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Molecular biology is a branch of biology that studies the chemical structures and processes of biological events involving molecules, the fundamental units of life. The study of molecular biology is concerned with nucleic acids (such as DNA and RNA) and proteins—macromolecules that are critical to biological processes—and how they interact and function within cells. Molecular biology is a branch of biology and chemistry that includes genetics and biochemistry.
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Key words: Genes, mutation, molecule, DNA, RNA, Genetics, biochemistry, macromolecules, fundamental units of life, nucleic acids, Molecular biology
History of Molecular Biology
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Warren Weaver, an American scientist, invented the phrase "Molecular Biology" in the year 1938. According to records, molecular biology was discovered in the early 1940s, and its basic development occurred in 1953 when two molecular biologists named James Watson and Francis Crick invented the double-helical structure of the DNA molecule.
The development of molecular biology was a merging of studies by geneticists, physicists, and structural chemists, despite its immediate antecedent being classical genetics. Indeed, Francis Crick used the term "molecular biologist" to condense his prior definition of himself as "a blend of a crystallographer, biophysicist, biochemist, and geneticist."
Also read: DNA Replication
The DNA
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- DNA is a group of molecules that is in charge of carrying and transferring hereditary information or genetic instructions from parents to children.
- The organic components found in all organisms in the form of DNA or RNA are known as nucleic acids. These nucleic acids are made up of nitrogenous bases, sugar molecules, and phosphate groups that are connected together in a series of sequences by various bonds.
- The basic genetic composition of our body is defined by the DNA structure. In fact, it determines the genetic composition of almost all living things on the planet.
- Deoxyribonucleic Acid is the scientific name for DNA. It's a molecularly distinct organic chemical with a unique molecular structure. It can be found in prokaryotic and eukaryotic cells alike.
- During his studies on white blood cells in 1869, Swiss researcher Johannes Friedrich Miescher detected and characterized DNA for the first time. There are 3 types of DNA; A DNA, B DNA, Z DNA.
DNA Structure
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The DNA molecule's structure resembles a twisted ladder. As shown in the diagram below, this structure is characterized as a double-helix. It's a nucleic acid, and nucleotides make up all nucleic acids. Nucleotides are the building blocks of DNA, and each nucleotide is made up of three separate components: sugar, phosphate groups, and nitrogen bases.
DNA STRUCTURE
Nucleotides, which are made up of a sugar group, a phosphate group, and a nitrogen base, are the fundamental building blocks of DNA. Each strand of DNA is formed by the sugar and phosphate groups linking the nucleotides together. Nitrogen bases include adenine (A), thymine (T), guanine (G), and cytosine (C).
Also read: DNA Genetic Material
The RNA
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- RNA (ribonucleic acid) is a complex high-molecular-weight molecule that participates in cellular protein production and, in certain viruses, substitutes DNA (deoxyribonucleic acid) as a carrier of genetic instructions.
- RNA is made up of strands of ribose nucleotides (nitrogenous bases bonded to a ribose sugar) connected by phosphodiester linkages. Adenine, guanine, cytosine, and uracil, which substitute thymine in DNA, are nitrogenous bases in RNA.
- RNA aids in protein synthesis in our bodies. In the human body, this nucleic acid is important for the formation of new cells. It's normally extracted from a molecule of DNA.
- The sole difference between RNA and DNA is that it only has one strand, whereas DNA has two, and it only contains a single ribose sugar molecule. There are 3 types of RNA; t RNA, r RNA, m RNA.
Also Read:
| Related Links | ||
|---|---|---|
| DNA Packaging | Structure of RNA | Transcription |
| DNA Replication | Translation | Bioinformatics |
| Genome and Genomics | Human Genome project | Lac Operon |
RNA Structure
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All of the components of ribonucleic acid are identical to those of DNA, with only two exceptions. Except for the Thymine, which is replaced by uracil, RNA has the same nitrogen bases as DNA: adenine, guanine, and cytosine. The basic building components of RNA are adenine and uracil, which form a base pair with the assistance of two hydrogen bonds.
RNA STRUCTURE
RNA has a hairpin structure, and nucleotides are generated in this ribonucleic material, just as they are in DNA. Nucleosides are phosphate groups that are occasionally used to aid in the synthesis of nucleotides in DNA.
Also read: Human Genome Project
Things to Remember
- The field of biology that explores the molecular foundation of biological activity is known as molecular biology.
- DNA and RNA are nucleic acids consisting of long chains of nucleotides collectively called a polynucleotide.
- DNA is the building blocks of genes that contain the coded instruction for building and maintaining a body.
- Warren Weaver invented the phrase "Molecular Biology" in the year 1938.
- The DNA molecule's structure resembles a twisted ladder, while RNA has a hairpin structure.
Sample Questions
Ques- Group the following as nitrogenous bases and nucleosides: Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine. [1 mark]
Ans: Nitrogenous Bases – Adenine, Uracil, Cytosine, Thymine.
Nucleosides – Cytidine, guanosine.
Ques- Depending upon the chemical nature of the template (DNA or RNA) and the nature of nucleic acids synthesized from it (DNA or RNA), list the types of nucleic acid polymerases. [3 marks]
Ans: The 4 types are
- Synthesis of DNA polymerase that is DNA dependent.
- Synthesis of DNA-dependent RNA polymerase.
- Retroviral nucleic acid RNA dependent DNA polymerase
- RNA polymerase that is RNA dependent - cDNA synthesis
Ques - What is called Central Dogma in molecular biology? [2 marks]
Ans: The central dogma describes the flow of genetic material inside cells, DNA replication, and RNA coding via transcription, as well as the translation of RNA codes into proteins.
Ques - How does molecular genetics support evolution? [3 marks]
Ans: To understand how molecular genetics aids evolution, we must first understand what genetics is and how important it is. As a result, we're all familiar with children inheriting specific characteristics from their parents or grandparents, whether it's visual features or behavioral characteristics. What is the rationale for this? It's The Gene, of course. The genetic substance DNA or RNA contains genes or a sequence of nitrogen bases. They are passed down through the generations. Let's speak about evolution now. What does evolution imply? It is nothing more than the growth and reproduction of living things. Occasionally, a whole new species emerge from an existing one owing to changes in the environment or DNA. This is done to guarantee that life continues.
We've probably all heard of Darwin's theory of survival of the fittest. It states that only the fittest individuals will live, while the remainder will perish. This is where the field of molecular genetics comes into play. If the DNA or genetic material experiences a mutation that is favorable to the organism or has a high likelihood of survival, that gene is most likely to be passed on to the next generation. This is because it boosts the species' chances of survival and keeps it from becoming extinct.
Ques - Why does Replication not take part in gene expression? [2 marks]
Ans: Replication is the duplication of a gene, but it has no effect on the creation of protein, and hence on gene expression. Transcription is the process of making RNA from DNA, whereas RNA processing is the process of stabilizing RNA in the cytosol and removing non-coding sections. The most important step in the production of a polypeptide chain is translation.
Ques - why do Hydrophobic interactions not contribute to the stability of tRNA? [2 marks]
Ans: Because of the negative charge on the tRNA backbone, the molecule is unlikely to be hydrophobic. As a result, hydrophobic interactions have no bearing on the molecule's structural stability. Other interactions, such as hydrogen bonding, resulting in base pairing, which results in the famous clover leaf model.
Ques - What is a DNA strand? [2 marks]
Ans: The DNA molecule is made up of two strands that create a double Helix structure when they loop around each other. Each strand's backbone consists of sugar and phosphate groups that alternate. Each sugar is made up of one of four different bases. It consists of adenine (A), cytosine (C), guanine (G), and thymine (T). Binds Adenine connects with Thymine and Cytosine bonds with Guanine between the bases that keep the two strands together. The backbone nucleotide sequence serves as a set of instructions for bringing protein and RNA molecules together.
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