lecture recording on 17 February 2025 at 12.22.15 PM

Introduction to DNA

• DNA, or deoxyribonucleic acid, is the hereditary molecule responsible for storing instructions necessary for cellular activities and biological traits.

• It carries genetic information through sequences of nitrogenous bases, where each base contains nitrogen.

• The combination of genetics and environmental factors influences physical characteristics and certain aspects of personality.

Nucleotides and Structure of DNA

• A nucleotide is the basic building block of DNA, composed of a sugar (deoxyribose), a phosphate group, and a nitrogenous base.

• The DNA structure resembles a twisted ladder, where:

  • The sides (backbone) of the ladder are made of alternating sugar and phosphate molecules connected by strong covalent bonds.

  • The rungs (steps) represent the paired nitrogenous bases (adenine, thymine, cytosine, guanine).

  • Bases pair specifically:

    • Adenine (A) bonds with Thymine (T)

    • Cytosine (C) bonds with Guanine (G)

• The pairs are held together by weaker hydrogen bonds, allowing the DNA to unzip during replication.

Function and Location of DNA

• Genetic material exists in all living cells, within the nucleus of eukaryotic cells and as plasmids in prokaryotic cells.

• Eukaryotic cells contain DNA neatly organized within the nucleus, whereas prokaryotic cells possess a nucleoid region where their circular DNA is found.

• Each human cell contains about 2 meters of DNA, totaling trillions of cells in a body, resulting in approximately 6 billion DNA bases and 20,000 genes per person.

Complementary Base Pairing

• The concept of complementary bases is vital for DNA function, ensuring that the correct sequences are replicated.

• The term antiparallel is used to describe the orientation of the two DNA strands; one strand runs in the opposite direction to the other.

• The structure facilitates proper bonding and structural integrity, crucial for genetic information storage and transfer.

Importance of DNA

• DNA is essential for all cellular functions and is integral in traits such as height, eye color, and predisposition to certain diseases.

• Gene regulation allows cells to activate or deactivate specific genes, which is necessary for cell specialization, as demonstrated by differences between skin cells and digestive cells despite containing the same DNA.

Cloning and DNA

• Cloning, exemplified in media like "Jurassic Park," illustrates the potential of DNA to guide the creation of identical organisms through cellular manipulation, reinforcing the significance of understanding DNA composition and function.

• Ethical considerations surround cloning and genetic engineering due to the power of manipulating life's fundamental instructions encoded in DNA.

Conclusion

• Understanding DNA, including its structure, function, and implications for genetics, is crucial for exploring biological and medical sciences. Familiarity with terms such as nucleotides, base pairing, and gene regulation lays foundational knowledge for future studies in genetics and biotechnology.