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The X chromosome

The X is often referred to as the ‘female’ chromosome; it is more accurately described as a ‘human’ chromosome. All of us, regardless of gender, have an active X chromosome in all of our cells. If you are female you were likely born with two Xs, so your cells will express one or the other. If you’re male, you likely only have one, so all your cells are the same.

This is the reason behind the higher incidence of autoimmune disease in women, the greater death rates of men and the male specific X chromosome disorders, such as colour blindness and Duchenne muscular dystrophy. That’s not to say that women are immune from these disorders. Usually when women are affected by them, it’s because…

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Articles of Interest

Minute to Understanding: What is a chromosome?

Our cells contain many structures that are essential for living. One of these key structures is a chromosome.

Cells Become Zombies When the Ends of Their Chromosomes are Damaged – a Tactic Both Helpful and Harmful for Health

When cells prepare to divide, their DNA is tightly wound around proteins to form chromosomes that provide structure and support for genetic material. At the ends of these chromosomes are repetitive stretches of DNA called telomeres that form a protective cap to prevent damage to the genetic material. However, telomeres shorten each time a cell divides. This means that as cells divide more and more as you age, your telomeres become increasingly shorter and more likely to lose their ability to protect your DNA.

Chromosomes and Genealogy

Are chromosomes different sizes, and does that matter? What are the mystery terms, cMs and SNPs? How does all of this intersect with genealogy? Do I care? These are all great questions, and of course, there are different ways to answer. Let’s start with some basics.

Chromosomes Aren’t Actually X Shaped

So much for all that memorizing you did in high school

DIY chromosomes

The first synthetic chromosome for a creature with complex cells, designed on a computer and made from scratch in a laboratory, is being put through its paces.

How Chromosomes X and Y Got Their Names, 1891

Why are the human sex chromosomes called “X” and “Y,” while the other 22 chromosomes are identified only by numbers?

How was your sex determined? It might be a lot more complicated than you think

Infinitely more complicated than baking a 20-layer Schichttorte are the biological processes that determine your sex. Your sex, like Schichttorte, has a lot of layers.

One in 500 men carry extra sex chromosome, research suggests

Research on more than 200,000 men enrolled with the UK Biobank suggests that about one in 500 in the general population has an extra X or Y chromosome, double the number found in earlier work, though only a fraction are likely to be aware of it. While most men have one X and one Y chromosome, some are born XXY or XYY, putting them at increased risk of health issues ranging from type 2 diabetes, blocked blood vessels and chronic obstructive pulmonary disease (COPD), a lung condition, the study found.

Scientists Discover That Chromosomes Are Fluid

When they are not in their division phases, chromosomes are fluid, though not quite liquid. This discovery was made possible by the first-ever direct mechanical manipulation of chromosomes in the nucleus of live cells.

Secrets of the Y Chromosome

It’s not just what makes males into males. The sex chromosome also influences health in hidden ways, some experts believe, and may even explain why men have shorter life spans.

The Disappearing Y Chromosome

It’s surprisingly common for men to start losing entire chromosomes from blood cells as they age.

The History of Chromosomes May Shape the Future of Diseases

Scientists hope that uncovering the history of chromosomes will have practical applications to diseases like cancer, in which rearranged chromosomes play a major part. Scientists have known for over 70 years that chromosomes can be rearranged. With a microscope, it is possible to make out the banded patterns on chromosomes and to compare the pattern in different species.

The myth that gender is binary is perpetuated by a flawed education system

High schools all teach the same narrative in sex-ed: Chromosomes determine genitals, which determine sex, which determines gender. Women are XX, and men are XY. One has a penis, the other a vagina. It’s science. Right?

The X chromosome: The supermom that's inside of us all

The X chromosome, like its shorter, stubbier but no less conspicuous counterpart, the Y chromosome, is a so-called sex chromosome, a segment of DNA entrusted with the pivotal task of sex determination. A mammalian embryo outfitted with an X and Y chromosomal set buds into a male, while a mammal bearing a pair of X chromosomes emerges as a female.

The Y Chromosome's Still-Uncharted Regions

The human genome has never actually been complete.

Update: Chromosomes Are Shaped Less Like X's, More Like O's

Tic-Tac-Toe, it turns out, is weirdly prescient about cell biology.

We get our DNA from our parents. So how are we all unique?

Each chromosome you have is a unique quilt of DNA, representing segments of the genome that have been passed down from generation to generation...

Why map your chromosomes?

We all have a “direct line.” Your biological mother and father each had a mother and father, and they each had a mother and father, going back in time. These people passed sections of their DNA down via their descendants all the way to you.

Resources

Chromosomes Fact Sheet

Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique. The term chromosome comes from the Greek words for color (chroma) and body (soma). Scientists gave this name to chromosomes because they are cell structures, or bodies, that are strongly stained by some colorful dyes used in research.

Counting Chromosomes

News, information, education, and opinion about DNA in general, with a focus on genetic genealogy and population genetics