Skip to main content

Sex Chromosomes

It's not quite accurate to say that everyone inherits two copies of every gene. In most mammals, the X and Y sex chromosomes determine whether an individual is male or female. Females have two X chromosomes, and therefore two copies of every gene. Males, however, have one X and one Y chromosome. For genes that appear only on the X chromosome or only on the Y (some do appear on both), males inherit just one copy.

Taken from http://www.eschooltoday.com/science/genetics/images/sex-chromosomes.jpg


Other living things have sex chromosomes too. Birds and reptiles have Z and W sex chromosomes. Unlike with X and Y, males have two Z chromosomes, and females have one Z and one W. Some insects and a few mammals have only an X chromosome. Females have two copies and males have one. However, sex is not always determined by chromosomes. With alligators, crocodiles, and most turtles, it's egg incubation temperature. And some fish can change gender in response to cues from the environment. Sex determination happens in many different ways.

 Source: http://learn.genetics.utah.edu/content/basics/inheritance/
Labels:

Comments

Post a Comment

Popular posts from this blog

History of Genetics

 Genetics is the branch of biology that studies heredity and variation in organisms. It is concerned with the molecular basis of inheritance and the ways in which genes are passed down from one generation to the next. The history of genetics can be traced back to the ancient Greeks, who were the first to speculate about the nature of heredity. In the 19th century, Gregor Mendel, an Austrian monk, conducted experiments on pea plants that led to the discovery of the laws of inheritance. His work, which he published in 1866, laid the foundation for modern genetics. Mendel's laws of segregation and independent assortment described how genes are passed from one generation to the next and how traits are inherited. In the early 20th century, Thomas Hunt Morgan and his colleagues at Columbia University conducted experiments on fruit flies that showed that genes are located on chromosomes. This discovery led to the development of the chromosome theory of inheritance, which states that genes
Post a Comment
Read more

What is genetics?

Genetics is the study of how traits such as hair color, eye color, and risk for disease are passed (“inherited”) from parents to their children. Genetics influence how these inherited  traits  can be different from person to person. Your genetic information is called your genetic code or “ genome .” Your genome is made up of a chemical called  deoxyribonucleic acid (DNA)  and is stored in almost every cell in your body. Reference:  Introduction to Genetics: https://www.my46.org/intro/what-is-genetics
Post a Comment
Read more

Chromosomes and Genes: An Introduction

Chromosomes are not visible in the cell’s nucleus—not even under a microscope—when the cell is not dividing. However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope.  Chromosome is composed of DNA coiled and condensed around nuclear proteins called histones. Humans inherit one set of chromosomes from their mother and a second set from their father. In total, most human cells contain 46 chromosomes with 22 pairs of autosomes, or non-sex chromosomes, and two sex-determining chromosomes. The sex chromosomes in humans are called X and Y. Females carry two X chromosomes, while males carry one X and one Y chromosome. Cells of the body that contain two sets of chromosomes are called diploid.   Gene: It is a linear sequence /segment of  DNA  that provides the coded instructions for synthesis of RNA, which, when translated into protein, leads to the expression of hereditary character. Source of info. 1
Post a Comment
Read more