Introduction to Biology PDF

# Introduction ## Mohammed Walid ElĊanai ### Seek Your Dream and You Will Reach It ### Online Biology for Pre-Medical Students ### Definition of Biology - Biology is the science that studies living organisms & their interactions with each other's & their environment. - Biology is the science o...

# Introduction ## Mohammed Walid ElĊanai ### Seek Your Dream and You Will Reach It ### Online Biology for Pre-Medical Students ### Definition of Biology - Biology is the science that studies living organisms & their interactions with each other's & their environment. - Biology is the science of life - Science attempts to describe & understand the nature of the universe. - All living organisms share several key properties: - Order - Response to stimuli - Reproduction - Growth & development - Regulation - Homeostasis - Energy processing - Adaption - Biology is very broad and includes many branches. ### The Chemical Foundation of Life 1. Elements in various combinations comprise all matter, including living things. 2. Some of the most abundant elements in living organisms include carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. 3. These elements form proteins, carbohydrates, lipids, and nucleic acids. 4. The four elements common to all living organisms are Oxygen (O), Carbon (C), Nitrogen (N), and Hydrogen (H). | Element | Human | Atmosphere | Earth's Crust | |---|---|---|---| | Oxygen (O) | 65% | %21 | %46 | | Carbon (C) | 18% | Trace | Trace | | Hydrogen | 10% | Trace | %0.1 | | Nitrogen(N) | 3 | %78 | Trace | ### 1. Order - Organisms are highly organized. - Even very simple (single-celled organisms) are remarkably complex inside each cell. Atoms make molecules, and these molecules make organelles. - In multicellular organisms, cells form tissues, and tissues collaborate to form organs. - Organs work together to form systems. ### 2. Sensitivity to Stimuli - Organisms respond to diverse stimuli. - For example, plants can bend toward a source of light or climb on fences and walls, or respond to touch. - Even tiny bacteria can move toward or away from chemicals (a process called chemotaxis) or light (phototaxis). - Positive response: Movement towards stimulus. - Negative response: Movement away from stimulus. ### 3. Reproduction - Single-celled organisms reproduce by first duplicating their DNA and then dividing it equally to form two new cells. - Multicellular organisms reproduce by producing sex germline cells that will form new individuals. - The DNA containing genes passes from parents to offspring, and this ensures that offspring will belong to the same species with similar characters. ### 4. Growth & Development - In all organisms, genes in the DNA contain the instructions for growth and development. ### 5. Regulation - It is the coordination of the internal functions, even in the smallest organisms, such as nutrient transport, blood flow, removing wastes, and cooling of the body. ### 6. Homeostasis - Its the ability of the organism to maintain constant internal conditions. - In order to function properly, the cells need to maintain optimal conditions, such as proper temperature, pH, and proper ion concentration. - The organisms are able to maintain internal conditions within a narrow range, almost constantly, despite environmental changes by (homeostasis). - Organisms that live in cold climates (like a polar bear) have body structures that help them to withstand low temperatures. - These animals use fur, feathers, blubber, and fat to withstand cold weather. - In hot climates, organisms have methods such as perspiration in humans and panting in dogs to shed the excess body heat. ### 7. Energy Processing - All organisms use a source of energy for their metabolic activities. - Example: Plants capture sunlight energy and convert it to chemical energy, and then animals use the chemical energy. ### Levels Of Organization - Atoms - Molecules - Cells - Tissues - Organs - Systems - Organism - Populations - Communities - Ecosystems - Biosphere ### Biological Macromolecules - The organisms get its nutrients from the food to survive. - The large molecules are polymers made up of monomers. - The 4 major classes of macromolecules are: - Carbohydrates. - Lipids - Proteins - Nucleic acids. ### Dehydration Synthesis - When monomers combine with each other using covalent bonds to form a large polymer, they release water molecules. ### Hydrolysi - When polymers are broken down into monomers that uses water molecules during the break down. - The polymer is broken down into two components, one part gains a hydrogen atom (H+) & the other part gains a hydroxyl molecule (OH-). ### Proteins Types & Functions | Type | Example | Functions | |---|---|---| | Digestive Enzymes | Amylase, lipase, pepsin, trypsin | Digestion of the food into monomers | | Transport | Hemoglobin, albumin | Transport oxygen and nutrients in blood and lymph | | Structural | Actin, tubulin, keratin | Forms Cytoskeleton | | Hormones | Insulin, thyroxin | Coordinate body functions | | Defense | Immunoglobulins | Immunity | | Contractile | Actin, myosin | Muscle contraction | | Storage | Legume storage proteins, egg white albumin | Provide nourishment to the embryo in early development |