Genetics Quiz: Golden Rice and Mendelian Theory

Golden Rice and Genetics

• Golden Rice is genetically engineered to have high vitamin A content.
• Genotype pertains to the genetic composition of an organism, important classifications include:
  • Homozygous Dominant: traits represented by two capital letters (AA)
  • Heterozygous: a combination of one dominant and one recessive allele (Aa)
  • Homozygous Recessive: traits represented by two small letters (aa)
• Organism’s complete set of heritable genes determines phenotype, which refers to observable physical traits.
• Variation refers to differences in traits between species, while phenocopy describes environmental influence on physical traits.
• Progeny is another term for offspring.

Gregor Mendel and Classical Genetics

• Gregor Mendel is recognized as the Father of Genetics, known for his work with pea plants.
• He formulated three key laws:
  • Law of Dominance and Uniformity
  • Law of Segregation
  • Law of Independent Assortment
• Established principles of heredity, particularly among royal families to maintain desirable traits.

Types of Classical Breeding

• Selective Breeding involves choosing parent organisms with desirable traits to enhance specific traits in offspring.

Steps in Selective Breeding:

• Identify important characteristics for selection.
• Select parents exhibiting those characteristics.
• Choose the best offspring for the next generation.
• Repeat to achieve desired traits continually.

Economic Importance of Selective Breeding

• Animals produced include:
  • Dachshund, bred for hunting skills.
  • Angus cattle, bred for increased muscle mass.
  • Egg-laying hens, bred for higher egg production.
• In plants, benefits include insect resistance and larger flowers.

Purpose and Risks of Selective Breeding

• Aims to improve traits like yield, disease resistance, and growth.
• Benefits include increased food quality and safety (e.g., hornless cattle).
• Risks include reduced genetic variation, susceptibility to diseases, and emergence of genetic diseases.

Hybridization

• Hybridization involves crossing individuals with distinct characteristics to enhance desirable traits.
• Different species or varieties may be crossed to produce hybrids with superior traits (hybrid vigor).
• Example: Liger (offspring of male lion) and Tigon (offspring of male tiger) exhibit larger sizes than their parents.

Steps in Hybridization:

• Select two genetically distinct parents.
• Cross-pollinate or mate to produce hybrids.
• Hybrids often show traits from both parents along with potential hybrid vigor.

Inbreeding and Plant Breeding

• Inbreeding is the continued breeding among similar individuals, increasing disease susceptibility.
• Plant breeding can be either self-pollination (single plant reproduction) or cross-pollination (involving multiple plants for greater variation).

Genetic Engineering Stages

• Isolation involves identifying donor traits and vectors (e.g., plasmids) for genetic transfer.
• Cutting utilizes restriction enzymes to remove desired genes.
• Ligation uses DNA ligase to bond genes into new configurations.
• Transformation creates transgenic organisms by inserting recombinant DNA.
• Methods for introducing plasmids include:
  • Biolistics (gene gun technique).
  • Heat shock (changes pore size in membranes).
  • Electroporation (electric shock to facilitate DNA uptake).

Taxonomy and Classification

• Taxonomy organizes and classifies organisms based on shared traits and evolutionary history.
• Classification involves arranging organisms from broad categories to specific species.

Classification Systems:

• Aristotle's System: Early taxonomy with limited effectiveness lasting 2000 years.
• Linnaean System, developed by Carolus Linnaeus, uses binomial nomenclature for naming organisms based on observable features.

Woese System

• Carl Woese proposed the three-domain system:
  • Bacteria: Prokaryote organisms without a nucleus.
  • Archae: Prokaryotes distinct from bacteria, often in extreme environments.
  • Eukaryote: More complex organisms with nuclei.

Main Taxonomic Categories

• The hierarchy includes Kingdom, Phylum, Class, Order, Family, Genus, Species, with Domain being broader than Kingdom.