Introduction to Biology PDF

Introduction to Biology Biology is the scientific study of life Properties of life include: ❖ Order: the highly ordered structure. ❖ Reproduction: the ability of organisms to reproduce their own kind (increase in number). ❖ Growth and development: consistent growth and development controlled by...

Introduction to Biology Biology is the scientific study of life Properties of life include: ❖ Order: the highly ordered structure. ❖ Reproduction: the ability of organisms to reproduce their own kind (increase in number). ❖ Growth and development: consistent growth and development controlled by inherited DNA (increase in size). ❖ Energy processing: the use of chemical energy to power an organism’s activities and chemical reactions (also termed as metabolism).  Introduction to Biology ❖ Response to the environment: an ability to respond to environmental stimuli (responsiveness), ❖ Regulation: control of an organism’s internal environment within limits that sustain life ❖ Evolutionary adaptation: adaptations evolve over many generations as individuals with traits best suited to their environments have greater reproductive success and pass their traits to offspring. ‫ت َ ََلؤُم تَك ِييف‬  Introduction to Biology ❖ Regulation of internal environment is critical. ❖The output or product of a process regulates that very process. The most common form of regulation in living systems is the negative feedback and Positive feedback mechanisms: The product stimulates its own production. Examples of positive and negative feedback is blood sugar and the two hormones insulin and glucagon. In feedback regulation, the output, or product, of a process regulates that very process Introduction to Biology  The study of life reveals common themes 1. Organization 2. Information 3. Energy and Matter 4. Interactions 5. Evolution Fig. 1-4 Levels of biological organization The biosphere Cells Organs and organ 10 µm systems Cell Ecosystems Organelles Communities 1 µm Atoms Tissues 50 µm Populations Molecules Organisms  Introduction to Biology ❖ Levels of Biological Organization: ⚫ Biosphere: all life on earth and the environments on Earth that support life. ⚫ Ecosystem: all the organisms living in a particular area and the physical components with which the organisms interact, ⚫ Community: the entire array of organisms living in a particular ecosystem; set of populations inhabiting a particular area. ⚫ Population: all the individuals of a species living in a specific area.  Introduction to Biology Organism: an individual living thing. Organ system: several organs that cooperate in a specific function. Organ: a structure that is composed of tissues and that provides a specific function for the organism. Tissues: a group of similar cells that perform a specific function for the organ. Cells: the fundamental unit of life. Organelle: a membrane-bound structure that performs a specific function in a cell. Molecule (compound): a cluster of small chemical units called atoms held together.  Introduction to Biology Emergent properties: ⚫ New properties that arise in each step upward in the hierarchy of life, ‫التسلسلُالهرمي‬ ⚫ Result from the arrangement and interactions among component parts (e.g. photosynthesis).  Introduction to Biology Cells are the level at which the properties of life emerge. A living cell can: ⚫ Regulate its internal environment (responsiveness) ⚫ Take in and use energy (metabolism) ⚫ Respond to its environment (responsiveness) ⚫ Develop and maintain its complex organization, and (growth and order). ⚫ Give rise to new cells (reproduction).  Introduction to Biology ⚫ Are enclosed by a membrane that regulates the passage of materials between the cell and its surroundings. (responsiveness and metabolism). ⚫ Use DNA as their genetic information (reproduction, responsiveness, growth)  Introduction to Biology There are two basic types of cells: ❖ Prokaryotic cells: -Were the first to evolve. -Are simpler. -Are usually smaller than eukaryotic cells. ❖Eukaryotic cells: -Contain membrane-enclosed organelles, including a nucleus containing DNA, and -Are found in human and other, plants, protests, and fungi. Introduction to Biology  Introduction to Biology In most ecosystems: ⚫ Plants are the producers that provide the food, ⚫ Consumers eat plants and other animals, and ⚫ Decomposers (Saprophytes)act as recyclers, changing complex matter into simpler mineral nutrients. The dynamics of ecosystems include two major processes: ❖ The recycling of chemical nutrients from the atmosphere and soil through producers, consumers, and decomposers back to the environment. Nutrient cycling and energy flow in an ecosystem The one-way flow of energy through an ecosystem, entering as sunlight, converted to chemical energy by producers, passed on to consumers, and exiting as heat Introduction to Biology  Introduction to Biology Genes: ⚫ Are the unit of inheritance that transmits information from parents to offspring. ⚫ Are grouped into very long DNA molecules called chromosomes, and control the activities of a cell. Introduction to Biology  Introduction to Biology We can think of biology’s enormous scope as having two dimensions. ❖ The “vertical” dimension is the size scale that stretches from molecules to the biosphere. The “horizontal” dimension spans across the great diversity of organisms existing now and over the long history of life on Earth. Diversity is the hallmark of life. ⚫ Biologists have identified about 1.8 million species.  Introduction to Biology ⚫ Estimates of the actual number of species ranges from 10 to 100 million. Taxonomy names species and classifies them into a system of broader groups. The diversity of life can be arranged into three domains. ✓ Bacteria are the most diverse and widespread prokaryotes. ✓ Archaea are prokaryotes that often live in Earth’s extreme environments. ✓ Eukarya have eukaryotic cells and include human and other animals, plants……..  Introduction to Biology Eubacteria domain Eukarya domain Archaea domain Protista Kingdom Plantae Archaea bacteria Kingdom Fungi Kingdom Animalia