Biological Science Seventh Edition PDF

Biological Science Seventh Edition Welcome to Biology 130! Course Introduction Biology: The Study of Life What Does It Mean to Say That Something is Alive? All living organisms share five fundamental c...

Biological Science Seventh Edition Welcome to Biology 130! Course Introduction Biology: The Study of Life What Does It Mean to Say That Something is Alive? All living organisms share five fundamental characteristics: 1. Cells: ▪ All organisms are made up of membrane-bound cells 2. Replication: ▪ All organisms are capable of reproduction 3. Information: ▪ All organisms process hereditary information encoded in genes as well as information from environment 4. Energy: ▪ All organisms acquire and use energy to stay alive 5. Evolution: ▪ Populations of organisms are continually evolving Theories Theory: – Explanation for a very general class of phenomena or observations supported by wide body of evidence: ▪ Differs from everyday usage of word “theory,” Three theories meaning form “speculation” framework for modernor “guess” biological science: – Cell theory: ▪ What are organisms made of? – Theory of evolution by natural selection: ▪ Where do organisms come from? – Chromosome theory of inheritance: ▪ How is hereditary information transmitted from one generation to the next? Life is Cellular and Replicates through Cell Division 1665 Robert Hooke devises microscope with 30x magnification: – Observed small compartments invisible to naked eye— termed them “cells” (Figure 1.1a) Anton van Leeuwenhoek: – Devised microscope with 300x magnification: ▪ Observed single-celled organisms (Figure 1.1b) “animalcules” 1800s—German biologists claim all organisms consist of cells. All Organisms Are Made up of Cells 1660s—Robert Hooke and Anton van Leeuwenhoek were first to observe cells Cells: – Highly organized compartments – Separated from their environment by membrane barrier Formed first part of cell theory: – All organisms are made up of cells – All cells come from preexisting cells Terminology Theory refers to explanations for broad patterns Hypothesis: – Testable statement that explains something observed Experiment—allows researchers to test effect of factor on particular phenomenon Prediction—measurable or observable result – Must be correct if hypothesis is valid Cell Theory vs Spontaneous Generation Cell theory challenged spontaneous generation: – All-cells-from-cells explanation was a hypothesis: ▪ Cells are produced when pre-existing cells grow and divide – Spontaneous generation was an alternative hypothesis: ▪ The belief that organisms could arise spontaneously under certain conditions  The Spontaneous Generation and All-Cells- From-Cells Hypotheses Were Tested Experimentally by Louis Pasteur Louis Pasteur’s hypothesis: Cells arise from cells Cells do not arise by spontaneous generation What can be concluded by this experiment? Life Replicates through Cell Division Cells must replicate for life to exist As predicted by cell theory: – All cells present in multicellular organism have descended from preexisting cells – They are connected by common lineage Evidence now shows that life arose from non-life early in Earth’s history by process of chemical evolution How is hereditary information encoded and passed on during cell divisions? Chromosomal theory of inheritance proposed by Sutton and Boveri: – Hereditary or genetic information is encoded in genes – Genes are units located on chromosomes 1950s—Chromosomes are molecules of deoxyribonucleic acid (DNA): – DNA is the hereditary material – Genes are segments of DNA that code for cell products  DNA is a Double Helix Rosalind Franklin, James Watson and Francis Crick proposed that DNA is a double-stranded helix Each stand is made up of four building blocks: A, T, C, and G Sequence of this code is like letters in a word DNA carries, or encodes, information needed for an organism’s growth and reproduction The two strands of double helix are joined by interactions between pairs of bases: A pairs with T C pairs with G m This pairing allows DNA to be copied and preserves information encoded in DNA  The Central Dogma Describes the Flow of Genetic Information The central dogma: Describes flow of information in cells Dogma means framework for understanding DNA codes for ribonucleic acid (RNA) which codes for proteins RNA: Molecules that carry out specialized functions in cells Messenger RNA (mRNA) is read to make proteins Proteins: Crucial to tasks required by cells Form structural components to promote chemical reactions D N A is copied to pass genetic information from cell to cell or from one organism to its offspring Copying DNA is highly accurate What happens when a mistake is made? – DNA sequence changes may lead to changes in proteins – Outward appearance is product of proteins produced – DNA sequence changes lead to heritable variations that underlie diversity of life Life Requires Energy Chemical reactions that take place inside cells require energy Organisms have two fundamental nutritional needs: 1. Acquiring chemical energy in form of adenosine triphosphate (ATP) 2. Molecules that can be used as building blocks to make DNA, RNA, proteins, etc. How organisms acquire energy is central to diversification of life Life Evolves What is evolution? Darwin and Wallace made two claims regarding natural world: – Species are related by common ancestry: – Characteristics of species can be modified from generation to generation: ▪ Darwin called this “descent with modification”  Evolution and Natural Selection Evolution: – Change in characteristics of population over time – Species are related to one another and can change through time Population: – Group of individuals of same species – Living in the same area at the same time Natural selection explains how evolution occurs Two conditions must be met for natural selection to occur in a population: 1. Individuals must vary in characteristics that are heritable—can be passed onto offspring 2. In particular environment, certain versions of these heritable traits help individuals reproduce more than other versions Natural Selection and Evolutionary Change Certain heritable traits lead to increased success in producing offspring: – Traits become more common in population over time Natural selection acts on individuals Evolutionary change occurs in populations Speciation occurs when populations diverge to form new species The Phylogenetic Tree of Life Phylogenetic tree: – Used to show the relationships between species – Branches that share recent common ancestor represent species closely related – Branches that do not share recent common ancestors represent species that are more distantly related – Tree of life estimated from genetic data: How is Genetic Variation Analyzed? Biologists study RNA and DNA from different organisms: – Compare sequences of building blocks (A ,T,C, G) – Fewer sequence variations between two Example: species may indicate closer relationship Land plant D N A: A – T – A – T – C – G – A – G Green algae D N A: A – T – A – T – G – G – A – G Brown algae D N A: A – A – A – T – G – G – A – C What is more closely related to the land plant?  The Tree of Life Was Produced by Comparing Genetic Sequence Data Tree of life indicates three major groups of organisms (Domains): 1) Eukaryotes (have nucleus): Eukarya Two groups of prokaryotes (lack nucleus): 2) Bacteria and 3) archaea Doing Biology The nature of science: – All scientists ask questions that can be answered by measuring things—by collecting data Science involves: – Formulating hypotheses – Finding evidence that supports or conflicts Critical with to those hypotheses include a control group: ▪ Example: Using “normal” organisms to check for other factors that might influence outcome – Experimental conditions must be constant – Repeating test essential – How do Foraging Desert Ants Navigate?  Pedometer Hypothesis for How Ants Navigate Pedometer hypothesis: – Ants always know how far they are from the nest – Track number of steps taken – Know length of their stride Null hypothesis: – Specifies what should be observed when hypothesis being tested is incorrect – If pedometer hypothesis is wrong, stride length and step number should have no effect on the way back to nest Experiments are powerful scientific tool because: – They allow researchers to test effect of single, well-defined factor on particular phenomenon  Experimental Setup Wittlinger’s group manipulated ants into three groups after walking from nest to feeder: 1. Stumps: ▪ Legs were cut to form shorter-than-normal legs 2. Normal: ▪ No change in leg length 3. Stilts: ▪ Bristles glued on legs to form longer-than-normal legs Team then measured distance ants traveled back to nest via different route Do Desert Ants Use a “Pedometer”? End of Chapter Questions to Practice Chapter 1 Review Questions 3, 4, 5, 7, 10 Copyright © 2020, 2017, 2014 Pearson Education, Inc. All Rights Reserved