Definition of Heredity: Transfer of biological characters from one generation to another via genes.
Pioneers in Genetics:
Gregor Johann Mendel: Considered the father of modern genetics; his work laid the foundation for the science of heredity.
Hugo de Vries (1901): Proposed the mutational theory which explained sudden changes in species.
Walter Sutton (1902): Observed paired chromosomes, establishing the connection between chromosomes and genetic material.
Oswald Avery, Mclyn McCarty, and Colin McLeod (1944): Proved that DNA is the genetic material in all living organisms except viruses.
Francois Jacob and Jack Monod (1961): Proposed a model for protein synthesis via DNA in bacterial cells, leading to the development of recombinant DNA technology.
Applications of Heredity Science:
Diagnosis and treatment of hereditary disorders.
Production of hybrid varieties in agriculture.
Industrial processes utilizing microbes.
Central Dogma of Molecular Biology: Genes present in DNA control cell functions and synthesize proteins.
RNA Role: RNA synthesizes proteins through three processes:
Transcription:
mRNA is synthesized from the DNA template (only one DNA strand is used).
Uracil replaces thymine in RNA.
Translation:
mRNA carries codes for amino acids (triplet codon) from the nucleus to the cytoplasm.
tRNA brings corresponding amino acids based on the mRNA codon, utilizing its anticodon.
Translocation:
The ribosome moves along the mRNA to facilitate amino acid bonding via peptide bonds to form proteins.
Resulting chains of amino acids form complex proteins essential for body functions.
Mutation:
Changes in nucleotide sequences can lead to genetic variations and disorders (e.g., sickle cell anemia).
Role of mRNA:
mRNA forms in the nucleus and conveys coded messages for amino acid sequences to cytoplasm.
Triplet codon format (three nucleotides) specified amino acids; Khorana's triplet codons defined this coding.
tRNA translates mRNA into amino acids to synthesize proteins, coordinating with rRNA in ribosomes.
Origins of Life Theory:
Life emerged approximately 3.5 billion years ago from simple organic and inorganic compounds.
Unicellular organisms gave rise to more complex forms via natural selection.
Diversity of Life:
Vast ranges of species evolved, with humans expressing curiosity about life's origins.
Gradual Development Theory:
Supported by various philosophical and cultural perspectives over centuries.
Definition of Evolution: Gradual changes leading to new species through natural selection over extensive periods.
Embryological and Morphological Evidence: Early similarities in embryonic development across species indicate common ancestry.
Comparative Anatomy: Similar bone structures in different species indicate common lineage.
Evidences of Evolution:
Morphological, anatomical similarities provide insight into shared ancestry among organisms.
Definition: Degenerated organs that retain no functional role in current organisms.
Examples: Appendix and wisdom teeth in humans serve significant roles in other species.
Evolutionary Implications: Vestigial organs support the theory of evolution, illustrating how certain structures may become obsolete in changing environments.
Fossil Study: Fossils represent remnants of extinct organisms, offering insights into past life forms and evolutionary pathways.
Carbon Dating: Method to determine the age of fossils, contributing significantly to the understanding of evolutionary history.
Embryonic Development Comparison: Early stages exhibit significant similarities among vertebrates, suggesting common ancestry.
Connecting Links: Species exhibiting traits of two different groups highlight evolutionary transitions (e.g., Peripatus, duck-billed platypus).
Principles of Natural Selection:
Proposed by Charles Darwin; emphasizes survival of the fittest and reproductive success of well-adapted organisms over generations.
Lamarckism: Jean-Baptiste Lamarck's theory suggested organism activities influence evolution, where acquired traits can be passed to descendants.
Critiques of Lamarckism: Later disproved due to inability to transfer acquired traits across generations.
Ancestors of Modern Humans:
Chart outlines progression from ancient species, highlighting evolutionary milestones leading to modern humans.
Early human-like species transitioned through distinct morphological changes over millions of years.
Homo Genus Development: Evolution from earlier ancestors to modern humans, illustrating brain development and tool usage.
Cultural Advancements: Significant milestones in human development include agriculture, urbanization, and the advent of writing.
Conceptual Understanding: Questions prompt thoughts on heredity, evolution, fossils, and natural selection, fostering deeper comprehension.
Projects and Discussions: Activities designed to encourage exploration and presentation of evolutionary concepts, enhancing engagement in biological sciences.