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Questions and Answers
What genetic disorder is specifically caused by a trisomy of chromosome 21?
What genetic disorder is specifically caused by a trisomy of chromosome 21?
What term describes the condition where one of the chromosomes is present in an abnormal number of copies?
What term describes the condition where one of the chromosomes is present in an abnormal number of copies?
In X-linked inheritance, how can a trait appear in offspring when neither parent exhibits the trait?
In X-linked inheritance, how can a trait appear in offspring when neither parent exhibits the trait?
What is a common consequence of chromosome non-disjunction during meiosis?
What is a common consequence of chromosome non-disjunction during meiosis?
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Which condition is characterized by having three or more copies of all chromosomes?
Which condition is characterized by having three or more copies of all chromosomes?
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What percentage of flowering plants is believed to have arisen through polyploidization?
What percentage of flowering plants is believed to have arisen through polyploidization?
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Which chromosome is affected by the deletion that causes Cri-du-Chat syndrome?
Which chromosome is affected by the deletion that causes Cri-du-Chat syndrome?
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What type of genetic alteration is involved in Burkitt’s lymphoma?
What type of genetic alteration is involved in Burkitt’s lymphoma?
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What is the most common chromosomal abnormality?
What is the most common chromosomal abnormality?
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Approximately how many live births result in Down syndrome?
Approximately how many live births result in Down syndrome?
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What is a common respiratory issue seen in children with Down syndrome?
What is a common respiratory issue seen in children with Down syndrome?
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Which of the following risks increases for women aged 35 and older regarding Down syndrome?
Which of the following risks increases for women aged 35 and older regarding Down syndrome?
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Which of the following therapies is suggested for children with Down syndrome?
Which of the following therapies is suggested for children with Down syndrome?
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Study Notes
Genetic Disorders
- Genetic disorders result from alterations in genes or chromosomes.
- Chromosome number and structure impact basic genetics, health, and evolution.
- Karyotype preparation involves specific steps: tissue sample, chemical stimulation of mitosis, incubation, chemical halting of mitosis, cell concentration, cell placement on a microscope slide, chromosome staining, chromosome identification, karyotype creation.
Chromosomes and Inheritance
- Genes reside on chromosomes.
- Knowing chromosome number and structure has wide-reaching importance for genetics, human health, and evolution.
- The image shows a human karyotype, displaying paired chromosomes.
Karyotype Preparation Procedure
- Tissue sample preparation is the first step
- Chemicals are used to stimulate mitotic cell division.
- Cells are then isolated and concentrated.
- Cells are placed onto microscope slides.
- Staining enhances chromosome visualization.
- Chromosomes are identified and arranged into a karyotype.
Chromosome View
- Showing different chromosomes separated and paired.
Chromosomes Cut Out & Arranged
- Displayed chromosomes are matched in pairs, representing their typical structure & numbering.
X-linked Inheritance
- In X-linked inheritance, men and women play different roles.
- Colorblindness is an X-linked recessive trait.
- Diagrams of X-linked recessive inheritance patterns are included to show how the trait appears through generations.
Pedigree Analysis
- Pedigree analysis is a crucial tool for understanding human genetics.
- Creating a pedigree involves figuring out genotypes until they fit the known traits.
A Pedigree of a Recessive Human Trait
- A pedigree chart illustrates the transmission of a specific trait across generations.
- The chart shows how an attached earlobe trait is passed down in a family, and that the trait can sometimes appear in offspring even though it's not present in the parents.
A Pedigree of a Dominant Human Trait
- Pedigree charts track a trait through generations.
- The trait (widow's peak) appears in every generation, and half of the offspring of an affected heterozygote inherit the trait.
Changes in Chromosome Number and Structure
- Changes in chromosome number and structure are essential for health and evolution.
- Down syndrome is caused by abnormal chromosome number.
Aneuploidy
- Aneuploidy occurs when one or more chromosomes have an abnormal number of copies.
- The condition has two forms, trisomy and monosomy.
- Examples: trisomy 21
Down Syndrome: Trisomy 21
- Down syndrome is caused by an additional chromosome 21.
- Aneuploidy is very common, resulting in unsuccessful conceptions.
- Aneuploidy also drives cancer progression.
Down Syndrome - Trisomy 21
- A karyotype visually depicts the extra chromosome 21.
Chromosome Non-Disjunction in Meiosis Causes Aneuploidy
- Non-disjunction during meiosis leads to aneuploidy, where chromosomes fail to separate correctly.
The Frequency of Chromosome Non-Disjunction and Down Syndrome Rises Sharply with Maternal Age
- The chance of a child with Down syndrome increases significantly with advancing maternal age.
- The table provides the data of probability of having a child with this condition increases as it gets older.
Sex Chromosome Aneuploid Conditions are Common
- Conditions like Turner syndrome (XO), Klinefelter syndrome (XXY), and Triple-X (XXX) arise from irregularities involving sex chromosomes.
Polyploidy
- Polyploidy occurs when cells have three or more copies of every chromosome.
- Polyploidy is common in plants but rare in animals.
Polyploidy is a Major Force in Plant Evolution
- Polyploidy is a notable factor in plant evolution, accounting for a large proportion of flowering plant species.
Chromosome Structural Changes
- Deletions, duplications, inversions, and translocations are different kinds of chromosome structural changes that affect human health.
- These changes frequently cause problems.
A Boy with Cri-du-Chat Syndrome
- Cri-du-chat syndrome is a disorder due to a missing part of chromosome 5.
Translocations Lead to a Number of Human Cancers
- Chromosome translocations contribute to cancer development.
- In Burkitt's lymphoma, a translocation causes a gene that controls cell division to remain active, promoting uncontrolled cell growth.
Searching for Chromosomal Defects
- Techniques like amniocentesis and chorionic villus sampling aid in identifying chromosomal deviations in fetuses.
- These methods provide detailed information about chromosomes at various points during pregnancy.
Searching for Chromosome and Gene Defects - Pre-Implantation Genetic Diagnosis
- Pre-implantation genetic diagnosis (PGD) is a method to test embryos for genetic abnormalities before they are implanted for the pregnancy.
What is Down Syndrome?
- Down syndrome is the most common chromosomal abnormality. It is caused by an extra copy of chromosome 21.
- The probability of having a child with Down syndrome increases with maternal age.
Intelligence
- Intelligence level in individuals with Down syndrome may range from severely below-average to low-normal, usually falling within the moderate range.
Social Development
- Social development in children with Down syndrome may lag two to three years behind typical peers, noticeably during early childhood.
Sensory Problems
- Sensory problems like myopia, hyperopia, excessive tearing, head tilt, and cataracts are common in those with Down syndrome.
Physical Disorders
- Individuals with Down syndrome often experience frequent respiratory infections, a higher risk of leukemia, and potential thyroid issues.
- Therapies like vitamins and minerals may improve some conditions and surgery can treat certain ones.
Prognosis
- Life expectancy for individuals with Down syndrome varies depending on the age.
- A child with Down syndrome entering their first year of life has a lower probability of surviving than a child without this condition.
Genetic Mutations
- Mutations can arise from DNA replication errors or environmental factors such as physical and chemical agents.
- Germ cell mutations are harmful, while somatic cell mutations are often harmless and do not get passed down.
Mutations Can Cause Genetic Disease
- Genetic diseases can be passed down through inheritance.
- Examples of such diseases include Tay Sachs and Sickle Cell disease.
Although Mutations Are Often Harmful
- Mutations are sometimes vital sources of genetic variation, contributing to evolution through natural selection.
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Description
Explore the fascinating world of genetic disorders and the karyotype preparation process. This quiz delves into how alterations in genes and chromosomes affect health and evolution, highlighting the steps involved in preparing a karyotype. Test your understanding of chromosomes and their significance in genetics.
