Introduction to Biology PDF

Ajman University of Science and Technology College Of Engineering Biomedical Engineering Biology 2181410 Introduction to Biology Dr. Enas AL Zu’abi  An introduction to biology Biology is the scientific study of (life) living o...

Ajman University of Science and Technology College Of Engineering Biomedical Engineering Biology 2181410 Introduction to Biology Dr. Enas AL Zu’abi  An introduction to biology Biology is the scientific study of (life) living organisms. Biological questions: –How does a single cell develop into an organism? –How does the human mind work? –How do living things interact in communities?  Characteristics of living organisms: Consist of one or more cells. Contain genetic information Use genetic information to reproduce themselves. Can convert molecules from their environment into new biological molecules. Have the ability to respond to changes in their environment called stimuli.  Characteristics of living organisms: Can extract energy from environment and use it to do biological work. Can regulate their internal environment in spite of the outside changes. (This balance is called This is called Homeostasis) Are genetically related and have evolved. Theme: New Properties Emerge at Each Level in the Biological Hierarchy Life can be studied at different levels, from molecules to the entire living planet The study of life can be divided into different levels of biological organization Figure 1.4 The biosphere Tissues Ecosystems Organs and organ systems Communities Cells Organelles Organisms Atoms Populations Molecules  Organization of Life The biosphere is the part of Earth that supports life. An ecosystem is a specific area within the biosphere with a common set of physical characteristics. For example: Climate, soil, landforms, etc. Organization of Life The biological community is made of all populations living and interacting in one ecosystem. A population includes all members of a species that live in the same community. An organism is an individual living thing Two Approaches to Studying Biology Reductionism Systems Biology The Power and Limitations of Reductionism Reductionism is the reduction of complex systems to simpler components that are more manageable to study – i.e., studying the molecular structure of DNA helps us to understand the chemical basis of inheritance An understanding of biology balances reductionism with the study of emergent properties – i.e., new understanding comes from studying the interactions of DNA with other molecules Systems Biology A system is a combination of components that function together Systems biology constructs models for the dynamic behavior of whole biological systems The systems approach poses questions such as – How does a drug for blood pressure affect other organs? – How does increasing CO2 alter the biosphere? Theme: Organisms Interact with Other Organisms and the Physical Environment Every organism interacts with its environment, including nonliving factors and other organisms Both organisms and their environments are affected by the interactions between them – For example, a tree takes up water and minerals from the soil and carbon dioxide from the air; the tree releases oxygen to the air and roots help form soil Figure 1.5 Sunlight Leaves absorb light energy from Leaves take in the sun. carbon dioxide CO2 from the air and release oxygen. O2 Cycling of chemical nutrients Leaves fall to Water and Animals eat the ground and minerals in leaves and fruit are decomposed the soil are from the tree. by organisms taken up by that return the tree minerals to the through soil. its roots. Theme: Life Requires Energy Transfer and Transformation A fundamental characteristic of living organisms is their use of energy to carry out life’s activities Work, including moving, growing, and reproducing, requires a source of energy Living organisms transform energy from one form to another – For example, light energy is converted to chemical energy, then kinetic energy Energy flows through an ecosystem, usually entering as light and exiting as heat Figure 1.6 Sunlight Heat When energy is used Producers absorb light to do work, some energy and transform it into energy is converted to chemical energy. thermal energy, which is lost as heat. An animal’s muscle cells convert Chemical chemical energy energy from food to kinetic energy, the energy of motion. A plant’s cells use chemical energy to do Chemical energy in work such as growing food is transferred new leaves. from plants to consumers. (a) Energy flow from sunlight to (b) Using energy to do work producers to consumers Figure 1.6a Sunlight Producers absorb light energy and transform it into chemical energy. Chemical energy Chemical energy in food is transferred from plants to consumers. (a) Energy flow from sunlight to producers to consumers Figure 1.6b Heat When energy is used to do work, some energy is converted to thermal energy, which is lost as heat. An animal’s muscle cells convert chemical energy from food to kinetic energy, the energy of motion. A plant’s cells use chemical energy to do work such as growing new leaves. (b) Using energy to do work Theme: Structure and Function Are Correlated at All Levels of Biological Organization Structure and function of living organisms are closely related – For example, a leaf is thin and flat, maximizing the capture of light by chloroplasts – For example, the structure of a bird’s wing is adapted to flight Figure 1.7 (a) Wings (b) Wing bones Theme: The Cell Is an Organism’s Basic Unit of Structure and Function The cell is the lowest level of organization that can perform all activities required for life All cells – Are enclosed by a membrane – Use DNA as their genetic information  A eukaryotic cell has membrane-enclosed organelles, the largest of which is usually the nucleus By comparison, a prokaryotic cell is simpler and usually smaller, and does not contain a nucleus or other membrane-enclosed organelles Figure 1.8 Prokaryotic cell Eukaryotic cell DNA (no nucleus) Membrane Membrane Cytoplasm Nucleus (membrane- enclosed) Membrane- DNA (throughout enclosed organelles nucleus) 1 m Theme: The Continuity of Life Is Based on Heritable Information in the Form of DNA Chromosomes contain most of a cell’s genetic material in the form of DNA (deoxyribonucleic acid) DNA is the substance of genes Genes are the units of inheritance that transmit information from parents to offspring The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms Genomics: Large-Scale Analysis of DNA Sequences An organism’s genome is its entire set of genetic instructions The human genome and those of many other organisms have been sequenced using DNA- sequencing machines Genomics is the study of sets of genes within and between species Concept 1.2: The Core Theme: Evolution, the Overarching Theme of Biology Evolution is the study of how the organisms on present-day Earth came to be; their ancestors and how they are adapted to their environment. Differences among organisms are explained by the accumulation of heritable changes Grouping Species: The Basic Idea Taxonomy is the branch of biology that names and classifies species into groups of increasing breadth Domains, followed by kingdoms, are the broadest units of classification Figure 1.14 Species Genus Family Order Class Phylum Kingdom Domain Ursus americanus (American black bear) Ursus Ursidae Carnivora Mammalia Chordata Animalia Eukarya The Three Domains of Life Organisms are divided into three domains Domain Bacteria and domain Archaea compose the prokaryotes –Archaea live in the Earth’s extreme environments Most prokaryotes are single-celled and microscopic Figure 1.15 (a) Domain Bacteria (b) Domain Archaea 2 m 2 m (c) Domain Eukarya Kingdom Animalia 100 m Kingdom Plantae Protists Kingdom Fungi  Domain Eukarya includes all eukaryotic organisms Domain Eukarya includes three multicellular kingdoms – Plants, which produce their own food by photosynthesis – Fungi, which absorb nutrients – Animals, which ingest their food Other eukaryotic organisms were formerly grouped into the Protist kingdom, though these are now often grouped into many separate groups 1. Unicellular Organisms: A single cell carries out all the functions of life. Organisms like the amoeba, Paramecium are single-celled organisms, Bacteria, archaea, protozoa, unicellular algae and unicellular fungi are the main groups of unicellular organisms.  1. Unicellular prokaryotic organisms - they are unicellular in nature and they do not have membrane bound nucleus and membrane bound cellular organelles. These organisms are usually bacteria and cyanobacteria. Example: E.coli, Salmonella, Nostoc, etc. E. coli  2. Unicellular eukaryotic organisms - these organisms are unicellular and are eukaryotes. They have membrane bound true nucleus and other membrane bound organelles. These are mainly free living or aquatic parasites like the protozoans, some fungi and algae or some protists.  2. Multicellular organisms: Composed of many cells that are specialized for different functions. Examples Multicellular organism are of two types Multicellular prokaryote and multicellular eukaryote organisms.  Multicellular prokaryotes are mostly multicellular bacterial species like myxobacteria.  Some cyanotbacteria like Chara, Spirogyra, etc are also multicellular prokaryotes. Sometimes these bacteria are considered as colonial instead of multicellular.  Multicellular eukaryotes - Most of the eukaryotic organisms are multicellular. These organisms have a well-developed body structure and they have specific organ to perform specific function. Most of the well developed plants and animals are multicellular. Examples are almost all species of plants and almost all animals are eukaryotic and mutlicellular.