Textbook Question
Name the primary placental hormones and their functions.
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Ch. 29 Development and Inheritance
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology25
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization29
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure33
- Ch. 7 The Axial Skeleton11
- Ch. 8 The Appendicular Skeleton17
- Ch. 9 Joints13
- Ch. 10 Muscle Tissue12
- Ch. 11 The Muscular System28
- Ch. 12 Nervous Tissue18
- Ch. 13 The Spinal Cord, Spinal Nerves, and Spinal Reflexes22
- Ch. 14 The Brain and Cranial Nerves20
- Ch. 15 Sensory Pathways and the Somatic Nervous System17
- Ch. 16 The Autonomic Nervous System and Higher-Order Functions30
- Ch. 17 The Special Senses15
- Ch. 18 The Endocrine System21
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation26
- Ch. 22 The Lymphatic System and Immunity25
- Ch. 23 The Respiratory System4
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes30
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance17
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011Not the one you use?Change textbook
Chapter 28, Problem 25
Hemophilia A, a condition in which blood does not clot properly, is a recessive trait located on the X chromosome (Xʰ). Suppose that a woman who is heterozygous for this trait (XXʰ) has children with a normal male (XY). What is the probability that the couple will have daughters with hemophilia? What is the probability that the couple will have sons with hemophilia?
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Identify the genotypes of the parents: The woman is heterozygous for hemophilia A, so her genotype is X X\^h (one normal X chromosome and one X chromosome with the hemophilia allele). The man is normal, so his genotype is X Y.
Determine the possible gametes each parent can produce: The woman can produce eggs carrying either X or X\^h. The man can produce sperm carrying either X or Y.
Set up a Punnett square to find all possible combinations of the offspring's sex chromosomes: Combine the woman's gametes (X and X\^h) with the man's gametes (X and Y) to get the genotypes of daughters and sons.
Analyze the daughters' genotypes: Daughters receive one X chromosome from each parent. The possible daughter genotypes are X X (normal) and X\^h X (carrier). Since hemophilia is recessive and X-linked, daughters must have two X\^h alleles (X\^h X\^h) to express the disease. Determine the probability of this genotype from the Punnett square.
Analyze the sons' genotypes: Sons receive the X chromosome from the mother and the Y chromosome from the father. The possible son genotypes are X Y (normal) and X\^h Y (hemophiliac). Since males have only one X chromosome, the presence of X\^h means the son will have hemophilia. Determine the probability of this genotype from the Punnett square.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
X-linked Recessive Inheritance
X-linked recessive traits are caused by genes located on the X chromosome. Males (XY) are more likely to express the trait because they have only one X chromosome, while females (XX) must inherit two copies of the recessive allele to express the trait. Females with one affected X are carriers but usually do not show symptoms.
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X-Linked Inheritance
Genotype and Phenotype of Parents
Understanding the parents' genotypes is essential: the mother is heterozygous (XXʰ), meaning she carries one normal and one affected X chromosome, while the father is normal (XY). This determines the possible combinations of sex chromosomes and alleles their children can inherit, influencing the probability of affected offspring.
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06:36Genotype & Phenotype
Probability of Inheritance in Offspring
Calculating the probability involves combining the inheritance patterns of sex chromosomes and the recessive allele. Daughters inherit one X from each parent, while sons inherit the X from the mother and Y from the father. This affects the likelihood of daughters or sons having hemophilia based on the mother's carrier status.
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07:23X-Linked Inheritance
Related Practice