome (47,XXX)?
Which syndrome involves an individual having an extra X chromosome (47,XXX)?
What is the chromosomal karyotype typically seen in individuals with XYY syndrome?
What is the chromosomal karyotype typically seen in individuals with XYY syndrome?
Which of the following syndromes is caused by an additional copy of chromosome 21?
Which of the following syndromes is caused by an additional copy of chromosome 21?
Which syndrome is characterized by a female type silhouette, gynaecomastia, and atrophy of seminiferous tubules?
Which syndrome is characterized by a female type silhouette, gynaecomastia, and atrophy of seminiferous tubules?
In which syndrome do individuals have an extra X chromosome resulting in a 47,XXX karyotype?
In which syndrome do individuals have an extra X chromosome resulting in a 47,XXX karyotype?
Individuals with which syndrome typically show a 45,X karyotype and suffer from primary amenorrhea and lack of menstruation?
Individuals with which syndrome typically show a 45,X karyotype and suffer from primary amenorrhea and lack of menstruation?
Which syndrome presents with normal phenotype but has an extra Y chromosome in males?
Which syndrome presents with normal phenotype but has an extra Y chromosome in males?
A 47,XX,+21 karyotype is associated with which genetic disorder showing symptoms such as epicanthal fold and mental retardation?
A 47,XX,+21 karyotype is associated with which genetic disorder showing symptoms such as epicanthal fold and mental retardation?
What type of chromosomal defect results in Down syndrome?
What type of chromosomal defect results in Down syndrome?
Which chromosomal abnormality involves the presence of an additional copy of a translocated chromosome or its fragment?
Which chromosomal abnormality involves the presence of an additional copy of a translocated chromosome or its fragment?
What type of chromosomal defect is observed in Turner syndrome?
What type of chromosomal defect is observed in Turner syndrome?
In which chromosomal abnormality does the amount of genetic material not change but its location shifts within the genome?
In which chromosomal abnormality does the amount of genetic material not change but its location shifts within the genome?
Which type of chromosomal defect results in an increased number of chromosomes, such as Klinefelter syndrome?
Which type of chromosomal defect results in an increased number of chromosomes, such as Klinefelter syndrome?
Which type of chromosomal aberration involves the breakage and rearrangement of fragments between two chromosomes?
Which type of chromosomal aberration involves the breakage and rearrangement of fragments between two chromosomes?
In humans, a reciprocal translocation occurs when the break and exchange of sections happen between which type of chromosomes?
In humans, a reciprocal translocation occurs when the break and exchange of sections happen between which type of chromosomes?
Which chromosomal abnormality involves the cross connection of products from breaks in acrocentric chromosomes resulting in the loss of the short arms and the connection of the long arms?
Which chromosomal abnormality involves the cross connection of products from breaks in acrocentric chromosomes resulting in the loss of the short arms and the connection of the long arms?
Which syndrome is characterized by an additional X chromosome in females, leading to developmental delays and learning disabilities?
Which syndrome is characterized by an additional X chromosome in females, leading to developmental delays and learning disabilities?
In which syndrome does an individual have only one X chromosome, leading to short stature, lack of puberty development, and infertility in females?
In which syndrome does an individual have only one X chromosome, leading to short stature, lack of puberty development, and infertility in females?
What medical condition is characterized by the absence of one X chromosome in females, leading to short stature and infertility?
What medical condition is characterized by the absence of one X chromosome in females, leading to short stature and infertility?
Which genetic disorder is characterized by an extra X chromosome in males, resulting in tall stature and behavioral problems?
Which genetic disorder is characterized by an extra X chromosome in males, resulting in tall stature and behavioral problems?
In which syndrome does an individual have an additional copy of chromosome 21, leading to characteristic facial features and intellectual disabilities?
In which syndrome does an individual have an additional copy of chromosome 21, leading to characteristic facial features and intellectual disabilities?
What genetic condition results from males having an extra Y chromosome, leading to increased height and learning difficulties?
What genetic condition results from males having an extra Y chromosome, leading to increased height and learning difficulties?
Which genetic disorder involves females having a missing or incomplete X chromosome, leading to short stature and infertility?
Which genetic disorder involves females having a missing or incomplete X chromosome, leading to short stature and infertility?
Which numerical aberration is associated with the presence of an additional chromosome from a given pair?
Which numerical aberration is associated with the presence of an additional chromosome from a given pair?
In which syndrome would you expect to find a karyotype of 47,XXY in males?
In which syndrome would you expect to find a karyotype of 47,XXY in males?
Which of the following is a condition that can result in a karyotype of 69,XXX and is associated with multiple developmental defects?
Which of the following is a condition that can result in a karyotype of 69,XXX and is associated with multiple developmental defects?
Which type of chromosomal abnormality is typically associated with a female having only one X chromosome (45,X)?
Which type of chromosomal abnormality is typically associated with a female having only one X chromosome (45,X)?
In which syndrome would you expect to find a male individual with a karyotype of 47,XYY?
In which syndrome would you expect to find a male individual with a karyotype of 47,XYY?
Which syndrome involves an individual having an extra Y chromosome (47,XYY)?
Which syndrome involves an individual having an extra Y chromosome (47,XYY)?
Which syndrome is characterized by the presence of an additional X chromosome in females (47,XXX)?
Which syndrome is characterized by the presence of an additional X chromosome in females (47,XXX)?
In which syndrome does an individual have an extra copy of chromosome 21?
In which syndrome does an individual have an extra copy of chromosome 21?
Which syndrome is characterized by the absence of one X chromosome in females?
Which syndrome is characterized by the absence of one X chromosome in females?
Individuals with Klinefelter syndrome have an additional chromosome. What is the karyotype for Klinefelter syndrome?
Individuals with Klinefelter syndrome have an additional chromosome. What is the karyotype for Klinefelter syndrome?
Which syndrome is characterized by individuals having a single X chromosome (45,X)?
Which syndrome is characterized by individuals having a single X chromosome (45,X)?
Study Notes
Genetic Abnormalities and Mutations
- Euploidy/Polyploidy: a state where a cell or organism has one or more than one set of chromosomes beyond the basic set, e.g. triploidy (3 sets), tetraploidy (4 sets).
- Gene mutations: changes in the nucleotide sequence of a DNA fragment in one gene, including:
- Single nucleotide polymorphism (SNP)
- Transition or transversion (substitutions)
- Insertion or deletion
- Leading to the creation of a new quality of the gene/allele
- Heteroploidy: an abnormal number of chromosomes in a cell, resulting from irregular mitosis, often in cancer cells.
- Induced mutations: caused by various mutagens, such as physical, chemical, or biological factors.
Chromosomal Aberrations
- Meiotic/mitotic nondisjunction: the failure of homologous chromosomes (during meiosis) or sister chromatids (during mitosis) to properly separate during cell division, resulting in their uneven segregation for daughter cells.
- Numerical aberrations:
- Aneuploidy: a change in the number of chromosomes from a given pair, including:
- Nullisomy: lack of chromosomes from a given pair (2n-2)
- Monosomy: lack of one chromosome from a given pair (2n-1)
- Trisomy: an additional chromosome from a given pair (2n+1)
- Tetrasomy: two additional chromosomes from a given pair (2n+2)
- Euploidy/Polyploidy: the presence of more than two complete haploid sets of chromosomes, e.g. triploidy (3n), tetraploidy (4n)
- Aneuploidy: a change in the number of chromosomes from a given pair, including:
- Structural aberrations:
- Deletion: loss of a chromosome segment
- Duplication: doubling of a specific segment of a chromosome
- Inversion: occurs as a result of breaks in two places of a chromosome, with the separated parts reversed and re-incorporated
- Translocation: breaking of chromosomes and rearrangement of fragments between two chromosomes, including:
- Reciprocal translocation
- Robertsonian translocation
Specific Genetic Disorders
- Cri du chat syndrome: caused by the deletion of part of the short arm of chromosome 5, resulting in:
- Low birth weight and delayed growth
- Hypotonia
- Microcephaly
- Unusual facial features
- Intellectual disability
- Down syndrome: caused by trisomy 21, resulting in:
- Epicanthal fold
- Large fissured tongue
- Brushfield spots on the iris
- Hypotonia
- Mental retardation
- Turner syndrome: caused by 45,X, resulting in:
- Short stature
- Rudimentary ovaries
- Poorly developed nipples
- Underdevelopment of secondary sexual characteristics
- Primary amenorrhea
- Klinefelter syndrome: caused by 47,XXY, resulting in:
- Female type silhouette
- Gynaecomastia
- Testicular dysgenesis
- Atrophy of seminiferous tubules
Other Key Concepts
- Thomas Hunt Morgan's chromosomal theory of heredity: proved that genes are located on chromosomes
- Drosophila melanogaster: a convenient experimental organism for genetic research, characterized by:
- Short development time
- High fertility
- Low maintenance costs
- Presence of polytene (giant) chromosomes
- Polytene chromosomes: oversized chromosomes that develop from standard chromosomes, found in the salivary glands of Diptera larvae
- Gene amplification: the process of multiple copies of genes permitting a high level of gene expression
- Puffs: representing active genes, formed by the unfolding of chromatid fibers in each chromomere of the corresponding chromosome band
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Description
Test your knowledge on different types of chromosomal mutations such as pericentric inversion, paracentric inversion, insertion, ring chromosome, and dicentric chromosome. Identify the characteristics and implications of each mutation.
