Basics of Genetics Overview

Double Helix: Structure formed by two strands of nucleotides.
Nucleotides: Building blocks of DNA, consisting of:
- Phosphate group
- Sugar (deoxyribose)
- Nitrogenous base (Adenine, Thymine, Cytosine, Guanine)

Gregor Mendel: Father of genetics, known for pea plant experiments.
Laws of Inheritance:
- Law of Segregation: Alleles segregate during gamete formation.
- Law of Independent Assortment: Genes for different traits segregate independently.

Sources:
- Mutation: Change in DNA sequence.
- Recombination: Mixing of parental genes during meiosis.
- Random fertilization: Any sperm can fertilize any egg, increasing diversity.

Genotype: Genetic makeup of an organism.
Phenotype: Observable characteristics; influenced by genotype and environment.

Dominant Traits: Only one allele needed for expression.
Recessive Traits: Two alleles needed for expression.
Codominance: Both alleles expressed equally (e.g., AB blood type).
Incomplete Dominance: Blending of traits (e.g., pink flowers from red and white parents).

Types:
- Monogenic: Caused by a single gene mutation (e.g., cystic fibrosis).
- Polygenic: Involves multiple genes (e.g., diabetes).
- Chromosomal: Due to structural changes in chromosomes (e.g., Down syndrome).

Genetic Testing: For predisposition to diseases; raises privacy concerns.
Gene Editing: Potential for unintended consequences; ethical implications in human applications.

Study of heredity and variation among organisms focuses on how traits are passed down through generations.
Genes serve as the fundamental units of heredity composed of DNA, dictating specific traits within an organism.
Alleles represent variations of a gene, existing in dominant forms, which express their traits even when paired with a recessive form, and recessive forms, which require two copies to manifest.

DNA is structured as a double helix formed by two interwoven strands of nucleotides, which provide stability and functionality.
Nucleotides consist of three components:
- A phosphate group that connects to sugar and bases,
- A sugar molecule called deoxyribose,
- A nitrogenous base, which can be Adenine (A), Thymine (T), Cytosine (C), or Guanine (G).

Chromosomes are DNA-protein complexes that house numerous genes, fundamental for genetic information storage and transfer.
Humans possess 46 chromosomes arranged in 23 pairs, with one chromosome inherited from each parent, ensuring genetic diversity.

Gregor Mendel, through his experiments with pea plants, established foundational principles of heredity, earning the title "Father of Genetics."
The Law of Segregation explains that alleles for a trait separate during the formation of gametes, ensuring offspring receive one allele from each parent.
The Law of Independent Assortment states that alleles for different traits segregate independently during gamete formation, contributing to genetic variation.

Genetic variation arises from several sources:
- Mutation leads to alterations in the DNA sequence, potentially introducing new traits.
- Recombination allows for genetic mixing of parental genes during meiosis, further enhancing diversity.
- Random fertilization permits any sperm to fertilize any egg, leading to diverse genetic combinations in offspring.

Genotype refers to the specific genetic makeup of an organism, encompassing all its alleles.
Phenotype describes the observable traits or characteristics of an organism, influenced by both genetic makeup and environmental factors.

Dominant traits require only one allele to be expressed in the phenotype, while recessive traits need both allele copies.
Codominance occurs when both alleles are equally expressed, exemplified by the AB blood type in humans.
Incomplete dominance features a blending effect in traits, such as pink flowers resulting from red and white parent plants.

Monogenic disorders result from mutations in a single gene, with cystic fibrosis as a primary example.
Polygenic disorders arise from the interaction of multiple genes, as seen in conditions like diabetes.
Chromosomal disorders are caused by structural abnormalities in chromosomes, such as Down syndrome, which stems from an extra chromosome 21.

Gene cloning allows for copying genes for investigative or therapeutic purposes, expanding understanding and application in genetics.
CRISPR represents a cutting-edge technology for precise gene editing, facilitating research and potential treatments.
Gene therapy aims to amend genetic disorders through the direct alteration or insertion of genes, providing a therapeutic avenue for previously untreatable conditions.

Genetic testing provides information on predisposition to diseases but raises concerns regarding personal privacy and discrimination.
Gene editing introduces potential risks and ethical dilemmas, particularly in human applications, emphasizing the need for responsible use of advanced biotechnologies.