Chap 2 Chem.

Chap 2 Life requires about 25 elements The “big elements that make up most of an organism’s mass -H: Hydrogen -O: Oxygen > - -N: Nitrogen HONC like -C: Carbon a Elements and homeostasis Living things have a fixed internal environment C Homeostasis - means the composition of the elements in our bodies is different from the environment goose ! The atom Is the smallest unit of matter that maintain the propertie's of the element Subatomic particles proton : (pt) electron (et Single positive charge : One atomic mass unit Atoms of the same & Single negative charge Has no mass Located in a “cloud” outside nucleus (valence electrons- element all have the outermost) same # of pr Neutron . ~ No electoral charge One atomic mass unit - Why We Care about atoms? Isotopes Ions Change in electron # · Positive or negative charge Cell signaling, nerve conduction, muscle contraction. Ex Changes in neutron # “Heavy” or “light” elements Some can be unstable and remit radiation when they decay. : Nat Cl KT, Ca2 , Applications + , PET Atomic number =# protons element symbol 9 H Atomic mass= average mass of all forms of element Nuclear ↑ Numbers on an - 1 008 . Ican - Mass number = protons t neutrons · Isotopes, If given into account the atomic mass, you can find the mass # by rounding to the nearest whole # scan ↑ periods (rows) Represent the # of electron shells More shells means more energy olumns) G ↑ Represent elements that react in a similar way ↑ The group corresponds to the number of outer (valence) electrons The octet rule - Forming bonds Atoms are most stable when they have a full outer (Valence) shell with 8 electrons. & - two this : ways of doing bords : covalent bonds ioni C Interactions between infilled electron shells allows atoms to form... Noble gasses— Group 8, stable because already has a full outer shell : Is this atom stable? Molecules - atoms bonded together Compounds- atoms of different elements bonded together Chemical reactions - are based on the interactions of Yes , 8 valence electrons (formation, or a breaking of bonds) electrons Atomic mass -# of protons =# of neutrons Covalent reactions : - two atoms share pairs of electrons to form a bond ( ( Co- = with/share, -valence = The electrons of the atoms spent in outer valence e- < Ionic reactions -How does shell of each atom Strong bond because shared electrons hold atoms together - Groups 4, 5, 7 sometimes 3 Electrons fulfill, the octet of both bonded atoms L A single bond is to shared electrons it work ? An atom donates its electron(s) to another ex. Like passing a ball Donor (Group 1 or 2, sometimes 3) has a positive charge Recipient (Group 7, sometimes 8) has a negative charge why ? - > Ionic bond - the ions of opposite charge are attracted to each other to form a bond Types of covalent bonds - - * Hydrogen bond: very weak bond, four by attraction Nonpolar covalent bond - even sharing of electrons between partial charges of polar molecules Between atoms with similar electro negativity C-C, C-N, C-H Water is Polar covalent bond - uneven sharing of electrons Polar a Molecule ! High heat capacity: the amount of energy required to raise 1 - Electrons spend more time close to the electronegative is - Electronegativity: the attraction of an atom for electrons in a covalent bond. gram of water 1 degree C. N Water is a good solvent ↑ Molecules that can attract. Water are M hydrophilic. phobic-hates water Dissolves most some sense to form a solution - Ex. Salt water, sugar water, alcohol ↑ philic - Hydrogen bonds absorb & store energy Temperature changes slowly, which helps maintain homeostasis. Molecules that repel water hydrophobic. - Properties of water > - loves Large bodies of water have consistent temp High heat of vaporization: temperature I wish a liquid turns into water a gas (boils) Water is cohesive (sticks together) and adhesive (sticks to other polar surfaces do two hydrogen bonding network) - I This allows organisms to transport materials throughout the body When exposed to air, has a high surface tension Frozen water is less dense than liquid water - - ↑ Solid water (ice) floats Makes life on Earth possible Ice doesn't fall to the bottom of the ocean/lake - Water Acid, Bases And Buffers Acids - molecules when dissociated in water result in an increase in hydrogen ions H+ HCI H+ Cl- (hydrochloric acid) H2SO4 H+ H+ SO4 - 2. (Sulfuric acid) Bases - molecules when dissociated in water result in an increase in OH- ions NaOH Na+ + OH- (sodium peroxide— lye LiOH ↓ H Li+ + OH- (lithium peroxide) is logarithmic < is neutral ! Dissociation of water produces equal number of hydrogen H+ and hydroxide ions OH- Buffers Each number represents 10x more/fewer ions - Lemon juice has a pH of 2, the pH of vinegar is 3 - Lemon juice is 10x more acidic than vinegar & Seawater has a pH of 8, coffee Buffers - are substances that take up excess H+ or OH- to resist pH changes This is how our body protects intestines - has a pH of 5 from stomach acid Central nervous system Sleepiness and loss of consciousness confusion headache Respiratory Coughing and shortness of E breath Heart Muscular / A reduction of serum pH from Weakness - 7.4 to 7.0 could be deadly! Many metabolic reactions may & & Arrhythmia Increased heart rate Gastri Nausea Vomiting Intestinal Diarrhea : only work in a narrow pH range Buffers help maintain pH homeostasis Functional groups Organic molecules Organic molecules contain carbon (and hydrogen) Total of six electrons— four in outer shell Can bond with carbon, hydrogen, nitrogen, and oxygen 4 electrons needed to fill outer valence shell Hydrocarbons - chains of Carbon A specific combination of bonded atoms bonded to hydrogen atoms atoms react in the same way. Store energy in bonds, serve as These groups give organic structural molecules molecules their properties Nonpolar Memorize these groups: Hydroxyl, Carboxyl, Amino, Phosphate (BIMS) Biologically Important Macromolecules Monomers make polymers Monomers: Small building block molecules Analogy: a single bead or a Lego Creating and breaking polymers Dehydration synthesis: Removes water to join monomers into a polymer Also called a condensation reaction Hydrolysis: Adding water to break a polymer into monomers Hydro- = water -lysis = to rupture, break Polymers: Big compounds made from made from joining monomers together Analogy: beads on a string, Legos lined together CARBS Carbohydrates Carbs Functions: - Carbs/starch - - Structure (cellulose in plants) ↑ Cell recognition protein Classified as: - protein - / ~ - ( Energy storage (starch, glycogen) Carbs Carbs , Starch Monosaccharides: simple sugars Disaccharides: two-sugars Polysaccharides: complex sugars Monosaccharides , protein Molecular formula are multiples of CH2O Have three to seven carbon atoms i Typically in a ring structure Glucose is critical to cellular metabolism (starting substrate for cellular respiration) Disaccharides Two simple sugars joined by dehydration synthesis Creates a glycosidic bond glucose + glucose = maltose Glucose + fructose = sucrose Three major kinds: Maltose (beer) Sucrose (sweetner, candy) Lactose (milk) Polysaccharides Starch: Plant storage of glucose Not highly branched (efficient use of space) Glycogen: Structural Polysaccharides Cellulose: Polysaccharides in plant cells walls Parallel glucose chains form rods with hydrogen bonds in between Cannot be digested by most animals Some animals have mutualistic relationship with bacteria to digest it Chitin Like glucose, but with NH2 Found in insects and fungi Animal storage of glucose Extensively branded for easier access to glucose Stored mostly in liver and muscle cells Lipids Main types: 1. Triglycerides Fats: solid atroom temp, usually of animal origin Oils: liquid at room temp, usually of plant origin 2. Phospholipids 3. Steroids All lipids are hydrophobic (Insoluble in water) - emulsifiers have a polar and non-polar end, which allows fats to mix with water efficient efficient - Ex. Soap bile salts Triglycerides Functions: / Long-term energy storage (efficient use of space) C Waterproofing of skin & hair Long term energy storage Composed of one glycerol and three fatty acids ↑ - formed through dehydration synthesis makes an ester bond Fatty acids & - Have an carboxyl group & long chain of hydrocarbons Hydrocarbon chain can bend/kink due to presence of a carbon double bond (C=C) Fatty acid structure and nutrition Unsaturated fat & Have a double bond that causes a kink in the chain Remains liquid at room temp ( - Protects against plaque formation Saturated fat All carbons are fully saturated with hydrogen (straight) - Solidifies more easily in arteries, causing fatty deposits C high consumption associated with high blood pressure and heart attacks H Trans fats & & Phospholipids Glycerol + 2 fatty acids + phosphate group Polar molecule & Hydrophilic- head created by phosphate group I Partially negative oxygen molecules attract water C Hydrophobic- tails created by fatty acids - Excluded from strong cohesive forces of water An unsaturated fat that has been "straighted out" also unhealthy because it solidifies more easily. Steroids Have a backbone of four fused Carbon rings 1 sex hormones (estrogen, testosterone) & cholesterol (also found in cell membrane Insoluble in water Proteins Protein ↑ protein - - - Adaptations and evolution - I Adaptations allow populations to participate in natural selection (difference in reproductive success that results in changes in the population over time) Variation is present in the population - ~ S Some variants help organisms survive and reproduce better in their environment. Successful variations become more common in population of organisms over time. If population change in different ways, new species may emerge. Car sis Protein