Genetics Overview and Mendelian Inheritance

Genetics Overview

• Genetics is the study of heredity, the process where parents pass genes to their children.
• Children inherit genes from their biological parents, expressing traits like physical characteristics, talents, and disorders.

Mendelian Inheritance

• Each person has two copies of every gene, one from each parent.
• Gene copies can have different variations called alleles, influencing traits.
• Traits may be observable, but genes are passed to future generations.

Mendel and Pea Plants

• Gregor Mendel studied pea plants to understand heredity.
• Pea plants were well-suited for this due to their flower structure, pollination/fertilization methods, and easily observable offspring.
• Mendel utilized cross-pollination to get offspring with different parental traits.

Mendel's Pea Plant Traits

• Mendel studied seven characteristics of pea plants, including seed shape (round or wrinkled), seed color (yellow or green), flower color (purple or white), pod shape (inflated or pinched), and stem length (long or short).

Mendel's Laws of Inheritance

• Law of Dominance: Some alleles are dominant over others for a given gene.
• Law of Segregation: Each parent only passes one allele of a gene to their offspring during gametogenesis.
• Law of Independent Assortment: Alleles of different genes segregate independently during gametogenesis.

Punnett Squares

• Punnett squares are tools to predict possible genotypes/phenotypes of offspring.
• They illustrate how alleles from parents combine to determine offspring traits.

Mendelian Inheritance in Humans

• Pedigrees are charts displaying family traits over multiple generations.
• Pedigrees show inheritance patterns of a trait in a group of relatives.
• Half-shaded symbols on a pedigree represent carriers, who are heterozygous (carrying one dominant and one recessive allele for the trait).
• Scientists can use pedigrees to determine modes and patterns of inheritance/traits.

DNA Recombination

• Recombinant DNA is artificially created DNA from combining sequences that don't usually occur together.
• The process can cause a combination of genes in a new organism.
• Gene splicing is involved in combining the genes.

Types of Recombination

• Homologous recombination: occurs between nearly identical sequences, often during meiosis.
• Site-specific recombination: occurs between sequences with limited similarity, involving specific sites.
• Transposition: a DNA element moves from one location to another, often with little sequence similarity involved.

Biological Roles of Recombination

• Recombination generates new gene combinations during meiosis (crossing over).
• It produces new genes, such as immunoglobulin gene rearrangements.
• The process plays a role in fixing errors in DNA.

Recombinant DNA Technology

• Recombinant DNA technology is a process used to create DNA molecules that generally don't occur naturally.
• Technologies that use recombinant DNA can create beneficial changes in living beings.
• Technologies can be beneficial to medical, agriculture, and environmental applications.

Recombinant DNA Cloning

• Gene cloning became a reality in the 1970s, allowing the creation of copies of a molecule, cell, or organism.
• The creation of gene clones is a result of the discovery and subsequent use of restriction enzymes (DNA cutting enzymes) and plasmid vectors.
• Plasmid DNA Vectors are circular forms of self-replicating DNA and can be manipulated, so beneficial traits can be inserted.

Main Steps of Recombinant DNA

• Isolating: the target gene/vector
• Cutting: cleaving the DNA using restriction enzymes
• Joining: ligating the desired pieces of DNA
• Transforming: transferring the DNA into the host organism
• Cloning: producing multiple copies of the genetically modified organism
• Selecting: identifying and purifying the successful clones

Cloning

• Cloning allows inserting DNA to be replicated and expressed in a host cell, which can be helpful to produce multiple copies of a gene or to make a specific gene product in a host/organism.

Practical Uses of Recombinant DNA Technology

• Recombinant DNA technologies are involved in many purposes, including studying genes and proteins, treating diseases, creating new microbes and genetically modified organisms.

GM Animals & Plants

• Many animals and plants are being genetically modified.
• Reasons for these modifications include insecticide resistance, drought/freeze resistance, higher yields, faster growth rates, improved nutrition qualities, and longer shelf lives.
• Genetic modifications can have other purposes, like increasing their abilities to fight diseases or produce new proteins.

GMO Concerns

• Concerns exist about genetically modified foods and animals.
• These concerns include potential harm to human health, environmental hazards, increased pesticide use, farmers' health issues, seed/pollen drift, and the creation of herbicide-resistant super weeds. There are differing viewpoints on the benefits and risks of GMO use.