BS 161 Final Examination Notes Chapter 1 1 Scientific Inquiry Observation the act of viewing the world around us Experimentation a disciplined and controlled way of asking and answering questions about the world in an unbiased manner Hypothesis Questions that arise from observations and proposing tentative explanations Exploration Investigation Communication This is known as Scientific Inquiry Variable a researcher deliberately introduces something different Test Group a theory that results change based on variable Control Group Expectation is that no effect will occur in this group A theory is a general explanation of natural phenomena supported by many experiments and observations Chapter 1 2 Chemical and Physical Principles The living and nonliving worlds follow the same chemical rules and obey the same physical laws First Law of Thermodynamics Energy can neither be created nor destroyed Second Law of Thermodynamics the degree of disorder number of possible positions and molecules in the universe tends to increase The Entropy is considered the disorder of a system Scientific inquiry shows that living organisms come from other living organisms For example microbial bacteria communities occur from letting live meat rot Chapter 1 3 The Cell Cell simplest entity that can exist as an independent unit of life Nucleic acids store and transmit information needed for growth function and reproduction In all organisms the information archive is a remarkable molecule known as deoxyribonucleic acid DNA DNA is a double stranded helix with each strand made up of varying sequences of four different kinds of molecules connected end to end The information encoded in DNA directs the formation of proteins Proteins the key structural and functional molecules that do the work of the cell Existing proteins create a copy of the DNA s information in the form of a closely related molecule known as ribonucleic acid RNA Transcription the synthesis of RNA from a DNA template Translation Specialized molecular structures within the cell then read the RNA molecule to determine which building blocks to use to create a protein The pathway from DNA to RNA mRNA to protein is known as the central dogma of molecular biology DNA Transcription RNA Translation Protein DNA can be replicated allowing genetic information to be passed from cell to cell or from an organism to its progeny Mutations Errors in DNA can and do occur during the process of replication and environmental insults can damage the DNA sequence Membranes define cells and spaces within cells Plasma Membrane Separates the living material within the cell from the nonliving environment around it The membrane selects certain molecules to enter exit the nucleus Nucleus houses the cell s DNA Cytoplasm a discrete space within the cell seperate from the space outside the nucleus Prokaryotic Cells with NO nucleus Eukaryotic Cells WITH a nucleus Three domains of life Bacteria Archaea and Eukarya Metabolism converts energy from the environment into a form that can be used by cells Metabolism describes chemical reactions by which cells convert energy from one form to another and build and break down molecules ATP All organisms use chemical reactions to break down molecules in the process of releasing energy that is stored in a chemical form A virus is genetic material that requires a cell to carry out its functions A virus infects a cell by binding to the cell s surface inserting its genetic material in the cell and in most cases using the cellular machinery to produce more of itself Chapter 2 1 Properties of Atoms Elements Materials of nature that are made up of a small number of fundamental substances combined in various ways Think Carbon Hydrogen and Oxygen Atoms consist of protons neutrons o and electrons Atomic mass Determined by protons and neutrons added together Isotopes atoms of the same element that have differing numbers of neutrons Ions Electrically charged atoms Electrons occupy regions of space called orbitals Orbital where an electron is present most of the time Elements have recurring or periodic chemical properties Chapter 2 2 Molecules and Chemical Bonds Atoms combine with other atoms to form molecules A chemical bond holds the two atoms together by force of attraction A covalent bond occurs when two atoms share electrons Valence Electrons outermost electrons with the highest energy level The orbitals of the two atoms merge causing a molecular orbital Double Bond when two adjacent atoms share two pairs of electrons A polar covalent bond is characterized by unequal sharing of electrons Electronegativity The unequal sharing of electrons results from a difference in ability of the atoms to attract electrons Electronegativity increases across a row Nonpolar Covalent Bond A covalent bond between atoms that have the same or nearly the same electronegativity An ionic bond forms between oppositely charged ions A chemical reaction involves breaking and forming chemical bonds Reactants Atoms or molecules independent Products the result of the molecules or atoms being chemically rearranged Chapter 2 3 Water Water is a polar molecule Polar attracts Polar Nonpolar attracts Nonpolar Hydrophilic Water loving or water attracting Hydrophobic Water Fearing or Water Repelling Water is a reliable solvent that can dissolve many substances when it is polar Water is repelled in Nonpolar environments A hydrogen bond is an interaction between a hydrogen atom and an electronegative atom H N O or F Hydrogen bonds give water many unusual properties Cohesion Hydrogen bonds give water molecules a property known as Cohesion that cause them to stick together pH is a measure of the concentration of protons in a solution pH 7 Neutral pH lower than 7 Acidic pH greater than 7 Basic Base Chapter 2 4 Carbon Organic Molecules Any living thing that contains Carbon molecules Carbon atoms form four covalent bonds Carbon based molecules are structurally and functionally diverse Isomers Molecules that have the same chemical formula but can be arranged in different structures Chapter 2 5 Organic Molecules Proteins Provide structural support and act as catalysts that facilitate chemical reactions Nucleic Acids Encode and transmit genetic information Carbohydrates Provide a source of energy and make up the cell wall in bacteria plants and algae Lipids Make up cell membranes store energy and act as signaling molecules Polymers Complex molecules made up of repeated simpler units that are