Campbell Essential Biology with Physiology (6th Edition)
6th Edition
ISBN: 9780134711751
Author: Eric J. Simon, Jean L. Dickey, Jane B. Reece
Publisher: PEARSON
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Chapter 8, Problem 11SQ
Summary Introduction
To explain:
The reason that why there are many more people with an extra chromosome 21, which causes Down syndrome, than people with an extra chromosome 3 or chromosome 16 when non disjunction is a random event.
Introduction:
Down syndrome is a genetic disorder which occurs due to the presence of an additional set of chromosome 21 that is trisomy 21. This disbalance of the distribution of chromosome occurs due to the failure of separation of chromosome 21 during the stage of meiosis I. This situation is called as non disjunction where chromosome segregation does not occur properly.
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Chapter 8 Solutions
Campbell Essential Biology with Physiology (6th Edition)
Ch. 8 - Which of the following is not a function of...Ch. 8 - In what sense are the two daughter cells produced...Ch. 8 - Prob. 3SQCh. 8 - A biochemist measures the amount of DNA in cells...Ch. 8 - Which two phases of mitosis are essentially...Ch. 8 - Complete the following table to compare mitosis...Ch. 8 - If an intestinal cell in a dog contains 78...Ch. 8 - Prob. 8SQCh. 8 - Prob. 9SQCh. 8 - A diploid body (somatic) cell from a fruit fly...
Ch. 8 - Prob. 11SQCh. 8 - Prob. 12IMTCh. 8 - Prob. 13IMTCh. 8 - Prob. 14IMTCh. 8 - A mule is the offspring of a horse and a donkey. A...Ch. 8 - Prob. 16PSCh. 8 - Interpreting Data The graph in the right hand...Ch. 8 - As described in the Biology and Society section,...Ch. 8 - Prob. 19BSCh. 8 - Prob. 20BSCh. 8 - Prob. 21BS
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- People with Down syndrome have an extra copy of chromosome 21, for a total of 47 chromosomes. However, in a few cases of Down syndrome, 46 chromosomes are present. This total includes two normal-looking chromosomes 21, one normal chromosome 14, and a longer-than-normal chromosome 14. Interpret this observation. How can these individuals have 46 chromosomes?arrow_forwardHuman sex chromosomes are XX for females and XY for males. a. With respect to an X-linked gene, how many different types of gametes can a male produce? b. If a female is homozygous for an X-linked allele, how many different types of gametes can she produce with respect to this allele? c. If a female is heterozygous for an X-linked allele, how many different types of gametes can she produce with respect to this allele?arrow_forwardVariations in Chromosome NumberAneuploidy Describe the process of nondisjunction and explain when it takes place during cell division.arrow_forward
- How does nondisjunction lead to abnormalities in chromosome number? Describe two types of genetic disorders that can result from nondisjunction.arrow_forwardConsider the example of the fusion of chromosome 21 and 14. By itself, this fusion does not cause any phenotypic differences in the carrier individuals. However, the children of carriers have a very high rate of down syndrome, as well as low fertility. Explain why this is? Be specific about what differences in chromosome number may occur in offspring, and how this occurs. Please answer asap and in short and content should not be palgarised please answer asap Consider the example of the fusion of chromosome 21 and 14. By itself, this fusion does not cause any phenotypic differences in the carrier individuals. However, the children of carriers have a very high rate of down syndrome, as well as low fertility. Explain why this is? Be specific about what differences in chromosome number may occur in offspring, and how this occurs.arrow_forwardA normal mother has translocations on chromosomes 14:21. With respect to chromosomes 14:21, how many combinations of chromosomes are possible? How many gametes are viable? If the woman has children with an normal father, what is the probability that there is a daughter with Down Syndrome or a son with an unaffected phenotype?arrow_forward
- describe a specific example of chromosome abnormality that leads to human cancers, such as leukemia, other than the Philadelphia chromosome that is derived from the translocation of chromosome 9 and 22arrow_forwardWhat is dosage compensation with respect to the sex chromosomes? Briefly explain how this is accomplished in humans.arrow_forwardA young couple is planning to have children. Knowing that there have been a substantial number of stillbirths, miscarriages, and fertility problems on the husband’s side of the family, they see a genetic counselor. A chromosome analysis reveals that, whereas the woman has a normal karyotype, the man possesses only 45 chromosomes and is a carrier of a Robertsonian translocation between chromosomes 22 and 13. a. List all the different types of gametes that might be produced by the man. b. What types of zygotes will develop when each of gametes produced by the man fuses with a normal gamete produced by the woman? c. If trisomies and monosomies entailing chromosomes 13 and 22 are lethal, approximately what proportion of the surviving offspring are expected to be carriers of the translocation?arrow_forward
- A diploid individual is heterozygous for a chromosome rearrangement. The original chromosome and its rearranged homolog have the following segments, where ∙ represents a centromere: A B ∙ C D E F G A B ∙ C F E D G While paired in prophase I, a single crossing-over occurs between segment E and segment D of the paired chromosomes. Describe the unusual crossing-over structure that forms as a result.What gamete types will result from crossing over when meiosis is complete? please asaparrow_forwardA man who is a carrier of a translocated 15/21 chromosome marries a genotypically normal woman. a. Show the possible gametes that will be formed by this man if the translocated 15/21 chromosome synapses with chromosome 21 at Prophase I.arrow_forwardThe incidence of Down syndrome will be high (nearly 50%) among the offspring of a parent with Down syndrome. Diagram meiosis in the Down syndrome parent to explain why progeny have such a high risk for chromosome 21 aneuploidy. Explain in addition why the incidence of Down syndrome among these children might be less than 50%.arrow_forward
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