Biology Introduction PDF - Definition, Macromolecules, & Organization

Here is the structured markdown format of the provided text from the images: # BIOLOGY ### Image Description The images show a presentation about biology for pre-medical students, with diagrams related to different components of life. ## INTRODUCTION ### I. MOHAMMED WALID ELĊANAI ### Source / Un...

Here is the structured markdown format of the provided text from the images: # BIOLOGY ### Image Description The images show a presentation about biology for pre-medical students, with diagrams related to different components of life. ## INTRODUCTION ### I. MOHAMMED WALID ELĊANAI ### Source / University Book ## 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: 1. Order 2. Response to stimuli 3. Reproduction 4. Growth & development 5. Regulation 6. Homeostasis 7. Energy processing 8. Adaptation * Biology is very broad & 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 & Phosphorus. 3. These elements form the protien, Carbohydrates, Lipids & Nucleic acids. 4. The four elements common to all living organisms are Oxygen (O), Carbon (C), Nitrogen (N) & Hydrogen (H) | Element | Human | Atmosphere | Earths 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, these molecules make organelles. * In multi-cellular organisms, cells form **tissues** & tissues collaborate to form **organ**. * Organs work together to form a **system**. 2. Sensitivity to stimuli: * Organisms respond to diverse stimuli. * Ex - plants can bend towards a source of light or climb on fences & walls or respond to touch. * Even tiny bacteria can move towards 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 & 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 & this ensures that offspring will belong to the same species with similar characters. 4. Growth & Development : * In all organisms, genes in the DNA contains the instructions for the growth & development. 5. Regulation : * It is the coordination of the internal functions even in smallest organisms such as nutrient transport, blood flow, removing wastes & cooling of the body. 6. Homeostasis : * It's 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, proper ion concentration. * The organisms are able to maintain internal conditions within a narrow range almost constantly despite environmental changes by (homeostasis ). * Organisms live in cold climate (polar bear) have body structures that help them to withstand low temperature. * These animals use fur, feathers, blubber & fat to withstand cold weather. * In hot climates, organisms have methods such as perspiration in human & panting in dogs to shed the excess body heat. 7. Energy processing: * All organisms use a source of energy for their metabolic activities. * Example: the plants capture the sun light energy & convert it into chemical energy & then the animals use the chemical energy. **LEVELS OF ORGANIZATION :** Atoms Molecules cells tissues Organs systems organism populations communities ecosystems biosphere. ## Biological Macromolecules : * The organisms gets its nutrients from the food to survive. * The large molecules are polymers made up of monomers. * The 4 major classes of macromolecules are: 1. Carbohydrates. 2. Lipids 3. Proteins 4. Nucleic acids. * The 4 classes are organic (containing carbon) & may contain hydrogen, oxygen, nitrogens * The 4 classes also make up the majority of the cell dry mass & water makes up the majority of the complete cell mass. * PROTEINS TYPES & FUNCTIONS:(NEXT PAGE) ### Dehydration synthesis: * When monomers combine with each other using covalent bonds to form a large polymer, they release water molecules ### Hydrolysis: * When polymers are broken down into monomers that use water molecule during the break down. * The polymer is broken down into two components, one part gains Hydrogen atom (H+) & the other part gains hydroxyl molecule (OH-) . **Image Description:** A diagram showing the atomic structure of a polymer before and after both undergoing: Dehydration synthesis, and, Hydrolysis. | TYPE | Example | Functions | |:-----------------|:-------------------------------|:-------------------------------------------| | Digestive enzymes | Amylase, lipase, pepsin, trypsin | Digestion of the food into monomers | | Transport | Hemoglobin, albumin | Transport oxygen & nutrients in blood & 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 |