Do All Cells Have DNA? No, all cells within the living body do not have DNA, and not all of our cells have the same DNA. Mature red blood cells and cells in the skin, hair, and nails contain no nucleus. Cells use DNA for their long-term information storage. In an organism, biological information is encoded in its DNA sequence. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are two different kinds of genetic material that exist. RNA is used for enzymatic functions and information transport.
Cell: Structure and Components
The cell is the structural, biological, and functional unit of life. The study of cells from their structure to the functions is called Cell Biology. It can replicate itself independently and is known as the building block of life.
Cells emerged at least 3.5 billion years ago on Earth. Cells are much larger than atoms, By Robert Hooke cells were discovered in 1665. In 1839 cell theory was first developed by Matthias Jakob Schleiden and Theodor Schwann. According to cell theory, all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function of life. And all cells come from pre-existing cells.
Cell Types:
According to the cellular structure, there are two types of cells:
- Prokaryotes
- Eukaryotes
Prokaryotic cells have no nucleus, and cell size ranges from 0.1 to 0.5 µm in diameter. Their hereditary material can either be DNA or RNA, generally reproduce by binary fission and they are all single-celled microorganisms. Found in archaea, bacteria, and cyanobacteria.
Eukaryotic cells have a true nucleus, and the size of the cells ranges between 10–100 µm in diameter. Eukaryotic DNA is organized in one or more linear molecules, and they reproduce sexually as well as asexually. Organized eukaryotic DNA in one or more linear molecules is known as chromosomes, are associated with histone proteins. Found in plants, fungi, protozoans, and animals.
| Eukaryotic cells | Prokaryotic cells | |
|---|---|---|
| Found in | bacteria, archaea | protists, fungi, plants, animals |
| Size | 1–5 μm | 10–100 μm |
| Type of nucleus | No true nucleus | True nucleus |
| DNA | usually circular | Linear molecules with histone proteins |
| RNA | coupled in the cytoplasm | In the nucleus RNA synthesis,In the cytoplasm protein synthesis |
| Cell division | binary fission | Mitosis,meiosis |
Cell Structure:
The components in cell structure include:
- cell wall
- cell membrane
- cytoplasm
- nucleus
- cell organelles
 Cell Membrane
|
The plasma membrane, or cell membrane is a membrane that surrounds the cytoplasm of a cell. The cell membrane separates the cell from the external environment. It forms the wall-like structure that protects the cellular component from damage and leakage. |
 Cell Wall
|
Prokaryotic and eukaryotic cells have a cell wall. Cell wall protect the cell mechanically and chemically from its surrounding structures. |
 Nucleus
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Nucleus contains the hereditary material of the cell, the DNA, nucleus is surrounded by the nuclear envelope, and nucleus protects the DNA. |
 Cell Organelles
|
Nucleolus (site of ribosome synthesis), Nuclear membrane (protects the nucleus), Chromosomes (determining the sex), Endoplasmic reticulum (involved in the transportation of substances), Golgi Bodies (involved in the transportation of materials), Ribosome (protein synthesisers), Mitochondria (produces ATP), Lysosomes, Chloroplast (contains the pigment chlorophyll), Vacuoles (stores food, water, and other waste materials). |
Chemical composition of a typical mammalian cell:
| Proteins | 18.0 |
 RNA |
1.1 |
|
DNA |
0.25 |
| Phospholipids and other lipids | 5.0 |
| Polysaccharides | 2.0 |
| Water | 70 |
| Inorganic ions (sodium, potassium, magnesium, calcium, chloride, etc.) | 1.0 |
| Miscellaneous small metabolites | 3.0 |
The Genetic Information Of Cells:
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are two different kinds of genetic material that exist. In an organism, the biological information is encoded in its DNA sequence, and RNA is used for information transport example mRNA and enzymatic functions example ribosomal RNA. During protein translation transfer RNA (tRNA) molecule are used to add amino acids.
DNA: The Genetic Material
Components of DNA:
All DNA is composed of a series of smaller molecules known as nucleotides. Each nucleotide is made up of 3 primary components:
- Nitrogenous base: A nitrogen-containing region.
- Deoxyribose: A carbon-based sugar molecule.
- Phosphate group: A phosphate-containing region attached to the sugar molecule.
There are 4 different kinds of DNA nucleotides:
- Adenine ( A )
- Thymine ( T )
- Guanine ( G )
- Cytosine ( C )
The central part of this DNA contains 5’ carbon atoms arranged in the shape of a ring, it is a site at which the phosphate group is attached to the nucleotides. Opposite to 5’ carbon atoms, is the 3’ carbon atoms which are not attached to the phosphate group. When nucleotides join together they form a structure called a polynucleotide. At polynucleotides, the 5’ end of the nucleotides attaches to the 3’ end of adjacent nucleotide through a phosphodiester bond. That’s forms the “backbone” of a DNA molecule.
A human cell has genetic material contained in the nuclear genome and the mitochondrial genome. All living organisms are composed of cells and these cells arising only from the growth and division of other cells accepted in the early 19th century.
After intensive observations of the microscopic structure of cells in 1885 evidence indicated that chromosomes (dark-staining threads in the cell nucleus) carried the cell heredity information. It was proved later that chromosomes are about half protein and half DNA by weight.
American James Watson and British Francis Crick proposed the DNA double helix model for the structure of the double-stranded DNA molecule. In this DNA double helix model, each strand serves as a template in the synthesis of a complementary strand.
Later research confirmed American geneticist and biophysicist James Watson and British biophysicist Francis Crick’s model of DNA replication and showed that for the reproduction of the entire cell DNA carries the genetic information.
Later studies identified small amounts of additional genetic information present in two types of organelles in the cytoplasm. Such as mitochondria in animal cells and the mitochondria and chloroplasts in plant cells.
In the human the nuclear genome is divided into 46 linear DNA molecules known as chromosomes, including a sex chromosomes pair , and 22 homologous pairs of chromosome. Distinct from the nuclear DNA the mitochondrial genome is a circular DNA molecule. Deoxyribonucleic acid (DNA) can also be artificially introduced into the cell called transfection process. If the DNA is not inserted into the cell’s genome this can be transient.
RNA: replicated from DNA
RNA molecules are synthesized in the cell nucleus. RNA is a single-stranded instead of a double-stranded structure, all of the RNA is synthesized by special enzymes and by using one strand of the DNA helix as a template.
Do all cells have DNA in them?
No, all cells do not have DNA in them. Mature red blood cells and cornified cells in the skin, nails, and hairs contain no nucleus therefore they have no DNA.
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During the maturation process, human RBCs destroy their cell nuclei. Red blood cells do this to carry as much oxygen as possible, they do this for maintaining their size so they can easily fit through narrow blood capillaries. Mammals have RBC’s without nuclei, while all other types of vertebrates do have nuclei in their RBC’s.
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During the cornification process, Cornified cells destroy their cell nuclei. Cornified cells do this to grow properly, and to maximize the space in the cell filled with the structural protein keratin (a strong protein that gives nails, skin, and t hair their toughness). Once the cornified cells destroy their nucleus then their space is filled by keratin. These cells have died after cornification but they are not useless. Despite being ■■■■, cornified cells giving structural strength and warmth to surrounding tissues.
Do all cells have the same DNA?
No, neurons have more, less, and rearranged DNA as compared to DNA in other cells. According to the latest studies brain, cells are revealing that their DNA blueprint is radically different than expected. This phenomenon is called genomic mosaicism.
Brain cells aren’t the only ones with rearranged DNA. An example of genomic mosaicism is our immune system. Our immune system rearranges DNA to create cells to protect us that can recognize and remove unwanted materials. No one knows how our neurons create these differences. Understanding the phenomena is a critical next step for biologists.
Is DNA a Non-Living thing?
Yes, DNA is a non-living thing. DNA is a molecule, not an organism, and this molecule is not sharing organisms in any property. Even in the replication process, DNA needs a co-worker. Example: enzymes, and RNA co-factors. It cannot maintain its homeostasis and does not have a metabolism of its own.
It can’t grow, and the process of replication is known as Duplication, not growth. DNA is a non-living thing because it is made up of codons and nucleotides, and codons and nucleotides are ■■■■ materials. As DNA is a non-living thing so DNA never dies.
Frequently Asked Questions
Peolpe are also wondering about for some common queries:
1-Where is DNA found in the cell?
DNA is found in the cell’s nucleus. A complete set of nuclear DNA in an organism is called its genome. DNA is located in the nucleus but complex organisms also have a small amount of DNA in mitochondria.
2- What human cells do not have DNA?
Mature red blood cells and cornified cells in the skin, hair, and nails do not have DNA.
3- Is DNA in the blood?
DNA is not present in red blood cells but it doesn’t mean our blood has no DNA. Blood is an excellent source of DNA because DNA is present in the white blood cells of humans. Approximately 50 µl volume of blood is enough for DNA for a typical VNTR analysis.
4- What are the three differences between transcription and translation?
| Transcription | Translation |
|---|---|
| 1. Transcription produces mRNA | 1. Translation produces amino acids |
| 2. It takes place in the nucleus. | 2. It takes place in the cytoplasm. |
| 3. It is catalyzed by RNA polymerase | 3. It is assisted by rRNA and mRNA. |
Conclusion:
Do all cells have DNA?
No, all cells do not have DNA. Because during the maturation and cornification process red blood cells and cornified cells destroy their nucleus. They do this to work and grow properly. Even not all cells have the same DNA. Neuron cells have a different arrangement of DNA as compared to other cells.
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