Introduction to Genetics

Introduction to Genetics

• Genetics is the study of heredity, specifically genes.
• It's a central pillar of biology and intersects with other fields like agriculture, medicine, and biotechnology.

Learning Objectives

• Describe the historical context of genetics.
• Explain the different branches of genetics.
• Identify various applications of genetics.

What is Genetics?

• Genetics studies genes at all levels of biological organization.
• It examines how genes function within a cell and are passed down between generations.
• Modern genetics focuses on DNA as the fundamental chemical substance underlying genes.
• It explores the influence of DNA on bodily processes.

Covid-19 Vaccine Types

• Vaccine platforms aim to train the immune system.
• Different types of component vaccines include protein subunit, virus-like particles (VLPs), DNA-based, RNA-based, non-replicating viral vector, and replicating viral vector.
• Whole-virus vaccines are further categorized into inactivated and live-attenuated vaccines.
• Vaccines train the immune system to recognize and combat antigens, like the SARS-CoV-2 spike protein.

Types of Vaccines

• Live attenuated: Uses weakened virus particles for immunity development. May not be suitable for people with compromised immune systems.
• Inactivated: Contains killed or inactivated virus particles. Safer and creates weaker immunity than live attenuated. Requires booster doses.
• Replicating viral vector: Employs a harmless virus to deliver viral antigens. Strong immune response, but may not be effective in individuals already immune to the vector virus.
• Non-replicating viral vector: Similar to the replicating type, but can't replicate inside the body as key viral replication genes are removed. Has improved efficacy and safety; requires high doses.
• DNA: Uses DNA plasmids containing viral antigen genes. Easy to produce, but possible immune system tolerance.
• RNA: Uses mRNA to produce viral antigens. Bypasses the risk of integration, but may trigger an unwanted immune response.
• Subunit: Contains antigenic protein fragments without genetic material. Relatively safer because there's no replication risk; requires multiple doses and adjuvants for stronger immunity.

How Covid-19 Vaccines Compare

• Listed in a table showing various vaccines, their type, number of doses, effectiveness, storage requirements, and cost.
• The data is based on phase three results which are not yet peer-reviewed.

What is Genetics 2

• Genetics encompasses genes at all levels, how these in the cell function, and their transmission.
• Modern genetics focuses on DNA (deoxyribonucleic acid) and how it influences cellular processes.
• DNA holds the instructions for the formation of traits.

Gene Action & Environment

• Gene activity hinges on interplay with the environment.

History of Genetics

• Early research in genetics can be traced back to Mendel's discoveries of laws governing trait inheritance.
• William Bateson made important contributions to establishing genetics as a scientific discipline rooted in Mendel's work (early 20th century).
• Aristotle (ancient Greece) believed blood carried hereditary traits.
• Hippocrates suggested a "pangenesis" theory.
• Preformationism (17th-18th Century) envisioned miniature versions of organisms in reproductive cells.
• Lamarck suggested “acquired characteristics” as a model for evolution.
• 1900s: Mendel's work revived; Meischer discovered DNA; Morgan linked traits to chromosomes. 1920-1949: X-rays mutate DNA. Beadle/Tatum studied the gene one-enzyme. McClintock identified jumping genes.
• Early 1950s: Chargaff revealed DNA base pairings. Hershey/Chase demonstrated DNA's role in heredity. Watson/Crick elucidated DNA's structure.
• Late 1950s: Crick formulated the central dogma of biology, and Meselson/Stahl explained semi-conservative DNA replication. Kornberg discovered DNA polymerase.
• 1960s: Nirenberg cracked the genetic code. Jacob/Monod studied gene regulation.
• 1970s: Cohen/Boyer created recombinant DNA. Kornberg deciphered chromatin structure, and Sanger developed DNA sequencing.
• 1980s: Mullis pioneered PCR. Jeffreys developed DNA fingerprinting.
• 1990s-Present: King identified genes linked to diseases. Venter/Collins completed the human genome project.

Applications of Genetics

• Genetics has wide-ranging applications:
  • Characterizing and diagnosing genetic diseases.
  • Creating advanced plant species and genetically modified organisms.
  • Genetic engineering.
  • Crop improvement.
  • Animal/plant breeding programs.
  • Understanding microbial characteristics, and using it for antibiotic resistance research.
  • Studying genetic patterns of inheritance.
  • Utilizing genetic/DNA medicines.
  • Performing cancer screening, prognosis, and diagnostics.
  • Identifying pathogenic mutations.
  • Preserving biodiversity.

Branches of Genetics

• Molecular Genetics: Study of DNA structure and function. Employs techniques like PCR and sequencing.
• Cytogenetics: Chromosome analysis to identify structural and numerical abnormalities.
• Human Genetics: Study of genetic alterations and their role in human disease development.
• Plant Genetics: Deals with genetic variations and chromosomal abnormalities in plants.
• Microbial Genetics: Studies microbial genes, genotypes, and gene expressions for genetic engineering.
• Metagenomics: Analyses environmental samples to identify and research microorganisms, without culturing them.
• Population Genetics: Studies genetic differences within/between populations. Uses calculations, stats, and analysis for predicting genetic variations.
• Epigenetics: Investigates gene expression profiles without mutations, analyzing the influence of external factors (diet, exercise, stress) on gene expression.
• Biochemical Genetics: Examines DNA, gene, chromosome and RNA structure and properties.
• Physiological Genetics: Understands physical properties (ex: blood types, sex determination).
• Quantitative Genetics: Analyzes continuously varying traits, correlating phenotypes and genotypes.
• Conservation Genetics: Evaluates genetic diversity in endangered organisms and species.
• Behavioral Genetics: Studies how genes influence behavior, acknowledging the interplay between genetic composition and environment.
• Preimplantation Genetics: Screens embryos for genetic abnormalities before implantation.