Lec 1 Introduction Biology Lecture Notes PDF

Biology Lecture : Introduction Definition of Biology : Biology :  It is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy. Bio = Life , Logos = science Function of human life : How to define li...

Biology Lecture : Introduction Definition of Biology : Biology :  It is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy. Bio = Life , Logos = science Function of human life : How to define life ?  Living organisms have certain characteristics that distinguish them from nonliving objects, they are : Organization, Metabolism, Responsiveness, Homeostasis, adaptation, Movement, Development, and Reproduction. Function of human life : 1. Organization  Living things are highly organized.  All living organisms are made up of one or more cells. Inside each cell, atoms make up molecules, which make up cell organelles and structures. In multicellular organisms, similar cells form tissues. Tissues, in turn, collaborate to create organs. Organs work together to form organ systems.  Cells organized in a way that maintains distinct internal compartments ,which keep body cells separated from external environmental threats and keep the cells moist and nourished. Levels of Organization :  Fundamental levels of organization that increase in complexity for body structures :  Subatomic particles (e.g. protons, neutrons, and electrons), ↓ Atoms, ↓ Molecules, ↓ Macromolecules (e.g. carbohydrates, lipids, proteins, and nucleic acids) ↓ Organelles, ↓ Cells, ↓ Tissues, ↓ ↓ ↓ ↓ ↓ ↓  Organs, Organ systems, Organisms, Population, Community, Ecosystem, Biosphere. Levels of Organization : Atom Molecule Biosphere Ecosystem Organelle Community Cell Tissue Population Organ organism Organ system Levels of Organization :  Elements, like hydrogen, oxygen, carbon, nitrogen, the smallest unit of any of these pure substances is an atom.  Atoms are made up of subatomic particles such as the proton, electron and neutron. Levels of Organization :  Two or more atoms combine to form a molecule, such as the water molecules, proteins, and sugars.  Molecules are the chemical building blocks of all body structures. Levels of Organization :  Organelle is a small part formed by molecules, inside a cell that has a specific functional or structural purpose. Levels of Organization :  Cell is the smallest independently functioning unit of a living organism.  All living structures of human anatomy contain cells. Levels of Organization :  A human cell typically consists of flexible membranes that enclose cytoplasm, a water-based cellular fluid together with a variety of tiny functioning units called organelles.  In humans, as in all organisms, cells perform all functions of life. Levels of Organization :  A tissue is a group of many similar cells (though sometimes composed of a few related types) that work together to perform a specific function. Levels of Organization :  An organ is an anatomically distinct structure of the body composed of two or more tissue types.  Each organ performs one or more specic physiological functions. Levels of Organization :  An organ system is a group of organs that work together to perform major functions or meet physiological needs of the body. Levels of Organization :  An organim is an individual living thing that carries on the activities of life by means of organs which have separate functions but are dependent on each other : a living person, plant, or animal. Levels of Organization :  Population: group of many organisms of the same type (species) in the same place or community at the same time. Levels of Organization :  Community : All of the different living things (organisms) in the same place at the same time. Levels of Organization :  Ecosystem: All of the living things (biotic) and the non-living factors (abiotic) in the same place at the same time. Levels of Organization :  Biosphere : The part of the earth's surface where living things can be found. Levels of Organization : Function of human life : 2. Metabolism  Is the term used to describe all chemical reactions involved in maintaining the living state of the cells and the organism  Organism consume foods molecules , convert some of it into fuel.  Sum of two types of reactions ( anabolism and catabolism). Function of human life : 2. Metabolism : Anabolism : Smaller, simpler molecules are combined into larger, more complex substances. Catabolism : Larger more complex substances are broken down into smaller simpler molecules. Catabolism releases energy. The complex molecules found in foods are broken down so the body can use their parts to assemble the structures and substances needed for life. Function of human life : 3. Responsiveness:  Adjust to changes in its internal and external environments in order to survive & reproduce.  Changes in an internal environment, such as increased body temperature, can cause the responses of sweating and the dilation of blood vessels in the skin in order to decrease body temp. Function of human life : 4. Homeostasis:  Cells require appropriate conditions ( proper temperature, pH, and concentrations of diverse chemicals) for proper function of cells.  Organisms are able to maintain internal conditions within the normal narrow range almost constantly by regulation , despite environmental changes, Function of human life : 5. Adaptation:  Fit to their environment.  Is a consequence of evolution by natural selection.  Adaptations sometimes are not constant.  As an environment changes, natural selection causes the characteristics of the individuals in a population to track those changes. Function of human life : 6. Movement :  Human movement includes actions at the joints of the body, the motion of individual organs and even individual cells (Like cytoplasmic streaming) Function of human life : 7. Development :  All of the changes of the body goes through in life.  Development includes the processes of differentiation, growth, and renewal(Reproduction). Growth : Is the increase in body size. grow by increasing the number of existing cells (multicellular), increasing the amount of noncellular material around cells , and, increasing the size of existing cells (unicellular ). Function of human life : Reproduction :  it is the formation of a new organism either asexually (mitosis) from a single parent organism, or sexually (sexual union of sex cells like sperm and egg) from two parent organisms.  So to humans it is the formation of a new organism from parent organisms sexually. Biological Macromolecules : Atom : Biological Macromolecules : Atom :  An atom is the smallest component of an element that retains all of the chemical properties of that element.  Hydrogen atoms cannot be broken down into anything smaller.  All organisms are made of a combination of elements.  In multicellular organisms, such as animals, molecules can interact to form cells. Biological Macromolecules : Atom :  A proton is a positively charged particle that resides in the nucleus ,has a mass of 1 and a charge of +1.  An electron is a negatively charged particle that travels in the space around the nucleus, it has a negligible mass and has a charge of 1. Biological Macromolecules : Atom :  Each element has its own unique properties.  Each contains a different number of protons and neutrons.  The atomic number of an element is equal to the number of protons that element contains.  The mass number, or atomic mass, is the number of protons plus the number of neutrons of that element. Biological Macromolecules : Isotope :  Isotopes are different forms of the same element that have the same number of protons, but a different number of neutrons.  Some elements, such as carbon, potassium have naturally occurring isotopes. Biological Macromolecules : Isotope :  Carbon-12, the most common isotope of carbon, contains six protons and six neutrons. Therefore , it has a mass number of 12 (six protons and six neutrons) and an atomic number of 6 (which makes it carbon).  Carbon-14 contains six protons and eight neutrons. Therefore, it has a mass number of 14 (six protons and eight neutrons) and an atomic number of 6, meaning it is still the element carbon. Biological Macromolecules : Isotope : Biological Macromolecules :  There are four major classes of biological macromolecules (carbohydrates, lipids, proteins , and nucleic acids)  Combined, these molecules make up the majority of a cell's mass.  They are organic , contain carbon ,in addition, they may contain hydrogen, oxygen, nitrogen, phosphorus , sulfur, and additional minor elements. Biological Macromolecules : Carbohydrates :  Provide energy to the body, particularly through glucose  Represented by the formula (CH2O)n, C(H2O)n  Three subtypes : Monosaccharides, Disaccharides, Polysaccharides. Biological Macromolecules : Carbohydrates : Monosaccharides :  Simple sugars, the most common is glucose.  The number of carbon atoms ranges from three to six.  During cellular respiration, energy is released from glucose, and that energy is used to help make adenosine triphosphate (ATP) ,The excess stored as starch  Galactose and fructose are other monosaccharides. Biological Macromolecules : Carbohydrates : Monosaccharides : Biological Macromolecules : Carbohydrates : Disaccharides :  Two monosaccharides  Include lactose, maltose, and sucrose Polyasccharides :  long chain of monosaccharides linked by covalent bonds , may contain different types of monosaccharides.  Starch, glycogen, and cellulose are examples of polysaccharides Biological Macromolecules : Carbohydrates :  Starch is the stored form of sugars in plants and is made up of amylose and amylopectin (both polymers of glucose).  Glycogen is the storage form of glucose in humans and other vertebrates, and is made up of monomers of glucose. Biological Macromolecules : Carbohydrates :  Cellulose is one of the most abundant natural biopolymers.  The cell walls of plants are mostly made of cellulose, which provides structural support to the cell.  made up of glucose monomers. Biological Macromolecules : Lipids :  Hydrophobic , or insoluble in water, because they are nonpolar molecules.  Perform many different functions :  Cells store energy for long-term use.  Provide insulation from the environment  They are building blocks of many hormones  They are an important constituent of the plasma membrane.  Lipids include fats, oils, phospholipids, and steroids. Biological Macromolecules : Lipids :  Fat molecule, such as a triglyceride, consists of two main components (glycerol and fatty acids).  Fatty acids have a long chain of hydrocarbons and an acidic carboxyl group (-COOH)  Fatty acids may be saturated or unsaturated.  Most unsaturated triglycerides are liquid at room temperature and are called oils.  Saturated fats are solid at room temperature. Biological Macromolecules : Lipids :  Phospholipids are the major constituent of the plasma membrane. composed of two fatty acid chains attached to a glycerol or similar backbone.  The third carbon of the glycerol backbone is bound to a phosphate group.  A phospholipid has both hydrophobic and hydrophilic regions !!  The fatty acid chains are hydrophobic and exclude themselves from water, whereas the phosphate is hydrophilic and interacts with water. Biological Macromolecules : Lipids :  Cells are surrounded by a membrane, which has a bilayer of phospholipids called Cell Membrane  The fatty acids of phospholipids face inside, away from water, whereas the phosphate group can face either the outside environment or the inside of the cell, which are both aqueous. Biological Macromolecules : Lipids : Biological Macromolecules : Lipids :  Steroids have a ring structure.  All steroids have four, linked carbon rings and several of them, like cholesterol, have a short tail. Biological Macromolecules : Proteins :  Proteins may be structural, regulatory, contractile, or protective; may serve in transport, storage, or membranes; or they may be toxins or enzymes.  Polymers of amino acids,  The functions of proteins are very diverse because there are 20 different chemically distinct amino acids Biological Macromolecules : Proteins :  Each protein has its own unique sequence and shape held together by chemical interactions.  If the protein is subject to changes in temperature, pH, or exposure to chemicals, the protein structure may change, losing its shape ( denaturation).  Denaturation is often reversible because the primary structure is preserved if the denaturing agent is removed, allowing the protein to resume its function.  Sometimes denaturation is irreversible, leading to a loss of function!! Biological Macromolecules : Nucleic Acids :  They carry the genetic blueprint of a cell and carry instructions for the functioning of the cell.  Two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Biological Macromolecules : Nucleic Acids :  DNA is the genetic material found in all living organisms  RNA, is mostly involved in protein synthesis.  DNA and RNA are made up of monomers (nucleotides.)  Each nucleotide is made up of three components: A nitrogenous base, A pentose (five-carbon) sugar, and A phosphate group Biological Macromolecules : Nucleic Acids : DNA nucleotides : contain the sugar deoxyribose and one of the four bases adenine (A),thymine (T),guanine (G), or cytosine (C). RNA nucleotides : contain the sugar ribose and one of the four bases A, uracil (U), G, or C. Nucleic Acids :