Properties of Genetic Material: Definition, Properties, DNA

Genetic material is responsible for storing and passing the information from one generation to the next. The two types of genetic material found in the living organisms are DNA and RNA. Understanding their differences is important in central dogma of biology, which explains the formation of DNA to RNA and then to proteins. While DNA stores the information, RNA helps in translating that information to proteins.

This Story also Contains

1. Genetic Material Definition
2. Importance Of Genetic Material In Biology
3. Characteristics Of Genetic Material
4. DNA
5. RNA
6. Genetic Code
7. Mutations
8. Genetic Material In Different Organisms
9. Applications Of Genetic Material
10. Recommended video on Properties of Genetic Material
11. MCQs on Genetic Material

In the molecular basis of inheritance, DNA and RNA play a key role in maintaining the structure, and function of living organisms. Studying genetic material is essential to understand inheritance of traits, mutations, and genetic disorders. It forms foundations of genetics, biotechnology, medicine, research and various other fields.

Genetic Material Definition

The molecules responsible for heredity and transmission of variation in organisms are known as genetic materials. The molecules contain all the information needed for the growth, functioning, and reproduction of all organisms. The two main types of genetic materials are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Importance Of Genetic Material In Biology

Genetic material plays a key role in the storage, transmission, and expression of the genes. It ensures that genetic information is transmitted effectively from parents to offspring. It controls cellular functions by encoding proteins. It also contributes to genetic variation through mutations and recombination, which help in the process of evolution in organisms. It is important in fields such as molecular biology, biotechnology, and medicine.

Characteristics Of Genetic Material

Genetic material exists in different forms. It can be single-stranded or double-stranded, and linear, or circular in shape. DNA and RNA act as carriers of genetic information. These structural and functional forms vary depending on the species.

• Genetic material must be stable enough to store information reliably throughout the life span of an organism. It should also be flexible to allow variations due to mutations as well as through recombination, helping in evolution and adaptation.

• During cell division, the genetic material must be replicated accurately so that both daughter cells receive the complete set of genetic instructions. It ensures that no genetic information is lost.

• DNA stores genetic information. This information is present in the form of nucleotide sequence. This sequence is arranged into genes that code for certain proteins or RNA molecules.

• Genetic information is used step by step in transcription and translation. This means that instructions in DNA will be translated into functional proteins.

• Genetic material must move from one generation of organisms to the next. This allows traits to be inherited and continue life through reproduction.

DNA

DNA is the primary hereditary material found in most living organisms. It carries the genetic information required for growth and development and passes over to the next generations. It exists in double-stranded forms in cells. The structure and functions of DNA are mentioned below:

Structure

• A DNA molecule is composed of two strands twisted around each other. This is called the double helix model, proposed by Watson and Crick.

• The building blocks of DNA are nucleotides. Nucleotide consists of a deoxyribose sugar, a phosphate group, and one nitrogenous base from adenine (A), thymine (T), cytosine (C), or guanine (G).

• DNA can replicate and carry information for development and maintenance.

• The backbone of DNA is made up of alternate sugar and phosphate molecules.

Functions

• Replication of DNA: DNA duplicates itself so that the genetic information is replicated and passed on during cell division.

• Transcription and Translation: DNA is coded into RNA through transcription, and RNA codes into proteins through translation.

RNA

RNA plays an important role in protein synthesis. Unlike DNA, RNA generally exists in single-stranded forms and contains ribose sugar. It helps carry genetic information from DNA and is involved in translating them into proteins. RNA is involved in other cellular processes. The types of RNA are:

Types Of RNA

• Messenger RNA (mRNA): It carries the genetic information from DNA to the ribosome, where proteins are made.

• Transfer RNA (tRNA): It carries the amino acids to the ribosome while making proteins, during translation.

• Ribosomal RNA (rRNA): It provides a mechanism to decode mRNA and plays a key role in protein synthesis. The structure of the ribosome is composed of rRNA and protein. It is responsible for peptidyl transferase activity, helping form peptide bonds between amino acids.

Structure And Composition

RNA is a single-stranded molecule. RNA is composed of the repeating units of nucleotides. Each nucleotide has a ribose sugar, a phosphate group, and a nitrogenous base from adenine (A), uracil (U), cytosine (C), or guanine (G).

• Nucleotide Composition: Unlike DNA, RNA contains uracil instead of thymine.

• Phosphodiester Bond: It is a covalent bond that links the phosphate group of one nucleotide to the sugar molecule of another. This forms the backbone of RNA.

Genetic Code

The genetic code is a universal set of instructions stored in DNA and RNA. It guides how genetic information will be translated into protein across organisms. Each sequence of three nucleotides, called a codon code for a specific amino acid. The genetic code is universal and ensures accurate protein synthesis.

Codons And Anticodons

Codon: It is a sequence consisting of triplet nucleotides found in mRNA molecules. It codes for specific amino acid sequences during translation.

Anticodons: It is a set of three nucleotides on a tRNA molecule. It pairs with codon on mRNA to provide the right amino acids in the growing polypeptide chain.

Characteristics Of Genetic Code

Universal: Genetic codes are almost the same in all organisms from bacteria to humans, showing the most important process of genetic code in life.

Flexible system due to redundancy: Several codons represent a single amino acid. The system resists mutations, which can change one or a few nucleotides without affecting the end amino acid product.

Non-overlapping and Unambiguous: The codons in the mRNA proceed continuously one after the other so that one codon specifies one single amino acid. This ensures that there is almost negligible possibility of a mistake in translation when sequences are converted from codons to amino acids.

Mutations

Mutations are abnormalities in the DNA sequence that may lead to permanent changes in the characteristics and activities of an organism. They also form a major portion of evolutionary history and can be employed in health and fitness outcomes.

Types Of Mutation

Point Mutation: A point mutation is a change in a single base of a DNA molecule. This change may result in the loss of a single amino acid in the protein or sometimes have no effect at all. For example, Sickle cell anaemia

Frameshift mutations: A frameshift mutation occurs when one or more nucleotides are added or deleted from the DNA sequence. This shifts the reading frame of the gene and the synthesised polypeptide. In many of these cases, the entire amino acid sequence changes, resulting in non-functional protein. For example, Tay-Sachs disease

Effects Of Mutations

The effects of mutations are widely variable and depend on the type and location of the change in the chromosomes. Mutations occur naturally as well as by external factors. They may affect single or multiple genes. Understanding mutations helps to track the disorders and also the evolution of traits. The various effects of mutations are:

Beneficial Mutations: Some mutations are beneficial and produce advantages, such as resistance to diseases, and increasing the life span of organisms.

Neutral Mutations: Neutral mutations do not have any effect, neither negative nor positive. Most of these neutral mutations arise in non-coding regions and in positions that do not significantly affect protein function.

Harmful Mutations: Some mutations cause human genetic disorders or disrupt the mechanism of systems in living organisms. They can reduce an organism's fitness or cause diseases.

Genetic Material In Different Organisms

Genetic material differs considerably between different types of organisms. This reflects the complexity and diversity of life forms. Understanding these differences helps us appreciate how such genetic information is organised, replicated, and expressed across various biological systems. It also helps in studying evolution and genetic disorders.

1. Prokaryotes: Typically a single, circular DNA in a non-membrane bound nucleoid

2. Eukaryotes: Multiple linear chromosomes in a membrane-bound nucleus.

3. Viruses: They are either DNA viruses or RNA viruses. In most cases, RNA viruses have higher mutation rates.

Applications Of Genetic Material

The genetic material, DNA or RNA, is involved in the storage, replication, expression, and finally transmission of genetic information. It shows the stability and diversity to allow evolution. These properties ensure continuity and variation of life forms. Developments in genetic research such as CRISPR and gene therapy promise to cure genetic disorders, improve agricultural practices, and understand the complexities of life at the molecular level.

• Recombinant DNA Technology: It helps to join DNA isolated from an organism to form new genetic combinations.

• Gene Therapy: A technique that uses the addition of new, beneficial genes to fight against diseases caused by genes with defects.

• CRISPR-Cas9: It is a tool with highly precise gene editing capabilities.

• GMOs: Genetically modified organisms for enhanced traits.

• Improvement of Crop: Increasing tolerance to pests and environmental stresses.

Recommended video on Properties of Genetic Material

MCQs on Genetic Material

Q1. A molecule that can act as a genetic material must fulfil the traits given below, except

1. it should be able to express itself in the form of 'Mendelian characters'

2. it should be able to generate its replica

3. it should be unstable structurally and chemically

4. it should provide the scope for slow changes that are required for evolution

Correct answer: 3) It should be unstable structurally and chemically.

Explanation:

Characteristics of Genetic Material -

1. It should be able to replicate.

2. Stable

3. Provide scope for mutations that are required for evolution.

4. Should be able to express itself in the form of (Mendelian Character)

Therefore, an unstable molecule cannot serve as genetic material.

Hence, the correct option is 3) It should be unstable structurally and chemically.

Q2. Which of the following best sums up the characteristics of genetic material?

1. Genetic material must possess the capacity for replication, be chemically and structurally stable, and manifest Mendelian traits.

2. Genetic material needs to be highly mutagenic, chemically reactive, and capable of replication.

3. Genetic material must possess the capacity for gradual alterations, replication, and molecular-directed polymerization.

4. Genetic material must be able to display Mendelian traits, be chemically and physically stable, and prefer RNA over DNA for storing information.

Correct answer: 1) Genetic material must possess the replication capacity, be chemically and structurally stable, and manifest Mendelian traits.

Explanation:

For genetic material to work effectively, it needs to have several important properties:
Ability to Duplicate: Genetic substance should be able to duplicate itself very accurately at cell division.
Chemical and structural stability. It should be stable and not mutated or degraded.
Mendelian Character Expression: It should show Mendel's pattern of inheritance in which traits can be transmitted from one generation to the next.
Thus, Option A is the answer because it provides all these key requirements for genetic material, with proper functioning in heredity and biological processes.

Hence the correct answer is Option 1) Genetic material must possess the replication capacity, be chemically and structurally stable, and manifest Mendelian traits.

Q3. Assertion: The genetic material possesses stability over generations.

Reason: Genetic material is protected by various mechanisms, such as DNA repair enzymes and histone proteins, which help maintain the stability of the genetic information.

1. Both A and R are true and R is the correct explanation of A.

2. Both A and R are true but R is NOT the correct explanation of A.

3. A is true but R is false.

4. A is false but R is true.

Correct answer: 1) Both A and R are true and R is the correct explanation of A.

Explanation:

The stability of genetic material is crucial for the accurate transmission of genetic information from one generation to the next. The assertion states that genetic material possesses stability over generations, which is supported by the reason provided.

DNA repair enzymes play a vital role in maintaining the stability of genetic material. These enzymes constantly monitor the DNA structure, and identify and repair any damage or mutations that may occur. They can correct various types of DNA damage, including breaks, base modifications, and crosslinks. By repairing DNA damage, these enzymes help preserve the integrity of the genetic material and minimize the risk of mutations that could be passed on to future generations.

Histone proteins also contribute to the stability of genetic material. These proteins help organize and package DNA into a highly compact and organized structure called chromatin. By forming nucleosomes and higher-order chromatin structures, histones protect DNA from damage and help maintain its structural integrity. They also play a role in regulating gene expression by modulating the accessibility of DNA to transcription factors and other regulatory proteins.

Together, DNA repair enzymes and histone proteins provide mechanisms that ensure the stability of genetic material over generations. They help protect the genetic information from external factors, maintain the accuracy of DNA replication, and minimize the accumulation of mutations. This stability is essential for the inheritance of genetic traits and the proper functioning of cells and organisms.

Hence the correct answer is option 1) Both A and R are true and R is the correct explanation of A.

Also Read:

• MCQs on Properties of Genetic Material

• RNA World

• Griffith’s Experiment and Transforming Principle