Chapter 1: Biology- The study of life A Hierarchy of Organization 1. Molecules 2. Organelle 3.
Cell 4. Tissue 5. Organ 6. Organism Emergent Properties- Novel properties that emerge as each step up the hierarchy of biological order is taken. Reductionism- Reducing complex systems to simpler components that are more manageable to study. Cells- The lowest level of structure capable of performing all the activities of life, all organisms are composed of cells which are the basic units of structure and function.
The cell theory- The ability of cells to divide to form new cells is the basis for all reproduction and for the growth and repair of multicellular organisms, including humans. Two Major Kinds of Cells Eukaryotic cells- Membrane enclosed organelles in which DNA is organized along with certain proteins into structures called chromosomes contained within a nucleus, the largest organelle of most eukaryotic cells. Around the nucleus is a cytoplasm in which are suspended the various organelles that perform most of the cells functions.Plants eukaryotic cells have tough cell walls external to their membranes, while animal eukaryotic cells do not.
Prokaryotic cells- DNA is not separated from the rest of the cell in a nucleus, prokaryotic cells lack the cytoplasm organelles typical of eukaryotic cells. Almost all prokaryotic cells have tough external walls. DNA- The substance of genes. The units of inheritance that transmit information from parents to offspring. Nucleotides- Four chemical building blocks that make up strands of DNA.
Genome- The entire “library” of genetic instructions that an organism inherits.Open System- An entity that exchanges materials and energy with its surroundings. Energy Conversi...
on- The exchange of energy between an organism and its surroundings involves the transformation of one form of energy to another. Negative Feedback (Feedback inhibition)- slows or stops processes. Positive Feedback- Speeds up a process. Diversity- Biologists have identified and named about 1.
5 million species. Taxonomy- The branch of biology that names and classifies species, formalizes this hierarchical ordering which includes kingdoms and domains.Natural Selection- An editing process, with heritable variations exposed to environmental factors that favor the reproductive success of some individuals over others. Chapter 2: Matter- Anything that takes up space and has mass.
Element- A substance that cannot be broken down to other substances by chemical reactions. Compound- A substance consisting of two or more elements combined in a fixed ratio. Trace elements- Elements required by an organism in only minute quantities, yet indispensible for life. Compound – A pure substance composed of two or more elements combined in a fixed ratio.Atom- the smallest unit of matter that still retains the properties of an element.
Subatomic particles The three most stable subatomic particles are: 1. Neutrons (neutral) 2. Protons [+1 electrostatic charge]. 3. Electrons [-1 electrostatic charge]. Atomic number – Number of protons in an atom of a particular element.
Mass number – Number of protons and neutrons in an atom. Isotopes – Atoms of an element that have the same atomic number but different mass number. Radioactive isotope – Unstable isotope in which the nucleus spontaneously decays, emitting subatomic particles and/or energy as radioactivity.Half life – Time for 50% of radioactive
atoms in a sample to decay.
Dating geological strata and fossils -Radioactive decay is at a fixed rate. -By comparing the ratio of radioactive and stable isotopes in a fossil with the ratio of isotopes in living organisms, one can estimate the age of a fossil. -The ratio of 14C to 12C is frequently used to date fossils less than 50,000 years old. Electrons – Light negatively charged particles that orbit around nucleus. Energy – Ability to do workPotential energy – Energy that matter stores because of its position or location. Electron configuration – Distribution of electrons in an atom’s electron shells, determines an atoms chemical behavior.
Valence electrons – Electrons in the outermost energy shell (valence shell), chemical properties of an atom depend upon the number of these valence electrons. Chemical bonds – Attractions that hold atoms together. Covalent bond – A strong chemical bond between atoms formed by sharing a pair of valence electrons, such as a molecular hydrogen (H2 ).Structural formula – Formula which represents the atoms and bonding within a molecule Molecular formula – Formula which indicates the number and type of atoms.
Molecules – Two or more atoms held together by covalent bonds. Compound – A pure substance composed of two or more elements combined in a fixed ratio. (Compounds can be molecular or ionic) Electronegativity – Atom’s ability to attract and hold electrons. -The more electronegative an atom, the more strongly it attracts shared electrons. Nonpolar covalent bond – Covalent bond formed by an equal sharing of electrons between atoms.Polar covalent bond – Covalent bond formed by an unequal sharing of electrons between atoms.
Molecular polarity – the overall polarity of a molecule. Ion – Charged atom or group of atoms. Anion – An atom that has gained one or more electrons from another atom and has become negatively charged; a negatively charged ion. Cation – An atom that has lost one or more electrons and has become positively charged; a positively charged ion.
Ionic bond – Bond formed between ions by the electrostatic attraction after the complete transfer of an electron from a donor atom to an acceptor.Hydrogen bond – Bond formed by the charge attraction when a hydrogen atom covalently bonded toone electronegative atom is attracted to another electronegative atom. Vander Wals Reactions – Weak interactions that occur between atoms and molecules that are very close together and result from charge asymetry in electron clouds. Chemical reactions – process of making and breaking chemical bonds leading to changes in the composition of matter. Chapter 3: Water •is a polar molecule.
•Its polar bonds and asymmetrical shape give water molecules opposite charges on opposite sides. Hydrogen bonding orders water into a higher level of structural organization. Water has extraordinary properties that emerge as a consequence of its polarity and hydrogen-bonding. Some of these properties are that water: – has cohesive behavior – resists changes in temperature – has a high heat of vaporization and cools surfaces as it evaporates – expands when it freezes – is a versatile solvent Cohesion – Phenomenon of a substance being held together by hydrogen bonds. Surface tension
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