Is DNA the only genetic material?
Written by Ayessa G. Ibañez
Genetic material is the hereditary substance holding all information specific to an organism. DNA (deoxyribonucleic acid) is the best example and most common. Although it is present in humans and almost all organisms, DNA is not the only genetic substance.
Considering the definition mentioned, the genetic substance can be a gene, a part of a gene, and a group of genes. Genes are the functional units of inheritance. It contains the data needed to specify traits that pass from parents to offspring.
Moreover, the hereditary substance can be a DNA or RNA molecule, its fragment, and a group of DNA or RNA molecules. You can even include the entire genome of an organism.
They all are raw cellular materials of inheritance. They influence all aspects of the structure and function of an organism.
Deoxyribonucleic acid is the hereditary substance we humans have. Most of them are in the cell nucleus but can also be in the mitochondria. The information in DNA is in the form of code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
Another type of hereditary substance is RNA or ribonucleic acid. We are not referring to the RNA present in our bodies. What is present in humans work as enzymes in protein synthesis, not as a hereditary substance.
The hereditary substance we refer to works in RNA viruses. It can be either single-stranded (ssRNA) or double-stranded (dsRNA).
There is also another form of inheritance material found in bacteria. Discrete, circular, and supercoiled, they are in the exterior chromosomes of certain bacteria. We call them plasmids.
Plasmids carry information encoding for non-essential characteristics like antibiotic resistance and toxins production. They are independent when replicating from the cell.
There are also conjugative plasmids that are extra-chromosomal deoxyribonucleic acid elements. They can transfer among bacteria making new features in the bacterial cell.
Although these are genetic information, most would prefer DNA as the main one. It is the molecule that fulfills the specific properties of hereditable material.
How do you identify genetic material?
There was a hypothesis stating that RNA stored genetic information in primitive cells. Some studies would say that RNA is the first hereditable material.
As already mentioned, most literature considers deoxyribonucleic acid as a genetic substance. But, before it was even deemed one, some geneticists found the hypothesis absurd. This is due to chromosomes, the carriers of the genetic material, having both DNA and protein.
The idea prompted scientists in the early 1900s to conduct experiments to prove it. The foundation of their studies relies on four criteria to identify genetic information. These are information, replication, stability, and mutation.
1. Information
The function of living things is dependent on the data provided by the genetic substance. Thus, it must have the information necessary to construct an entire organism. It must provide the blueprint to determine the inherited traits of an organism.
2. Replication
“A genetic material must carry out two jobs: duplicate itself and control the development of… the cell…,” quoted by Francis Crick.
Replication refers to the duplication of its genetic substance by consistent replication. The process is by duplicating the nucleic acid molecule.
This concept is familiar to most due to DNA replication. It is a rule before cell division, guaranteeing that each daughter cell has a copy of the genome.
This criterion is vital as hereditable substance passes down from parents to offspring.
3. Stability
A genetic substance must be stable. Its structure is not easy to alter with the changing stages of life and the age of physiology of living beings.
For example, DNA can survive in heat-killed bacteria. Both the strands of deoxyribonucleic acid, which are complementary, can separate.
The hereditary stability depends on an accurate DNA replication system. It also relies on the success at various levels of DNA repair systems in the cells.
4. Mutation
Mutations are crucial to evolution.
A genetic substance must have the capacity to cope with slow changes or mutations to evolve. Such change from mutation must inherit with stability.
Every new DNA sequence is due to a particular gene created from a new allele. Thus, every feature an individual has is a result of mutation.
What is another name for genetic material?
As already discussed, DNA is the raw material of inheritance of almost all living things. Another name that can also stand for genetic substance is a gene, the basic unit of heredity.
Genes are a small section of deoxyribonucleic acid. They are biochemical instructions within the genome that code for proteins. These proteins, in turn, impart or control the characteristics that create our individuality.
The role of genes is crucial as they store information.
The complete set of genetic instructions characteristic of an organism is the genome. It includes the protein-encoding genes and other DNA sequences.
The protein-encoding gene can vary in base sequence from person to person. The different forms of genes are the alleles.
Alleles with particular genes are in pairs, placed one on each chromosome. The combination of alleles influences an individual’s observable traits or phenotype.
Same alleles with a particular gene are homozygous. An individual will inherit the same alleles for a particular gene from both parents. For example, assume the gene of skin color has identical color alleles on the pairs.
Different alleles are heterozygous for that gene. The gene of hair color has two alleles, one code for white (R) and the other code for black (r).
A gene can mutate, causing changes in the DNA sequence that distinguish alleles. The change from the mutation passes on during cell division of the cell it contains.
If the change is in a sperm or egg cell that becomes a fertilized egg, it passes to the next generation.
What are the characteristics of genetic material?
An information carrier is not enough character to describe a hereditary substance. Several attributes a genetic material owns make it apart from others.
Below are the properties and functions that define the genetic substance.
- It is present in every cell.
2. It contains all the necessary biological information.
3. It is stable both in chemical and physical aspects.
4. It can store information in coded form.
5. It has control of the biological functions of cells.
6. It expresses its information in the form of Mendelian characters.
7. It is the same both in quantity and quality in all the somatic cells.
8. It presents diversity corresponding to the variety existing in the organisms.
9. Its replication is precise and passes over its true copies to the next generation.
10. It is capable of variations, for instance, mutation. The variations are stable and inheritable.
11. It can generate its own kind and new kinds of molecules.
12. It is capable of differential expressions. This factor allows diversity despite the same genetic information.
How is genetic material inherited?
We get most of our features from our parents, either our mom or dad or even our grandparents. Your body physique is from your dad, or you got your curly hair from your mom. Sometimes, you even wish you got your mother’s hazelnut eyes which you did not because you got your dad’s.
The similarity of the characteristics within your family is because of inheritance.
The concept of inheritance is somehow like the terminology used in finance. You pass down an asset to a particular individual or individual. But, in genetics, what you will pass down is your genetic information, an intangible asset we all have.
Inheritance is the transmission of traits from one generation to the next.
A deoxyribonucleic acid molecule comprises a chromosome. These chromosomes are in the nuclei of all human cells, excluding mature red blood cells. In every cell, there are 23 chromosomes of different pairs.
In sexual reproduction, the egg and sperm cells combine to form the first cell of a new organism. This process refers to fertilization.
The fertilized egg carries two sets of 23 chromosomes. We call this a diploid cell, meaning it has paired chromosomes, one from each parent. In total, the cell has 46 chromosomes.
The data within your parents’ chromosomes have a copy of the new cells made during cell division. The fertilized egg now has the complete set of instructions needed to make more cells.
The inheritance of hereditary substances is evident in the characteristics your family has. Heritage is not limited to physical traits, but diseases can be also passed down.
There are instances of genetic mutation, and the parents can also pass it down to their children. This is why some members can get the diseases that run in families.
Why is deoxyribose called deoxyribose?
Deoxyribose or 2-deoxyribose is the DNA’s sugar. It is a pentose sugar with five carbon atoms connected to each other to form a ring-like shape.
Its five-sided ring-like structure consists of four carbons. The fifth carbon is in the ring, which is branching off.
The structure of deoxyribose coins the name itself.
The pentagon shape of the molecule has 1′-4′ starting at the carbon at the right side of the oxygen. The numbering of carbon moves in a clockwise direction.
The numbers have the upper-right stroke mark (‘). They are not written in plain numbers because the mark indicates that it is a prime. A prime denotes carbon atoms in sugar from the carbon and nitrogen atoms in the nitrogenous base.
The term for the sugar of DNA is deoxyribose because it does not have a hydroxyl group at the 2′ position. Instead, it has hydrogen.
There is a change in the standard ribose form, causing replacement on the hydroxyl group (–OH) of 2′ carbon. A hydrogen group (–H) replaces the hydroxyl group (–OH).
What is the backbone of DNA?
The DNA molecule is a polymer of long, chainlike molecules of monomers. Monomers are subunits of a larger polymer chain. In deoxyribonucleic acid, the repeating structural unit is the nucleotides.
Nucleotides are the basic unit of deoxyribose acid. In the body, they are part of the components of nucleic acids or work as individual molecules.
The nucleotide is a complex molecule made up of three distinct components. These are sugar, a nitrogenous base, and a phosphate group.
Phosphate groups are a set of specific atoms of phosphorus. They are identical across all nucleotides.
As for the sugar, the component is exactly what it sounds like—the usual sugar, like the ones which are part of our diets. Nucleotides may contain one of the various types of sugar molecules. For deoxyribonucleic acid, the sugar found in the nucleotides is pentose.
From its root word pent-, a pentose is a sugar that comprises five carbon atoms. The certain type of pentose present in the nucleotides found in DNA is 2’-deoxyribose.
Pentose sugars can be in two forms. It can be straight-chain, or Fischer structure; and the ring, or Haworth structure. In DNA, it is the ring form of 2’-deoxyribose that is present in the nucleotide.
Nucleotides join into long chains between the deoxyribose sugars and the phosphates. This creates a continuous sugar-phosphate backbone.
Hence, the backbone of a DNA strand consists of a phosphate group and a pentose sugar, deoxyribose.
References
Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. The RNA World and the Origins of Life. Available from: https://www.ncbi.nlm.nih.gov/books/NBK26876/
Ancestry (n.d.) DNA Structure. Retrieved from https://www.ancestry.com/lp/dna-structure
Ancestry (n.d.) What Is DNA’s Sugar? Retrieved from https://www.ancestry.com/lp/what-is-dna-made-of/dna-sugar#:~:text=The%20carbons%20in%20 the%20pentagon,group%20at%20the%202’%20position.
Biology Online Editors. (2022). Genetic material. Retrieved from https://www.biologyonline.com/dictionary/genetic-material.
Bhagavan, N. & Ha, C. (2015). Chapter 22 – DNA Replication, Repair, and Mutagenesis. Essentials of Medical Biochemistry (Second Edition) With Clinical Cases 2015, Pages 401-417. https://doi.org/10.1016/B978-0-12-416687-5.00022-1.
Brown, T. (2012). Introduction to Genetics: A Molecular Approach. Garland Science, Taylor & Francis Group, LLC. ISBN 978-0-8153-6509-9
BYJU. (n.d.). Genetic Material- DNA vs RNA. Retrieved from https://byjus.com/biology/genetic-material-dna-rna/.
Carlin, J. L. (2011) Mutations Are the Raw Materials of Evolution. Nature Education Knowledge 3(10):10
Collins, F. (n.d.). Gene. Retrieved from https://www.genome.gov/genetics-glossary/Gene.
Genetic Material: Definition, Structure & Function. (2016). Retrieved fromhttps://study.com/academy/lesson/genetic-material-definition-structure-function.html.
Genetic Science Learning Center. (2016) What is Inheritance? Retrieved February from https://learn.genetics.utah.edu/content/basics/inheritance/
John R.McCarrey, J. (2018). Genetic Vs. Epigenetic Inheritance Overview. Encyclopedia of Reproduction (Second Edition) Volume 3, 2018, Pages 434-435.
Kumar, S. (n.d.). Top 8 Characteristics and Properties Genetic Material. Retrieved from https://www.biologydiscussion.com/genetics/genetic-material/top-8-characteristics-and-propertie s-genetic-material/15434
Lewis, R. (2009). Human Genetics: Concepts and Applications. 9th Ed. McGraw−Hill Primis. ISBN−10: 0−39−023244−0
Samiksha, S. (n.d.) Genetic Material: Nature and Properties of Genetic Material. Retrieved from https://www.yourarticlelibrary.com/genetics/genetic-material-nature-and-properties-of-genetic-m aterial/12145
The American Phytopathological Society (n.d.) Mutation. Retrieved from https://www.apsnet.org/edcenter/disimpactmngmnt/topc/PopGenetics/Pages/Mutation.aspx#:~:te xt=Mutation%20is%20important%20as%20the,specific%20gene%20through%20intragenic%20r ecombination.
Viguera E. (2011) Replication (Genetics). In: Gargaud M. et al. (eds) Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-11274-4_1366
Yourgenome (2016). What is a gene? Retrieved from https://www.yourgenome.org/facts/what-is-a-gene
Yourgenome (2021). What is inheritance? Retrieved from https://www.yourgenome.org/facts/what-is-inheritance
