UNIT ONE Chapter 1 Themes in the Study of Life 1 1 The Themes of this book make connections across different areas of biology Yellow highlighted vocabulary from study guides Bold vocabulary words from text Evolution the process of change that has transformed life on earth from its earliest beginnings to the diversity of organisms living today Biology the scientific study of life Some properties of life regulation energy processing reproduction evolutionary adaptation response to the environment Emergent properties new properties that arise with each step upward in the hierarchy of life owing to the arrangement interactions of parts as complexity increases Watson Crick inferred that DNA served as the chemical basis of inheritance Systems biology is an approach that attempts to model the dynamic behavior of whole biological systems based on a study of the interactions among the systems parts o Biosphere seeing the globe from space and recognizing regions o Ecosystems a forest all the living things in a particular area i e o Communities the entire array of organisms inhabiting a particular ecosystem o Populations all the individuals of a species living w in the bounds o Organisms individual living things are called organisms o Organs and organ systems consist of multiple tissues i e a plant of land a desert of an area or stem o Tissues made up of a group of cells that work together performing functions o Cells single multicellular division of labor among specialized o Organelles i e chloroplasts various functional components cells present in cells o Molecules a chemical structure consisting of two or more small chemical units called atoms Eukaryotic membrane enclosed organelles w a DNA containing nucleus vs prokaryotic lacking in such organelles DNA genetic info is encoded w in the nucleotide sequences transmits heritable info from parent to offspring Gene expression the process by which info is encoded in DNA directs the synthesis of proteins or in some cases RNAs that are not translated into proteins and instead function as RNAs Negative feedback accumulation of an end product slows the process Positive feedback the end product stimulates the production of more that makes that product product 1 2 The Core Theme Evolution accounts for the unity and diversity of life Three Domains of Life o Bacteria most diverse and widespread prokaryotes and are now classified into multiple kingdoms Made up of prokaryotic organisms o Archaea most of the prokaryotic organisms that make up this classification live in earths extreme environments i e salty lakes or hot springs o Eukarya made up of three kingdoms of multicellular eukaryotes Kingdom Plantae consists of terrestrial multicellular eukaryotes land plants that carry out photosynthesis Kingdom Fungi i e mushrooms absorb nutrients from outside their bodies Protists are mostly unicellular eukaryotes and some relatively simple multicellular relatives Kingdom Animalia consists of multicellular eukaryotes that ingest other organisms Darwin describe the evolutionary history of species as descent with modification second main point was natural selection a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals b c of those traits Each species is one twig of a branching tree extending back in time through ancestral species more and more remote All of life is connected through its long evolutionary history 1 3 In studying nature scientists make observations and then form and test hypotheses Science is a way of knowing an approach to understanding the natural world Inquiry a search for information and explanation often focusing on specific questions Data recoded observations qualitative data often in the form of recorded descriptions rather than numerical measurements quantitative data generally recorded as measurements Inductive Reasoning derive generalizations from a large number of specific observations Deductive Reasoning logic that flows from the general to the specific Observation Question Hypotheses Prediction Test of Prediction Test does does not falsify hypothesis Controlled experiment one that is designed to compare an experimental group with a control group scientists do not control the experimental environment to keep everything constant Theory a much broader in scope than a hypothesis i e evolutionary adaptions arise by natural selection 1 4 Science Benefits from a cooperative approach and diverse viewpoints Model Organism a species that is easy to grow in the lab and lends itself particularly well to the questions being investigated Scientists work off the work of others scientists must repeat others results This diversity in viewpoints promotes progress in science Chapter 12 The Cell Cycle 12 1 Most Cell Division Results in Genetically Identical Daughter Cells Cell division the reproduction of cells cell cycle the life of a cell from the time it is first formed from a dividing parent cell until its own division into two daughter cells genome a cell s endowment of DNA its genetic information prokaryotic genome is often a single DNA molecule eukaryotic genomes usually consist of a number of DNA molecules Chromosomes dna molecules packaged into identifiable structures Chromatin the entire complex of DNA and proteins that is the bulding material of chromosomes Somatic cells all body cells excluding gametes made up of 46 chromosomes Gametes sperm eggs made up of 23 chromosomes Although humans have 46 chromosomes other organisms have a wide variety in number of chromosomes i e elephants have 56 chromosomes When a cell is not dividing even when it replicates DNA in preparation for cell division each chromosome is in the form of a long thin chromatin fiber After DNA replication each chromatin fiber becomes densely coiled and Each duplicated chromosome has two sister chromatids that also hold a centromere which is a region containing specific DNA sequences where the chromatid is attached most closely to its sister chromatid folded Through cell division the two sister chromatid of each duplicated chromosome separate and move into two new nuclei one forming at each end of a cell Once the sister chromatids separate they are now individual chromosomes that move into the new nucleus Mitosis the division of genetic material in the nucleus Cytokinesis the division of the cytoplasm 12 2 The Mitotic Phase Alternates with Interphase in the Cell Cycle Phases of the Cell Cycle
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