Introduction to Genetics

Genes
- Segments of DNA that code for proteins and determine traits.
- Basic unit of heredity.
DNA (Deoxyribonucleic Acid)
- Molecule that carries genetic instructions.
- Composed of nucleotides: adenine (A), thymine (T), cytosine (C), guanine (G).
Chromosomes
- Structures that organize and store DNA.
- Humans have 23 pairs of chromosomes (46 total).
Alleles
- Different versions of a gene.
- Can be dominant or recessive.
Genotype vs. Phenotype
- Genotype: Genetic makeup of an individual (e.g., AA, Aa, aa).
- Phenotype: Observable traits (e.g., flower color, height).

Mendelian Inheritance
- Based on Gregor Mendel’s principles.
- Principal types:
  - Dominant: Expressed in the phenotype if present.
  - Recessive: Expressed in the phenotype only if two copies are present.
Non-Mendelian Inheritance
- Includes incomplete dominance, codominance, and polygenic traits.

Occurs due to mutations, recombination during meiosis, and independent assortment.
Essential for evolution and adaptation.

Molecular Genetics
- Study of the biochemical basis of genetic expression and regulation.
Genomics
- Study of genomes, including sequencing and analyzing the structure and function of genes.
Gene Therapy
- Experimental technique to treat or prevent diseases by modifying genes.

Genetic testing and screening raise questions about privacy, discrimination, and consent.
Discussion on genetic engineering, CRISPR, and designer babies.

Medicine: Understanding genetic diseases, personalized medicine.
Agriculture: Genetically modified organisms (GMOs) for better yield and resistance.
Forensic science: DNA profiling for identification purposes.

Genetics explores how traits are passed down through generations and why individuals differ.
It focuses on genes, the fundamental units of heredity, and the mechanisms of genetic variation.

DNA, a double-helix molecule, carries genetic instructions for building and maintaining organisms.
It's composed of four nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G), arranged in specific sequences.

Genes are segments of DNA that provide instructions for making proteins, which determine traits.
These instructions are encoded in the specific sequence of nucleotides within a gene.

Alleles are alternative versions of a gene, responsible for the diversity of traits within a population.
They can be dominant, expressing their trait even if only one copy is present, or recessive, requiring two copies for expression.

Genotype refers to the genetic makeup of an individual, represented by combinations of alleles (e.g., AA, Aa, aa).
Phenotype refers to the observable characteristics expressed due to the genotype, like flower color or height.

Based on the principles of Gregor Mendel, Mendelian inheritance describes patterns of dominant and recessive alleles.
Dominant alleles always express their trait if present, while recessive alleles only express their trait if two copies are present.

Non-Mendelian inheritance encompasses more complex patterns than simple dominance and recessiveness.
This includes incomplete dominance (intermediate expression of both alleles), codominance (both alleles expressed simultaneously), and polygenic traits (determined by multiple genes).

Genetic variation, essential for evolution and adaptation, arises from mutations, changes in DNA sequences, and recombination during meiosis.
Meiosis, the process of cell division that produces gametes (sperm and egg), shuffles genetic material, creating new combinations of alleles in offspring.

Molecular genetics delves into the biochemical mechanisms of genetic expression and regulation, studying how genes are activated and controlled.
Genomics encompasses the study of entire genomes, analyzing the structure, function, and evolution of genes.
Gene therapy, an experimental technique, aims to treat or prevent diseases by altering faulty genes.

Genetic testing and screening raise concerns about privacy, potential discrimination based on genetic information, and informed consent for testing.
Genetic engineering, using CRISPR technology, to alter genes for specific traits, presents moral and ethical dilemmas, raising concerns about designer babies and the implications of altering the human genome.

Genetics plays a crucial role in medicine, enabling the understanding of genetic diseases, personalized medicine tailored to individual genetic makeup, and new approaches to disease treatment and prevention.
In agriculture, genetically modified organisms (GMOs) are developed to improve crop yield, disease resistance, and nutrient content.
Forensic science employs DNA profiling to identify individuals, solve crimes, and establish paternity.