Biology Lecture Notes PDF

Biology/lec 2 Dr. Tuka Al-Sawaf Introduction to Biology Biology is the study of living things. It encompasses the cellular basis of living things, the energy metabolism that underlies the activities of life, and the genetic...

Biology/lec 2 Dr. Tuka Al-Sawaf Introduction to Biology Biology is the study of living things. It encompasses the cellular basis of living things, the energy metabolism that underlies the activities of life, and the genetic basis for inheritance in organisms. Biology also includes the study of evolutionary relationships among organisms and the diversity of life on Earth. It considers the biology of microorganisms, plants, human and animals, for example, and it brings together the structural and functional relationships that underlie their day-to-day activities. Biology draws on the sciences of chemistry and physics for its foundations and applies the laws of these disciplines to living things. All living things are made of cells; the cell itself is the smallest fundamental unit of structure and function in living organisms. One of the first scientists to observe cells was Robert Hooke. In the mid-1600s. Some cells contain aggregates of macromolecules surrounded by membranes; these are called organelles. Organelles are small structures that exist within cells and perform specialized functions. Some organisms consist of a single cell and others are multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes are single-celled organisms that lack organelles surrounded by a membrane and do not have nuclei surrounded by nuclear membranes; in contrast, the cells of eukaryotes do have membrane-bound organelles and nuclei. The cells from one organism to the next always varies but they do often have many similarities. Almost all cells contain DNA, are surrounded by a membrane, and perform similar functions such as respiration and the production of proteins. 1  Biology/lec 2 Dr. Tuka Al-Sawaf Single-celled prokaryotes and single-celled eukaryotes are also considered organisms and are typically referred to as microorganisms. Divisions of Biology Anatomy The branch of biology that studies the structure of organisms and their parts. It is a fundamental discipline in medicine and biology, providing insights into how organisms are put together and how their components interact. Biotechnology Utilizes cellular and biomolecular processes to develop technologies and products that help improve our lives and the health of our planet. Biochemistry Explores the chemical processes and substances that occur within living organisms. It bridges biology and chemistry and is foundational for understanding cellular processes, metabolism, and molecular biology. Botany The scientific study of plants, from the smallest algae to the largest trees. Botany covers plant structure, function, ecology, and evolution. Ecology The study of how organisms interact with each other and their environment. It addresses the distribution, abundance, biomass, and health of organisms within ecosystems, as well as the impact of human activity. Genetics The science of heredity and variation in living organisms. Genetics explores how genetic information is passed from parents to offspring. Immunology The study of the immune system and its role in defending the body against infectious disease and foreign invaders. Immunology covers how the body recognizes and combats pathogens, the development of vaccines, and the treatment of allergies, autoimmune diseases, and immune deficiencies. Microbiology The study of microscopic organisms, including bacteria, parasite, fungi, and protozoa. Microbiologists investigate how these organisms live, 2  Biology/lec 2 Dr. Tuka Al-Sawaf grow, and interact with their environments, with applications in health, agriculture, and environmental management. Virology The study of viruses and viral diseases. Virologists examine the structure, function, and classification of viruses, how viruses infect and exploit host cells for reproduction, and how they can be combated with vaccines and antiviral drugs. Physiology Investigates the functions and mechanisms of the human body and other organisms. Physiologists study how systems, organs, tissues, and cells perform their functions and respond to challenges. Zoology The scientific study of animals, their biology, behavior, and interaction with their ecosystems. Zoologists research the diversity of animal life, from the simplest sponges to complex mammals. Characteristics of Life Everything can be classified as either biotic and abiotic. Abiotic things are nonliving, meaning that they are missing one or more of the 8 characteristics of life, while biotic things are living, which means they do have all 8 of these characteristics. These 8 characteristics are: 1- Complex organization Living things have a level of complexity and organization not found in lifeless objects. At its most fundamental level, a living thing is composed of one or more cells. These units, generally too small to be seen with the naked eye, are organized into tissues. A tissue is a series of cells that accomplish a shared function. Tissues, in turn, form organs, such as the stomach and kidney. A number of organs working together compose an organ system. An organism is a complex series of various organ systems. (see figure 1) 3  Biology/lec 2 Dr. Tuka Al-Sawaf Figure 1: From an atom to the entire Earth, biology examines all aspects of life. 4  Biology/lec 2 Dr. Tuka Al-Sawaf 2- Metabolism Living things exhibit a rapid turnover of chemical materials, which is referred to as metabolism. Metabolism involves exchanges of chemical matter with the external environment and extensive transformations of organic matter within the cells of a living organism. Metabolism generally involves the release or use of chemical energy. Non living things do not display metabolism. 3- Responsiveness All living things are able to respond to stimuli in the external environment. For example, living things respond to changes in light, heat, sound, chemical and mechanical contact. To detect stimuli, organisms have means for receiving information, such as eyes, ears, and taste buds. A system of nerves and a number of chemical regulators called hormones coordinate activities within an organism. The organism responds to the stimuli by means of a number of effectors, such as muscles and glands. Energy is generally used in the process. 4- Growth Growth requires an organism to take in material from the environment and organize the material into its own structures. To accomplish growth, an organism expends some of the energy it acquires during metabolism. An organism has a pattern for accomplishing the building of growth structures. A non living organism does not display this characteristic. 5- Reproduction A living thing has the ability to produce copies of itself by the process known as reproduction. These copies are made while the organism is still living. 5  Biology/lec 2 Dr. Tuka Al-Sawaf Among plants and simple animals, reproduction is often an extension of the growth process. More complex organisms engage in a type of reproduction called sexual reproduction, in which two parents contribute to the formation of a new individual. During this process, a new combination of traits can be produced. Asexual reproduction involves only one parent, and the resulting cells are generally identical to the parent cell. For example, bacteria grow and quickly reach maturity, after which they split into two organisms by a process of asexual reproduction called binary fission. 6- Evolution Living organisms have the ability to adapt to their environment through the process of evolution. During evolution, changes occur in populations, and the organisms in the population become better able to metabolize, respond, and reproduce. They develop abilities to cope with their environment that their ancestors did not have. Evolution also results in a greater variety of organisms than existed in previous eras. This proliferation of populations of organisms is unique to living things. 7- Ecology The environment influences the living things that it surrounds. Ecology is the relationships between organisms and their their environment. Both biotic factors (living things) and abiotic factors (nonliving things) can alter the environment. Rain and sunlight are non-living components, for example, that greatly influence the environment. Living things may migrate or hibernate if the environment becomes difficult to live in. 6  Biology/lec 2 Dr. Tuka Al-Sawaf 8- Heredity Heredity is the ability to pass on genetic material (DNA) from parent to offspring. This can be in the form of phenotypic traits (the way a living thing looks on the outside) and genotypic traits (the actual genetic code that determines how something behaves and looks). 7