This document discusses the history of ideas about the origin of life. It describes how Aristotle proposed the theory of spontaneous generation, which held that living things could arise from nonliving matter. This idea lasted about 2000 years until experiments disproved it. The document outlines examples used to support spontaneous generation and describes Francesco Redi's experiments in 1668, which used sealed and unsealed flasks containing meat. Redi found that maggots only developed in unsealed flasks, disproving the idea for larger organisms. The scientific method is also defined and it is explained how Redi's experiments followed this process to test and disprove the hypothesis of spontaneous generation.
This study aimed to identify pinworm species infecting a colony of Syrian hamsters and determine if transmission could occur to immunodeficient mice. The pinworm was identified as Syphacia mesocriceti based on morphology and 28S rDNA sequencing, though dimensions were slightly larger than reported. Weekly transfers of infected hamster bedding to sentinel hamsters and mice showed no transmission to mice by tape tests or PCR over 5 weeks, suggesting S. mesocriceti is host-specific.
The document provides information about laboratory mice and rats. It describes their key physical characteristics including small size and high fecundity for mice and larger size for rats. It also outlines their taxonomy, common uses in research, physiological norms and development stages, breeding cycles, housing and identification. Common diseases and euthanasia methods are also mentioned.
Laboratory animal cage washing has traditionally employed very hot rinse or wash water to assure the destruction of microbial agents which can cause disease in laboratory animals. This study shows an alternative that may conserve substantial amounts of energy and still provide suitable results.
This document outlines various branches of biology, including agronomy which is the study of crops and soils; anatomy which is the study of living structures; and ecology which is the study of organism interactions within environments. Other branches mentioned are bacteriology, biochemistry, biogeography, botany, cytology, embryology, entomology, ethology, genetics, horticulture, ichthyology, microbiology, oceanography, paleontology, physiology, taxonomy, virology, and zoology.
- In 1665, Robert Hooke discovered cells in cork and coined the term "cell" from the Latin word "cellula" meaning small compartment. He published his findings in Micrographia.
- In 1674, Anton van Leeuwenhoek observed red blood cells, sperm, bacteria and single-celled organisms using his improved microscope.
- In 1839, Theodor Schwann and Matthias Schleiden established the cell theory - that all living things are composed of cells, all cells come from preexisting cells, and the cell is the basic unit of structure and function in living things.
The document describes the main parts and functions of a compound microscope. It details the mechanical, illuminating, and magnifying parts. The mechanical parts include the base, pillar, and stage, and are used to support and adjust the microscope. The illuminating parts provide light, and include the mirror, lamp, and condenser. The magnifying parts magnify the specimen and include the objectives and ocular lenses. It provides instructions on using a compound microscope, including focusing, adjusting the diaphragm and objectives, and carrying the microscope properly. Mounting specimens on slides and staining are also summarized.
This document discusses the history of ideas about the origin of life. It describes how Aristotle proposed the theory of spontaneous generation, which held that living things could arise from nonliving matter. This idea lasted about 2000 years until experiments disproved it. The document outlines examples used to support spontaneous generation and describes Francesco Redi's experiments in 1668, which used sealed and unsealed flasks containing meat. Redi found that maggots only developed in unsealed flasks, disproving the idea for larger organisms. The scientific method is also defined and it is explained how Redi's experiments followed this process to test and disprove the hypothesis of spontaneous generation.
This study aimed to identify pinworm species infecting a colony of Syrian hamsters and determine if transmission could occur to immunodeficient mice. The pinworm was identified as Syphacia mesocriceti based on morphology and 28S rDNA sequencing, though dimensions were slightly larger than reported. Weekly transfers of infected hamster bedding to sentinel hamsters and mice showed no transmission to mice by tape tests or PCR over 5 weeks, suggesting S. mesocriceti is host-specific.
The document provides information about laboratory mice and rats. It describes their key physical characteristics including small size and high fecundity for mice and larger size for rats. It also outlines their taxonomy, common uses in research, physiological norms and development stages, breeding cycles, housing and identification. Common diseases and euthanasia methods are also mentioned.
Laboratory animal cage washing has traditionally employed very hot rinse or wash water to assure the destruction of microbial agents which can cause disease in laboratory animals. This study shows an alternative that may conserve substantial amounts of energy and still provide suitable results.
This document outlines various branches of biology, including agronomy which is the study of crops and soils; anatomy which is the study of living structures; and ecology which is the study of organism interactions within environments. Other branches mentioned are bacteriology, biochemistry, biogeography, botany, cytology, embryology, entomology, ethology, genetics, horticulture, ichthyology, microbiology, oceanography, paleontology, physiology, taxonomy, virology, and zoology.
- In 1665, Robert Hooke discovered cells in cork and coined the term "cell" from the Latin word "cellula" meaning small compartment. He published his findings in Micrographia.
- In 1674, Anton van Leeuwenhoek observed red blood cells, sperm, bacteria and single-celled organisms using his improved microscope.
- In 1839, Theodor Schwann and Matthias Schleiden established the cell theory - that all living things are composed of cells, all cells come from preexisting cells, and the cell is the basic unit of structure and function in living things.
The document describes the main parts and functions of a compound microscope. It details the mechanical, illuminating, and magnifying parts. The mechanical parts include the base, pillar, and stage, and are used to support and adjust the microscope. The illuminating parts provide light, and include the mirror, lamp, and condenser. The magnifying parts magnify the specimen and include the objectives and ocular lenses. It provides instructions on using a compound microscope, including focusing, adjusting the diaphragm and objectives, and carrying the microscope properly. Mounting specimens on slides and staining are also summarized.
The document traces the history and development of the microscope from 1000AD to present day. Some of the key developments include the first magnifying lenses in the 13th century, compound microscopes in the 16th century, Hooke's discovery of cells in 1665 using basic microscopes, and Leeuwenhoek's description of bacteria in 1674. Major innovations continued with improvements to lens quality and the invention of things like the electron microscope, phase-contrast microscope, and scanning tunneling microscope, allowing visualization of ever smaller objects down to the atomic level. Many pioneers in microscope technology, such as Abbe, Ruska, and Binnig, received Nobel Prizes for their contributions.
Fungi are eukaryotic, nonphotosynthetic organisms that absorb nutrients from dead or living organic matter. They grow as microscopic filaments called hyphae and produce both sexual and asexual spores. Fungi play important roles in decomposition as saprobes and form mutually beneficial relationships with plants through mycorrhizal associations and with algae or cyanobacteria as lichens. They include mushrooms, molds, yeasts, rusts, and smuts and have cell walls made of chitin.
1. The document describes the structures and functions of plant and animal cells. It details organelles common to both like the nucleus, cytoplasm, mitochondria, and cell membrane.
2. Structures unique to plant cells are described like chloroplasts, which perform photosynthesis, and vacuoles for storage. The cell wall provides support and protection.
3. Animal cell specific structures include centrioles and lysosomes, which function in cell reproduction and waste disposal, respectively.
This document summarizes characteristics of animal-like protists. It describes that they are single-celled microscopic organisms that move using cilia, flagella, pseudopodia, or are sessile. They can be free-living, commensal, parasitic, or mutualistic. Locomotion methods include cilia, flagella, pseudopodia projections, or being sessile without movement. Nutrition is heterotrophic or parasitic and reproduction can be asexual through binary fission or budding, or sexual through conjugation. Examples mentioned include Amoeba, Arcella, Trypanosoma, Paramecium, Vorticella, and Stentor.
Protists are a diverse group of eukaryotic organisms that can be unicellular or multicellular, and include photosynthetic and heterotrophic species. They include algae, which are photosynthetic protists that can be single-celled or colonial, and diatoms and dinoflagellates, which are important marine algae with distinctive cell coverings or structures. Reproduction in algae can occur sexually through meiosis or asexually through cell division or fragmentation.
This document discusses different types of ecological relationships between organisms including competition, herbivory, predation, and symbiosis. It provides examples for each relationship type. Competition occurs when organisms fight for limited resources. Herbivory is when a primary consumer feeds on a producer. Predation is when a consumer feeds on another consumer in the food chain. Symbiosis describes long-term relationships where organisms live closely together and at least one benefits, including mutualism where both benefit, commensalism where one benefits and the other is unaffected, and parasitism where one benefits and the other is harmed.
This document provides information about bacteria, including that there are three kingdoms of bacteria - Archaea, Eubacteria, and Cyanobacteria. It discusses the characteristics of bacteria such as their cell structure, ability to be autotrophs or heterotrophs, and ability to reproduce through binary fission or conjugation. The document also outlines some examples of useful bacteria that produce antibiotics, vitamins, or aid in food production, as well as harmful bacteria that can cause disease.
1) For over 2000 years, the theory of spontaneous generation proposed that living organisms could arise from non-living matter.
2) In the 1600s, experiments by Redi and Needham were influential but did not conclusively disprove spontaneous generation.
3) Later experiments by Spallanzani and especially Pasteur provided stronger evidence against spontaneous generation by demonstrating that microbes arise only from existing microbes or parent cells, not from non-living matter. This established the theory of biogenesis.
Redi, Needham, Spallanzani, and Pasteur all conducted experiments to test the theory of spontaneous generation. Redi showed that flies only emerged from meat when it was exposed to adult flies, supporting biogenesis. Needham's experiments seemed to support spontaneous generation, but he did not eliminate microbes. Spallanzani boiled broth for an hour, killing microbes and preventing growth. Pasteur used S-shaped flasks to prove microbes only arose from other microbes, not inorganic matter, definitively disproving spontaneous generation.
It is necessary for students to understand the history of cell theory development for several reasons. Learning about the early scientists who discovered cells and contributed ideas that led to the modern cell theory provides context for why we accept cells as the fundamental unit of life. Understanding the process of how the cell theory was developed and built upon over time shows how scientific knowledge advances through experiments, observations, and collaboration between scientists. Tracing the key experiments that helped reject ideas like spontaneous generation helps students appreciate how scientific understanding progresses. A brief overview of the history helps students grasp the full significance and universal acceptance of the modern cell theory in biology.
I'm Sorry this pptx presentation is not good enough but i use this as my report in our subjetct Earth and Life Science and the teacher is Happy :) Enjoy
Presentation on history of microbiology.siam (ppt file)Kamruzzaman Siam
This document provides an overview of the history of microbiology. It discusses early observations of cells by Robert Hooke and microbes by Anton van Leeuwenhoek in the 17th century. It also outlines the development of the cell theory and experiments refuting the theory of spontaneous generation, establishing that life arises only from pre-existing life through the work of scientists like Francesco Redi, Lazzaro Spallanzani, and Louis Pasteur in the 18th-19th centuries. The document also summarizes Pasteur's contributions to germ theory and microbiology through his studies of fermentation, pasteurization, and diseases.
This document discusses the spontaneous generation theory and biogenesis theory of microbial origins. It describes how early scientists like Francesco Redi, Lazzaro Spallanzani, and Louis Pasteur experimentally disproved the theory of spontaneous generation through controlled experiments. Redi showed that flies, not decaying meat, produced maggots. Spallanzani demonstrated that boiling broth killed microbes and they came from air, not from non-living matter. Pasteur's experiments with flasks proved microbes arose from pre-existing cells, supporting biogenesis over spontaneous generation. Through scientific investigation, these scientists established that life arises from pre-existing life, not non-living matter.
- The spontaneous generation/abiogenesis theory stated that living organisms could arise from non-living matter, without the need for parents. This was widely believed for over 2000 years.
- In 1665, Francesco Redi disproved this theory at the macroscopic level by showing that flies did not spontaneously generate from decaying meat when protected from eggs. Later experiments by Spallanzani and Pasteur provided further evidence against spontaneous generation.
- Through a series of experiments using flasks with S-shaped openings, Pasteur definitively disproved spontaneous generation by showing that microbes came from ambient dust particles, not non-living matter, establishing the theory of biogenesis. This resolved the long-standing
This document provides a summary of the history of microbiology, from the ancient belief in spontaneous generation to the modern acceptance of the germ theory of disease. It describes key experiments and findings, including:
- Redi's experiments disproving spontaneous generation by showing flies lay eggs on meat.
- Van Leeuwenhoek discovering "animalcules" like bacteria and protozoa using microscopes.
- Pasteur's experiments definitively disproving spontaneous generation and supporting germ theory through controlled experiments with broth in flasks.
- Koch's work isolating anthrax bacteria and formulating his postulates linking specific bacteria to specific diseases.
- Semmelweis, Holmes, and Snow
1. Biologists use the scientific method to systematically study problems through observation, hypothesis formation, experimentation, and conclusion drawing.
2. In the 1600s, scientists like Redi and van Leeuwenhoek used controlled experiments to disprove the theory of spontaneous generation and show that living things arise from other living things, not from non-living material.
3. In the 1700s, Spallanzani's experiments further supported biogenesis over spontaneous generation, though his methods were criticized. Pasteur later designed elegant experiments using swan neck flasks that definitively showed microbes arise from existing microbes, not spontaneously from non-living sources.
This document provides a history of biotechnology including key definitions and timelines. It discusses how biotechnology has been used for thousands of years to produce improved food and healthcare. Some highlights include:
- The term "biotechnology" was coined in 1919 to refer to using living organisms to modify human health and environment.
- Biotechnology has advanced significantly since the 1800s with gains in understanding genetics and DNA research.
- Traditional applications include using yeast to make beer and discovering how to make leavened bread using yeast.
- Modern biotechnology now enables developing improved products more safely and rapidly.
The Special Creation Theory holds that God created the universe and all life directly, as described in the book of Genesis. It was widely accepted before the scientific era began challenging it with theories like evolution. While science developed alternative origin of life theories, some religious groups strongly defended creationism based on the Bible. Over time, compromises were made, like the idea that God used evolution as his method, but the debate between science and religion on this issue continues today.
Unit 1.1.a. principle of genetics defintion and history- early concepts of i...Simranjit Singh
This document provides an overview of the early concepts of inheritance in genetics. It discusses key figures like Gregor Mendel who performed experiments on pea plants in the 1860s and deduced Mendel's laws of heredity. It also discusses earlier concepts including Aristotle's views on spontaneous generation and the experiments of Francesco Redi in the late 1600s which challenged this idea. The document also outlines the contributions of Antony van Leeuwenhoek who discovered microorganisms in the 1600-1700s and Louis Pasteur's experiments in the 1800s which provided strong evidence against spontaneous generation.
Microbiology: History perspective - Simran Sonule.pptxSimranSonule
This presentation describe the discovery of microbial world.
Theory of Abiogenesis and Biogenesis and
Contribution of scientist in the field of Microbiology
Nematodes are one of the most abundant metazoans on Earth, with over 25,000 known species. They occupy nearly every habitat and play important roles as free-living organisms, plant parasites, and parasites of humans and other animals. Nematodes have been used extensively as model organisms in fields like genetics and developmental biology due to traits like small size, short lifecycles, and fully sequenced genomes. Major nematode parasites of humans include roundworms, pinworms, hookworms, filarial worms, and guinea worms, which collectively infect over a billion people globally.
Scientists debated whether living things could arise from nonliving things (spontaneous generation) or only from other living things (biogenesis). Through controlled experiments over centuries, evidence increasingly supported biogenesis. Redi showed maggots came from fly eggs, not meat. Spallanzani found boiling sealed containers prevented microbe growth, supporting biogenesis. Pasteur's famous experiment using a swan-necked flask conclusively demonstrated that microbes only entered once the air could, disproving spontaneous generation.
The document traces the history and development of the microscope from 1000AD to present day. Some of the key developments include the first magnifying lenses in the 13th century, compound microscopes in the 16th century, Hooke's discovery of cells in 1665 using basic microscopes, and Leeuwenhoek's description of bacteria in 1674. Major innovations continued with improvements to lens quality and the invention of things like the electron microscope, phase-contrast microscope, and scanning tunneling microscope, allowing visualization of ever smaller objects down to the atomic level. Many pioneers in microscope technology, such as Abbe, Ruska, and Binnig, received Nobel Prizes for their contributions.
Fungi are eukaryotic, nonphotosynthetic organisms that absorb nutrients from dead or living organic matter. They grow as microscopic filaments called hyphae and produce both sexual and asexual spores. Fungi play important roles in decomposition as saprobes and form mutually beneficial relationships with plants through mycorrhizal associations and with algae or cyanobacteria as lichens. They include mushrooms, molds, yeasts, rusts, and smuts and have cell walls made of chitin.
1. The document describes the structures and functions of plant and animal cells. It details organelles common to both like the nucleus, cytoplasm, mitochondria, and cell membrane.
2. Structures unique to plant cells are described like chloroplasts, which perform photosynthesis, and vacuoles for storage. The cell wall provides support and protection.
3. Animal cell specific structures include centrioles and lysosomes, which function in cell reproduction and waste disposal, respectively.
This document summarizes characteristics of animal-like protists. It describes that they are single-celled microscopic organisms that move using cilia, flagella, pseudopodia, or are sessile. They can be free-living, commensal, parasitic, or mutualistic. Locomotion methods include cilia, flagella, pseudopodia projections, or being sessile without movement. Nutrition is heterotrophic or parasitic and reproduction can be asexual through binary fission or budding, or sexual through conjugation. Examples mentioned include Amoeba, Arcella, Trypanosoma, Paramecium, Vorticella, and Stentor.
Protists are a diverse group of eukaryotic organisms that can be unicellular or multicellular, and include photosynthetic and heterotrophic species. They include algae, which are photosynthetic protists that can be single-celled or colonial, and diatoms and dinoflagellates, which are important marine algae with distinctive cell coverings or structures. Reproduction in algae can occur sexually through meiosis or asexually through cell division or fragmentation.
This document discusses different types of ecological relationships between organisms including competition, herbivory, predation, and symbiosis. It provides examples for each relationship type. Competition occurs when organisms fight for limited resources. Herbivory is when a primary consumer feeds on a producer. Predation is when a consumer feeds on another consumer in the food chain. Symbiosis describes long-term relationships where organisms live closely together and at least one benefits, including mutualism where both benefit, commensalism where one benefits and the other is unaffected, and parasitism where one benefits and the other is harmed.
This document provides information about bacteria, including that there are three kingdoms of bacteria - Archaea, Eubacteria, and Cyanobacteria. It discusses the characteristics of bacteria such as their cell structure, ability to be autotrophs or heterotrophs, and ability to reproduce through binary fission or conjugation. The document also outlines some examples of useful bacteria that produce antibiotics, vitamins, or aid in food production, as well as harmful bacteria that can cause disease.
1) For over 2000 years, the theory of spontaneous generation proposed that living organisms could arise from non-living matter.
2) In the 1600s, experiments by Redi and Needham were influential but did not conclusively disprove spontaneous generation.
3) Later experiments by Spallanzani and especially Pasteur provided stronger evidence against spontaneous generation by demonstrating that microbes arise only from existing microbes or parent cells, not from non-living matter. This established the theory of biogenesis.
Redi, Needham, Spallanzani, and Pasteur all conducted experiments to test the theory of spontaneous generation. Redi showed that flies only emerged from meat when it was exposed to adult flies, supporting biogenesis. Needham's experiments seemed to support spontaneous generation, but he did not eliminate microbes. Spallanzani boiled broth for an hour, killing microbes and preventing growth. Pasteur used S-shaped flasks to prove microbes only arose from other microbes, not inorganic matter, definitively disproving spontaneous generation.
It is necessary for students to understand the history of cell theory development for several reasons. Learning about the early scientists who discovered cells and contributed ideas that led to the modern cell theory provides context for why we accept cells as the fundamental unit of life. Understanding the process of how the cell theory was developed and built upon over time shows how scientific knowledge advances through experiments, observations, and collaboration between scientists. Tracing the key experiments that helped reject ideas like spontaneous generation helps students appreciate how scientific understanding progresses. A brief overview of the history helps students grasp the full significance and universal acceptance of the modern cell theory in biology.
I'm Sorry this pptx presentation is not good enough but i use this as my report in our subjetct Earth and Life Science and the teacher is Happy :) Enjoy
Presentation on history of microbiology.siam (ppt file)Kamruzzaman Siam
This document provides an overview of the history of microbiology. It discusses early observations of cells by Robert Hooke and microbes by Anton van Leeuwenhoek in the 17th century. It also outlines the development of the cell theory and experiments refuting the theory of spontaneous generation, establishing that life arises only from pre-existing life through the work of scientists like Francesco Redi, Lazzaro Spallanzani, and Louis Pasteur in the 18th-19th centuries. The document also summarizes Pasteur's contributions to germ theory and microbiology through his studies of fermentation, pasteurization, and diseases.
This document discusses the spontaneous generation theory and biogenesis theory of microbial origins. It describes how early scientists like Francesco Redi, Lazzaro Spallanzani, and Louis Pasteur experimentally disproved the theory of spontaneous generation through controlled experiments. Redi showed that flies, not decaying meat, produced maggots. Spallanzani demonstrated that boiling broth killed microbes and they came from air, not from non-living matter. Pasteur's experiments with flasks proved microbes arose from pre-existing cells, supporting biogenesis over spontaneous generation. Through scientific investigation, these scientists established that life arises from pre-existing life, not non-living matter.
- The spontaneous generation/abiogenesis theory stated that living organisms could arise from non-living matter, without the need for parents. This was widely believed for over 2000 years.
- In 1665, Francesco Redi disproved this theory at the macroscopic level by showing that flies did not spontaneously generate from decaying meat when protected from eggs. Later experiments by Spallanzani and Pasteur provided further evidence against spontaneous generation.
- Through a series of experiments using flasks with S-shaped openings, Pasteur definitively disproved spontaneous generation by showing that microbes came from ambient dust particles, not non-living matter, establishing the theory of biogenesis. This resolved the long-standing
This document provides a summary of the history of microbiology, from the ancient belief in spontaneous generation to the modern acceptance of the germ theory of disease. It describes key experiments and findings, including:
- Redi's experiments disproving spontaneous generation by showing flies lay eggs on meat.
- Van Leeuwenhoek discovering "animalcules" like bacteria and protozoa using microscopes.
- Pasteur's experiments definitively disproving spontaneous generation and supporting germ theory through controlled experiments with broth in flasks.
- Koch's work isolating anthrax bacteria and formulating his postulates linking specific bacteria to specific diseases.
- Semmelweis, Holmes, and Snow
1. Biologists use the scientific method to systematically study problems through observation, hypothesis formation, experimentation, and conclusion drawing.
2. In the 1600s, scientists like Redi and van Leeuwenhoek used controlled experiments to disprove the theory of spontaneous generation and show that living things arise from other living things, not from non-living material.
3. In the 1700s, Spallanzani's experiments further supported biogenesis over spontaneous generation, though his methods were criticized. Pasteur later designed elegant experiments using swan neck flasks that definitively showed microbes arise from existing microbes, not spontaneously from non-living sources.
This document provides a history of biotechnology including key definitions and timelines. It discusses how biotechnology has been used for thousands of years to produce improved food and healthcare. Some highlights include:
- The term "biotechnology" was coined in 1919 to refer to using living organisms to modify human health and environment.
- Biotechnology has advanced significantly since the 1800s with gains in understanding genetics and DNA research.
- Traditional applications include using yeast to make beer and discovering how to make leavened bread using yeast.
- Modern biotechnology now enables developing improved products more safely and rapidly.
The Special Creation Theory holds that God created the universe and all life directly, as described in the book of Genesis. It was widely accepted before the scientific era began challenging it with theories like evolution. While science developed alternative origin of life theories, some religious groups strongly defended creationism based on the Bible. Over time, compromises were made, like the idea that God used evolution as his method, but the debate between science and religion on this issue continues today.
Unit 1.1.a. principle of genetics defintion and history- early concepts of i...Simranjit Singh
This document provides an overview of the early concepts of inheritance in genetics. It discusses key figures like Gregor Mendel who performed experiments on pea plants in the 1860s and deduced Mendel's laws of heredity. It also discusses earlier concepts including Aristotle's views on spontaneous generation and the experiments of Francesco Redi in the late 1600s which challenged this idea. The document also outlines the contributions of Antony van Leeuwenhoek who discovered microorganisms in the 1600-1700s and Louis Pasteur's experiments in the 1800s which provided strong evidence against spontaneous generation.
Microbiology: History perspective - Simran Sonule.pptxSimranSonule
This presentation describe the discovery of microbial world.
Theory of Abiogenesis and Biogenesis and
Contribution of scientist in the field of Microbiology
Nematodes are one of the most abundant metazoans on Earth, with over 25,000 known species. They occupy nearly every habitat and play important roles as free-living organisms, plant parasites, and parasites of humans and other animals. Nematodes have been used extensively as model organisms in fields like genetics and developmental biology due to traits like small size, short lifecycles, and fully sequenced genomes. Major nematode parasites of humans include roundworms, pinworms, hookworms, filarial worms, and guinea worms, which collectively infect over a billion people globally.
Scientists debated whether living things could arise from nonliving things (spontaneous generation) or only from other living things (biogenesis). Through controlled experiments over centuries, evidence increasingly supported biogenesis. Redi showed maggots came from fly eggs, not meat. Spallanzani found boiling sealed containers prevented microbe growth, supporting biogenesis. Pasteur's famous experiment using a swan-necked flask conclusively demonstrated that microbes only entered once the air could, disproving spontaneous generation.
The document discusses the origin and evolution of life on Earth from its earliest beginnings. It describes how early Earth conditions like primordial soup, meteorite impacts, and undersea vents could have facilitated the formation of simple organic molecules and polymers. The RNA world hypothesis proposes that self-replicating RNA arose first before DNA and proteins, as evidence shows some RNA can function as enzymes. The emergence of life is now seen as an inevitable consequence of cosmic evolution and the fundamental laws of physics given the right conditions over billions of years.
Practical reptile keeping september 2015Saulo Gomes
This issue of Practical Reptile Keeping magazine features news of a major theft of marginated tortoises from a private collection, introductions of new planted vivarium substrates from ProRep, and the arrival of a male Komodo dragon named Ganas at ZSL London Zoo.
Louis Pasteur was born on 27th december 1822, in dole, france. He was a soldier in napoleon’s army and his job was a gravedigger. As a child louis loved to paint but the age of 19, he decided to start a scientific career. He studied physics and chemistry and in 1846 he recived a PH.D in CHEMISTRY.He worked as a professor at the university of strasbourg,paris.Louis pasteur is known as the “FATHER OF MICROBIOLOGY & IMMUNOLOGY”
This document provides information on tapeworms (cestodes) that infect poultry and other animals. It describes the general characteristics of tapeworms, including their ribbon-like shape and life cycles. Specific information is given on several important tapeworm genera and species that infect poultry (Raillietina, Davainea), dogs (Dipylidium caninum), and horses (Anoplocephala, Moniezia). Key details are provided on the morphology, life cycles, and pathogenesis of these tapeworms. The document also discusses the taeniid tapeworms of humans (Taenia saginata, T. solium) and compares aspects of their morphology and life cycles.
This document summarizes and compares the living conditions of battery caged hens and "free range" hens in the egg production industry. It notes that both are debeaked without anesthetic at a young age and force molted through starvation. Male chicks are killed for both and hens considered "spent" at 18 months are slaughtered. While some view free range eggs as more humane, the document argues that no egg production can be humane as it ultimately relies on the same practices of animal abuse and slaughter.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
2. 2
Aristotle (384 –322 BC)Aristotle (384 –322 BC)
Proposed the theory ofProposed the theory of
spontaneous generationspontaneous generation
Also calledAlso called abiogenesisabiogenesis
Idea thatIdea that living things canliving things can
arise from nonlivingarise from nonliving mattermatter
Idea lasted almostIdea lasted almost 20002000
yearsyears
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4. 4
Spontaneous GenerationSpontaneous Generation
For centuriesFor centuries,, people basedpeople based theirtheir
beliefsbeliefs onon their interpretations oftheir interpretations of
what they sawwhat they saw going on in the worldgoing on in the world
around them without testing theiraround them without testing their
ideasideas
TheyThey didn’t use the scientificdidn’t use the scientific
methodmethod to arrive at answers to theirto arrive at answers to their
questionsquestions
Their conclusions were based onTheir conclusions were based on
untested observationsuntested observations
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6. 6
Example #1Example #1
Observation:Observation: Every year in theEvery year in the
spring, thespring, the Nile River floodedNile River flooded
areas of Egypt along the river,areas of Egypt along the river,
leaving behind nutrient-rich mudleaving behind nutrient-rich mud
that enabled the people to growthat enabled the people to grow
that year’s crop of food.that year’s crop of food.
However, along with the muddyHowever, along with the muddy
soil,soil, large numbers of frogslarge numbers of frogs
appeared that weren’t around inappeared that weren’t around in
drier timesdrier times
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Example #1Example #1
Conclusion:Conclusion: It was perfectlyIt was perfectly
obvious to people back thenobvious to people back then
thatthat muddy soil gave rise tomuddy soil gave rise to
the frogsthe frogs
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Example #2Example #2
Observation:Observation: In many parts ofIn many parts of
Europe, medieval farmers storedEurope, medieval farmers stored
grain in barnsgrain in barns with thatchedwith thatched
roofs (like Shakespeare’s house).roofs (like Shakespeare’s house).
As a roof aged, it was notAs a roof aged, it was not
uncommon for it to start leaking.uncommon for it to start leaking.
This could lead toThis could lead to spoiled orspoiled or
moldy grainmoldy grain, and of course there, and of course there
werewere lots of mice aroundlots of mice around..
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Example #2Example #2
Conclusion: It was obvious toIt was obvious to
them that thethem that the mice camemice came
from the moldy grain.from the moldy grain.
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10. 10
Example #3Example #3
Observation:Observation: In the citiesIn the cities
centuries ago, there were nocenturies ago, there were no
sewers, no garbage trucks, nosewers, no garbage trucks, no
electricity, and no refrigeration.electricity, and no refrigeration.
Sewage flowed down the streets,Sewage flowed down the streets,
and chamber pots and left overand chamber pots and left over
foodfood were thrown out into thewere thrown out into the
streets each morning. Manystreets each morning. Many
cities also had majorcities also had major ratrat
problemsproblems and a disease calledand a disease called
Bubonic plagueBubonic plague..
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Example #4Example #4
Observation:Observation: Since there were noSince there were no
refrigerators, the mandatory,refrigerators, the mandatory,
daily trip to the butcher shop,daily trip to the butcher shop,
especially in summer,especially in summer, meantmeant
battling the flies around thebattling the flies around the
carcassescarcasses. Typically, carcasses. Typically, carcasses
were “hung by their heels,” andwere “hung by their heels,” and
customers selected which chunkcustomers selected which chunk
the butcher would carve off forthe butcher would carve off for
them.them.
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13. 13
Example #4Example #4
Conclusion: Obviously, theObviously, the
rotting meatrotting meat that had beenthat had been
hanging in the sun all day washanging in the sun all day was
thethe source of the fliessource of the flies..
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14. 14
Abiogenesis RecipesAbiogenesis Recipes
Recipe for bees:Recipe for bees:
Kill a young bullKill a young bull, and, and bury itbury it
in an upright position soin an upright position so
that itsthat its horns protrude fromhorns protrude from
the groundthe ground. After a month,. After a month,
a swarm of bees will fly outa swarm of bees will fly out
of the corpse.of the corpse.
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15. 15
Abiogenesis RecipesAbiogenesis Recipes
Recipe for mice:Recipe for mice:
Place aPlace a dirty shirtdirty shirt or some rags inor some rags in
anan open pot or barrelopen pot or barrel containing acontaining a
few grains of wheatfew grains of wheat or some wheator some wheat
bran, and inbran, and in 21 days21 days, mice will, mice will
appear. There will be adult malesappear. There will be adult males
and females present, and they willand females present, and they will
be capable of mating andbe capable of mating and
reproducing more mice.reproducing more mice.
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17. 17
Francesco Redi (1668)Francesco Redi (1668)
In 1668, FrancescoIn 1668, Francesco RediRedi, an, an
Italian physician, did anItalian physician, did an
experiment withexperiment with fliesflies andand wide-wide-
mouth jars containing meatmouth jars containing meat
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18. 18
Redi’s ExperimentRedi’s Experiment
Redi usedRedi used open & closedopen & closed
flasksflasks whichwhich contained meatcontained meat..
HisHis hypothesishypothesis was thatwas that
rotten meat does not turnrotten meat does not turn
into flies.into flies.
HeHe observedobserved these flasksthese flasks toto
see in which one(s) maggotssee in which one(s) maggots
would develop.would develop.
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19. 19
Redi’s FindingsRedi’s Findings
He found that if a flask wasHe found that if a flask was
closedclosed with a lid sowith a lid so adult fliesadult flies
could not get in, no maggotscould not get in, no maggots
developed on the rotting meatdeveloped on the rotting meat
within.within.
In a flaskIn a flask without a lidwithout a lid,,
maggots soon were seenmaggots soon were seen in thein the
meat because adult flies had laidmeat because adult flies had laid
eggs and moreeggs and more adult flies soonadult flies soon
appeared.appeared.
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20. 20
Redi’s (1626-1697) Experiments
Evidence against spontaneous generation:Evidence against spontaneous generation:
1.1. UnsealedUnsealed – maggots on meat– maggots on meat
2.2. SealedSealed – no maggots on meat– no maggots on meat
3.3. GauzeGauze – few maggots on gauze, none on meat– few maggots on gauze, none on meat
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21. 21
Results of Redi’s ExperimentsResults of Redi’s Experiments
The results of thisThe results of this
experimentexperiment disproved the ideadisproved the idea
of spontaneous generation forof spontaneous generation for
larger organisms,larger organisms, but peoplebut people
still thought microscopicstill thought microscopic
organisms like algae ororganisms like algae or
bacteria could arise that way.bacteria could arise that way.
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Did Redi Use theDid Redi Use the
Scientific Method?Scientific Method?
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The Scientific MethodThe Scientific Method
ObservationObservation
HypothesisHypothesis
ExperimentExperiment
Accept, Reject, or Modify hypothesisAccept, Reject, or Modify hypothesis
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Step 1 - ObservationStep 1 - Observation
There were flies around meatThere were flies around meat
carcasses at the Butchercarcasses at the Butcher
shop.shop.
Where do the flies comeWhere do the flies come
from?from?
Does rotting meat turn intoDoes rotting meat turn into
or produce rotting flies?or produce rotting flies?
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26. 26
Step 2 - HypothesisStep 2 - Hypothesis
Rotten meat does not turnRotten meat does not turn
into flies.into flies. Only flies canOnly flies can
make more flies.make more flies.
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27. 27
Step 3 - TestingStep 3 - Testing
Wide-mouth jarsWide-mouth jars each containing a piece ofeach containing a piece of
meat were subjected to several variations ofmeat were subjected to several variations of
“openness”“openness” while allwhile all other variables wereother variables were
kept the same.kept the same.
Control groupControl group — These jars of meat were— These jars of meat were
set outset out without lidswithout lids so the meat would beso the meat would be
exposed to whatever it might be in theexposed to whatever it might be in the
butcher shop.butcher shop.
Experimental group(s)Experimental group(s) — One group of jars— One group of jars
werewere sealedsealed with lids, and another group ofwith lids, and another group of
jars had gauze placed over them.jars had gauze placed over them.
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28. 28
Step 4 - DataStep 4 - Data
Presence or absence of fliesPresence or absence of flies
and maggots observed in eachand maggots observed in each
jar wasjar was recordedrecorded..
Control groupControl group – flies entered,– flies entered,
laid eggs, & maggots emergedlaid eggs, & maggots emerged
Gauze coveredGauze covered – flies on gauze,– flies on gauze,
but not in jarbut not in jar
Sealed jarsSealed jars – No maggots or– No maggots or
flies on the meatflies on the meat
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29. 29
Step 5 - ConclusionStep 5 - Conclusion
Only flies can make more fliesOnly flies can make more flies. In the. In the
uncovered jarsuncovered jars, flies entered and laid eggs, flies entered and laid eggs
on the meat. Maggots hatched from theseon the meat. Maggots hatched from these
eggs and grew into more adult flies. Adulteggs and grew into more adult flies. Adult
flies laid eggs on the gauze on the gauze-flies laid eggs on the gauze on the gauze-
covered jars. These eggs or the maggotscovered jars. These eggs or the maggots
from them dropped through the gauze ontofrom them dropped through the gauze onto
the meat. In thethe meat. In the sealed jarssealed jars, no flies,, no flies,
maggots, nor eggs could enter, thus nonemaggots, nor eggs could enter, thus none
were seen in those jars. Maggots arose onlywere seen in those jars. Maggots arose only
where flies were able to lay eggs.where flies were able to lay eggs. ThisThis
experiment disproved the idea ofexperiment disproved the idea of
spontaneous generation for larger organisms.spontaneous generation for larger organisms.
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31. 31
Anton van Leeuwenhoek (1674)Anton van Leeuwenhoek (1674)
Leeuwenhoek beganLeeuwenhoek began makingmaking andand
looking throughlooking through simple microscopessimple microscopes
He often made a new microscopeHe often made a new microscope
for each specimenfor each specimen
HeHe examined waterexamined water and visualizedand visualized
tiny animals, fungi, algae, andtiny animals, fungi, algae, and
single celled protozoa;single celled protozoa;
“animalcules”“animalcules”
By end of 19By end of 19thth
century, thesecentury, these
organisms were calledorganisms were called microbesmicrobes
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John Needham (1745)John Needham (1745)
Showed that microorganismsShowed that microorganisms
flourished in various soups thatflourished in various soups that
had been exposed to the airhad been exposed to the air
Claimed that there was aClaimed that there was a “life“life
force” present in the moleculesforce” present in the molecules
of all inorganic matterof all inorganic matter, including, including
air and the oxygen in it, thatair and the oxygen in it, that
could cause spontaneouscould cause spontaneous
generation to occurgeneration to occur
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Needham’s ResultsNeedham’s Results
Needham’s experimentsNeedham’s experiments
seemed to supportseemed to support the ideathe idea
ofof spontaneous generationspontaneous generation
PeoplePeople didn’t realizedidn’t realize bacteriabacteria
were already present inwere already present in
Needham’s soupsNeedham’s soups
NeedhamNeedham didn’t boil longdidn’t boil long
enoughenough to kill the microbesto kill the microbes
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37. 37
Lazzaro Spallanzani’s (1765)Lazzaro Spallanzani’s (1765)
Boiled soups for almost an hourBoiled soups for almost an hour
and sealed containers byand sealed containers by meltingmelting
the slender necks closedthe slender necks closed.
TheThe soups remained clearsoups remained clear..
Later, heLater, he broke the sealsbroke the seals & the& the
soups became cloudysoups became cloudy withwith
microbes.microbes.
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ConclusionConclusion
CriticsCritics said sealed vials didsaid sealed vials did
not allow enough air fornot allow enough air for
organisms to survive and thatorganisms to survive and that
prolonged heating destroyedprolonged heating destroyed
“life force”“life force”
Therefore,Therefore, spontaneousspontaneous
generation remainedgeneration remained thethe
theory of the timetheory of the time
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How Do Microbes Arise?How Do Microbes Arise?
ByBy 18601860, the debate had become so, the debate had become so
heated that theheated that the Paris Academy ofParis Academy of
SciencesSciences offered a prizeoffered a prize for anyfor any
experiments that would help resolveexperiments that would help resolve
this conflictthis conflict
TheThe prize was claimed in 1864 byprize was claimed in 1864 by
Louis PasteurLouis Pasteur, as he published the, as he published the
results of an experiment he did toresults of an experiment he did to
disproved spontaneous generation indisproved spontaneous generation in
microscopic organismsmicroscopic organisms
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Pasteur's ProblemPasteur's Problem
Hypothesis:Hypothesis: Microbes comeMicrobes come
from cells of organisms on dustfrom cells of organisms on dust
particles in the air; not the airparticles in the air; not the air
itself.itself.
Pasteur put broth into severalPasteur put broth into several
specialspecial S-shaped flasksS-shaped flasks
Each flask wasEach flask was boiled and placedboiled and placed
at various locationsat various locations
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Pasteur's Experiment -Pasteur's Experiment - Step 1Step 1
S-shaped FlaskS-shaped Flask
Filled withFilled with brothbroth
The special shaped wasThe special shaped was
intended tointended to trap anytrap any
dust particlesdust particles
containing bacteriacontaining bacteria
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Pasteur's Experiment -Pasteur's Experiment - Step 3Step 3
Flask left at variousFlask left at various
locationslocations
DidDid not turn cloudynot turn cloudy
Microbes not foundMicrobes not found
Notice theNotice the dustdust thatthat
collected in the neckcollected in the neck ofof
the flaskthe flask
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48. 48
Pasteur’sPasteur’s S-shaped flask kept microbesS-shaped flask kept microbes
out but let air inout but let air in..
Proved microbes only come from otherProved microbes only come from other
microbes (life from life) -microbes (life from life) - biogenesisbiogenesis
The Theory of BiogenesisThe Theory of Biogenesis
Figure 1.3copyright cmassengale
50. 50
1668:1668: Francisco RediFrancisco Redi filled sixfilled six
jars with decaying meat.jars with decaying meat.
Evidence Pro and ConEvidence Pro and Con
Conditions:Conditions: Results:Results:
3 jars covered with fine3 jars covered with fine
netnet
No maggotsNo maggots
3 open jars3 open jars Maggots appearedMaggots appeared
From where did the maggots come?From where did the maggots come?
What was the purpose of the sealed jars?What was the purpose of the sealed jars?
SSpontaneous generation or biogenesis?pontaneous generation or biogenesis?
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1745:1745: John NeedhamJohn Needham put boiledput boiled
nutrient broth into covered flasks.nutrient broth into covered flasks.
Evidence Pro and ConEvidence Pro and Con
Conditions:Conditions: Results:Results:
Nutrient brothNutrient broth
heated, then placedheated, then placed
in sealed flaskin sealed flask
Microbial growthMicrobial growth
From where did the microbes come?From where did the microbes come?
SSpontaneous generation or biogenesis?pontaneous generation or biogenesis?
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1765:1765: Lazzaro SpallanzaniLazzaro Spallanzani boiledboiled
nutrient solutions in flasks.nutrient solutions in flasks.
Evidence Pro and Con
Conditions:Conditions: Results:Results:
Nutrient brothNutrient broth
placed in flask,placed in flask,
heated, thenheated, then
sealedsealed
No microbialNo microbial
growthgrowth
SSpontaneous generation orpontaneous generation or
biogenesis?biogenesis?
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1861:1861: Louis PasteurLouis Pasteur demonstrateddemonstrated
that microorganisms are present inthat microorganisms are present in
the air.the air.
Evidence Pro and ConEvidence Pro and Con
Conditions:Conditions: Results:Results:
Nutrient broth placed inNutrient broth placed in
flask, heated, notflask, heated, not
sealedsealed
Microbial growthMicrobial growth
Nutrient broth placed inNutrient broth placed in
flask, heated, thenflask, heated, then
sealedsealed
No microbial growthNo microbial growth
SSpontaneous generation or biogenesis?pontaneous generation or biogenesis?
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