non dis junction
QUESTIONS
Q1 DISCUSS THE CHROMOSOMAL BASICS OF SEX DETERMINATION
The chromosomal basis of sex varies with the organism. In most species, sex is determined by the presence or absence of special chromosomes. As a result of meiotic segregation, each gamete has one sex chromosome to contribute at fertilization. Sex determination is strictly chromosomal and is not usually influenced by the environment. There are two types of sex namely
Heterogametic sex: The sex that produces two kinds of gametes and determines the sex of the offspring.
Homogametic sex : The sex that produces one kind of gamete Humans, have an X-Y mechanism that determines sex at fertilization. There are two chromosomes, X and Y. The XY sex chromosomes are different in shape and size from each other. Each gamete has one sex chromosome, so when sperm cell and ovum unite at fertilization, the zygote receives one of two possible combinations: XX or XY. Males are the heterogametic sex (XY). Half the sperm cells contain an X chromosome, while the other half contains a Y chromosome. And females are the homogametic sex (XX) that is all ova carry an X chromosome. Whether an embryo develops into a male or female depends upon the presence of a Y chromosome. If the egg receives a Y chromosome from the sperm, the individual is XY, forms testes, and is male. The Y chromosome carries a gene that encodes a testis-determining factor. Chromosomes carry different genes; chromosomal differences between the sexes also result in unique phenotypes and inheritance patterns such as the shape and contour of the body, the distribution of body hair, and the pitch of the voice. The male hormones stimulate production of spermatozoa in men, and the female hormones control ovulation, pregnancy, and the menstrual cycle in women
A British research team has identified a gene, SRY (sex-determining region of Y), on the Y chromosome that is responsible for triggering the complex series of events that lead to normal
Q1 DISCUSS THE CHROMOSOMAL BASICS OF SEX DETERMINATION
The chromosomal basis of sex varies with the organism. In most species, sex is determined by the presence or absence of special chromosomes. As a result of meiotic segregation, each gamete has one sex chromosome to contribute at fertilization. Sex determination is strictly chromosomal and is not usually influenced by the environment. There are two types of sex namely
Heterogametic sex: The sex that produces two kinds of gametes and determines the sex of the offspring.
Homogametic sex : The sex that produces one kind of gamete Humans, have an X-Y mechanism that determines sex at fertilization. There are two chromosomes, X and Y. The XY sex chromosomes are different in shape and size from each other. Each gamete has one sex chromosome, so when sperm cell and ovum unite at fertilization, the zygote receives one of two possible combinations: XX or XY. Males are the heterogametic sex (XY). Half the sperm cells contain an X chromosome, while the other half contains a Y chromosome. And females are the homogametic sex (XX) that is all ova carry an X chromosome. Whether an embryo develops into a male or female depends upon the presence of a Y chromosome. If the egg receives a Y chromosome from the sperm, the individual is XY, forms testes, and is male. The Y chromosome carries a gene that encodes a testis-determining factor. Chromosomes carry different genes; chromosomal differences between the sexes also result in unique phenotypes and inheritance patterns such as the shape and contour of the body, the distribution of body hair, and the pitch of the voice. The male hormones stimulate production of spermatozoa in men, and the female hormones control ovulation, pregnancy, and the menstrual cycle in women
A British research team has identified a gene, SRY (sex-determining region of Y), on the Y chromosome that is responsible for triggering the complex series of events that lead to normal