Chromatin vs. Chromosome

Chromatin and Chromosome are two types of structures Of the DNA that are formed in different stages of the life cycle of the cell. The DNA is a double-helix in a structure that contains genetic information stored in the nucleus.

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During interphase of the cell cycle, the DNA is in the chromatin form (loosely bounded on histone proteins) and is replicated, resulting in 2 copies of each DNA strand while in prophase of mitosis, each DNA strand condenses down to become much shorter and thicker by winding up much more tightly, in a process called supercoiling that allows each strand of DNA to become a visible chromosome that appears at the metaphase of the nuclear division.

The key difference between chromatin and chromosome is the structure of DNA. Chromatin consists of the unraveled condensed structure of the DNA to compress it into a compact unit that will be less voluminous and can within the nucleus whereas the chromosome consist of the highest condensed structure of the DNA double-helix  for the proper segregation of genetic material between daughter cells.

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Comparison Chart

 BasisChromatinChromosome
DefinitionIt is a combination of DNA, ribonucleic acids, and proteins called histones that fill the cell nucleusIt is the highest condensed structure of DNA double helix with protein wherein the mass the nucleic acid and protein is nearly equal
ConstituentComposed of nucleosomesChromosomes are condensed chromatin fibers
AppearanceUnder the microscope, chromatin looks like beads on a stringWhen spaghetti-like chromatin compresses by a factor of 10,000 resulting in a condensed body called as chromosome that looks like a big X with four arms that are joined at the central portion called the centromere

Phase of Cell Cycle                                    

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Chromatin appears in the interphase of the cell cycleChromosomes appear during the metaphase and exist in the anaphase of the nuclear division
StructureThin, long, and uncoiledIt looks like thick, compact, and ribbon-like
ReplicationIt occurs in the chromatin phaseIt cannot occur in chromosome phase
PairSingle, unpaired fibersMost human cells have 46 chromosomes that appear in two sets of 23, each set donated by a parent
CondensationChromatin can be condensed up to 50 times than the normal DNA double-helixThey can be condensed up to 10,000 times than the normal DNA double-helix
Visualization             Visualized under the electron microscopeChromosomes can be seen under light microscope
FunctionAllows the genetic material to be packed into the nucleus while regulating the gene expressionEnsure the proper arrangement of genetic material in the cell equator to allow equal separation of genetic material between daughter cells

What is Chromatin?

Chromatin is a complex of DNA and proteins that condense to form chromosomes within the nucleus of eukaryotic cells and is located in the nucleus of our cells.

Structure of Chromatin

Under the electron microscope, chromatin looks like a beads of nucleosomes on a string. Each nucleosome is composed of DNA wrapped around eight proteins called histones. The nucleosomes are then coiled into a hollow tube shape (30 nm) called a solenoid, where additional histone proteins support the chromatin structure.

Phases of Chromatin in Mitosis

  • Prophase

During prophase of mitosis, chromatin fibers start getting coiled into chromosomes and each replicated chromosome consists of two chromatids that are joined at a centromere.

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  • Metaphase

During metaphase, the chromatin becomes extremely condensed and aligns at the metaphase plate as chromosomes.

  • Anaphase

During Anaphase, the paired chromosomes (sister chromatids) are pulled by spindle microtubules to opposite ends of the cell.

  • Telophase

In telophase, each new daughter chromosome is separated into its own nucleus and producing genetically identical daughter cells that have the same number of chromosomes. During telophase, the chromosomes continue to uncoil and elongate forming chromatin.

Chromatin only begin to form into chromosomes in the beginning of mitosis or meiosis (metaphase and anaphase)

What is Chromosome?

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) that consist of thousands of genes that determine everything about an individual from the sex, eye color, dimples, to the freckles.

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The genetic information is passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.

The word “chromosome” comes from the Greek word “chroma” meaning color, and “soma” meaning body.

Visualization of Chromosome

To see the chromosomes, cells can be isolated as they divide and then dropped onto a small sheet of glass. This is then dipped into a special chemical dye called Giemsa and viewed using a microscope.

Chromosomes need to be magnified 1000 times in order to see them. Scientists routinely take photos of the chromosomes and sort them by cutting and pasting them in size order, and finding pairs by matching bands.

Function of Chromosome

The unique compactness of the chromosome plays an important role in helping to organize genetic material during cell division and enabling it to fit inside nucleus of the cell.

For an organism to grow and function properly, cells must constantly divide to produce new cells to replace old, worn-out cells. During cell division, it is essential that DNA remains intact and evenly distributed among cells. Chromosomes are a key part of the process that ensures DNA is accurately copied and distributed in the vast majority of cell divisions. Still, mistakes do occur on rare occasions.

Changes in the number or structure of chromosomes in new cells may lead to serious problems. For example, in humans, one type of leukemia and some other cancers are caused by defective chromosomes made up of joined pieces of broken chromosomes.

It is also crucial that reproductive cells, such as eggs and sperm, contain the right number of chromosomes and that those chromosomes have the correct structure. If not, the resulting offspring may fail to develop properly. For example, people with Down syndrome have three copies of chromosome 21, instead of the two copies found in other people.

Key Differences between Chromatin and Chromosome

  1. Chromatin is a complex of DNA, RNA, and protein called histones that fill the cell while the chromosome is the highly condensed form of chromatin.
  2. Chromatin allows the genetic material to be fit within the nucleus while chromosomes allow equal separation of genetic material between daughter cells.
  3. Chromatin appears in the interphase of the cell cycle while chromosomes appear during the metaphase and exist in the anaphase of the nuclear division.
  4. Chromatin is composed of nucleosomes while chromosomes are condensed into chromatin fibers.

Comparison Video

Conclusion

Both chromatin and chromosomes are two different types of DNA that are formed in different stages of the life cycle. During the eukaryotic division of parent cell into two daughter cells, chromatin fibers become extremely condensed and align themselves at the metaphase plate as chromosomes that contains genetic information to transfer into daughter cells when the parent cell divide.

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