INTRODUCTION TO LIFE SCIENCE Concept of Life • All living things are made of cells. Some are unicellular and consist of only single cell that carries out all life processes. • Other organisms are multicellular and are composed of many cells which perform specialized and specific functions. • IRRITABILITY is the ability of living things to respond or react to the factors of the environment such as : 1. Life 2. Temperature 3. Pressure 4. Tension 5. Chemicals 6. Gravity • Example: a. A sunflower responds to light by facing the sun b. The fruit fly is attracted to electric light and grows in fruit media. MRS GREN MRS GREN M ovement can also refer to the motion of a single part of an organism. Plants show movement when a leaf bud opens or when a flower closes at night. R espiration is the conversion of energy from carbohydrates and fats into energy that can be used by cells. In multi-cellular organisms, respiration is built around the breakdown of sugars with the use of oxygen. This produces carbon dioxide as a by-product. MRS GREN S ensitivity refers to the way organisms respond to their environment. All organisms are able to sense changes in their environment and will respond accordingly. G rowth means that living things can become larger or increase the number of cells in their bodies. Growth in all animals begins when the zygote starts to develop. MRS GREN Reproduction means that living things can produce offspring. Excretion is the ability to clear waste from the body. For example, humans excrete nitrogen when they urinate and carbon dioxide when they breathe out. Plants excrete oxygen through their leaves. MRS GREN E nergy and nutrients are essential for growth, survival and reproduction. • Animals acquire nutrients by eating other organisms. • Plants use energy from the sun to convert carbon dioxide in the atmosphere into sugars and their roots absorb water and nutrients from the soil. Activity #2 Group into 4 then form a circle. DO: Based on your book on page 182 about 7 characteristics of life, discuss with your group mates then choose 4 and make a drawing on a bond paper and write why these characteristics you’ve chosen are important? ORIGIN OF THE FIRST LIFE FORMS Theories of Origin of Life 1. Special creation theory 2. Spontaneous generation theory 3. Biogenetic theory 4. Abiogenetic synthesis theory 1. Special Creation Theory • Many people believe that everything in this world was created by a Supreme Being. • It emphasizes that the source of all creations is God and with him nothing is impossible. 2. Spontaneous Generation Theory • It is a hypothetical process by which living organisms developed from unplanned event. • In 1668, Francisco Redi conducted an experiment to see if the theory was true. • He put a piece of snake meat, a fish, and a slice of veal in flasks, covered these with muslin cloth, and waited to see if maggots would develop on the meat. • He discovered that maggots grew only when flies laid their eggs on it. • But Lazaro Spallanzani, Louis Pasteur, and John Tyndall performed similar experiments to prove that the spontaneous generation theory was wrong. 3. Biogenetic theory • Biogenesis is a process by which life forms produce other life forms. • For example, a spider lays eggs that become another spiders. • According to biogenesis, life originated from pre-existing life. A demonstrative experiment, which showed biogenesis right down to the bacterial level, was devised by Louis Pasteur in 1859. 4. Abiogenetic Synthesis Theory • Alexander Oparin and John Haldane proposed that living cells arose gradually from nonliving matters through a sequence of chemical reactions. • According to Oparin, gases present in the atmosphere of primitive earth, when induced by lightening or other sources of energy, would react from a simple organic compounds. • But Louis Pasteur finally disapproved abiogenesis and proved biogenesis. Other Theories on the Origin of Life 1. Beneath the Ice 2. Electricity 3. Panspermia (Cosmozoic Theory) 4. RNA world 5. Simple Metabolism and Reactions 6. Clay Breeding Ground 7. Submarine Hydrothermal Vents 8. Adaptation 9. Evolution 10. Biology and Society 1. Beneath the Ice • Ice may have been hundreds of meters thick and was mainly due to the sun being much less fierce than it is nowadays • This theory contends that the ice may have protected the compounds, allowing them to interact and, thereby, creating life. 2. Electricity • It has been proven that electricity can produce simple sugars and amino acids from simple elements in the atmosphere. • This leads to the theory that lightning may have been responsible for the origins of life, primarily by striking through rich volcanic clouds. 3. Panspermia (Cosmozoic Theory) • Panspermia is the proposal that life on Earth began from Rocks , and other debris from impacts, in the form of highly resistant spores (cosmozoa) such as meteorite. • In fact, rocks from Mars have been found here on Earth, and it has been suggested that any one of these would have brought microbes that could have kick-started life. 4. RNA (Ribonucleic acid) world • This theory states that all life sprouted from a complex RNA world. • RNA is known for its role in the expression of genes. • To put it simple, DNA (Deoxyribonucleic acid) 5. Simple Metabolism and Reactions • This approach suggests that the primordial soup simply continued to react by itself over time, producing more and more complex molecules, eventually yielding life. • The "primordial soup" idea came about when Russian scientist Alexander Oparin and English geneticist John Haldane each came up with the idea independently. • It had been theorized that life started in the oceans • Oparin and Haldane thought that with the mix of gases in the atmosphere and the energy from lightning strikes, amino acids could spontaneously form in the oceans. This idea is now known as "primordial soup." 6. Clay Breeding Ground • The latest theory is that clay - which is at its most basic, a combination of minerals in the ground - acts as a breeding laboratory for tiny molecules and chemicals which it 'absorbs like a sponge'. • It is suggested that clay may have served as an area of concentrated chemical activity, providing a breeding ground for DNA and other components. • The process takes billions of years, during which the chemicals react to each other to form proteins, DNA and, eventually, living cells, scientists told the journal Scientific Reports. • Biological Engineers from Cornell University's department for Nanoscale Science in New York state believe that clay 'might have been the birthplace of life on Earth'. 7. Submarine Hydrothermal Vents • The theory suggests that life may have begun at the submarine hydro thermal vents which emit the hydrogen rich molecules. • The rocky niches might have gathered all the molecules together and provided minerals to act as a catalyst for reactions to occur. • These vents still constitute chemical and thermal energy to sustain vibrant ecosystems. 8. Adaptation • An adaptation is an inherited trait that helps the organism's ability to survive and reproduce in its particular environment. • In Natural selection, genetic trait helps some individual s of species survive and reproduce more successfully than others in a particular environment. 9. Evolution • Evolution - “ a process of change” • It is a genetic make-up of a subgroup of population of a particular species. • It links observations from all elements of biology and cells to the biosphere. • It is simply a long -term response to the environment • mean a generation-togeneration change in the proportion of different inherited genes in a population 10. Biology and Society • Modern biology is changing human’s lives. New findings about DNA affect such fields as medicine and agriculture. The study of evolution is helping health professionals understand how disease-causing bacteria become resistant to antibiotic drugs. • Environmental issues such as water and air pollution are changing how people think about their relationship to the biosphere. Unifying Themes in the Study of Life 1. Biological System 2. The Cellular Basis of Life Unifying Themes in the Study of Life 1. Biological System 2. Cellular Basis of Life a. Systems of the body b. Ecosystem c. Interaction of organisms Biological System A. Systems of the body - is an organized group of related parts that interact to form a whole EXAMPLE: Organ System B. Ecosystem - is a physical environment with different species that interact with one another and with nonliving things. EXAMPLE: - organisms in the ecosystem require a steady supply of certain chemicals to live. Plants obtain most of their necessary chemicals from soil, water, and air. Animals acquire most of the chemicals they need by eating plants or other animals. C. Interaction of organisms • Organisms interact with organisms with the same species and different species. • Organisms use the environment to get sunlight and oxygen for cell respiration to get energy. • Organisms also interact with the environment for shelter and protection, food and water • Organisms camouflage with the environment to hide from their predators. • Plants interact with the environment to get sunlight necessary for photosynthesis. • Temperature and climate of the environment may be appealing and vital for survival of certain organisms too. Cellular Basis of Life The Cellular Basis of Life • All living things on Earth are either unicellular or multi-cellular. • Most multi-cellular organisms have cells that are specialized for different function. Most multi-cellular organisms have higher levels of organization. • • Beginning with the cellular level, next is tissue, wherein similar cells together perform a specific function. EXAMPLE: Nerve tissue consists of many nerve cells organized into a complex network. • Several types of tissue together make up a structure called ORGAN EXAMPLE: The brain is an organ that consists of nerve tissue and other types of tissues. • Finally, several organs together carry out a major body function make up an Organ system. EXAMPLE: The brain , spinal cord, and nerves make up the organ system called Nervous system. 1 Form and function • AKA “form fits function” EXAMPLE: Aero-dynamic shape of a bird’s wing - The structure of the bird’s bones contributes to its ability to fly. - Inside the bones, an open, honeycomb-like structure provides great strength with little weight. 2. Reproduction and Inheritance • “Life begets life.” -Organisms reproduce their own kind Genes (units of genetic information) are responsible for family inheritance Genes are made up of DNA - Inherited info in the form of DNA enables organisms to reproduce their own kind. 3. Interaction with the Environment • Each organisms interacts continuously with its environment. EXAMPLE: A plant obtains water and nutrients from the soil, carbon dioxide gas from the air, and energy from sunlight. • The plants use these three “inputs” from its environment for photosynthesis (the process by which plants make food). • The plant also has an impact on its surroundings. EXAMPLE: Plants release oxygen as a by-product of photosynthesis. Other organisms as well as plants use this oxygen for their own survival. 4. Energy and Life • Moving, growing, reproducing, and other activities of life require organisms to perform work. • Work depends on a source of energy. • Energy is obtained in chemical form in sugars, fats, and other “fuel-like” molecules in your food. 5. Regulation • The ability of organisms to regulate their internal conditions. • HOMEOSTASIS is a mechanism that makes organisms regulates their internal condition despite changes in their external environment. • EXAMPLE: You have a “thermostat” in your brain that reacts whenever your body temperature varies slightly from 37⁰C. If this internal thermostat detects a slight rise in your body temperature on a hot day, your brain signals your skin to produce sweat. SWEATING helps cool your body. PANTING - a dog pants on a hot day. PANTING causes moisture on the large surface of the animal’s lungs to evaporate, cooling the body as a result.