final 14 !

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Questions and Answers

What is primarily affected in 70-80% of CMT cases?

Duplication of chromosome 22

Duplication of chromosome 17 (correct)

Translocation of large regions on chromosome 9

Deletion of peripheral myelin protein 22

What is a consequence of abnormal myelin production in CMT?

Increase in muscle mass

Enhanced breathing capacity

Demyelinating neuropathy (correct)

Improvement of touch sensation

What typically occurs due to unbalanced translocation in gametes?

Loss of genetic material without phenotypic impact

Gain or loss of chromosomal material leading to phenotypic impact (correct)

Enhanced cell function

Total chromosomal stability

What characterizes the Philadelphia Chromosome associated with CML?

Fragment of chromosome 9 fused to chromosome 22 Signup and view all the answers

Why is early diagnosis critical in genetic diseases?

It allows immediate treatment and sometimes prevention Signup and view all the answers

What type of mutation involves a permanent change in the DNA sequence?

Single base pair mutation Signup and view all the answers

Which of the following is an example of a copy number variation?

Frameshift caused by deletion Signup and view all the answers

What results from a duplication of the MYC gene?

Increased cell growth and proliferation Signup and view all the answers

Which genetic disorder is associated with repeat expansion of the CAG sequence?

Huntington’s disease Signup and view all the answers

Down Syndrome is a result of which chromosomal abnormality?

Nondisjunction of chromosome 21 Signup and view all the answers

What is a common effect of chromosomal mutations?

Changes in the structure of an entire chromosome Signup and view all the answers

What type of mutations are hereditary mutations usually associated with?

Germline mutations Signup and view all the answers

What characterizes de novo mutations?

They arise during germline development or after fertilization. Signup and view all the answers

Which of the following statements is true regarding acquired/somatic mutations?

They occur in an individual's DNA at some point in life. Signup and view all the answers

What is the correct term for two identical alleles of a gene?

Homozygous Signup and view all the answers

How are autosomal dominant disorders inherited?

The disease appears in every generation. Signup and view all the answers

What is true about a recessive allele?

It can only produce its trait when homozygous. Signup and view all the answers

What type of inheritance results in an equal likelihood of being affected for both males and females?

Autosomal Dominant Signup and view all the answers

What is indicated by a genotype of Bb for eye color?

Heterozygous for brown eyes. Signup and view all the answers

What percentage chance does a child have of being affected by an autosomal dominant disorder if one parent is affected?

50% Signup and view all the answers

What distinguishes a dominant allele from a recessive allele?

A dominant allele produces its trait regardless of the other allele. Signup and view all the answers

What is a common consequence of gamete nondisjunction in germ cells?

Embryos often resulting in trisomy or monosomy Signup and view all the answers

Which of the following is true regarding trisomy 21?

It is positively correlated to maternal age. Signup and view all the answers

What is a characteristic phenotype of Klinefelter's syndrome?

Atrophic testicles and reduced fertility Signup and view all the answers

Which chromosomal abnormality is characterized by a deletion on the short arm of chromosome 5?

Cri Du Chat Syndrome Signup and view all the answers

Which syndrome is associated with an extra X chromosome in males?

XYY Syndrome Signup and view all the answers

What effect does gamete nondisjunction have on autosomal chromosomes?

It can lead to spontaneous abortions or severe chromosomal abnormalities. Signup and view all the answers

What best describes the outcome of chromosome duplications during meiosis?

Altered gene dosage with potential for partial trisomy Signup and view all the answers

Which syndrome typically results in a small uterus and underdeveloped secondary sex characteristics?

Turner's Syndrome Signup and view all the answers

Which of the following is not a common symptom of Triple X syndrome?

Severe cognitive impairment Signup and view all the answers

What is the primary reason for the difference in severity between sex chromosomal abnormalities and autosomal abnormalities?

X chromosome inactivation in females Signup and view all the answers

What is required for an autosomal recessive disorder to manifest in an individual?

Individual inherits one defective allele from each parent Signup and view all the answers

Which symptom is NOT associated with Cystic Fibrosis?

High blood pressure Signup and view all the answers

How is an X-linked recessive disorder inherited in males?

Males express the trait if they inherit one defective X chromosome Signup and view all the answers

What is the primary reason color blindness is more common in males than females?

Females have two X chromosomes which can mask the defective gene Signup and view all the answers

What is the purpose of karyotyping?

To identify chromosome abnormalities Signup and view all the answers

What is a common use of a pedigree chart?

To track the inheritance of specific genetic traits Signup and view all the answers

What is the effect of mitogen in karyotyping?

It encourages cells to divide Signup and view all the answers

How do autosomal chromosomes get numbered?

In descending order based on size Signup and view all the answers

What role does trypsin play in the karyotyping process?

It degrades proteins bound to DNA Signup and view all the answers

Which of these disorders is classified as a multi-gene disorder?

Diabetes Signup and view all the answers

What is a missense mutation?

A mutation that results in a change in one amino acid. Signup and view all the answers

Which type of mutation can lead to frameshifts?

Insertions and deletions. Signup and view all the answers

What is the consequence of a nonsense mutation?

It results in a premature stop codon. Signup and view all the answers

Which category does a duplication of genetic material fall into?

Copy number variations. Signup and view all the answers

Cystic Fibrosis is primarily caused by which type of mutation?

Nonsense mutations in the CFTR gene. Signup and view all the answers

What is a characteristic of a conservative missense mutation?

The new amino acid resembles the original in properties. Signup and view all the answers

Which statement is true regarding frame shifts?

They can result from insertion or deletions of nucleotides. Signup and view all the answers

What is a consequence of gamete nondisjunction during meiosis?

The gametes will have an abnormal number of chromosomes. Signup and view all the answers

Which chromosomal abnormality is most commonly associated with advanced maternal age?

Down Syndrome Signup and view all the answers

What is a common outcome for embryos with significant chromosomal deletions?

They often do not develop to term. Signup and view all the answers

Which syndrome is characterized by the presence of an extra X chromosome in males?

Klinefelter's Syndrome Signup and view all the answers

What is a typical phenotypic feature of Triple X Syndrome?

Tall stature with normal sexual development Signup and view all the answers

What is the primary consequence of a frameshift mutation?

Altered protein function due to a change in the reading frame Signup and view all the answers

What mechanism leads to Down Syndrome?

Nondisjunction during cell division resulting in trisomy Signup and view all the answers

Which of the following is an example of a chromosomal abnormality?

Duplication of chromosome segments Signup and view all the answers

Which type of mutation is characterized by the formation of inclusion bodies in cells?

Repeat expansion Signup and view all the answers

What is a common feature of copy number variations?

They can lead to gene duplications or deletions. Signup and view all the answers

How does a missense mutation differ from a nonsense mutation?

A missense mutation results in a different amino acid being incorporated. Signup and view all the answers

What role does the MYC gene play in cancer biology?

It regulates cell growth and proliferation. Signup and view all the answers

What is the significance of a germline mutation?

It can be passed from parent to child. Signup and view all the answers

What best describes the term 'nondisjunction'?

Failure of chromosomes to separate during cell division Signup and view all the answers

Which type of mutation occurs due to environmental factors or mistakes during DNA replication?

Acquired/somatic mutations Signup and view all the answers

What is the result of inheriting a homozygous genotype, such as BB or bb?

The individual will express only recessive traits. Signup and view all the answers

Which statement accurately describes autosomal dominant inheritance?

Males and females are affected equally. Signup and view all the answers

What is true about the structure of DNA in human cells?

DNA in each cell measures about 2 meters in length. Signup and view all the answers

What type of genetic disorder transmission occurs when a dominant allele is present?

There is a 50% chance of being affected in each child. Signup and view all the answers

What does the genotype Bb indicate regarding eye color?

The individual is heterozygous for brown eyes. Signup and view all the answers

Which of the following best describes recessive alleles?

They only manifest when the genotype is homozygous recessive. Signup and view all the answers

How does a child inherit an autosomal recessive disorder?

Both parents must be carriers or affected individuals. Signup and view all the answers

What best represents autosomal recessive inheritance in a pedigree analysis?

Both male and female offspring are equally affected. Signup and view all the answers

What is the inheritance pattern of Huntington's Disease?

Autosomal Dominant Signup and view all the answers

At what age do symptoms of Huntington's Disease typically begin to appear?

30-45 years Signup and view all the answers

What is a common symptom associated with Huntington's Disease?

Personality disturbances Signup and view all the answers

How likely is a child to inherit Huntington's Disease if one parent is affected?

50% chance Signup and view all the answers

Which of the following is NOT a symptom of Huntington's Disease?

Complete recovery Signup and view all the answers

What ethical consideration might arise regarding genetic testing for Huntington's Disease in Carl's fetus?

Psychological impact of results Signup and view all the answers

Which symptom has Carl's mother exhibited that might indicate a neurodegenerative disorder?

Mood swings Signup and view all the answers

What is a potential outcome of the physical deterioration caused by Huntington's Disease?

Difficulty swallowing Signup and view all the answers

What is one of the primary components of the HTT gene related to Huntington's Disease?

Neuronal huntingtin protein Signup and view all the answers

What type of genetic mutation is associated with Huntington's Disease?

Expansion CAG repeat Signup and view all the answers

What is the primary result of a nonsense mutation in a genetic sequence?

It leads to a premature stop codon in protein synthesis. Signup and view all the answers

Which of the following is an example of a copy number variation due to insertions?

Fragile X Syndrome Signup and view all the answers

What is a defining feature of a frameshift mutation?

It shifts the reading frame, changing all subsequent codons. Signup and view all the answers

Which category does an inversion in a chromosome fall under?

Chromosomal abnormality Signup and view all the answers

Which type of genetic mutation is specifically characterized by a change that maintains similar chemical properties in the amino acid?

Conservative missense mutation Signup and view all the answers

What consequence can occur from a non-multiple of three nucleotides being deleted in a DNA sequence?

It will lead to a frameshift mutation. Signup and view all the answers

Cystic Fibrosis is characterized by which of the following mechanisms caused by the CFTR gene mutation?

Impaired chloride ion transport Signup and view all the answers

What is the primary reason for the high prevalence of miscarriages associated with aneuploidy in pregnancies?

Monosomy generally results in incompatible fetal development. Signup and view all the answers

Which chromosomal abnormality is characterized by a deletion occurring on the short arm of chromosome 5?

Cri Du Chat Syndrome Signup and view all the answers

In what way do sex chromosome abnormalities generally differ in severity compared to autosomal abnormalities?

Phenotypic effects are often mitigated through X chromosome inactivation. Signup and view all the answers

Which trisomy syndrome is most commonly associated with advanced maternal age and has a higher likelihood of allowing live births?

Trisomy 21 Signup and view all the answers

What is a common outcome of mosaicism resulting from zygote nondisjunction during mitosis?

Presence of cells with different karyotypes within an individual. Signup and view all the answers

What is the characteristic feature of autosomal dominant disorders?

They have a 50% chance of being passed on. Signup and view all the answers

Which of the following describes a de novo mutation?

A mutation that is present in all cells of an affected child. Signup and view all the answers

What defines a heterozygous genotype concerning alleles?

One allele is dominant and the other is recessive. Signup and view all the answers

What is the effect of environmental factors on acquired/somatic mutations?

They can lead to mutations later in a person's life. Signup and view all the answers

In the context of eye color genetics, what does a genotype of 'BB' indicate?

The individual is homozygous and expresses the dominant trait. Signup and view all the answers

Which of the following statements accurately describes recessive alleles?

They require two copies to manifest their traits. Signup and view all the answers

For an autosomal recessive disorder to be expressed in an individual, which condition must be met?

Both parents must be heterozygous carriers. Signup and view all the answers

Which type of mutation is primarily responsible for genetic variations in an individual's cells after conception?

Acquired/somatic mutations. Signup and view all the answers

What is the key inheritance pattern of sex-linked disorders?

Typically affects males more than females. Signup and view all the answers

At what age do symptoms of Huntington's Disease typically appear?

30-45 years Signup and view all the answers

Which symptom is NOT associated with Huntington's Disease?

Increased appetite Signup and view all the answers

Which gene is commonly associated with Huntington's Disease?

HTT Signup and view all the answers

What percentage chance does a child of a parent with Huntington's Disease have of inheriting it?

50% Signup and view all the answers

Which symptom of Huntington's Disease is primarily physical?

Involuntary movements Signup and view all the answers

What ethical consideration arises from genetic testing for Huntington's Disease?

Informed consent Signup and view all the answers

What is a common misconception among families regarding hereditary conditions like Huntington's Disease?

There is a cure available. Signup and view all the answers

Which of the following issues might complicate the decision for Carl to undergo testing for Huntington's Disease?

All of the above Signup and view all the answers

What is the ultimate outcome of untreated Huntington's Disease?

Complete incapacitation and death Signup and view all the answers

What is the likelihood of a child being affected by an autosomal recessive disorder if both parents are carriers of the defective allele?

25% Signup and view all the answers

Which statement is true regarding the inheritance pattern of X-linked recessive traits?

Males who inherit a defective X chromosome will express the trait. Signup and view all the answers

What is a notable characteristic of the pedigree chart in familial inheritance?

It tracks the inheritance of specific genetic traits over multiple generations. Signup and view all the answers

Which of the following correctly describes the role of colchicine in the karyotyping procedure?

It halts cell division to allow chromosome examination. Signup and view all the answers

What genetic characteristic contributes to the higher prevalence of color blindness in males compared to females?

Males have only one X chromosome. Signup and view all the answers

What is the primary purpose of G-banding in karyotyping?

To identify chromosome abnormalities. Signup and view all the answers

What is an implication of the mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene?

It leads to protein malfunction affecting mucus regulation. Signup and view all the answers

Which of the following statements best describes karyotyping?

It assesses chromosomal structure and abnormalities. Signup and view all the answers

What is a common symptom associated with autosomal recessive disorders like cystic fibrosis?

Difficulty breathing and chronic lung infections. Signup and view all the answers

Which of the following best explains the relationship between close intermarriages and autosomal recessive disorders?

It raises the probability of both parents being carriers. Signup and view all the answers

Study Notes

HSS2305: Molecular Mechanisms of Disease

Lecture 14 covers Genetics and Disease
The outline for the lecture includes Announcements, Genetics and Disease.
Genetic mutations are a permanent change in the DNA sequence.
General categories of genetic mutations include:
- Single base pair or point mutation (substitution)
- Copy number variations (insertions and deletions, can result in frameshifts; duplication and repeat expansion)
- Chromosomal abnormalities (duplication, inversion, deletion, insertion, translocation, nondisjunction)
Types of Single Base Pair Mutations:
- Missense mutation - results in a change in amino acid
- Nonsense (stop) mutation - results in a premature stop codon
- Silent mutation - no change in amino acid
An example of a missense mutation is Sickle Cell disease, where a change in amino acid sequence leads to hemoglobin molecules crystallizing and red blood cells becoming sickle-shaped. This can cause the cells to get stuck in blood vessels.
A nonsense mutation example is Cystic Fibrosis, where a change causes a protein that maintains the balance of salt and water in tissues, leading to thick mucus that results in persistent lung infections.
Copy number variations include insertions and deletions causing frameshifts (shifts in the reading frame of codons), and duplication and repeat expansions.
Chromosomal abnormalities involve structural changes like duplication, inversion, deletion, insertion, translocation, and nondisjunction.
An example of an abnormality is Down Syndrome, caused by trisomy 21, where an extra chromosome 21 occurs due to nondisjunction.
There are three types of mutations that occur:
- Hereditary/germline mutations
- De novo mutations
- Acquired/somatic mutations.
An example of a single gene disorder is Huntington's Disease (HD), caused by an expansion of CAG repeats in the HTT gene. This leads to toxic protein aggregations and eventually cell death.
Another example is Autosomal Recessive disorders like Cystic Fibrosis caused by mutations in the CFTR gene leading to abnormal salt and water balance, and resulting in respiratory complications.
Sex-linked recessive disorders such as colourblindness occur on the X chromosome.
Multi-gene disorders are caused by interactions of multiple genes and environmental factors, such as Diabetes or Allergies.
There are several methods for diagnosing genetic diseases including amniocentesis or chorionic villus sampling.
Gene therapy involves altering or inserting genes to treat disease, but there are various limitations including issues with the longevity of gene integration, immune responses, and multi-gene disorders.
The next lecture covers cell signaling and G-coupled receptors.

Review of Genetics

Each cell contains 2 meters of DNA, 25,000 protein-coding genes, 46 chromosomes including 44 autosomal and 2 sex chromosomes (X and/or Y).
Alleles are alternative forms of a gene (e.g., B for brown eyes, b for blue eyes).
Homozygous refers to having two identical alleles for a gene (BB or bb).
Heterozygous means having two different alleles for a gene (Bb).
A dominant allele always expresses its trait when present, while a recessive allele only expresses its trait when homozygous.
Review of Inheritance.
Karyotype is a characterization of chromosomes (shape, size, number).
Karyotyping determines the presence or absence of chromosomal abnormality that are inherited or cause issues in becoming pregnant.
A biological sample (like blood, amniotic fluid, placenta) is used to determine the details of the karyotype.
Common methods for detecting chromosomal abnormalities include G-banding, and the steps taken for sample preparation for karyotyping.

Genetics and Disease: Chromosomal Abnormalities

4 types of chromosomal abnormalities are presented:
- 1. Chromosome abnormality,
- 1. Numerical chromosomal anomalies
- 1. Structural chromosomal anomalies,
- 1. Errors during cell division resulting in mosaics.
Meiosis, a type of cell division in reproduction, is described; as are its stages.
In meiosis, homologous chromosomes or sister chromatids fail to separate this is known as nondisjunction, with potentially harmful results and associated diagnoses.
Various examples of nondisjunction are given, including Trisomy 21 (Down Syndrome), Trisomy 18 (Edwards Syndrome), Trisomy 13 (Patau Syndrome), and examples of sex chromosome nondisjunction like Klinefelter's Syndrome (XXY) and Turner's Syndrome (XO).
There are also details about triple X Syndrome (47,XXX) and XYY syndrome (47,XYY)
Different types of chromosomal abnormalities are discussed (deletions, duplication and translocation examples) including specific details and diagnoses.

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Description

This quiz focuses on Lecture 14 of HSS2305, which covers the crucial connection between genetics and disease. Students will explore various genetic mutations, including point mutations, copy number variations, and chromosomal abnormalities. The implications of these mutations, illustrated through examples like Sickle Cell disease, will be assessed.