BSC 109 Chapter One Notes The Scope of Life Biology is the study of life 7 Characteristic of Living Things They have order They regulate themselves called homeostasis maintaining steady state They grow and develop They use energy They respond to the environment They reproduce Populations evolve Theme 1 The Scope of Life and Emergent Properties Life consists of vertical hierarchy o Molecules Biosphere o Be familiar with Fig 1 2 on page 5 Example of Emergent Property photosynthesis Theme 2 Organisms exchange matter and energy within ecosystems Every organism interacts with its environment o Both are affected o Ex Plants use CO2 to make food o All O2 in the atmosphere comes from photosynthesis Nutrients are recycled Energy flows from sunlight to producers to consumers o Energy exits as heat Theme 3 Cells are an organism s basic unit Cells are the lowest level of organization that can perform all the activities of life All cells o Are enclosed by a membrane o Use DNA as the recipe for the process of life 2 kinds of cells prokaryotic and Eukaryotic Theme 4 The Continuity of Life is based on the information in DNA Chromosomes contain most of a cell s genetic material in the form of DNA DNA is the substance of genes Genes are the units of inheritance that transmit information from parents to offspring Theme 5 Diversity is the hallmark of life and the diverse forms of life fit their functions There are three main groups of life called domains o Eukarya o Bacteria o Archae Living Organisms Can Be Classified Eukaryote Organisms with a true nucleus o Anamalia o Plants Fungi o o Protista algae kelp Theme 6 Evolution Heritable changes in populations over generations Biology s core theme o The scientific explanation for both o The unity of life and the diversity of life Science The word science is derived from a Latin verb meaning to know It is both a way of knowing and a body of knowledge Scientists use two main forms of inquiry 1 Discovery science describes natural structures and processes 2 Hypothesis based science Hypothesis is an idea that can be tested Often hypotheses must be modified See circle graph in slide show Failure to falsify a hypothesis does not prove it Theories in Science A theory us much broader in scope that a hypothesis Theories only become widely accepted in science if o They are supported by an accumulation of extensive and varied evidence From multiple hypotheses o There are only a few theories in biology Theories can be changed but it is unlikely Evaluating Science It is based on good observation Who are the scientists and for whom do the work Free of bias Has it been reproduced Is there more than one source that came to the same conclusion o o Is it recent Chapter Two What is matter Mater is anything that has mass and occupies space Composed of elements Elements Cannot be broken down to a simpler form Periodic table of elements lists all known elements Protons neutrons electrons Periodic Table Group number defines each column how they react with the world Atomic number integer number of protons Atomic mass protons neutrons Isotopes differ in number of neutrons average weight of all possible scenarios in life Protons stay the same and neutrons can change Neutral atom number of neutrons equal number of protons Atoms Smallest Function Unit That Retains the Properties of an Element Proton o Positive charge o Determines element Neutron Electron o No charge o Determine isotope o Negative charge o Participates in chemical reactions o Outer shell electrons determine chemical behavior Nucleus Hydrogen o Consists of neutrons and protons Each element consists of one type of atom o 1 proton o Really reactive because first shell wants another electron Oxygen o 8 protons o 8 neutrons o 8 electrons in 2 shells o Sodium o 11 protons o 11 neutrons o 11 electrons in 3 shells o Need to know the first 3 shells First shell needs 2 electrons Second shell wants to have 8 Third shell wants to have 8 as well More info on Periodic Table Of the 92 naturally occurring elements 25 are essential to life Four of these make up about 96 of the weight of the human body carbon hydrogen oxygen nitrogen Trace elements occur in smaller amounts Carbon 18 5 Oxygen 65 Hydrogen 9 5 Chemical Bonds Link Atoms to Form Molecules Compounds two or more elements Kinds of chemical bonds o Covalent bonds Ionic bonds o o Hydrogen bonds Covalent Bonds Covalent bonds form when atoms share electrons Very strong bonds Examples o Hydrogen molecule H2 o Oxygen molecule O2 o Water H2O Ionic Bond Ion an electrically charged atom or molecule Positively charged ion forms if an atom or molecule loses electrons Negatively charged ions forms if an atom or molecule gains electrons Ionic bond attractive force between oppositely charged ions Example NaCl Hydrogen Bond Form between polar molecules Polar molecules o Contain polar covalent bonds in which there is unequal sharing of Hydrogen bond electrons molecules o Electrically neutral overall but uneven charge distribution o Weak attraction between oppositely charged regions of polar o Example weak forces between water molecules The amazing life giving properties of water 75 of Earth s surface is water The Structure of Water H2O is a polar molecule Why o 1 proton o 8 protons o Oxygen grabs hydrogen January 17 2014 Lipids insoluble in water Triglycerides energy storage molecules Phospholipids cell membrane structure Steroids carbon based ring structures Triglycerides Also known as fats and oils Composed of glycerol and three fatty acids o Fatty acids Saturated in fats Unsaturated in oils Stored in adipose tissue fat tissue Energy storage molecules See Figure 2 16 Phospholipids Structure o Glycerol two fatty acids and phosphate group o One end of molecule is water soluble hydrophilic o Other end is water insoluble hydrophobic Function o Primary component of cell membranes Steroids Structure Examples o Composed of four carbon rings o Cholesterol o Hormones Estrogen and testosterone Cholesterol is a normal component of the cell membrane Estrogen is the female sex hormone synthesized from cholesterol Testosterone is male sex hormone synthesized from cholesterol Proteins Long chains polymers of subunits called amino acids Amino acids o 20 different types o Amino end carboxyl end R group Amino acids are joined by peptide bonds which are produced by dehydration synthesis reactions Protein Function Depends on Structure Primary structure o Amino acid sequence o Stabilized by peptide bonds