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SEVEN PAIR OF CONTRASTING CHARACTERS MENDELIAN GENETICS SELECTED BY MENDEL FOR HIS EXPERIMENT. All living organisms reproduce, resulting in the formation of offspring of the same kind. The resulting offspring often do not exactly resemble t...

SEVEN PAIR OF CONTRASTING CHARACTERS MENDELIAN GENETICS SELECTED BY MENDEL FOR HIS EXPERIMENT. All living organisms reproduce, resulting in the formation of offspring of the same kind. The resulting offspring often do not exactly resemble the parent. GREGOR JOHANN MENDEL: FATHER OF GENETICS Lifespan: 1822-1884 Background: ○ Born into a poor peasant family in Moravia, Austria (now part of the Czech Republic). ○ Had to suspend his schooling due to poverty. Monastic Life: ○ Joined a monastery in 1843. ○ Became head of the monastery in Brunn, Austria (now Brno, Czech Republic) in 1847. Education and Research: ○ Studied natural history and mathematics at the University of Vienna (1851-1853). ○ After returning, worked as a teacher in natural history and mathematics. Hybridization Experiments: ○ Conducted breeding experiments with pea plants between 1856 and 1865. ○ Analyzed the results and provided a mathematical interpretation. Publication: Mendel selected the pea plant because of the ff: ○ In 1865, published his results titled Pure variety is available. "Translation of the Characters" in the Pea plants are easy to cultivate. Natural History Society of Brunn. Life cycle of plants is only a few months. Rediscovery: So that result can be got early. ○ Mendel's work went largely unrecognized Contrasting traits are observed. until 1900. Flowers are bisexual and normally ○ Rediscovered independently by three self-pollinated. scientists: Flowers can be cross-pollinated only manually. Hugo de Vries (Holland) Hybrids are fertile. Franz Correns (Germany) Erich Tschermak (Austria) Legacy: Mendel is regarded as the "father of classical genetics" for his pioneering work on heredity. VOCABULARY The phenotypic ratio would be Genetics is the branch of life science that deals 3:1. This means that 3 purple with the study of heredity and variation. flowers, 1, white flower Heredity is the transmission of characters from ★ Genotypic ratio: The correct proportion of parents to their offsprings. genotype in population. Variation is the difference among the offsprings ○ Example: In a genetic cross between and with their parents. two heterozygous plants ("Bb" × "Bb"), Hereditary variations: These are genetical and where "B" represents the dominant allele inheritable. for purple flowers and "b" represents Environmental variation: These are acquired the recessive allele for white flowers: and non heritable. ○ The genotypic ratio would be 1:2:1, which means: 1 offspring will be homozygous dominant BB – (purple flower) 2 offspring will be heterozygous TERMINOLOGIES IN GENETICS: Bb (purple flower) 1 offspring will be homozygous ★ Factor or Gene: Functional unit of heredity recessive, bb. (white flower) responsible for the expression of character in the ★ Homozygous: The individual heaving identical progeny. genes in an allelic pair for a character. ★ Locus: The position of the gene on the ○ Example: TT, tt. chromosomes. ★ Heterozygous: The individual heaving un- ★ Allele: The alternative form of a gene for a identical genes in an allelic pair for a character. contrasting character present on identical locus ○ Example: Tt. of homologous chromosomes. ★ Dominant gene: The gene that expresses its ○ Example: TT, Bb, Rr, ii. character in heterozygous conditions. ○ The allele is the letters themselves. ★ Recessive: The gene that fails to express its ★ Phenotype: The external appearance of an character in heterozygous conditions. organism due to the influence of genes and ★ Hybrid: The progeny obtained by crossing two environmental factors. parents that differ in characters. ○ Example: Eye color, height, and blood ★ Back cross: The cross between F1 hybrid and type are all aspects of an organism's one of its parents. phenotype. ★ Test cross: The cross between hybrid and its ★ Genotype: The genetic constitution of an homozygous recessive parent. It is used to individual responsible for the phenotype. The identify the genotype of the hybrid. genetic makeup of an organism, consisting of the specific alleles (gene variants) present in its DNA. The genotype determines the potential traits an organism can exhibit, although the MENDELIAN LAWS OF HEREDITY environment can influence the expression of Law of paired factors: Factors are responsible those traits. for the transmission of characters. These are ○ Example: Genotype might be present in pairs. represented as "BB," "Bb," or "bb," where Law of dominance: In hybrid dominant "B" is a dominant allele and "b" is a character suppresses the expression of recessive allele. recessive character. ★ Phenotypic ratio: The correct proportion of Mendel’s 1st law or Law of segregation or phenotype in population. Law of purity of gametes: ○ Example: In a simple Mendelian cross ○ It states that ‘when a pair of factors for a between two heterozygous plants for character is brought together in a hybrid, flower color they segregate (separate) during the ○ (e.g., "Bb" × "Bb", where "B" = purple formation of gametes. and "b" = white): INHERITANCE OF ONE GENE Used when looking at inheritance patterns of 2 Inheritance of one gene can be explained by genes on different chromosomes monohybrid cross. Independent assortment will separate the 2 The cross between two parents differing in one homologous chromosomes independently from pair of contrasting character is called each other monohybrid cross. Because of this, you must find the probability that each allele on each chromosome will combine with the other alleles Example: Monohybrid Cross for Flower Color in Peas Let's consider Mendel’s classic example of pea plants with two traits for flower color: Purple (P) = Dominant trait. White (p) = Recessive trait. Step-by-Step Explanation: 1. Parental Generation (P): ○ One parent is homozygous dominant (PP) for purple flowers. ○ The other parent is homozygous recessive (pp) for white flowers. ○ Cross: PP (Purple) × pp (White) 2. F1 Generation: ○ All offspring will have the genotype Pp, which is heterozygous. ○ Because purple (P) is dominant over white (p), all F1 plants will have purple flowers. 3. Self-pollination of F1 Generation (Pp × Pp): ○ Each F1 plant (Pp) can produce two types of gametes: P and p. ○ These gametes will combine to form the F2 generation. 4. F2 Generation and Punnett Square: ○ A Punnett square shows the possible combinations: Phenotypic ratio: 3 purple : 1 white Genotypic ratio: 1 PP : 2 Pp : 1 pp MENDELIAN GENETICS: DIHYBRID CROSS OKAY, EXAMPLE!  ★ Step 1: Find ALL possible gametes that can be made from each parent. Remember, each gamete must have one B and one R. NON-MENDELIAN GENETICS Mendelian Genetics describes inheritance patterns based on Complete Dominance or Recessiveness. There are other types of inheritance that Mendel never considered: ○ Incomplete Dominance ○ Codominance ○ Multiple Alleles After using Foil, our possible gametes are: ○ Polygenic Traits ○ Sex-linked Trait BR Br bR br 1. Incomplete Dominance The hybrid (heterozygous) offspring ★ Step 2: Arrange all possible gametes for dad on displays a THIRD Phenotype! Neither trait the top of your Punnett Square, and mom down is completely dominant, as a result, there the side appears to be a blending phenotype. Incomplete Dominance Problem What is the probability of pink flowers if pink flowers are bred with red flowers?  2. Co Dominance Both traits are dominant, and show up in the phenotype together. Co means “together”. A heterozygote expresses both phenotypes at the same time. Codominance Problem What are all the possible phenotypes when two spotted cows are bred? Mendel’s law of Independent Assortment Two traits will be inherited independently of each other, provided their genes are located on non-homologous chromosomes. 4. Sex linked inheritance When gametes form, the alleles for different Genes for some traits are found on the traits segregate independently of each other. sex chromosomes (X or y) Most of these traits are recessive the normal gene is dominant 3. Multiple Alleles Heterozygous Females (XXc) are Some traits are controlled by more than 2 carriers. They do not show the trait, but different alleles types. carry a gene for the trait. Homozygous Females (XcXc) have the Blood type displays both co-dominance trait and complete dominance Males with the gene (XcY) have the trait.—They do not have another X to - Red Blood cells can either have a carbohydrate counterbalance the affected gene on their surface or not. - The presence of a carbohydrate (I) is dominant to the absence of a carb (i). - Additionally, there are two types of carbs that may exist on the surface of RBCs called A (IA) and B (IB). - Cell surface carbs A and B are codominant, which means they could also show up at the same time on an RBC.  6. Mendelian dihybrid cross (b): A 9:3:3:1 phenotypic ratio typically indicates a dihybrid cross where two traits are being analyzed, each with two alleles, following Mendelian inheritance. 7. Polygenic inheritance (b): Polygenic traits are characterized by continuous variation because they are influenced by multiple genes, resulting in a range of phenotypes rather than distinct categories. 8. Not fitting Mendelian principles (b): Traits influenced by multiple genes and environmental factors represent a more complex inheritance 5. Polygenic Traits pattern, diverging from Mendelian simplicity. Require more than one gene (allele) to determine trait. 9. True statement about Mendelian inheritance Skin tone is determined by 4-6 (c): Mendelian inheritance is based on genes—that means that there may be six predictable patterns of segregation and different chromosomes involved! independent assortment, as demonstrated by Gregor Mendel's experiments. GENETICS TOPIC: DEFINITIONS OVERVIEW 1. Mendelian inheritance (b): Mendelian 10. Importance of understanding inheritance inheritance is defined by simple differences (a): Understanding the differences dominant-recessive relationships, where traits between Mendelian and non-Mendelian are controlled by single genes with clear inheritance helps predict how traits will be dominant and recessive alleles. passed on to future generations, which is crucial for genetics and breeding. 2. Non-Mendelian inheritance (b): Human blood types demonstrate codominance and multiple alleles, making it an example of non-Mendelian inheritance. In contrast, pea plant traits like flower color and height follow Mendelian principles. 3. Polygenic Inheritance (c): Traits controlled by two or more genes exhibit polygenic inheritance, resulting in a continuous range of phenotypes (like height or skin color), as opposed to clear categories. 4. Incomplete dominance (b): Incomplete dominance occurs when the phenotype is a blend of both alleles. For example, in snapdragons, crossing red and white flowers results in pinK flowers. 5. Sex-Linked Inheritance (d): Traits located on sex chromosomes (X or Y) follow sex-linked inheritance patterns. Examples include color blindness and hemophilia, which are associated with the X chromosome.  - Since the second plant can only contribute yr, the Punnett square simplifies to: - PRACTICE QUESTION!! - In pea plants, yellow seeds (Y) are dominant over green seeds (y), and rounded peas (R) are dominant over wrinkled peas (r). Cross (what do ★ Step 4: Analyze the Offspring you have to draw?) a plant that is heterozygous - From the Punnett square, we can list the for both traits with a plant that is homozygous possible genotypes of the offspring: recessive for both traits. Draw a Punnett square 1. YyRr (2 instances) to show all possible offspring, and determine the 2. Yyrr (2 instances) genotypic and phenotypic ratios. 3. yyRr (2 instances) 4. yyrr (2 instances) Traits Yellow seeds (Y) = Dominant Green seeds (y) = Recessive ★ Step 5: Genotypic and Phenotypic Ratios Rounded peas (R) = Dominant Wrinkled peas (r) = Recessive Genotypic Ratio Genotypes 2 YyRr : 2 Yyrr : 2 yyRr : 2 yyrr Simplified ratio: 1 YyRr : 1 Yyrr : 1 yyRr : 1 yyrr 1. The heterozygous plant will have the genotype YyRr (one allele for each trait). Phenotypic Ratio 2. The homozygous recessive plant will have the genotype yyrr (both alleles for each trait are Yellow, Round (YyRr): 2 (YyRr) recessive). Yellow, Wrinkled (Yyrr): 2 (Yyrr) ★ Step 1: Cross the Plants Green, Round (yyRr): 2 (yyRr) Green, Wrinkled (yyrr): 2 (yyrr) Cross: YyRr (heterozygous) × yyrr (homozygous recessive) This results in: ★ Step 2: Determine Possible Gametes Phenotypic Ratio: 2 Yellow, Round : 2 Yellow, For YyRr: The possible gametes are YR, Yr, yR, Wrinkled : 2 Green, Round : 2 Green, Wrinkled yr. Simplified ratio: 1 Yellow, Round : 1 Yellow, For yyrr: The possible gametes are yr (since Wrinkled : 1 Green, Round : 1 Green, Wrinkled both alleles are recessive). In this cross, we find a 1:1:1:1 ratio for the genotypes ★ Step 3: Draw the Punnett Square and phenotypes of the offspring - We will set up a Punnett square with the gametes from each parent:  differences in beak sizes and shapes due to genetic diversity. Species Diversity Species diversity refers to the variety of life forms and the number of different species in a biological community. For example, wild cats include lions, cheetahs, tigers, panthers, and cougars, each adapted to different habitats. Lions and cheetahs live in the savannas of Africa, while tigers are solitary hunters found in Asia’s jungles and grasslands, although their habitats are now fragmented. Species Richness: This term describes the number of species in a specific area. Species Abundance: This refers to the number of individuals of a particular species in an area. BIODIVERSITY For instance, a desert may have low species richness with few species (like scorpions and Biodiversity combines "biological" and rattlesnakes) but high species abundance if "diversity" and refers to the variety of living there are many rattlesnakes. Conversely, a species on Earth. There are millions of species tropical rainforest may have high species with scientists officially naming nearly two richness due to many different species but low million. They estimate that about 30 million species evenness if certain species (like species may exist, many of which remain macaques) are more numerous than others (like undiscovered, especially in rainforests and deep orangutans). oceans. Unfortunately, many species become extinct before they can be identified due to Ecosystem Diversity habitat destruction. Ecosystem diversity refers to the variety of A rich diversity of organisms in an area helps ecosystems within a biosphere. Factors like maintain ecosystem stability and overall health. climate and sunlight determine which organisms Biodiversity includes all living organisms at can thrive in a habitat. different levels: genes, species, and Ecosystem diversity includes different biomes, ecosystems. such as tropical rainforests, grasslands, and coniferous forests, as well as aquatic Components of Biodiversity ecosystems like coral reefs, mangroves, seas, Organisms within an ecosystem differ from one another and lakes. Coral reefs, though they cover less and even among their own species. than one percent of the ocean, host about twenty percent of all saltwater fish species and Genetic diversity refers to the variety of genes play crucial ecological roles. in a population. Genes determine traits passed from parents to offspring, influencing survival. A Functional Diversity population with diverse traits is healthier and Functional diversity involves the biological and chemical more adaptable. For instance, variations in traits processes that support life, including energy flow, like color, size, and speed can help organisms nutrient cycles, and interactions among organisms. survive. Species interact in various ways, such as mutualism, While members of a species share common competition, parasitism, commensalism, and predation. genes, they may also have unique traits. For Producers, consumers, and decomposers are essential example, cheetahs may differ in agility, which for nutrient cycling in food chains and webs. affects their hunting success. This variation - Sharks, for example, are more than just allows the more agile individuals to survive and predators. They help control populations of the reproduce. Similarly, Galapagos finches show  marine prey species they prey on. Likewise, - Biomagnification is the buildup of chemicals in minute organisms acting as decomposers play a organisms as they move up the food chain. big role in breaking down wastes or dead bodies Human activities that threaten biodiversity are of organisms, which in turn serve as resources summarized by HIPPCO: for other organisms for continuous nutrient recycling. Habitat destruction - Without decomposers, Earth will be Introduced species overwhelmed with plant litter, animal waste, Pollution corpses of organisms, and other waste products. Population overuse of resources Climate change Overexploitation. Effective biodiversity conservation includes the species approach (focusing on individual species) and the ecosystem approach (protecting entire habitats). Importance of Biodiversity People have different beliefs about the value of biodiversity. Some see it as a resource for economic gain, while others respect all living organisms, believing that every species has a right to exist on our planet. Many individuals work to conserve biodiversity for the benefit of future generations. Biodiversity holds significant economic value. For instance, the Philippines has rich ecosystems that provide numerous benefits, including: Basic Necessities: Plants, animals, and microorganisms offer food, materials for medicine, shelter, and clothing. Natural Products: Many items found in markets and supermarkets come from diverse ecosystems. Energy Sources: In developing countries, firewood is a major energy source for cooking and heating. Medicinal Resources: Chemicals derived from various species can lead to new medicines and potential cures for diseases. Protecting biodiversity is essential for safeguarding future economic resources. Additionally, ecotourism is growing in popularity, offering wildlife tours in rainforests, savannas, and mountains, and providing important livelihoods for many people. Biodiversity refers to the variety of life at different levels: genetic, species, and ecosystem. It has various values, including economic, ecological, and aesthetic benefits. - Biodiversity loss occurs due to both natural causes and human actions.