Modern Biology Chapter 1 Lecture Notes PDF

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lecture notes for chapter 1 modern biology...

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Modern Biology Chapter 1 What is life? All living organisms share five fundamental characteristics: 1. Energy a. All organisms acquire and use energy b. Maintain homeostasis (internal constancy) 2. Cells a. All organisms are made of membrane-bound cells 3. Information a. All organisms process hereditary information and information from the environment 4. Growth and replication a. All organisms are capable of growth and reproduction 5. Evolution a. Populations of organisms are continually evolving Is it alive? Check for the five characteristics ● Energy ● Organization ● Internal constancy ● Reproduction, growth, and development ● Evolution The characteristics of life: all organisms are made of cells ● Cells are the basic units of life ● Every organism, or living individual, consists of one or more cells ○ Bacterial and Archaea Domains ■ Cells lack nuclei (prokaryotic) ■ Most are unicellular ○ Protista (multiple kingdoms) ■ Unicellular or multicellular ■ Autotrophs or heterotrophs Life is Organized ● The matter that makes up life is organized into atoms ○ All matter, living and nonliving, is composed of atoms ○ Atom: the smallest chemical unit of a type of pure substance (element). ■ Example: Carbon atom ● Atoms are organized into molecules ○ Molecule: a group of joined atoms. ■ Example: DNA

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Molecules are organized into organelles ○ Some cells,but not all cells, are composed of organelles ○ Organelle: a membrane-bound structure that has a specific function within the cell ■ Example: Chloroplast Organelles are organized into cells ○ All life is composed of cells, although some cells do not have organelles ○ Cell: the fundamental unit of life ■ Example: leaf cell Cells are organized into tissues ○ Tissue: a collection of specialized cells that function in a coordinated fashion ■ Example: epidermis of leaf Tissues are organized into organs ○ Organs: a structure consisting of tissues organized to interact and carry out specific functions Organs are organized into organ systems ○ Organ System: organs connected physically or chemically that function together. ■ Example: above ground part of a plant Organ systems are organized into individual organisms ○ Organisms: a single living individual ■ Example: one acacia tree

What is an individual organism? ● Some organisms are single-celled, like bacteria and amoebas. This means they are composed of just one cell. ● Other organisms are multicellular (composed of many cells), like sea sponges, moss, and mushrooms. ● Still other organisms are composed of tissues, like jellyfish and certain worms. More complex organisms are composed of organs, tissues, and organ systems, such as you, a fish, and this tree. Life is Organized: ● Individual organisms are organized into populations ● Populations are organized into communities ● Communities are organized into ecosystems ● Ecosystems are organized into a biosphere Organization leads to emergent properties ● Emergent properties arise at each level of biological organization. ● The components interact, and the whole is greater than the sum of the parts. ● Example: the interacting brain cells have properties that brain cells alone lack. ● Properties of the mind such as consciousness and memory “emerge.” ● The brain can do these things only when its cells interact in complex networks

LIfe requires energy: Producers, Consumers, Decomposers ● Producers: extract energy and nutrients from the nonliving environment ● Consumers: obtain energy and nutrients by eating other organisms ● Decomposers: are consumers that obtain nutrients from dead organisms and wastes How do we do science? The scientific method follows six steps: 1. Scientists make an”observation” or notices something 2. Leads to a question. Why? How? 3. A possible,TESTABLE, explanation or answer (statement that answers the question) 4. Leads to a testable prediction. If…, then… 5. Designs a way to test prediction 6. Do results support hypothesis or not? Theory and hypothesis ● A theory : explanation for a general phenomenon or observations that are supported by evidence . ● A hypothesis is a testable statement that explains something observed ● A prediction is measurable or observable result that must be correct if a hypothesis is valid ● Louis Pasteur’s hypothesis: ○ Cells arise from cells ○ Cells do not arise by spontaneous generation Implications of the Cell Theory ● Because all cells come from preexisting cells ○ All individuals in a population of single-celled organisms are related by common ancestry ● All of the cells present in a multicellular organism ○ Have descended from preexisting cells ○ And are connected by common ancestry The Theory of Evolution by natural selection ● In 1858, Charles Darwin and Alfred Russel Wallace made two claims regarding the natural world: ○ All species are related by common ancestry (pattern). ○ Characteristics of species can be modified from generation to generation ● Evolution: ○ It is a change in the characteristics of a population over time ○ It means that species are related to one another and can change through time ● Natural selection explains how evolution occurs Fitness and Adaptation Drives Natural Selection ● Fitness is

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The ability of an individual to produce offspring ■ Individuals with high fitness produce many more surviving offspring than do others in the population Adaptation is ○ A trait that increases the fitness of an individual in a particular environment

The Tree of Life ● The cell theory and the theory of evolution by natural selection ○ Imply that all species come from preexisting species ○ And that all species, past and present, trace their ancestry back to a single common ancestor ● Speciation is ○ A divergence process in which natural selection has caused populations of one species to diverge to form new species

Scientists use taxonomy to name and classify organisms ● The tree of life includes three main branches (domains). ● All forms of life can be broadly categorized as either: ○ Domain Bacteria ○ Domain Archaea ○ Domain Eukarya ● Domains are divided into kingdoms ○ All three domains include one or more kingdoms, representing thousands to millions of different species. Life’s three domains: Bacteria and Archaea ● Domains bacteria and archaea consist of small, prokaryotic and unicellular organisms Eukarya, kingdom Protista ● Organisms in Domain Eukarya have larger, more complex cells with nuclei ● Protists are the most diverse group of eukaryotes, with multiple kingdoms, including amoebas, slime molds, algae, and other species. Eukarya, Kingdom Animalia ● Animals are a familiar group of eukaryotes, including vertebrates such as fish, frogs, and mammals, as well as invertebrates such as a bee. Eukarya, Kingdom Fungi ● Fungi are nature’s decomposers. Most are multicellular, like this mushroom; many are microscopic and unicellular, like yeast. Eukarya, Kingdom Plantae ● Plants are producers that capture light energy from the sun. Energy from plants is passed to consumers and decomposers. Phylogeny

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The actual genealogical relationships among all organisms rRNA (Ribosomal RNA) can change in populations over time thus closely related species will have similar sequence

The Phylogenetic Tree of LIfe ● A phylogenetic tree ○ Is used to show the relationships between species ○ Branches that share a recent common ancestor represent species that are closely related ○ Branches that do not share recent common ancestors represent species that are more distantly related Three domains of life ● The tree of life indicates three major groups of organisms: ○ Eukaryotic cells have membrane-bound nucleus ○ Prokaryotic cells do not have a membrane-bound nucleus. (bacteria and archaea)...