Evolution and Taxonomy PDF

Evolution and Taxonomy The 9 Major Phyla of Animal Kingdom (From simplest to most complex) UNIQUE CHARACTERISTICS AND ADAPTATIONS IN VARIOUS TAXA.  PORIFERA Rep: Sponges The phylum with the simplest body plan. Unique Characteristics: Lack...

Evolution and Taxonomy The 9 Major Phyla of Animal Kingdom (From simplest to most complex) UNIQUE CHARACTERISTICS AND ADAPTATIONS IN VARIOUS TAXA.  PORIFERA Rep: Sponges The phylum with the simplest body plan. Unique Characteristics: Lack of true tissues and organs. Adaptation: Porous body structure allows water to flow through, facilitating filter feeding. PORIFERA Rep: Sponges Choanocytes – The versatile cell of sponges.  CNIDARIA Jellyfish, Anemone, Polyps Stinging animals such as corals, sea anemones, and jellyfish. Unique Characteristics: Presence of specialized stinging cells called cnidocytes. Adaptation: Cnidocytes for defense and prey capture.  Platyhelminthes Flatworms, Planarians Unique Characteristics: Ability to regenerate lost body parts. Adaptation: Flatworms can regenerate entire individuals from small body fragments Platyhelminthes Flatworms, Planarians Regeneration of Planarians is allowed by clonogenic neoblasts which are pluripotent stem cells that provide the cellular basis for planarian regeneration.  Nematoda Round Worms Unique Characteristics: Complete digestive system with a separate mouth and anus. Adaptation: Well-developed muscles and complete digestive tract.  Mollusca Octopus, Slugs, Snails Unique Characteristics: Presence of a muscular foot in many species. Adaptation: The foot is used for locomotion in gastropods (e.g., snails) and burrowing in bivalves (e.g., clams).  Annelida Earthworm, Leeches Annelids have a segmented body plan and well- developed organ systems, representing further complexity in evolutionary history. Unique Characteristics: Presence of setae, bristle-like structures, on each body segment. Adaptation: Setae aid in locomotion by anchoring the body to the substrate and providing traction.  Arthropoda Insects The largest phylum of the animal kingdom as about 84% of all animal species belong to this phylum. Unique Characteristics: Jointed appendages and a segmented body. Adaptation: Allows for precise movement and manipulation of objects, as well as specialization of appendages for various functions such as walking, swimming, or feeding.  Echinodermata Starfish, Sea Urchins, Sea Cucumbers With a unique body plan characterized by radial symmetry and a water vascular system, representing a complex evolutionary lineage. Unique Characteristics: Presence of tube feet. Adaptation: Tube feet are used for locomotion, feeding, and gas exchange, providing versatility in movement and feeding strategies.  Chordata Vertebrates representing the highest level of complexity among animal phyla. Unique Characteristics: Dorsal nerve cord, notochord, and pharyngeal slits in all chordates during embryonic development. Adaptation: Nerve cord serves as the CNS. Notochord develops into a backbone. Pharyngeal slits are modified for various functions such as respiration, filter feeding, or sound production. Chordata Invertebrate Chordates SPECIES DIVERSITY  SPECIES DIVERSITY refers to the variety of different species present within a specific area or ecosystem. QUICK FACTS ABOUT PHILIPPINE BIODIVERSITY Speciation is the process by which new species arise from a single ancestral species over time. 4 Types of Speciation -Allopatric -Sympatric -Parapatric -Peripatric ALLOPATRIC SPECIATION Occurs when populations become geographically isolated from one another, often due to physical barriers such as mountains, rivers, or oceans. SYMPATRIC SPECIATION New species arise within the same geographic area without physical isolation. The new species continue to live with the members of the original population but cannot interbreed anymore. PARAPATRIC SPECIATION Occurs when a smaller population is isolated, usually at the periphery of a larger group, and becomes differentiated to the point of becoming a new species. PERIPATRIC SPECIATION Involves the rapid evolution of a new species from a small, isolated peripheral population of a larger ancestral population. When small groups break off from a larger group and form a new species.  CENTRAL DOGMA OF MOLECULAR BIOLOGY PROTEIN SYNTHESIS  DNA A molecule that contains the genetic code that is unique to every individual. Building Block: NUCLEOTIDES  DNA contains instructions for making a protein. Proteins are the building blocks of life, forming the structure, enzymes, and functions that make up and sustain every living organism.  PHOTO 51 captured by Rosalind Franklin revealed information about DNA´s three-dimensional structure WATSON AND CRICK'S MODEL OF DNA The structure of DNA, as represented in Watson and Crick's model, is a double- stranded, antiparallel, right-handed helix.  CENTRAL DOGMA OF MOLECULAR BIOLOGY A theory that states that genetic information flows only in one direction, from DNA to RNA to protein. 1. DNA Replication 2. Transcription 3. Translation DNA REPLICATION An enzyme called Helicase unwinds the double helix DNA strand exposing the Leading and Lagging strands.  An enzyme called Primase attaches to the 2 DNA strands. Primases add primers which are very short strands of RNA to both the Leading and Lagging strands. An enzyme called DNA Polymerase attaches to the primer and begins adding DNA nucleotides to each of the strands. This process can only be done by the DNA Polymerase from 5’ end to 3’ end of the DNA strand.  As the Helicase continues to unwind the DNA strand, the addition of nucleotide bases in the leading strand is continuous while discontinuous in the lagging strand due to the direction of the DNA polymerase being opposite to the Helicase.  Due to the movement of the DNA Polymerase in the lagging strands, several Okazaki Fragments are being created. A different type of DNA Polymerase removes the primers and replace them with DNA strands. The gaps between the Okazaki fragments are being sealed by the enzyme called DNA Ligase.  The series of adding primers, DNA Nucleotides, removal of primers, and sealing of gaps by DNA Ligase continues until the entire DNA strand is replicated.  2 strands of DNA are now formed and are genetically identical with each other. This process is not only utilized for Central Dogma but is also the primary step in Cellular Divisions Mitosis and Meiosis.  TRANSCRIPTION The process by which a cell makes an RNA copy from a piece of DNA. The TRANSCRIPTION process is characterized by 3 sub-steps. 1.Initiation 2.Elongation 3.Termination The main goal is to create Messenger RNA (mRNA) that will be utilized for the Synthesis of Protein  Transcription begins RNA Polymerase with the attachment of an enzyme called RNA Polymerase to a segment of DNA. This segment is the gene that codes for a particular protein.  The RNA Polymerase unwinds a specific portion of the DNA Non-Template strand where the Transcription process will take place. This unwinding phase creates the Template Strand and Non- Template Strand.  During the elongation phase of the Transcription, the RNA Polymerase transcribes the template Strand by adding in complementary base pairs following the pairing rule.  The RNA Polymerase follows the complementary base pair to create the mRNA from the template strand. Guanine – Cytosine TEMPLATE STRAND Cytosine – Guanine Thymine – Adenine Adenine – Uracil Non- Template Strand G-C-T-A-A-T-C-C-G-G-C-T-A-T-C Template Strand C-G-A-T-T-A-G-G-C-C-G-A-T-A-G mRNA Strand G-C-U-A-A-U-C-C-G-G-C-U-A-U-C The mRNA strand created during transcription has the same sequence as the non- template strand, however, they differ in terms of Uracil and Thymine.  The mRNA strand created during transcription exits the Nucleus and goes to the Cytoplasm and will now be going through the next step to complete the Protein Synthesis.  TRANSLATION Translation is the process by which a protein is synthesized from the information contained in a molecule of messenger RNA (mRNA).  CODON A sequence of three consecutive nucleotides in a DNA or RNA molecule that codes for a specific amino acid. An intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell Transfer ribonucleic acid (tRNA) is a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. A tRNA carries an Amino acid that corresponds to the codon ALANINE in the mRNA and not with the anticodon carried by the tRNA itself. The initiation stage is marked by creation of an initiation complex consisting of 30S Ribosomal Subunit, F-Methionyl tRNA attaching to an mRNA. As the tRNA attaches to the mRNA, the 50S Ribosomal Subunit joins the complex The translation process begin at the AUG codon of the mRNA. AUG is known as the START CODON. Remember that the 30S and 50S subunits of Ribosome create a 70S Ribosome. The 70 S ribosome contains 2 sites where the amino acids carried by the tRNAs will bind: Peptidyl (P-Site) Acceptor (A-Site) Exit (E-site) – where tRNA exits the process and is released to the cytoplasm Remember that the tRNA carries an Anti-codon which is a complementary codon of those that can be found in the mRNA. The 2nd tRNA enters the complex through the A-Site. F-Met will bind with the amino acid carried by the 2nd tRNA. The Ribosome moves to a distance of one codon to allow entry of another tRNA through the A-site. tRNA that loses its amino acid will exit the complex through the E- Site POLYPEPTIDE CHAIN a continuous, unbranched chain of amino acids joined by peptide bonds. POST-TRANSLATIONAL EVENTS of PROTEIN SYNTHESIS  PROTEIN FOLDING is a process by which a polypeptide chain folds to become a biologically active protein in its native 3D structure. Protein structure is crucial to its function. Folded proteins are held together by various molecular interactions.  PRIMARY STRUCTURE The Primary structure of proteins is the exact ordering of amino acids forming their chains. The exact sequence of the proteins is very important as it determines the final fold and therefore the function of the protein.  SECONDARY STRUCTURE refers to local folded structures that form within a polypeptide due to interactions between atoms of the backbone. This structure arises due to the regular folding of the backbone of the polypeptide chain due to hydrogen bonding  TERTIARY STRUCTURE This structure arises from further folding of the secondary structure of the protein. Primarily caused by ionic bonds between the positively charged and negatively charged R-group of amino acids.  QUATERNARY STRUCTURE The quaternary structure arises from the association of individual tertiary structures, and the interactions between these subunits are critical for the overall stability and function of the protein complex. ORIGIN AND HISTORY OF LIFE ON EARTH Brief History of Life on Earth Earth formed about 4.6 billion years ago from cosmic dust and gas, undergoing a process of accretion. 3.5 Billion Years Ago Development of Prokaryotic Life: The first life forms were prokaryotic cells, such as Archaebacteria and Eubacteria, thriving in anaerobic environments. 2.5 Billion Years Ago Oxygen Revolution and Prokaryotic Communities: Cyanobacteria played a crucial role in the Oxygen Revolution through photosynthesis.  2 Billion Years Ago Rise of Eukaryotic Life  541 Million Years Ago CAMBRIAN EXPLOSION It was when most of the major animal groups started to appear in the fossil record. 500 Million Years Ago Plant and Animal Adaptations Vascular plants adapted to terrestrial life, followed by arthropods and tetrapods, marking the transition from sea to land. 230 Million Years Ago EMERGENCE OF DINOSAURS  MAJOR EXTINCTIONS ACROSS EARTH’S HISTORY 66 Million Years Ago Rise of Early Mammals 4 Million – 2 Million Years Ago Hominid Development Started in Mid-20th Century Anthropocene Epoch The Geologic Time Scale of Earth's History -is the “calendar” for events in Earth’s history. UNITS OF GEOLOGIC TIMESCALE  PRE-CAMBRIAN EONS the longest eon and encompasses most of the Earth's history. PHANEROZOIC EON the most recent eon in Earth's history. Divided into 3 Eras namely: Paleozoic, Mesozoic, and Cenozoic.  Phanerozoic Eon PALEOZOIC ERA (541 million to 252 million years ago) “ancient life” It witnessed the emergence of fish, plants, insects, and the first terrestrial vertebrates.  Phanerozoic Eon MESOZOIC ERA (252 million to 66 million years ago) often known as the era of middle life and is famous for the dominance of reptiles, including dinosaurs.  Phanerozoic Eon CENOZOIC ERA (66 million years ago to the present) the era of recent life and spans from the aftermath of the Cretaceous- Paleogene extinction event to the present day.  Paleozoic Era CAMBRIAN PERIOD (541 to 485.4 million years ago) known for the "Cambrian” Explosion. Trilobites Brachiopods Mollusks, Other complex organisms with hard shells.  Paleozoic Era ORDOVICIAN PERIOD (485.4 to 443.8 million years ago) evolution of diverse marine invertebrates. The first vertebrates, jawless fish appeared. Ended with the Ordovician- Silurian Extinction  Paleozoic Era SILURIAN PERIOD (443.8 to 419.2 million years ago) colonization of land by early vascular plants First arachnids and centipedes appeared.  Paleozoic Era DEVONIAN PERIOD (419.2 to 358.9 million years ago) Called the "Age of Fish" due to the diversification of jawed fish. The first amphibians evolved. The first trees, emerged. Ended with the Late Devonian Extinction  Paleozoic Era CARBONIFEROUS PERIOD (358.9 to 298.9 million years ago) Amphibians were diverse, and the first reptiles appeared. Insects became more abundant and diverse.  Paleozoic Era PERMIAN PERIOD (298.9 to 252 million years ago) evolution of reptiles, including early synapsids. ended with the Permian- Triassic extinction event which is the largest extinction in Earth’s history.  Mesozoic Era TRIASSIC PERIOD (252 to 201.3 million years ago) Early dinosaurs First mammals Archosaurs Ichthyosaurs Plesiosaurs Ended with the Triassic- Jurassic Extinction  Mesozoic Era JURASSIC PERIOD (201.3 to 145 million years ago) known for the dominance of dinosaurs. The first birds evolved. Pangaea began to break apart, leading to the formation of separate landmasses.  Mesozoic Era CRETACEOUS PERIOD (145 to 66 million years ago) continued diversification of dinosaurs Flowering plants became widespread First true snakes appeared. ended with Cretaceous- Paleogene mass extinction event,  Cenozoic Era PALEOGENE PERIOD (66 to 23 million years ago) Adaptive radiation and diversification of Mammals Early primates appeared setting the stage for the evolution of monkeys and apes.  Cenozoic Era NEOGENE PERIOD (23 to 2.58 million years ago) Evolution of hominids (ancestors of humans). Evolution of grazing mammals like horses and elephants.  Cenozoic Era QUATERNARY PERIOD (2.58 million years ago to the present) Homo sapiens, modern humans, evolved and became the dominant species on Earth. continents continued to move and drift, affecting global climate and influencing the distribution of species  THEORIES ABOUT THE ORIGIN OF LIFE ABIOGENESIS RNA WORLD HYPOTHESIS PANSPERMIA also known as "chemical suggests that self- proposes that life, or evolution" proposes replicating RNA molecules at least the building that life emerged from played a crucial role in the blocks of life, may non-living matter early stages of life. have originated through a series of outside of Earth. chemical reactions. MECHANISMS and EVIDENCE OF EVOLUTION Evolutionary History of Different Organismal Groups  PLANT CHARACTERISTICS Multicellular Photosynthetic Exhibit a wide eukaryotes with autotrophs, range of forms, cell walls producing from small containing energy through mosses to large cellulose. photosynthesis. trees.  PLANT DIVERSITY MOSSES GYMNOSPERM FERNS ANGIOSPERM Plant Diversity MOSSES Typically small, non-vascular plants with simple structures. Often found in moist environments, forming dense carpets in shady areas. Reproduce via spores, lacking seeds and flowers. Plant Diversity FERNS Characterized by often large, feathery leaves. Possess vascular tissue (xylem and phloem) for efficient nutrient and water transport. Reproduction via Spores  Plant Diversity GYMNOSPERMS Seeds are not enclosed within fruits but are exposed on the surface of cone scales. Conifers, a common group of gymnosperms, include pines, spruces, and firs. Well-adapted to cold and dry environments.  Plant Diversity ANGIOSPERMS Produce flowers for sexual reproduction, leading to the formation of seeds within fruits Efficient seed dispersal mechanisms, including wind, animals, and water.  ANIMAL CHARACTERISTICS Multicellular Heterotrophic, Diverse in eukaryotes obtaining energy terms of lacking cell by consuming structure, walls. other organisms. behavior, and habitat.  9 MAJOR PHYLA OF THE ANIMAL KINGDOM PORIFERA CNIDARIA PLATYHILMENTHIS NEMATODA ANNELIDA ARTHROPODA MOLLUSCA ECHINODERAMATA CHORDATA ANIMAL DIVERSITY: INVERTEBRATES ANIMAL DIVERSITY: VERTEBRATES MICROORGANISM CHARACTERISTICS Unicellular or simple multicellular organisms. BACTERIA FUNGI VIRUS ARCHEA PROTISTS  Microorganism Diversity BACTERIA and ARCHEA Prokaryotic cells, often found in diverse environments. Play crucial roles in nutrient cycling, nitrogen fixation, and symbiotic relationships. Microorganism Diversity FUNGI Eukaryotic, often multicellular organisms. Important decomposers, forming symbiotic relationships with plants (mycorrhizae). Microorganism Diversity PROTISTS Eukaryotic, mostly unicellular organisms. Include diverse groups such as algae and protozoa. Microorganism Diversity VIRUS Non-living entities composed of genetic material enclosed in a protein coat. Depend on host cells for reproduction. MECHANISMS OF EVOLUTIONARY CHANGE The mechanisms of evolutionary change are the driving forces behind the incredible diversity of life on Earth. They dictate how species emerge, adapt, and interact within their environments. Mechanism of Evolution 1. NATURAL SELECTION (Survival of the Fittest) A key mechanism of evolution proposed by Charles Darwin. It is the process by which heritable traits that increase an organism's fitness for survival and reproduction become more prevalent in a population over successive generations. Mechanism of Evolution 1. NATURAL SELECTION GIRAFFE NECK LENGTH Variation in neck length among giraffes. Natural selection favored longer necks, allowing giraffes to reach higher foliage for food, increasing their fitness. Mechanism of Evolution 1. NATURAL SELECTION PEPPERED MOTHS Dark-colored moths became more prevalent during the Industrial Revolution due to better camouflage against soot- covered trees. Mechanism of Evolution 2. ARTIFICIAL SELECTION Also known as selective breeding, is a process in which humans intentionally select and breed individuals with desired traits to perpetuate those traits in successive generations. Mechanism of Evolution 2. ARTIFICIAL SELECTION DOG BREEDS Humans selectively breed dogs with specific traits such as size, coat color, and behavior. Mechanism of Evolution 3. GENETIC DRIFT Refers to the random fluctuations in the frequency of alleles within a population over generations due to chance events. Mechanism of Evolution 3. GENETIC DRIFT FOUNDER EFFECT A small group of individuals establishes a new population in a different geographical area. Mechanism of Evolution 3. GENETIC DRIFT BOTTLENECK EVENTS A significant reduction in population size due to a catastrophic event (e.g., natural disaster, disease outbreak). Mechanism of Evolution 4. MUTATION Refers to a heritable change in the DNA sequence of an organism. Mutations can occur spontaneously during DNA replication or be induced by external factors such as radiation or chemicals. Mechanism of Evolution 4. MUTATION ANTIBIOTIC RESISTANCE Mutations in bacterial genes leading to resistance against antibiotics. Mutated bacteria have a selective advantage in the presence of antibiotics, leading to the survival and proliferation of resistant strains. EVIDENCE OF EVOLUTIONARY RELATIONSHIPS  Evolutionary Relationships refer to the patterns of relatedness and ancestry among different species, as inferred from their shared evolutionary history.  EVIDENCE OF EVOLUTIONARY RELATIONSHIPS MOLECULAR MORPHOLOGICAL FOSSIL MOLECULAR DATA refers to information obtained from studying molecules within organisms, primarily DNA, RNA, and proteins. provides direct evidence of the genetic relationships among organisms, offering insights into their evolutionary history. PROTEIN SEQUENCES serve as evidence of evolutionary relationships by reflecting the genetic changes accumulated over time due to evolutionary processes such as mutation and natural selection.  HOMOLOGOUS STRUCTURES anatomical features that share a common evolutionary origin, indicating they are derived from a common ancestor.  ANALOGOUS STRUCTURES anatomical features that have similar functions or purposes but do not share a common evolutionary origin. FOSSILS the preserved remains or traces of organisms from past geologic ages, providing direct evidence of ancient life forms. can be used to reconstruct evolutionary relationships by comparing the morphological features of extinct species with living organisms. DEVELOPMENTAL CHARACTERISTICS USED IN TAXONOMY Developmental characteristics in taxonomy refer to observable traits and processes related to the growth, and life cycle of organisms that are used to categorize them into taxonomic groups.  Developmental characteristics used in Taxonomy EMBRYONIC DEVELOPMENT During vertebrate development, all embryos exactly look the same during the very early stages of development. This is an evidence of shared evolutionary history of vertebrates. All belong to Phylum Chordata.  Developmental characteristics used in Taxonomy METAMORPHOSIS / LIFE CYCLE Despite differences in adult appearance and behavior, both butterflies and moths exhibit similar metamorphic changes and life cycle. Both are within Order Lepidoptera. PREDICTING GENOTYPES and PHENOTYPES  Homozygous vs. Heterozygous Homozygous= two alleles that are the same for a trait (Pure) Heterozygous = two different alleles for a trait (Hybrid) PP Pp pp Homozygous Heterozygous Homozygous Dominant Recessive PP Pp pp  Punnett Square A Punnett Square is a tool developed by Reginald Punnett. He used it to predict the number and variety of genetic combinations passed from generation to generation. Reginald Punnett  Punnett Squares: Using letters to represent alleles We use two letters to represent the genotype. A capital letter represents the dominant form of a gene. A lowercase letter is the abbreviation for the recessive form of the gene. Example: V = dominant violet v = recessive white  Using letters to represent alleles The phenotype for this The phenotype for this flower is white. flower is violet. While its genotype is vv. What are the possible genotype? To be white, the flower must have two recessive VV (homozygous) copies of the allele. Vv (heterozygous). Next, put the genotype of one parent across the top and the other along the left side. For this example, let’s consider a genotype of VV crossed with vv. V V v Notice only one letter goes above each box It does not matter which parent’s genotype goes on either side. v Next, fill in the boxes by copying the column and row head- letters down and across into the empty spaces. Write the capital letter first. What are the Genotypes V V of the offspring? -All Vv v Vv Vv What are the Phenotypes v Vv Vv of the offspring? -All Violet Sample Problem: Parent 1 is a homozygous for a trait and parent 2 is heterozygous for the same trait. What are the Genotypes V V of the offspring? -VV and Vv V VV VV What are the Phenotypes v Vv Vv of the offspring? -All Violet  Genotypic Ratio Phenotypic Ratio The ratio of different genotypes in the The ratio of different phenotypes in the offspring. offspring. 2:2 or 1:1 4:0 or 1:0 Genotypic Probability Phenotypic Probability The likelihood of a specific genotype The likelihood of a specific phenotype occurring in the offspring, expressed as a appearing in the offspring, expressed as percentage or fraction. a percentage or fraction. VV: 50% or ½ Violet: 100% or 1/1 Vv: 50% or ½ In a given population, red hair color is dominant over blond. Make a cross between a hybrid for red hair and a blond and identify the genotypic and phenotypic probability of having an offspring with a red hair. R r r Rr rr Genotypic Probability of offspring with Red Hair: 50% or ½ Rr rr r Phenotypic Probability of offspring with Red Hair: 50% or ½ Black eyes are dominant over red eyes in rats. If a heterozygous rat is crossed with rat with red eyes, what is the probability of having a red-eyed offspring? B b What is the probability of a b Bb bb red-eyed offspring? b Bb bb 50% Will there be a possibility for a black-eyed offspring? DIHYBRID CROSS  DIHYBRID CROSS In a rabbit population, Gray fur is a dominant trait while White fur is recessive, and Black eye color is dominant over Red eye color. If a male rabbit that is purely Gray furred and has red eyes is crossed with a rabbit that has white fur and is a hybrid for a black eye color, identify the possible genotypic and phenotypic ratio of the offspring  DIHYBRID CROSS In a rabbit population, Gray fur is a dominant trait while White fur is recessive, and Black eye color is dominant over Red eye color. If a male rabbit that is purely Gray furred and has red eyes is crossed with a rabbit that has white fur and is a hybrid for a black eye color, identify the possible genotypic and phenotypic ratio of the offspring. Step 1: Assign letters to represent the dominant and recessive trait. FUR COLOR EYE COLOR G – Gray B – Black g - White b - Red  DIHYBRID CROSS In a rabbit population, Gray fur is a dominant trait while White fur is recessive, and Black eye color is dominant over Red eye color. If a male rabbit that is purely Gray furred and has red eyes is crossed with a rabbit that has white fur and is a hybrid for a black eye color, identify the possible genotypic and phenotypic ratio of the offspring. Step 2: Determine the possible genotypes and phenotypes. FUR COLOR EYE COLOR GG – Gray BB – Black Gg – Gray Bb – Black gg – White bb - Red  DIHYBRID CROSS In a rabbit population, Gray fur is a dominant trait while White fur is recessive, and Black eye color is dominant over Red eye color. If a male rabbit that is purely Gray furred and has red eyes is crossed with a rabbit that has white fur and is a hybrid for a black eye color, identify the possible genotypic and phenotypic ratio of the offspring. Step 3: Identify possible genotypes of the parents. MALE: FEMALE: Purely gray fur and White fur and red eyes heterozygous black eyes GGbb ggBb  DIHYBRID CROSS Step 4: Do the FOIL method to identify the gene combinations in the parents. Apply the method between alleles of different genes. MALE: FEMALE: Gb gB GGbb Gb gb ggBb Gb gB Gb gb  DIHYBRID CROSS Step 5: Plot the combinations on the Punnet Square Gb Gb Gb Gb Genotypic Ratio: 8 GgBb : 8 Ggbb gB GgBb GgBb GgBb GgBb 1 GgBb : 1 Ggbb gb Ggbb Ggbb Ggbb Ggbb Phenotypic Ratio: gB GgBb GgBb GgBb GgBb 8 Gray Hair, Black Eyes : 8 Gray Hair, Red Eyes gb Ggbb Ggbb Ggbb Ggbb 1 Gray Hair, Black Eyes : 1 Gray Hair, Red Eyes Holiday Genetics 3 Members per Group  SCARF HAT Scarf Present: SS or Ss No Hat: HH or Hh No Scarf: ss Hat Present: hh 2 snowmen who are both a hybrid for having a Scarf and a hybrid for having no Hat are crossed, what is the possible genotypic and phenotypic ratio of the offspring?  Parents: Both Hybrid for Having Scarf but with No Hat Genotype of both: SsHh SSHH – 1 SH Sh sH sh SSHh – 2 SH SSHH SSHh SsHH SsHh SsHH – 2 Sh SSHh SShh SsHh Sshh SShh – 1 sH SsHH SsHh ssHH ssHh SsHh – 4 sh SsHh Sshh ssHh sshh Sshh – 2 ssHH – 1 Genotypic Ratio: 1:2:2:1:4:2:1:2:1 ssHh – 2 ssHh – 1  Parents: Both Hybrid for Having Scarf but with No Hat Genotype of both: SsHh SH Sh sH sh With Scarf ; No Hat 9 SH SSHH SSHh SsHH SsHh With Scarf ; With Hat Sh SSHh SShh SsHh Sshh 3 sH SsHH SsHh ssHH ssHh No Scarf ; With Hat sh SsHh Sshh ssHh sshh 3 Phenotypic Ratio: 9:3:3:1 No Scarf ; No Hat Probability: 56.25% : 18.75% : 18.75% : 6.25% 1 GENETICS and MENDELIAN PATTERN OF INHERITANCE  The Science of Heredity Is your hair curly or straight? What color are your eyes? Do you have a hitchhiker’s thumb or a widow’s peak? These are just some traits or characteristics you inherited from your parents.  GENETICS the scientific study of how traits or characteristics are passed from one generation to another. explores the diversity of traits within populations. BRIEF BACKGROUND OF GREGOR MENDEL Farm Father of Tender Genetics Augustinian Beekeeper Academician Monk 4 Mendel’s Experiments with Pea Plants Mendel chose to study pea plants because: They grow quickly Produce a large amount of offspring in one generation. They have many traits with only two forms.  Mendel’s Experiments He started with purebred plants and cross-pollinated plants with different forms of a trait such as flower color. violet flower pea plant and white flower pea plant  Self-pollination Self-pollinating plants – Have both male and female reproductive parts – Also known as “true breeding” plants or “purebred” Mendel’s Experiments: P Generation P Generation (parents) Mendel crossed a purebred violet flowered pea plant with a purebred white flowered pea plant F1 (First generation) All of the offspring were violet. The white flower color trait seemed to have disappeared. Mendel’s Experiments: F1 & F2 Generations Mendel allowed the F1 generation to self-pollinate The resulting F2 generation (2nd generation) contained both violet and white flowers. One-fourth of the offspring had white flowers.  Mendel’s Experiments: F1 & F2 Generations Mendel got similar results for each cross. One trait was always present in the first generation, and the other trait seemed to disappear. This is known as Mendel’s Law of Dominance.  Mendel’s Law of Dominance Dominant traits: Traits or characteristics that override or mask the other trait. Recessive Traits: The trait or characteristics that are being hidden or prevented from being expressed.  Mendel’s Law of Segregation Because you receive one set of genes from each parent, you have two genes for each trait. Mendel called this the Law of Segregation. Genes for a certain trait such as the color of your eyes are in the same place on each homologous chromosome. Factors that control each trait, known as alleles, exist in pairs.  CHROMOSOME vs GENE vs ALLELE CHROMOSOME A thread-like structure made of DNA and proteins that carries genetic information. GENE A specific segment of DNA on a chromosome that codes for a particular trait or characteristic. ALLELE Different versions of a gene that Parent 1 Parent 2 determine variations of a trait.  Mendel’s Law of Independent Assortment The Law of Independent Assortment states that genes for different traits are sorted separately from one another so that the inheritance of one trait is not dependent on the inheritance of another. – Example: the purple allele for pea plant flower color doesn’t affect whether the plant will pass on a short or tall height gene. ALLELE, GENOTYPE, and PHENOTYPE  Homozygous vs. Heterozygous Homozygous= two alleles that are the same for a trait (Pure) Heterozygous = two different alleles for a trait (Hybrid) BB Bb bb Homozygous Heterozygous Homozygous Sex-Linkage and Recombination  SEX CHROMOSOMES chromosomes involved in determining an organism’s biological sex. Females have two X chromosomes in their cells, while males have one X and one Y.  SEX CHROMOSOMES bears 100 contains 900 protein-coding protein-coding genes genes Ex: SRY Gene for determination of male biological gender Source: National Human Genome Research Institute  RECOMBINATION a process by which pieces of DNA are broken and recombined to produce new combinations of alleles. a process that creates genetic diversity at the level of genes that reflects differences in the DNA sequences of different organisms.  CROSSING OVER The exchange of DNA between paired homologous chromosomes (one from each parent) that occurs during the development of egg and sperm cells (meiosis). What do we call the site of crossing over? Chiasma or Chiasmata  Sex-Linked Traits refers to characteristics or traits that are influenced by genes carried on the sex chromosomes. often referred to as X-linked or Y-linked traits, depending on whether the genes are located on the X or Y chromosome.  Sex-Linked Traits The Science behind the 50/50 Chance of Biological Sex X Y Male Sex Chromosome: XY X XX XY Female Sex Chromosome: XX X XX XY 50% 50%  COLORBLINDNESS Inability to see colors in a normal way. A sex-linked recessive characteristic carried by the X chromosome. TYPES OF COLORBLINDNESS  BASICS OF SEX-LINKED INHERITANCE A mother is a carrier of color XC Y blindness (XCXc), and the father has normal vision (XCY). XC C XX C C XY Determine the probability of having a color-blind son and a carrier daughter. Xc C XX c c XY Colorblindness is an X-linked 50% chance of having a colorblind son. recessive trait. 25% chance of having a colorblind offspring 50% chance of having a carrier daughter.  BASICS OF SEX-LINKED INHERITANCE A woman who has a pure normal Xc Y vision marries a colorblind man. Determine the probability of XC C XX c C XY having a color-blind offspring and carrier daughter. XC C XX c C XY Colorblindness is an X-linked recessive trait. 0% chance of having a colorblind offspring 100% chance of having a carrier daughter.  BASICS OF SEX-LINKED INHERITANCE If a woman who is a carrier for a Xc Y gene that codes for colorblindness marries a XC C XX c C XY colorblind, what is the probability of having a colorblind offspring? Xc c XX c c XY Colorblindness is an X-linked recessive trait. 50% chance of having a colorblind offsrping.  HEMOPHILIA an X-linked recessive disorder. an inherited bleeding disorder in which a person lacks or has low levels of certain “clotting factors” and the blood doesn’t clot properly as a result leading to excessive bleeding. Internal Bleeding due to Hemophilia  BASICS OF SEX-LINKED INHERITANCE A woman who is a carrier of hemophilia is married to a man XH Y without hemophilia. What is the phenotypic ratio of the offspring? XH H X XH H X Y Probability of having a carrier daughter? Xh H X Xh h XY Hemophilia is an X-linked recessive trait. PR: 3 Normal : 1 Hemophiliac 50% probability of a carrier daughter  BASICS OF SEX-LINKED INHERITANCE A purely normal woman is married to a man with hemophilia. What is Xh Y the phenotypic ratio of the offspring? Probability of having a XH H X Xh H X Y daughter with hemophilia? Hemophilia is an X-linked recessive XH H X Xh H X Y trait. 0% probability of a daughter with Hem. 100% chance of having normal offspring.  HYPOPHOSPHATEMIC RICKETS disorder characterized by impaired mineralization of bones due to low levels of phosphate in the blood. This condition leads to soft, weak bones and various skeletal abnormalities. follows an X-linked dominant pattern.  BASICS OF SEX-LINKED INHERITANCE A woman with hypophosphatemic Xr Y rickets marries a normal man. What is the phenotypic ratio of their R r R offspring, and what is the probability XR XX XY of having a daughter with HR if the mother is heterozygous for the condition? Xr r XX r r XY HR is an X-linked Dominant trait. Phenotypic Ratio 2 Normal : 2 With HR 50% chance of having a daughter with Hypophosphatemic Rickets  BASICS OF SEX-LINKED INHERITANCE A purely normal woman has a child XR Y with a man who suffers from Hypophosphatemic Rickets. What is R r r the phenotypic ratio of their Xr XX XY offspring, and what is the probability of having a son with HR? Xr R XX r r XY HR is an X-linked Dominant trait. Phenotypic Ratio 2 Normal : 2 With HR 0% chance of having a son with Hypophosphatemic Rickets  QUIZ ½ sheet of paper 1.A mother is a carrier of color blindness (x-linked recessive), and the father has normal vision. What is the phenotypic probability of having a colorblind son? 2.In a couple, the wife is homozygous for Rett Syndrome - an X-linked dominant trait, and the husband is completely normal. Determine the phenotypic probability of having offspring with Rett Syndrome.  QUIZ ½ sheet of paper ANSWERS 1. A mother is a carrier of color blindness (x-linked recessive), and the father has normal vision. What is the phenotypic probability of having a colorblind son? Mother: XCXc Father: XCY XC Xc XC C XX C C XX c Y XCY XcY Phenotypic probability of having a colorblind son: 50% 2. In a couple, the wife is homozygous for Rett Syndrome - an X-linked dominant trait, and the husband is completely normal. Determine the phenotypic probability of having an offspring with Rett Syndrome Mother: XRXR Father: XrY XR XR Xr R XX r R XX r Y XRY XRY Phenotypic probability of having a normal offspring: 100%