Genetics and Heredity: Understanding Inheritance Patterns
Genetics and Heredity
Introduction to Genetics
Genetics is the science that studies the inheritance of characters, their evolution, transmission, and expression.
Basic Concepts in Genetics
- Haploid: A cell or body containing only one gene for each character.
- Diploid: A cell or body containing two genes for each character.
- Genes: Specific DNA segments that control structures and cellular functions. These are Mendel’s hereditary factors.
- Chromosomes: Structures in the nucleus of eukaryotic cells, formed by
DNA Replication, Transcription, and Genetic Information Flow
DNA: The Blueprint of Life
Griffith’s Experiment
Griffith worked with two strains of bacteria: a rough strain (R) and a smooth strain (S). The R strain lacked a polysaccharide capsule and was harmless to mice. The S strain, possessing a polysaccharide capsule, caused fatal infections. When dead S strain bacteria were mixed with live R strain bacteria and injected into mice, the mice died. This suggested a transforming principle from the dead S strain bacteria had altered the live R strain.
Hershey-
Read MoreMeiosis and Apoptosis: Cellular Processes Explained
Meiosis
Each organism has a characteristic chromosome number. Gametes (cells specializing in sexual function) have half the chromosome number of somatic cells (which form the rest of the body). These are referred to as haploid (n) and diploid (2n), respectively. The diploid cell produced by the fusion of two gametes is called a zygote. The purpose of meiosis is to reduce chromosome number and establish restructuring in homologous chromosomes through the exchange of genetic material.
Phases of Meiosis
Read MoreBlood Groups, STIs, and HIV/AIDS: A Comprehensive Guide
Blood groups: A, B, AB, and O. Group O has no A or B antigens on red blood cells but contains anti-A and anti-B antibodies in the plasma. Group A has A antigens and anti-B antibodies; Group B has B antigens and anti-A antibodies. This explains transfusion reactions: Group O is a universal donor (can donate to all groups) but can only receive from O. Group A can donate to A and AB and receive from A and O. Group B donates to B and AB and receives from B and O. Group AB is a universal recipient (
Read MoreMendel’s Laws and Chromosome Role in Inheritance
Mendel’s Laws
Mendel’s experiments began by crossing two purebred individuals with contrasting traits. He observed several characters. For instance, the smooth seed character dominates over the wrinkled seed character. When crossing a purebred smooth seed plant with a purebred wrinkled seed plant, the resulting parental generation (P) produced only smooth seeds. Self-pollination of the F1 generation resulted in both smooth and wrinkled seeds, with a ratio of approximately three smooth seeds for
Read MorePhotosynthesis: Light Absorption, Pigments, and Processes
Photosynthesis
Absorption of Light by Photosynthetic Pigments
Absorption Spectrum and Color
Chlorophylls have two main absorption peaks in the visible light spectrum:
- One in the blue light region (400-500 nm wavelength)
- Another in the red region of the spectrum (600-700 nm)
They reflect the middle of the spectrum, which corresponds to green light (500-600 nm). This is why chlorophylls appear green and give this color to tissues with active chloroplasts in their cells.
Chlorophylls are accompanied by accessory
Read More