Thursday, May 23, 2024

Sex Linked Inheritance pdf

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Introduction

Generally, we think that both mother and father have identical contributions to the beginning of a child, however, one main exception to that is sex linkage as may be found in the attached sex linked inheritance pdf. Sex linkage takes place whilst a gene that controls a trait is placed on a sex chromosome. In addition to genes directly related to sex determination, there are numerous genes on the sex chromosome. Inheritance in those genes happens in a particular fashion.

Our own genomes carry the story of evolution, written in DNA, the language of molecular genetics, and the narrative is unmistakable.

by Kenneth R. Miller

Sex chromosomes show dimorphism. Due to differences in chromosome complement, the amount of genes placed at the Y chromosome includes genes that are more often than not associated with male differentiation. Whereas the X chromosome is chargeable for genes which can be vital for a few fundamental functions. Because females have X chromosomes, they have double X linkage genes at the same time as men have the most effective one.

sex linked inheritance pdf

It all relies upon the sex chromosomes whether the offspring can be a male or a woman. In mammals along with human beings, X and Y are the sex chromosomes. Each of them has a pair of those chromosomes i.e. Male has an X and Y chromosome pair whilst a female has a couple of X chromosomes. There are other kinds of chromosomes too which might be known as autosomes or non-sex chromosomes. Sex linked inheritance pdf is discussed in the post.

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Chromosomal Theory of Inheritance and Sex Linkage

The idea that chromosomes carry genes is known as the chromosomal theory of inheritance. This theory is attributed to Walter Sutton and Theodore Boveri. Both of them concluded from their separate experiments that the behavior of genes during gamete production in peas is exactly equivalent to the behavior of chromosomes during meiosis. The following similarities were observed between the two (gametes and genes):

  1. Genes also exist in pairs and so do chromosomes.
  2. The number of gene pairs is equally combined in the gametes and similarly, the members of the pair of homologous chromosomes also disintegrate.
  3. Different gene pairs work independently, just like chromosomes.

sex linked inheritance pdf

Sex linked inheritance pdf is discussed in the post.

Sex Linked Inheritance pdf

Sex-linked inheritance, additionally called X-linked inheritance, is a sort of genetic inheritance pattern that involves genes located on the sex chromosomes, particularly the X and Y chromosomes as explained in the connected Sex Linked Inheritance pdf. Chromosomal anomaly is found in humans as females have X chromosomes (XX), at the same time as males have one X and one Y chromosome (XY). Due to this natural situation, genetic trends positioned on the X chromosome have a tendency to specific unique inheritance patterns. This outcomes in certain genetic conditions or trends being more usually expressed in one sex than the other. Sex linked inheritance pdf is discussed in the post.

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X Linked Traits in Humans

Let’s begin with the aid of looking at tendencies determined by way of genes at the X-chromosome, referred to as X-related tendencies. The human X chromosome incorporates many genes wished in both sexes, whilst the Y chromosome has few genes, mainly for maleness. More than 200 developments are X-linked, while only some are Y-linked. Traits controlled with the aid of genes on the X chromosome are also referred to as sex-linked.

sex linked inheritance pdf

X-linked and sex-linked are used interchangeably, however, it is more correct to name them X-connected tendencies because they follow the X-chromosome’s inheritance pattern. X-linked trends have a unique inheritance sample because ladies have two doses of X-linked genes, even as males have the handiest one. Males are hemizygous for X-related traits.

There are two main categories of sex-linked inheritance:

  • X-linked Dominant
  • X-linked Recessive

Sex linked inheritance pdf is discussed in the post.

X-linked Dominant Inheritance

X-linked dominant genes show their effects in both males and females. When there’s one copy of the X-linked dominant allele, it affects both sexes. In males, the gene is passed to all daughters but not to sons. Fathers don’t pass the gene to their sons. Heterozygous females pass the trait to half of their children, regardless of gender. However, females with two copies of the dominant allele have all their children affected by the trait. Sex linked inheritance pdf is discussed in the post.

In this category, a single copy of the dominant allele on the X chromosome is enough to explicit the trait or condition. Since adult males have only one X chromosome, they can express dominant X-related trends even though they have only one replica of the allele. Some disorders related to X-linked dominant genes are listed below:

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You are reading sex linked inheritance pdf here

Vitamin D Resistant Rickets

Vitamin D-resistant rickets is a rare hereditary disorder that affects bone development. Normally, vitamin D helps the body absorb calcium, which is essential for strong bones. But, in this condition, the body is not able to respond properly to Vitamin D, causing the bones to become soft and weak.

sex linked inheritance pdf

This disorder is associated with mutations in the gene that provides instructions for making a protein called the vitamin D receptor. This receptor is like a lock that must be opened for vitamin D to do its job. Sex linked inheritance pdf is discussed in the post.

Since the gene is located on the X chromosome, inheritance patterns may differ between males and females. Males are more severely affected because they only have one X chromosome, so if it contains the mutated gene, they will develop the disorder. Women, on the other hand, have two X chromosomes, so if only one of their However, some women with the mutation may be affected as severely as men.

In short, vitamin D-resistant rickets is a condition where the body does not respond properly to vitamin D, causing weak bones. It is associated with mutations in the gene for the vitamin D receptor, which is located on the X chromosome and follows an X-linked dominant inheritance pattern. Sex linked inheritance pdf is discussed in the post.

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Incontinentia Pigmenti

Incontinentia pigmenti is an unprecedented genetic ailment that affects most women, especially the skin. It is because of a mutation inside the IKBKG gene, that’s positioned at the X chromosome. This gene offers commands for making a protein which is essential for the development and function of many special tissues in the body.

sex linked inheritance pdf

In X-connected dominant inheritance, the gene responsible for the circumstance is positioned at the X chromosome. There are two X chromosomes in ladies, while best one X and one Y chromosome are found in males. Since the gene is positioned at the X chromosome, inheritance styles may additionally fluctuate among men and women. Sex linked inheritance pdf is discussed in the post.

In women who have two X chromosomes, the severity of incontinentia pigmenti can range. If a lady inherits a mutated reproduction of the IKBKG gene on one of her X chromosomes, she may have moderate signs or be unaffected. However, if she has inherited a mutated copy on both X chromosomes, her symptoms may be extra extreme.

In men, who have the highest X chromosome, the sickness is because of inheriting a mutated reproduction of the IKBKG gene. Men with incontinentia pigmenti frequently have more extreme signs and symptoms than women.

In short, incontinentia pigmenti is a genetic disease resulting from a mutation inside the IKBKG gene, which is positioned on the X chromosome. The inheritance sample is X-related dominant, which means that the gene is passed from one technology to the following through the X chromosome. The severity of the ailment can vary depending on the variety of mutated copies of the gene a person inherits. Sex linked inheritance pdf is discussed in the post.

Rett Syndrome

Dr. Andreas Rett in 1966 first time reported some cases of Rett syndrome. It is a rare neurodevelopmental disorder that primarily affects females. Rett syndrome is usually caused by de novo (new) mutations that occur spontaneously in the affected individual’s DNA, rather than being inherited from parents. Because Rett syndrome is an X-linked dominant disorder, a single mutation on one of the X chromosomes is sufficient to cause the disorder in females.

Fragile X Syndrome

Fragile X syndrome is inherited in an X-linked dominant manner, though it affects males more severely due to their single X chromosome. Carrier mothers can pass the expanded CGG repeat to their children, and the likelihood and severity of the syndrome can vary based on the number of CGG repeats and whether the mutation is passed from the mother or father. Sex linked inheritance pdf is discussed in the post.

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X-Linked Recessive Inheritance

For recessive alleles, the situation is different. In males, who have one X chromosome, recessive X-linked alleles always show their effects. On the other hand, females express recessive alleles only when they have two copies of them (homozygous). As a result, the occurrence of X-linked recessive traits is generally lower in females compared to males. Most X-linked genes are recessive, and these traits become noticeable when their harmful effects appear in males. Males pass their X chromosome to all daughters and their Y chromosome to all sons.

sex linked inheritance pdf

The inheritance pattern of recessive X-linked traits often involves the trait being expressed only in males every other generation. A male carrier transmits the recessive allele to his daughters, who don’t show the trait because they are heterozygous. Sex linked inheritance pdf is discussed in the post.

However, there’s a 50% chance that each of her sons will receive and express the allele, making the trait appear in 1/4 of her total offspring (since half are expected to be male and 1/2 of those sons receive the recessive allele: 1/2 × 1/2 = 1/4). The heterozygous female is considered a carrier of the allele. This type of inheritance is often described as a crisscross pattern, where the allele is passed from male to female and vice versa, with the trait being expressed only in males in alternate generations.

In this category, the gene responsible for the trait or condition is located on the X chromosome. Females have two X chromosomes, so they can be either homozygous (XX) or heterozygous (Xx) for the gene. Males, on the other hand, having only one X chromosome, are hemizygous (Xy) for the gene. Sex linked inheritance pdf is discussed in the post.

There are two most discussed examples of X-linked Recessive Inheritance:

Color Blindness

A renowned Physicist, Chemist, and meteorologist who postulated the atomic theory i.e. John Dalton is called the father of color blindness. He suffered from color blindness.

Red-green color blindness, the most common type of color blindness, is a well-known example of X-linked recessive inheritance. The genes responsible for different cone photo-pigments are located on the X chromosome. Since males have one X and one Y chromosome, a single mutation on their X chromosome can result in color blindness. Females, on the other hand, have two X chromosomes, so they are less likely to be affected because the normal gene on the other X chromosome can compensate for the mutation. Sex linked inheritance pdf is discussed in the post.

Hemophilia

This mysterious condition was first reported by Dr.  John Conrad Otto in 1803, and the term “Hemophilia” was first used at the University of Zurich.

Hemophilia is another evident example of X-linked recessive inheritance. It negatively affects the blood’s ability to clot properly. Males with a hemophilia gene on their X chromosome will have the disorder, while females need two copies of the gene (one from each parent) to express the disorder.

Conclusion

In summary, sex-linked inheritance refers to the inheritance pattern of genes located on the sex chromosomes (X and Y). X-linked recessive traits are more commonly expressed in males due to their single X chromosome, while X-linked dominant traits may affect both sexes but can have varying levels of severity. These inheritance patterns have significant implications for the prevalence and expression of certain genetic conditions in different sexes. Sex linked inheritance pdf is discussed in the post.

Sex linked inheritance pdf  (Credits- Government Women College Gandhinagar)

Sex linked inheritance pdf  (Credits- Lucknow University)

Sex linked inheritance pdf  (Credits- Veer Bahadur Singh Purvanchal University)

Frequently Asked Questions (FAQS)

Ques- What is sex-linked inheritance?

Ans- It is a kind of biological process that involves the transmission of certain characteristics from parents to offspring. It depends upon the combination of X and Y chromosomes. You can explore the Sex linked inheritance pdf in the post for more detailed information.

Ques- What are the examples of sex-linked inheritance pattern?

Ans- Color blindness, Hemophilia, and muscular dystrophy.

Ques- What is the sex-linked inheritance of females?

Ans- A female has two X Chromosomes or a pair of X Chromosomes (one from the mother and one from the father).

Ques- What is the sex-linked inheritance of males?

Ans- A male has two chromosomes, one is the X chromosome (from the mother) and the other is the Y chromosome (from the father).

Ques- Can fathers pass on X-linked traits to their sons?

Ans- No, fathers can pass only Y Chromosomes to their sons. X-linked traits can only be inherited from mothers. Sex linked inheritance pdf is available in the post.

Ques- Give an example of a Y-linked trait.

Ans- Male pattern baldness

Ques- Why are Y-linked traits less than X-linked traits?

Ans- As the Y chromosome carries fewer genes than the X chromosome, the Y-linked traits are less than the X-linked traits.

Ques- Color blindness is an example of which trait?

Ans- Color blindness is an example of a sex-linked trait. The gene responsible for color vision is located on the X chromosome. You can explore the Sex linked inheritance pdf in the post for more detailed information.

Ques- which chromosome carries the fewest number of genes?

Ans- Y chromosome carries the fewest number of genes as compared to the X chromosome. It carries only 344 genes approximately.

Ques- How many genes do X chromosomes have?

Ans- The x chromosome has approximately 900 to 1400 genes. The X chromosome represents about 5% of total DNA in cells.

Ques- sex-linked inheritance was discovered by whom?

Ans- Sex-linked inheritance was discovered by Thomas Hunt Morgan based on the experiments conducted on Drosophila Melanogaster in 1910. The scientist was awarded Noble Prize in 1933 for his findings about the role of chromosomes in heredity. Sex linked inheritance pdf is available in the post.

Ques- Who is most often affected by sex-linked inheritance?

Ans- Males are more often affected by sex-linked inheritance because males have only one X chromosome.

Ques- Which X-lined inheritance mainly affects male offspring?

Ans- Hemophilia is a sex-linked inheritance condition that mainly affects male offspring.

Ques- What are the types of hemophilia?

Ans- Hemophilia is of two types: Hemophilia A (caused by a deficiency in clotting factor VIII) and Hemophilia B (caused by a deficiency in clotting factor IX). The sex-linked inheritance pdf should be referenced for more information. You can explore the Sex linked inheritance pdf in the post for more detailed information.

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