Where is chromosomes found

Some Natural Phenomena Light Stars and the Solar System Q 7 Where are chromosomes found in a cell? State their function. Looking to do well in your science exam? Learn from an expert tutor.

Book a free class! Solution Transcript. Solution 7: Chromosomes are found in the nucleus of the cell. They carry genes and help in inheritance or transfer of characters from parents to offspring. Set your child up for success with Lido, book a class today!

Maths Class 6 Class 7 Class 8. Chromosomes are structures within cells that contain DNA and many genes. A gene is One of the two X chromosomes in females is turned off through a process called X inactivation. On the right, a microscopic specimen of a cell nucleus from a female shows this inactive X chromosome as a dense lump arrow. On the left, a specimen from a male is shown for comparison.

If a female has a disorder in which she has more than two X chromosomes, the extra chromosomes tend to be inactive. Thus, having one or more extra X chromosomes causes far fewer developmental abnormalities than having one or more extra nonsex chromosomes. Genes contain Males who have more than one Y chromosome Home. There are several types of chromosome abnormalities Overview of Chromosome and Gene Disorders Chromosomes are structures within cells that contain a person's genes.

A gene is a segment of deoxyribonucleic acid DNA and contains the code for a specific protein that functions in one or A person may have an abnormal number of chromosomes or have abnormal areas on one or more chromosomes. Many such abnormalities can be diagnosed before birth see Testing for chromosome and gene abnormalities Testing for chromosome and gene abnormalities Chromosomes are structures within cells that contain a person's genes.

Abnormal numbers of nonsex chromosomes usually result in severe abnormalities. For example, receiving an extra nonsex chromosome may be fatal to a fetus or lead to abnormalities such as Down syndrome Down Syndrome Trisomy 21 Down syndrome is a chromosome disorder caused by an extra chromosome 21 that results in intellectual disability and physical abnormalities.

Down syndrome is caused by an extra chromosome Absence of a nonsex chromosome is fatal to the fetus. Large areas on a chromosome may be abnormal, usually because a whole section was left out called a deletion or mistakenly placed in another chromosome called translocation. For example, chronic myelogenous leukemia Chronic Myeloid Leukemia CML Chronic myeloid leukemia is a slowly progressing disease in which cells that normally would develop into neutrophils, basophils, eosinophils, and monocytes become cancerous see also Overview This abnormality can be inherited or be the result of a new mutation Mutation Genes are segments of deoxyribonucleic acid DNA that contain the code for a specific protein that functions in one or more types of cells in the body.

Mitochondria Cells Often thought of as the smallest unit of a living organism, a cell is made up of many even smaller parts, each with its own function.

Unlike other structures inside cells, each mitochondrion contains its own circular chromosome. This chromosome contains DNA mitochondrial DNA that codes for some, but not all, of the proteins that make up that mitochondrion. Mitochondria from the sperm usually do not become part of the developing embryo. A trait is any gene-determined characteristic. Many traits are determined by the function of more than one gene.

For example, a person's height is likely to be determined by many genes, including those affecting growth, appetite, muscle mass, and activity level.

However, some traits are determined by the function of a single gene. Variation in some traits, such as eye color or blood type, is considered normal. Other variations, such as albinism Albinism Albinism is a rare hereditary disorder in which little or none of the skin pigment melanin is formed. The skin, hair, and eyes, or sometimes just the eyes, are affected. Typically, the hair This syndrome is caused However, not all such gene abnormalities are uniformly harmful. For example, one copy of the sickle cell gene can provide protection against malaria, but two copies of the gene cause sickle cell anemia.

A genetic disorder is a detrimental trait caused by an abnormal gene. The abnormal gene may be inherited or may arise spontaneously as a result of a new mutation. Gene abnormalities are fairly common. Every humans carries an average of to abnormal genes different ones in different people. However, most of the time the corresponding gene on the other chromosome in the pair is normal and prevents any harmful effects. In the general population, the chance of a person having two copies of the same abnormal gene and hence a disorder is very small.

However, in children who are offspring of close blood relatives, the chances are higher. Chances are also higher among children of parents who have married within an isolated population, such as the Amish or Mennonites. Merck and Co. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world.

The Manual was first published in as a service to the community. What is inheritance? What does DNA do? What is a gene? What is a chromosome disorder? How helpful was this page? What's the main reason for your rating? Which of these best describes your occupation? What is the first part of your school's postcode? The core particle of each nucleosome consists of eight histone molecules, two each of four different histone types: H2A, H2B, H3, and H4.

The structure of histones has been strongly conserved across evolution, suggesting that their DNA packaging function is crucially important to all eukaryotic cells Figure 4. Histones carry positive charges and bind negatively charged DNA in a specific conformation. In particular, a segment of the DNA double helix wraps around each histone core particle a little less than twice. The exact length of the DNA segment associated with each histone core varies from species to species, but most such segments are approximately base pairs in length.

Furthermore, each histone molecule within the core particle has one end that sticks out from the particle. These ends are called N-terminal tails , and they play an important role in higher-order chromatin structure and gene expression. Figure 4: The nucleosome structure within chromatin. Each nucleosome contains eight histone proteins blue , and DNA wraps around these histone structures to achieve a more condensed coiled form.

Figure 5: To better fit within the cell, long pieces of double-stranded DNA are tightly packed into structures called chromosomes. Although nucleosomes may look like extended "beads on a string" under an electron microscope, they appear differently in living cells. In such cells, nucleosomes stack up against one another in organized arrays with multiple levels of packing.

The first level of packing is thought to produce a fiber about 30 nanometers nm wide. These 30 nm fibers then form a series of loops, which fold back on themselves for additional compacting Figure 5.

The multiple levels of packing that exist within eukaryotic chromosomes not only permit a large amount of DNA to occupy a very small space, but they also serve several functional roles. For example, the looping of nucleosome-containing fibers brings specific regions of chromatin together, thereby influencing gene expression.

In fact, the organized packing of DNA is malleable and appears to be highly regulated in cells. Chromatin packing also offers an additional mechanism for controlling gene expression.

Specifically, cells can control access to their DNA by modifying the structure of their chromatin. Highly compacted chromatin simply isn't accessible to the enzymes involved in DNA transcription , replication , or repair. Thus, regions of chromatin where active transcription is taking place called euchromatin are less condensed than regions where transcription is inactive or is being actively inhibited or repressed called heterochromatin Figure 6.

Figure 6: The structure of chromatin in interphase Heterochromatin is more condensed than euchromatin. Typically, the more condensed chromatin is, the less accessible it is by transcription factors and polymerases. The dynamic nature of chromatin is regulated by enzymes.

For example, chromatin can be loosened by changing the position of the DNA strands within a nucleosome. This loosening occurs because of chromatin remodeling enzymes, which function to slide nucleosomes along the DNA strand so that other enzymes can access the strand. This process is closely regulated and allows specific genes to be accessed in response to metabolic signals within the cell.

Another way cells control gene expression is by modifying their histones with small chemical groups, such as methyl and acetyl groups in the N-terminal tails that extend from the core particle. Different enzymes catalyze each kind of N-terminal modification. Scientists occasionally refer to the complex pattern of histone modification in cells as a "histone code.