**Refer to your pre-lecture notes for all the sections we will be covering to help you keep an eye on the big picture

Transcription

1 Section 1: Human Organization and the chemistry of life **Refer to your pre-lecture notes for all the sections we will be covering to help you keep an eye on the big picture Biology Bio = life ology = the study of therefore, Biology= scientific study of living organisms and their environments A) Characteristics of living things: All living things share 7 basic characteristics: They 1. are organized 2. Take materials and energy from environment 3. reproduce 4. grow and develop 5. are homeostatic = internal conditions have narrow range of variation 6. respond to external and internal stimuli 7. can adapt to changing environment (have an evolutionary history) B) Organization of living things Atom the smallest unit of an element (note: periodic table) Molecule - union of 2 or more atoms chemically bonded together can be made of the same or different elements Cell -the structural and functional unit of all living things composed of macromolecules Tissue groups of cells with specialized structure and function (4 types: connective tissue, muscle tissue, nervous tissue, epithelial tissue) Organ groups of tissues working together for specific function (heart, lung, liver etc) Organ system groups of organs working together (we will cover: digestive system, urinary system, cardiovascular system, lymphatic system, respiratory system, skeletal, muscle, nervous system) Organism: an individual, can be Unicellular (1 cell) or multicellular (has many different types of cells) - may contain organ systems in this class - human

2 The Big Picture: Use these levels of organization to help visualize the big picture relate each new thing we learn to the Big Picture of how we are put together and how those parts work together to keep our bodies working C) Chemistry of life I. Elements Listed on periodic table (~111) Cannot be broken down by chemical means and still retain the same chemical and physical characteristics Biological organisms composed mainly of 4 elements: 1. Carbon C 2. Hydrogen H 3. Oxygen O 4. Nitrogen N Plus micronutrients such as: iron (Fe), sulfur (S), calcium (Ca), sodium (Na), potassium (K), and magnesium (Mg) Arranged in periodic table according to number of protons, atomic mass and chemical reactivity II. Atoms Smallest unit of an element that still retains its chemical and physical characteristics Building blocks of everything!! Made up of subatomic particles these particles determine the atomic mass and how it will bond.

3 Subatomic particles: Particle Symbol Charge Location Atomic mass Proton p + nucleus 1 neutron n No charge nucleus 1 electron e- - orbitals 0 Atoms are electrically neutral # of protons = # of electrons Example: sodium (Na) has 11 protons has 11 electrons These electrons are found in rings or orbitals around the nucleus. First orbital hold a max of 2, and we will say the rest have max of 8e- (it s more complicated but to keep it simple) Each atom is made up of protons, neutrons and electrons the mass of the atom = the amount of these Each proton and neutron have atomic mass unit of 1 E- so light, practically 0 don t effect mass of atom What the periodic table symbol tells us: =# of protons =# of protons+ neutrons carbon has 6 protons, 6 electrons, and 6 neutrons (atomic mass atomic # = # of neutrons)

4 III. Matter Classification of matter Ionic compound Covalent compound Matter = anything that has mass and occupies space Can be invisible (i.e., air) Matter is made up of tiny particles called atoms Matter divided into: 1. Pure substance 2. Mixture 1. Pure substance = 1 or more atoms chemically bonded together When 2 or more atoms are bonded together call it either a molecule or a compound. a) Molecule = Molecules form when two or more atoms form chemical bonds with each other. It doesn't matter if the atoms are the same or are different from each other. Examples: H2O (water) O3 (ozone) C6H12O6 (glucose, a type of sugar) **and Single atoms of elements are not molecules

5 If a molecule is made up of 1 type of element (but more than 1 atom) then then you call it by its element name. b) Compounds = Molecules made up of two or more elements are called compounds. Water and glucose are molecules that are compounds ozone is not! All compounds are molecules; not all molecules are compounds. Compounds are divided into the 2 types: All elements want to be stable, elements are stable when they have 8 electrons in their outer orbital (shell) i. Ionic compounds an ionic compound is held together by attractive forces between + and charges. One atom of an ionic compound gives up electrons (loses e-), and the other atom will gain electrons so they get 8e- in their outer shell so they transfer e- from one to the other to become stable i.e. sodium chloride (salt) Attraction between cation (=positive ion) and anion (=negative ion) (ion=charged atom) forms ionic bond. ii. Covalent compounds formed when elements share electrons in outer orbit Formed by electron sharing between atoms Important for building biological macromolecules (carbohydrates, proteins, lipids, nucleic acids) because they don t dissolve in water (ionic bonds do) human body is ~60-70% water.

6 Strong! Example: water 2. Mixture = 2 or more pure substances physically mixed together subdivided according to appearance: 1) Homogenous mixture appears uniform when physically mixed together black coffee& white milk when mixed 2) Heterogeneous mixture non uniform in appearance exampleaggregate cement D) Water and Living things 60 to 95 % of an organism is composed of water due to the chemical and physical properties of water, life on earth has evolved and is able to continue. Why is water like it is? Because the oxygen atom has 8 protons, the electrons in hydrogen atoms are more attracted to the oxygen nucleus and spend more time nearer this atom. Oxygen has a slightly negative charge ( δ- ) because it is hogging the e- hydrogen atoms get the shared electrons less, therefore is slightly positive (δ+)

7 This makes a water molecule polar: δ- oxygen end δ+ hydrogen end Because water is a polar molecule, it can form hydrogen bonding with other water molecules: A hydrogen bond is formed when a δ+ hydrogen atom in one molecule is attracted to a δ- atom in another molecule However, it is weak - broken relatively easily Six Properties of water: (Due to polarity and hydrogen bonding) 1. liquid at room temperature. Usually low molecular weight compounds are gases at room temp, but water molecules are cohesive (stick together) because of hydrogen bonding. 2. Temperature of water rises and falls slowly: hydrogen bonding can absorb lots of heat has high heat capacity highest almost of any compound on earth - therefore gain and lose heat slowly = maintains internal temperature (homeostasis) 3. Water has hi heat of vaporization takes lots of energy to turn water liquid to gas (steam) - therefore moderates earths temp so life can exist. 4. Frozen water is less dense than liquid water therefore ice floats - water expands when it freezes because hydrogen bonds are farther apart in rigid ice - therefore isolates and protects aquatic organisms. 5. Water molecules are cohesive therefore can fill blood vessels - allows dissolved and suspended molecules to move throughout the body. 6. Like dissolves like - water is a polar solvent; dissolves other charged (ionic) substances - helps chemical reactions inside body.

8 A couple of definitions... Hydrophilic ions and molecules interact with water are water loving Hydrophobic molecules (nonionized/nonpolar) do not interact with water are water hating 4-sticky-water-video.htm E) Acids and Bases (Chapter 2.3) Acid: An Acid is a substance that gives H + ions when dissolved in water. Acids are compounds that contain Hydrogen (Hydrochloric, HCl; Sulphuric, H2SO4). Not all compounds that contain Hydrogen are acids (Water, H2O; Methane, CH4). Base: A Base is a substance that gives OH - ions when dissolved in water. Bases are usually metal hydroxides (MOH). Examples include Sodium Hydroxide, NaOH, Calcium Hydroxide, Ca(OH)2. Water also dissociates (breaks apart) a few molecules at a time H2O H + + OH - Hydrogen ions hydroxide ions When water dissociates into H+ and OH- ions, the amount of these ions in a solution can affect how acidic or basic a solution is. Acidic solutions: Have high hydrogen ion concentration Release excess H + in solution Low ph number Basic solutions: Release OH - (hydroxide ions) in solution High ph number

9 ph Scale = Acidity is measured on a scale called ph. The value of ph determines how acidic or basic a solution is. A ph of 1 is very acidic; a ph of 14 is a strong base (alkali). A neutral solution (or pure water) has a ph of 7. ph scale = as it goes from one number to the next up the scale, the next # up has 10x fewer H + ph scale=potential hydrogen ion concentration acidic neutral basic Buffers: a buffer is a substance that keeps ph within normal limits. They resist ph changes because these substances are able to take up excess H+ or OH- ions to stabilize ph. Buffers are extremely important in our bodies because we have to keep a stable ph in our blood of ~ 7.4. F) Intro to Molecules of Life: Macromolecules (no reading) Molecules of life are organic molecules Organic molecules = contain carbon and hydrogen atoms (salts, and water are inorganic molecules- have no carbon there are organic acids and bases) Biological 1 macromolecules are important cellular components and perform a wide array of functions necessary for the survival and growth of living organisms. they are polymers (poly= many) that are synthesized via dehydration reactions out of smaller components called s or monomers. they can be broken back down into their simpler components via hydrolysis rxn. 1 Source: Boundless. Types of Biological Macromolecules. Boundless Biology. Boundless, 21 Jul Retrieved 28 Jul from 1

10 4 major types of macromolecules (Macro = big!) Name Carbohydrates Proteins lipids Nucleic acids Subunits (what molecules it is made of) monosaccharides (sugar molecules) Amino acids Glycerol + 3 fatty acids nucleotides Dehydration synthesis = chemical rxn where s (+monomer) join together H+ ion is pulled from one of the molecules, and OH- ion is pulled from the other molecule and they join where they were the H+ and OH- were pulled off Hydrolysis - chemical rxn where s (monomers) come apart from each other in a chemical rxn called hydrolysis - water breaks down and H+ from water attaches to one of the broken s, and the OH- from the water joins the other broken molecule. Subunit + macromolecule + H2O OH H dehydration reaction H 2 O a. OH H hydrolysis reaction H 2 O b.

11 An intro to a Specialized Nucleotide: ATP ATP = Adenosine Triphosphate= a specialized nucleotide = (nucleotide = of nucleic acid) ATP is an energy carrier molecule in cells Energy is used in cellular metabolism to make macromolecules, or in muscle cells for muscle contraction, and in nerve cells for conduction of nervous impulses etc. ATP is formed from the breakdown of glucose (a sugar molecule) it is stored as glucose (usually in the liver) until the cell requires energy, then the glucose is converted to ATP A glucose molecule contains too much energy to be used as a direct source in cell reactions. Instead the energy of glucose is converted to ATP.ATP has an amount of energy that a cell can use to supply chemical reactions in cells.