Although not as familiar as DNA, chromosomes are found to have an association with this molecule. But do you understand precisely what a chromosome is? How many chromosomes do humans have: 21, 23, and 24?
The 46 pairs of chromosomes that humans have are normal, but male and female in them have different amounts. For more information let’s take a look at some of the following facts.
What are chromosomes?
Chromosomes are derived from the Greek words chroma and soma. Chroma means color, while soma means body. Scientists give this name because these molecules are cell or body structures consisting of certain colors when viewed under a microscope.
This molecule was initially detected in the late 1800s. But at the point the character and function of the cell structure weren’t yet obvious. In the early 1900s, Thomas Hunt Morgan re-examined this section. Morgan discovered a link between chromosomes and innate properties in living things.
Thus, it can be broadly concluded that the chromosome is a collection of DNA that is tightly circular and located inside the nucleus (cell nucleus) of almost every cell in the body. This DNA collection is a thread-like molecule that carries hereditary information from height, skin color, to eye color.
These molecules are made of proteins and one DNA molecule that contains genetic clues of an organism derived from its parents. In humans, animals, and plants most chromosomes are arranged in pairs inside the cell nucleus.
Are chromosomes made up of genes?
A chromosome is made of a very long strand of DNA and containing many genes (hundreds to thousands). Genes on each chromosome are arranged in a specific order, and each gene has a specific location on that chromosome (called its locus).
How many chromosomes do humans have: 21, 23, and 24
Usually, people have 23 pairs of chromosomes within their own bodies, or equivalent to 46 copies. But in plants and animals, the number varies greatly. Each DNA set has two short arms, two longer arms, and one centromere in the center.
Why do humans have 23 chromosomes?
46 chromosomes in person calling, arranged in 23 pairs. This is because our chromosomes exist in a matching pair – with one chromosome of each pair inherited from each biological parent. Each cell in the human body contains 23 pairs of such chromosomes; Therefore, our diploid number is 46, our haploid number is 23.
The unique structure of the chromosome makes DNA wrap around a coil-like protein called a histone. Without such twists, DNA molecules would be too long to fit into cells.
For example, if all the DNA molecules in a human cell were released from its history, it would be about 6 feet long or the equivalent of 1.8 meters.
For an organism or living creature to grow and function properly, cells must continue to divide. The goal is to replace the old damaged cells with new ones. During this process of cell division, it is important that DNA remains intact and evenly distributed between cells.
Well, it’s the chromosomes which play an significant role in the process. Because this molecule is tasked to ensure that DNA is copied and distributed accurately in most cell divisions. But sometimes, it remains possible that this DNA collection made a mistake in its cleavage process.
Changes in the number or structure of DNA pools in cells can only cause serious problems. For example, certain types of leukemia and some other cancers are caused by the destruction of this DNA collection.
In addition, it is also important for the egg and sperm to contain the right number of chromosomes with the correct structure. Otherwise, the resulting offspring can also fail to develop properly.
The chromosomes of each living creature are different
In number and form, this collection of DNA varies greatly in each living being. Most bacteria have one or two circular chromosomes. Meanwhile, people, animals, and plants have linear chromosomes arranged in pairs at the cell nucleus.
The only human cells that do not contain chromosomal pairs are reproductive cells or gamete. These reproductive tissues take just 1 copy of every.
When two reproductive cells unite, they become a single cell containing two copies of each chromosome. These cells then divide themselves until they eventually produce a complete adult individual with a complete set of paired chromosomes on almost all of their cells.
A collection of circular form DNA is also found in mitochondria. Mitochondria are where cells breathe. This part is then tasked to burn glucose and produce the energy needed by the body.
Inside the mitochondria, this collection of DNA has a much smaller size. This collection of circular DNA located outside the cell nucleus in the mitochondria serves as a cell powerhouse.
How to inherit chromosomes
In humans and most other living things, one copy of each collection of DNA is inherited from female and male broods. Therefore, every child born must inherit some of his mother and father’s traits.
However, this devolution pattern is different for small DNA groups found in mitochondria. Mitochondrial DNA is always inherited from the female mother or egg only.
Male and female chromosomes in humans
In addition to being physically different, men and women also have different DNA sets. This distinct assortment of DNA is known as the sex chromosome. A woman has two X chromosomes in her cell (XX). Even though men have one X and one Y (XY).
A person who has too many or too few copies of the sex chromosome can cause serious problems. In women who have more copies of the X chromosome (XXX) can trigger mental retardation.
Meanwhile, guys that have more than 1 X chromosome (XXY) may encounter Klinefelter syndrome. This syndrome is usually characterized by small, not descending testicular size, enlarged breasts (gynecomastia), lower muscle mass, and larger hips such as women.
Additionally, yet another syndrome brought on by an imbalance in the amount of sexual chromosomes is Turner syndrome. Girls with Turner syndrome are distinguished with just 1 X chromosome.
Types of chromosomal abnormalities
Chromosomal abnormalities are usually divided into two large groups, namely numerical and structural abnormalities.
Numerical abnormalities occur when the number of chromosomes is less or more than it should be, i.e. two (pairs). If a person loses one of them, this condition is called monosomy in the group of DNA groups concerned.
Meanwhile, in case a individual has a lot more than just two chromosomes the affliction is known as trisomy.
Among those health issues brought on by numerical abnormalities is Down syndrome. This condition is characterized by mental retardation of the sufferer, different and distinctive facial shapes, and poor muscle strength.
Individuals who’ve Down syndrome have a few copies of chromosome 21. That’s the reason this problem is known as trisomy 21.
Structural abnormalities Normally Vary due to several Items, Specifically:
- Removal, part of the chromosome is missing.
- Duplication, some chromosomes multiply resulting in additional genetic material.
- Translocation, partly chromosomes are transferred to other chromosomes.
- Inversion, partly chromosome is damaged, reversed, and reconnected which makes its genetic material upside down.
- Rings, partially damaged chromosomes, and form circles or rings.
Generally, most cases of this structural abnormality occur due to problems in the egg and sperm. In cases like this, abnormalities arise in each cell of their human body.
However, some abnormalities can also occur after conception so that some cells have abnormalities and some do not.
This disorder can also be inherited from parents. Therefore, when a child has abnormalities in his DNA collection, the doctor will perform a check on his parents’ DNA collection.
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Causes of chromosomal abnormalities
There are several sources, chromosomal abnormalities usually occur when there is an error in the process of cell division. The process of cell division is divided into two, mitosis and meiosis.
Mitosis is a process of division that results in two duplicate cells from the original cell. This cleavage occurs in all parts of the body except the reproductive organs. Meiosis, meanwhile, is a cell division that produces half of the number of chromosomes.
Well, in both of these processes there could be errors that cause too few or too many cells. Errors can also occur when these DNA sets are being duplicated or duplicated.
In addition, other factors that can increase the risk of abnormalities in this DNA collection, namely:
Females are born complete with eggs. Some researchers believe that this disorder can arise due to changes in the genetic material of the egg as it ages.
Typically, women of older age have a higher risk of giving birth to babies with chromosomal abnormalities, compared to those who become pregnant at a younger age.
Environmental factors may contribute to the emergence of genetic errors. However, further evidence is still needed to determine what is affecting it.
Diseases caused by chromosomal abnormalities
Down syndrome is a genetic disorder also referred to as trisomy condition 21. This ailment is just one of one of the absolute most often occurring hereditary birth defects resulting from the accession of chromosome 21. Like a consequence, infants possess 47 duplicates of chromosomes, which generally people have just 46 duplicates (23 pairs).
One of the strongest factors that cause this problem is the age of the mother while pregnant. Usually, the risk will increase every year after the mother turns 35 years old.
Kids with Down syndrome can typically be readily known with their own physiological faculties. Here are the common signs of Down Syndrome:
- Eyes that tend to tilt upwards
- Small ears that are usually slightly folded
- Smallmouth size
- Short neckline
- Joints tend to be weak
This ailment is actually a hereditary illness that normally happens in ladies. This happens when the child loses one of its chromosomes, totaling only 45. Usually, children with Turner syndrome have a shorter body compared to their peers.
In addition, some of the other symptoms that mark Turner syndrome are:
- It has a wide neck with skin folds on the sides.
- Shout from the Form and Location of Their ears
- Flat chest
- Has many small brown moles on the skin more than usual
- Small jaws
Klinefelter syndrome is also referred to as XXY state where guys have an additional X chromosome in their cells. Usually, babies with this syndrome have weak muscles. Therefore, its development tends to be slower compared to others.
In puberty, men with XXY syndrome usually do not produce as much testosterone as other boys. In addition, they also have small and infertile testicles.
This condition makes the child less muscular, the lack of facial and body hair, even breasts that are larger than normal size.
Trisomy 13 and 18
Trisomy 13 and 18 are genetic abnormalities that result in birth defects. Trisomy 13 means the infant born has 3 copies of chromosome number 13. Trisomy 13 is called Patau syndrome.
A kid with three copies of chromosome 18, or trisomy 18, is named Edwards syndrome. Normally, kids who have both states won’t survive until age one year.
Babies with trisomy 13, or Patau syndrome, are usually characterized by:
- Low birth weight
- Small head with a slanted forehead
- Structural problems in the brain
- Adjacent eye size
- Cleft lip and palate
- The testicles do N’t descend into the scrotum
Meanwhile, Infants with trisomy 18 (Edwards syndrome) are characterized by:
- Failed to develop
- Small head
- Smallmouth and jaw
- Short sternum
- Hearing problems
- Arms and legs in a bent position
- The spinal cord is not completely covered (spina bifida)