Invitation to Biology Chapter 1

Biology Scientific study of life Lays the foundation for asking basic questions about life and the natural world

What is Alive? Acquire and use energy Grow and Develop Reproduce using DNA Respond to Stimuli Maintain Homeostasis Organization Have the ability to evolve

Energy Flow Usually starts with energy from the sun Transfers from one organism to another Flows in one direction Eventually is lost as heat

Life’s Underlying Unity Life’s organization extends from the molecular level to the biosphere Shared features at the molecular level are the basis of life’s unity

Fig. 1-1a, p.2 atom Smallest unit of an element that still retains the element’s properties. Electrons, protons, and neutrons are its building blocks. This hydrogen atom’s electron zips around a proton in a spherical volume of space

Fig. 1-1b, p.2 molecule Two or more joined atoms of the same or different elements. The “molecules of life” are complex carbohydrates, lipids, proteins, DNA, and RNA. In today’s world only living cells make them

Fig. 1-1c, p.2 cell Smallest unit that can live and reproduce on its own or as part of a multicellular organism. It has an outer membrane, DNA, and other components

Fig. 1-1d, p.2 tissue Organized cells and substances that interact in a specialized activity. Many cells (white) made this bone tissue from their own secretions

Fig. 1-1e, p.2 organ Two or more tissues interacting in some task. A parrotfish eye, for example, is a sensory organ used in vision

Fig. 1-1f, p.2 organ system Organs interacting physically, chemically, or both in some task Parrotfish skin is an organ system with tissue layers, organs such as glands, and other parts

Fig. 1-1g, p.3 multicelled organism Individual made of different types of cells Cells of most organisms, including this Red Sea parrotfish, are organized as tissues, organs, and organ systems

Fig. 1-1h, p.3 population Group of single-celled or multicelled individuals of the same species occupying a specified area This is a fish population in the Red Sea

Fig. 1-1i, p.3 community All populations of all species occupying a specified area This is part of a coral reef in the Gulf of Aqaba at the northern end of the Red Sea

Fig. 1-1j, p.3 ecosystem A community that is interacting with its physical environment It has inputs and outputs of energy and materials Reef ecosystems flourish in warm, clear seawater throughout the Middle East

Fig. 1-1k, p.3 the biosphere All regions of the Earth’s waters, crust, and atmosphere that hold organisms Earth is a rare planet; without its abundance of free-flowing water, there would be no life

Molecules of Life Atoms are the basic units of matter Living things are made up of a certain subset of molecules: –Nucleic acids –Proteins –Carbohydrates –Lipids

DNA (deoxyribonucleic acid) Signature molecule of life Molecule of inheritance Directs assembly of amino acids

DNA and Inheritance Inheritance –Acquisition of traits through transmission of DNA from parent to offspring Reproduction –Mechanism by which parents transmit DNA to offspring

Interdependencies among Organisms Producers Make their own food Consumers Obtain energy by eating other organisms Decomposers Break down remains and wastes

Energy input, from sun Nutrient Cycling Producers plants, and other self-feeding organisms Consumers animals, most fungi, many protists, many bacteria Energy output (mainly metabolic heat) Fig. 1-3, p.5

Sensing and Responding Organisms sense and respond to changes in their environment Receptors detect specific forms of energy (stimuli) Sensing and responding helps to maintain homeostasis

Sensing and Responding

Homeostasis Organisms maintain certain conditions in their internal environment A defining feature of life

Unity of Life All organisms –Consist of one or more cells –Have the capacity to reproduce based on instructions in DNA –Engage in metabolism –Sense and respond to the environment

Levels of Organization Cell Multicelled organism Population Community Ecosystem Biosphere

Life’s Diversity Millions of living species Millions more now extinct Each species has some unique traits

Scientific Names Two-part name –Humphead parrotfish is Scarus gibbus –First part (Scarus) is genus name –Second name is a particular species within the genus

Classification Systems Organisms are grouped into three domains: Eubacteria (Bacteria) Archaebacteria (Archaea) Eukaryotes (Eukarya)

Origin of life Eubacteria Archaebacteria Eukaryotes ProtistansPlantsFungiAnimals Major Groups

Single celled No nucleus Smaller, less complex Archaebacteria, eubacteria ProkaryotesEukaryotes Single- or multicelled Nucleus Larger, more complex Fungi, protistans, plants, animals

Bacteria The most common prokaryotes

Archaea Prokaryotes

Protists

Plants Generally photosynthetic

Fungi Decomposers, parasites and pathogens

Animals Multicelled eukaryotes

Mutation: Source of Variation Mutation = change in structure of DNA Basis for variation in heritable traits May be harmful, neutral, or beneficial

Evolution Heritable change in a line of descent over time Changes in populations result in diversity

Natural Selection Individuals vary in some heritable traits Different forms of heritable traits are most helpful under different conditions Natural selection is an outcome of differences in survival and reproduction among individuals that vary in their traits

Scientific Method Observe phenomenon Develop hypotheses Make predictions Devise test of predictions Carry out test and analyze results

Role of Experiments Study a phenomenon under known conditions Tests the prediction of the hypothesis Can never prove a hypothesis 100% correct

Experimental Design Control group –A standard for comparison –Identical to experimental group except for variable being studied Experimental group –Includes one variable being studied

Scientific Theory An explanation of the causes of a wide range of related phenomena Is consistent with all collected data Used to make predictions Still can be disproved