Gene as Unit of Inheritance
- Definition: Gene is a unit of heredity, a segment of DNA that carries information from one generation to the next. It is a sequence of nucleotides that code for a specific protein or RNA molecule.
- Functions:
- Transcribes genetic information from DNA to RNA
- Codes for the production of proteins or RNA molecules
- Regulates gene expression and expression of other genes
- Types and Location:
- Genes: Located in chromosomes, either autosomal (non-sex linked) or sex-linked (X or Y)
- Genomic DNA: Located in the nucleus of eukaryotic cells
- Mitochondrial DNA: Located in the mitochondria of eukaryotic cells
Types of Inheritance
- Definition: Types of inheritance refer to the mode of transmission of genes from parents to offspring.
- Autosomal Inheritance:
- Definition: Autosomal inheritance refers to the transmission of genes located on non-sex chromosomes (autosomes).
- Examples: Polygenic traits (e.g., height, eye color), monogenic traits (e.g., sickle cell anemia)
- Inheritance Pattern: Autosomal dominant or recessive
- Sex-Linked Inheritance:
- Definition: Sex-linked inheritance refers to the transmission of genes located on sex chromosomes (X or Y).
- Examples: Hemophilia (X-linked recessive), color blindness (X-linked recessive)
- Inheritance Pattern: X-linked dominant or recessive
- Mitochondrial Inheritance:
- Definition: Mitochondrial inheritance refers to the transmission of genes located in the mitochondria.
- Examples: Leber's hereditary optic neuropathy (LHON)
- Inheritance Pattern: Maternal inheritance, since only egg cells contribute mitochondria to the zygote
Hereditary Diseases
- Definition: Hereditary diseases are conditions caused by genetic mutations or variations.
- Examples: Sickle cell anemia, cystic fibrosis, Huntington's disease
- Causes: Genetic mutations, gene deletion or duplication, chromosomal abnormalities
Meiosis
Meiosis ↓ Formation of gametes ↓ Fertilisation ↓ Formation of zygote
Genetic Mutations
A → B ↓ C → D
Gene Expression
A ↓ Transcription ↓ Translation ↓ Protein synthesis
Gene Regulation
A ↓ Promoter region ↓ Transcription factor binding ↓ Gene expression
Gene as Unit of Inheritance
- Definition: Gene is a unit of heredity, a segment of DNA that carries information from one generation to the next.
- Functions:
- Transcribes genetic information from DNA to RNA
- Codes for the production of proteins or RNA molecules
- Regulates gene expression and expression of other genes
- Types and Location:
- Genes: Located in chromosomes, either autosomal (non-sex linked) or sex-linked (X or Y)
- Genomic DNA: Located in the nucleus of eukaryotic cells
- Mitochondrial DNA: Located in the mitochondria of eukaryotic cells
Types of Inheritance
- Definition: Types of inheritance refer to the mode of transmission of genes from parents to offspring.
- Autosomal Inheritance:
- Definition: Autosomal inheritance refers to the transmission of genes located on non-sex chromosomes (autosomes).
- Examples: Polygenic traits (e.g., height, eye color), monogenic traits (e.g., sickle cell anemia)
- Inheritance Pattern: Autosomal dominant or recessive
- Sex-Linked Inheritance:
- Definition: Sex-linked inheritance refers to the transmission of genes located on sex chromosomes (X or Y).
- Examples: Hemophilia (X-linked recessive), color blindness (X-linked recessive)
- Inheritance Pattern: X-linked dominant or recessive
- Mitochondrial Inheritance:
- Definition: Mitochondrial inheritance refers to the transmission of genes located in the mitochondria.
- Examples: Leber's hereditary optic neuropathy (LHON)
- Inheritance Pattern: Maternal inheritance, since only egg cells contribute mitochondria to the zygote
Hereditary Diseases
- Definition: Hereditary diseases are conditions caused by genetic mutations or variations.
- Examples: Sickle cell anemia, cystic fibrosis, Huntington's disease
- Causes: Genetic mutations, gene deletion or duplication, chromosomal abnormalities