Biol Lab Practical #1 S.G (1).docx

Mechanisms of Evolution lab Natural selection, gene flow, genetic drift Natural Selection: Understand how differential survival and reproduction of individuals cause alleles to become more or less common in a population. Remember, natural selection acts on phenotypes, not genotypes. Gene Flow: Learn...

Mechanisms of Evolution lab Natural selection, gene flow, genetic drift Natural Selection: Understand how differential survival and reproduction of individuals cause alleles to become more or less common in a population. Remember, natural selection acts on phenotypes, not genotypes. Gene Flow: Learn about the transfer of genetic variation from one population to another. Gene flow can introduce new genetic variation into a population, affecting allele frequencies and potentially leading to more similarity between different populations. Genetic Drift: Get to grips with how random changes in allele frequencies can lead to significant evolutionary changes, especially in small populations. Genetic drift can result in the loss of genetic variation over time. Hardy-Weinberg Equilibrium lab Be able to apply the equation to a problem. Know the assumptions of a population in Hardy-Weinberg equilibrium. Understand how sickle cell disease is inherited and why it is an example of heterozygote advantage in some environments Applying the Equation: Be prepared to use the Hardy-Weinberg equation p^2+2pq+q^2=1 to calculate allele and genotype frequencies within a population. Understanding how to manipulate this equation will allow you to assess whether or not a population is in genetic equilibrium. Assumptions of Hardy-Weinberg Equilibrium: Familiarize yourself with the five conditions a population must meet to be in Hardy-Weinberg equilibrium: no mutation, random mating, no gene flow, infinite population size, and no selection. These conditions are idealized and not often met in nature, but they serve as a useful model for studying genetic changes. Sickle Cell Disease and Heterozygote Advantage: Learn how sickle cell disease, a genetic disorder that affects hemoglobin in red blood cells, is inherited. It's an example of heterozygote advantage, where individuals with one sickle cell allele (AS genotype) and one normal allele (AA genotype) are less susceptible to malaria than individuals with two normal alleles. This phenomenon provides a compelling example of how genetic diseases can persist in populations due to the advantages they confer in certain environments. Prokaryotes Characteristics of prokaryotic cells Bacteria cell shapes Bacteria colony morphology: form and margin Cyanobacteria characteristics Cell Structure: Prokaryotic cells are unicellular organisms without a nucleus. Their genetic material is not enclosed in a membrane-bound nucleus but is instead found in a nucleoid. They lack membrane-bound organelles found in eukaryotes, such as mitochondria and the endoplasmic reticulum. Cell Wall Composition: Most prokaryotic cells have a cell wall that maintains cell shape, provides protection, and prevents the cell from bursting in hypotonic environments. The composition of the cell wall differs between archaea and bacteria, with bacteria typically having a peptidoglycan layer. Reproduction: Prokaryotes reproduce asexually through binary fission, a process where the cell duplicates its genetic material and divides into two identical cells. Bacteria Cell Shapes Understanding the various shapes of bacterial cells is crucial for identification and classification: Coccus (plural: cocci): Spherical or oval-shaped bacteria. They can exist as single cells, in pairs (diplococci), chains (streptococci), or clusters (staphylococci). Bacillus (plural: bacilli): Rod-shaped bacteria. Like cocci, they can be found singly, in chains (streptobacilli), or in pairs. Spirillum (plural: spirilla): Spiral-shaped bacteria that are rigid and capable of movement. Spirochete: Similar to spirilla but are more flexible and move by means of axial filaments. Bacteria Colony Morphology When grown on an agar plate, bacteria form colonies that can be distinguished by their form and margin: Form: Refers to the shape of the colony. Common forms include circular, irregular, filamentous, and rhizoid (root-like). Margin: Describes the edge of the colony. Margins can be smooth (entire), wavy (undulate), lobate (lobed), filamentous, or irregular. Cyanobacteria Characteristics Cyanobacteria, also known as blue-green algae, are a group of photosynthetic bacteria with unique features: Photosynthesis: Unlike other bacteria, cyanobacteria perform oxygenic photosynthesis, releasing oxygen as a byproduct. They contain chlorophyll a, similar to plants, and phycobilins, which give them their distinctive blue-green color. Habitats: They are found in a wide range of freshwater, marine, and terrestrial habitats. Some cyanobacteria are known for forming blooms in nutrient-rich waters, which can be harmful to aquatic life and human health. Cell Structure: Cyanobacteria can be unicellular or form colonies. Some species form filaments of cells, known as trichomes, which can be enclosed in a gelatinous sheath. Nitrogen Fixation: Some cyanobacteria have specialized cells called heterocysts, which are dedicated to the fixation of atmospheric nitrogen into ammonia, a process crucial for nutrient cycling in ecosystems. Protists are a diverse group of eukaryotic microorganisms, which don't fit neatly into plant, animal, or fungal kingdoms. They exhibit a wide range of characteristics in terms of locomotion, nutrition, and organization. Here's a simplified overview that might help you grasp the basics about protists, focusing on their common names, supergroups, modes of locomotion, organization, nutrition, and key characteristics. Common Protists Amoebas (Supergroup: Amoebozoa) Locomotion: Pseudopodia (false feet) Organization: Mostly unicellular Nutrition: Heterotrophic (phagocytosis) Important Characteristics: Flexible shape, engulfs food particles. Slime Molds (Supergroup: Amoebozoa) Locomotion: Spore dispersal for reproduction; some move via pseudopodia Organization: Unicellular or multicellular Nutrition: Heterotrophic Important Characteristics: Life cycle includes both single-celled and multicellular forms. Paramecium (Supergroup: Alveolata, Subgroup: Ciliophora) Locomotion: Cilia Organization: Unicellular Nutrition: Heterotrophic (oral groove to ingest bacteria and small protists) Important Characteristics: Complex cells with a "mouth" known as the oral groove Dinoflagellates (Supergroup: Alveolata) Locomotion: Flagella Organization: Mostly unicellular Nutrition: Mixotrophic (both photosynthetic and heterotrophic capabilities) Important Characteristics: Bioluminescence, red tides Diatoms (Supergroup: Stramenopila) Locomotion: Gliding motion, not truly motile Organization: Unicellular Nutrition: Autotrophic (photosynthesis) Important Characteristics: Silica cell walls form unique patterns. Euglena (Supergroup: Excavata) Locomotion: Flagella Organization: Unicellular Nutrition: Mixotrophic; primarily photosynthetic but can absorb nutrients directly Important Characteristics: Eyespot to detect light, chloroplasts derived from green algae. Kelp (Supergroup: Stramenopila, Subgroup: Phaeophyceae) Locomotion: Non-motile Organization: Multicellular Nutrition: Autotrophic (photosynthesis) Important Characteristics: Forms underwater "forests," important habitat for marine life Plasmodium (Supergroup: Alveolata, Subgroup: Apicomplexa) Locomotion: Non-motile (adult stage) Organization: Unicellular Nutrition: Parasitic Important Characteristics: Causes malaria, complex life cycle involving mosquitoes and vertebrates Specimens to ID Archaeplastida Green Algae Slide: Blue and green algae Chlamydomonas: Unicellular, flagellated algae, often found in freshwater Spirogyra: Filamentous, characterized by spiral chloroplasts. Volvox: Colonial green algae, forms spherical colonies that move via coordinated flagella. Red Algae Nemalion: Filamentous, often found in marine environments, exhibits a bushy appearance. Porphyra: Known for thin, leafy fronds, important in marine ecosystems and as a food source (nori). Chromalveolata Brown Algae Laminaria: Known as kelp, large, multicellular seaweeds with a holdfast, stipe, and blade structure. Diatoms Pennate (Bacillariophyceae): Bilaterally symmetrical. Centrate (Centrales): Radially symmetrical, often circular. Dinoflagellates Peridinium: Characterized by two flagella, one encircling the cell; known for bioluminescence and red tides. Ciliates Paramecium: Slipper-shaped, covered with cilia for movement and feeding. Stentor: Trumpet-shaped, can be very large for a single-celled organism, also uses cilia. Apicomplexans Plasmodium: Parasites responsible for malaria, complex life cycle involving Anopheles mosquitoes and vertebrates. Rhizaria Foraminifera Globigerina: Shelled protozoa (test made of calcium carbonate), important in marine sediment. Excavata Euglena: Flagellated, photosynthetic in light, heterotrophic in darkness, characterized by an eyespot. Trypanosoma: Parasitic, flagellated protozoan, causes diseases like sleeping sickness. Amoebozoa Amoeba: Famous for its pseudopodial movement, engulfing food through phagocytosis. Physarum: A type of slime mold, exists as a plasmodium (a single, multinucleate, amoeboid mass). Slime Mold Opisthokonta Opisthokonta is a big category in the tree of life that includes some very different organisms: animals (like humans, fish, and insects), fungi (like mushrooms and yeast), and a group of single-celled organisms called choanoflagellates. What makes all these groups part of the Opisthokonta is that they share a common ancestor, and scientists can see similarities in their DNA and some of their cell structures. A cool thing about choanoflagellates is that they look a lot like the cells you find in sponges, which are some of the simplest animals. This similarity helps scientists understand how simple single-celled organisms might have started to come together to form more complex multicellular ones like animals. So, when you think of Opisthokonta, think of it as a big family that includes everything from mushrooms to humans, showing how diverse life can be even when it comes from the same roots! Top of Form Fungi Phylum Chytridiomycota (Chytrids), no specimens Name: Batrachochytrium dendrobatidis (causes chytridiomycosis in amphibians) Reproduction: Mainly asexually through zoospores; some species have sexual stages. Noted Structures: Zoospores, motile spores with a single flagellum. Important Characteristics: Aquatic fungi; some species are pathogenic to plants and amphibians; only fungal phylum with motile spores. Phylum Zygomycota (Conjugation Fungi) Name: Rhizopus (black bread mold) Reproduction: Asexually by sporangiospores; sexually through the formation of zygospores. Noted Structures: Sporangia, structures that produce spores; zygospores, thick-walled resting spores. Important Characteristics: Mostly molds; found on decaying plant and animal matter; important in soil fertility. Rhizopus mycelium zygospores Asexual Phylum Ascomycota (Sac Fungi) Name: Saccharomyces (yeast), Penicillium Reproduction: Asexually by conidia; sexually through the formation of ascospores within asci (sacs). Noted Structures: Asci (singular: ascus), a sac-like structure where spores are formed. Important Characteristics: Includes yeasts, molds, and morels; responsible for fermentations, antibiotic production (e.g., Penicillin). PEZIZA Penicillium Phylum Basidiomycota (Club Fungi) Name: Agaricus (button mushrooms), Amanita (fly agaric) Reproduction: Asexually by conidia (rare); sexually through the formation of basidiospores on basidia. Noted Structures: Basidia, club-shaped structures on the gills of mushrooms where spores are produced. Important Characteristics: Includes mushrooms, toadstools, puffballs, and shelf fungi; some species are edible while others are highly toxic. Coprinus gill Structure Lichens: Mutualistic Relationship and Body Forms Phylum: Not applicable (Lichens are a symbiotic association of organisms from multiple kingdoms, primarily fungi (from Ascomycota or Basidiomycota), algae (green algae), and/or cyanobacteria). Name: Not specified (Lichens are named as a single entity, even though they are composed of multiple organisms). Reproduction: Lichens reproduce asexually through the dispersion of soredia or isidia, structures that contain both fungal and algal components. Some lichens also reproduce sexually through the fungal partner, producing spores that must then re-establish the symbiotic relationship with an algal or cyanobacterial partner. Important Characteristics: Mutualistic Relationship: The fungus provides structure, protection, and moisture for the algae or cyanobacteria, which in turn provide carbohydrates and other nutrients through photosynthesis. Environmental Indicators: Lichens are sensitive to air pollution, making them valuable bioindicators of environmental quality. Habitat: Capable of colonizing harsh environments, contributing to ecosystem biodiversity and stability. Ecological Role: Initiate soil formation, contribute to the nitrogen cycle, and provide habitat and food for various organisms. ID: Three Body Forms: Crustose (Crusty Lichens): Form thin crusts that are tightly adhered to the substrate (e.g., rocks, tree bark). They cannot be removed without damaging the substrate. Foliose (Leafy Lichens): Have a leaf-like structure that is somewhat loosely attached to the substrate, often with a distinguishable upper and lower surface. Fruticose (Branched Lichens): Possess a more three-dimensional, often branched structure, and can hang down or rise up from the substrate, resembling small shrubs. 5. Phylum: Glomeromycota General/Unique Characteristics: Form symbiotic relationships with plants through arbuscular mycorrhizae. Reproduction: Mainly asexual through large multinucleate spores. Noted Structures: Arbuscules within plant root cells, where nutrient exchange occurs. Important Characteristics: Essential for plant nutrient uptake, particularly phosphorus, enhancing plant growth and health. Important Fungal Characteristics Fungi are heterotrophic, obtaining nutrients by absorbing dissolved organic material. They have cell walls made of chitin, unlike plants, which have cellulose walls. Fungi play key roles in nutrient cycling, ecological interactions, and human industry. Which group of organisms are most closely related to land plants? The group of organisms most closely related to land plants (Embryophytes) is the Charophytes, a group of green algae. Charophytes and land plants share several distinctive traits, such as similar chlorophyll pigments, cell wall formations during cell division, and certain molecular and genetic sequences, indicating a close evolutionary relationship. This suggests that land plants likely evolved from a charophyte ancestor that lived in freshwater habitats. Which group of organisms are most closely related to animals? The group of organisms most closely related to animals are the Choanoflagellates, a group of free-living unicellular and colonial flagellate eukaryotes. Choanoflagellates and animals share a common ancestor, and the choanoflagellates' morphology is remarkably similar to that of the collar cells (choanocytes) found in sponges, which are among the simplest animals. Molecular evidence also supports their close relationship. Which groups of organisms make monophyletic groups? Which make paraphyletic groups? Monophyletic groups (clades) consist of an ancestor and all its descendants, representing a single "branch" on the tree of life. Examples include: Birds (Aves): All birds share a common ancestor that was itself a bird, making them a monophyletic group. Mammals: All mammals, from monotremes to placentals, share a common ancestor that was itself a mammal. Paraphyletic groups include an ancestral species and some, but not all, of its descendants. These groups are often identified by shared primitive traits rather than a unique common ancestor with a distinct set of traits. Examples include: Reptiles: Traditionally, reptiles exclude birds, even though birds evolved from a reptilian ancestor. Therefore, "reptiles" as traditionally defined are a paraphyletic group because they don't include all descendants of their most recent common ancestor. Protists: The term "protists" encompasses a diverse group of mostly unicellular organisms that are not animals, plants, or fungi. Because this group is defined more by what its members are not rather than by shared derived characteristics, protists are considered a paraphyletic group. Top of Form