Chromosomal Theory of Inheritance PDF

Chromosomal Theory of Inheritance Reporter: John Kenneth S. Felizarta Eddie Tarong Duran Jr. Instructor: Jestoni Salinas Learning Objectives: At the end of the lesson, students are expected to: a. Understand the Chromosomes Structure b. Explore Chromosome Behavior during Cell...

Chromosomal Theory of Inheritance Reporter: John Kenneth S. Felizarta Eddie Tarong Duran Jr. Instructor: Jestoni Salinas Learning Objectives: At the end of the lesson, students are expected to: a. Understand the Chromosomes Structure b. Explore Chromosome Behavior during Cell Division c. Unveil the Mechanisms of Inheritance d. Analyze Sex Chromosomes and Sex- linked traits Introduction The Chromosomal Theory of Inheritance The Chromosomal Theory of Inheritance proposes how traits are passed from parents to offspring. This theory revolutionized our understanding of heredity, demonstrating that chromosomes, not just invisible “factors” as Mendel proposed, are the physical carriers of genetic information. This groundbreaking theory, developed through meticulous observation and experimentation, has had a profound impact on our understanding of life itself. Scientist who proposed the Chromosomal Theory of Inheritance WALTER SUTTON American cytologist Walter Sutton, studying grasshopper cells, observed that chromosomes paired up during meiosis, mirroring Mendel’s concept of paired factors. He proposed that these paired chromosomes were the carriers of Mendel’s “factors,” later called  THEODOR BOVERI German biologist Theodor Boveri, working on sea urchin eggs, \ demonstrated the importance of chromosomes in development. He discovered that each chromosome carried unique genetic information and that a complete set was crucial for proper embryonic development.  THOMAS HUNT MORGAN American geneticist Thomas Hunt Morgan, studying fruit flies, provided crucial experimental evidence supporting the theory. He observed mutations in fruit flies linked to specific chromosomes, proving that genes reside on chromosomes and are inherited together. Chromosomes: The Carriers of Genetic Information DNA – Chromosomes are composed of DNA, a long, double-stranded molecule that carries the genetic code. This code is made up of four nucleotide bases: adenine (A), thymine (T), guanine (G), and cytosine (C). GENES – Genes are specific segments of DNA that code for particular traits. Each gene occupies a specific locus, or position, on a chromosome  Chromosome Structure and Behavior Centromere – Constricted region where sister chromatids are attached, crucial for chromosome movement during cell division. Sister Chromatids – Identical copies of a chromosome created during DNA replication, ensuring that each daughter cell receives a complete set of genetic information. Telomeres – Protective caps at the ends of chromosomes that prevent degradation and ensure chromosome stability.  Meiosis and Gametogenesis: The Production of Haploid Gametes Meiosis 1 – The first division of meiosis involves homologous chromosomes pairing up and exchanging genetic material through crossing over. This process shuffles genetic information, contributing to the genetic diversity of offspring. Meiosis 2 – The second division of meiosis separates sister chromatids, resulting in four haploid daughter cells, each containing a single set of chromosomes. These haploid cells are gametes, sperm or egg cells.h INHERITANCE - During reproduction, chromosomes are replicated and passed on to offspring. This ensures that offspring inherit a complete set of genetic instructions, half from each parent. Gametogenesis – Gametogenesis is the process of producing gametes. In males, it’s called spermatogenesis, producing sperm cells. In females, it’s called oogenesis, producing egg cells. Fertilization and Zygote Formation: The fusion of Haploid Gametes Sperm- A sperm cell is a haploid gamete produced by the male, carrying half the genetic information needed for offspring. Fertilization and Zygote Formation Egg – An egg cell is a haploid gamete produced by the female, carrying the other half of the genetic information needed for offspring. Zygote – When a sperm and egg cell fuse, they form a zygote, a diploid cell with a complete set of chromosomes, half from each parent. Inheritance Patterns: Unveiling the mechanisms of traits transmission Dominant traits – Traits controlled by dominant alleles are expressed even if only one copy of the dominant allele is present. For example, brown eyes are dominant over blue eyes. Recessive traits – Traits controlled by recessive alleles are only expressed if two copies of the recessive allele are present. For example, blue eyes are only expressed if an individual inherits two copies of the recessive blue eye allele.  Codominance – In codominance, both alleles are expressed equally. For example, a person with AB blood type inherits both A and B alleles, both of which are expressed. Sex Chromosomes and Sex-Linked Traits: Determining Gender and Unique Inheritance Patterns Sex Chromosomes -Humans have two sex chromosomes: X and Y. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The Y chromosome is smaller and carries fewer genes than the X chromosome. GENETIC DISORDER AND MUTATIONS Genetic Disorder and Mutations Genetic disorders are health conditions caused by abnormalities in a person’s genetic material, specifically their DNA sequence. These abnormalities, known as mutations or variants, can affect a single gene, multiple genes, or even entire chromosomes.  Genetic disorders can be Types of categorized into three main genetic types 1.Single-Gene Disorders disorders 2. Chromosomal Disorders  1. Single-Gene Disorders Examples include cystic fibrosis, sickle cell disease, and Huntington’s disease.  Chromosomal Disorders Examples include Down syndrome, Turner syndrome, and Klinefelter syndrome. Complex Disorders Examples include heart disease, diabetes, cancer, and autism spectrum disorder. Causes of Genetic Mutations Genetic mutations can arise due to various factors: Spontaneous Errors: DNA replication is a complex process, and errors can occur during the copying of genetic material Environmental Factors: Exposure to radiation, certain chemicals, and environmental toxins can damage DNA and lead to mutations. Lifestyle Choices: Smoking, alcohol consumption, and exposure to sunlight can increase the risk of developing certain genetic disorders. Impact and legacy of the Chromosomal Theory of Inheritance The Chromosome Theory of Inheritance laid the foundation for modern genetics by: Gene Mapping: The theory led to the development of gene mapping, which allows scientists to determine the relative positions of genes on chromosomes. Genetic Recombination: The theory explained the phenomenon of genetic recombination, where offspring inherit combinations of traits different from either parent. This occurs due to the exchange of genetic material between homologous chromosomes during meiosis, a process known as crossing over.  Understanding of Sex Determination: The theory led to the discovery of sex chromosomes (X and Y) and their role in determining sex. This understanding was crucial for understanding sex-linked inheritance, where traits are passed down differently depending on the sex of the Development of Genetic Technologies: The parent. theory paved the way for the development of genetic technologies, such as DNA sequencing, gene editing, and genetic screening. These technologies have revolutionized our understanding of human health, agriculture, Damo nga salamat!