Biology 1010 Class Notes PDF

Class Business Biology 1010 Assessments Office Hours – Must bring lab manual to all – Gunnels (WH 264) labs W: 10 – 12 – Please refer to the syllabus By appointment...

Class Business Biology 1010 Assessments Office Hours – Must bring lab manual to all – Gunnels (WH 264) labs W: 10 – 12 – Please refer to the syllabus By appointment – cc Gissela Bravo for the schedule ([email protected]) Today’s Agenda – Chapter 1 – Life: Evolution – Chapter 2 – Chemical Basis of Life Chapter 2 – Chemical Basis of Life  Chemical Context of Life Matter – Matter takes up space and has mass Elements in pure form (Hydrogen, Oxygen) – 92 naturally occurring elements Compounds in combination (H2O, O2) – Infinite combinations C:\Documents and Settings\cgunnels\Desktop\FGCU USB Files\Biology 1010\Spring 2008\Lectures\Week 1 - Chap 1_2\sweaty t-shirt test.jpg MHC Sweaty T-shirts and Human Mate Choice  Smallest particles that retain chemical elements Cannot be broken down by chemical reactions Atoms Foundation of life Largely indivisible Made up of subatomic particles  Anatomy of an Atom Helium Proton - Neutron Electron Nucleus + + - Atomic Number = Proton Atomic Mass ≈ Proton + Neutron  Filled electrons = Atom of Major 4 Occupied electrons = First Outermost electron shell electron shell (can hold (can hold Valence Shell = Outer shell 2 electrons) 8 electrons) Hydrogen (H) Carbon (C) Nitrogen (N) Oxygen (O) Atomic number = 1 Atomic number = 6 Atomic number = 7 Atomic number = 8 What is the atomic mass of each atom?  Biologically important Elements Big 6 (96% - CHNOPS) 5 Minor (4%) – Carbon (C) – Ca, K, Na, Cl, Mg – Hydrogen (H) 14 Trace – Nitrogen (N) – Oxygen (O) – Phosphorus (P) DNA & ATP – Sulfur (S) Protein folding Average Percentage in Living Organisms  Trace Elements Iodine deficiency results in enlarged thyroid gland, i.e., Goiter Triiodothyronine and thyroxine not produce – Iodine in these hormones  Goiter What is the role of triiodothyronine and thyroxine in the development of the thyroid gland? Iodine Deficiency The presence of triiodothyronine and thyroxine act as negative feedback in the production of thyroid stimulating hormone.  Isotopes Proton number is consistent for each element Neutron number can variation Carbon Isotopes describe the different forms of elements C-12 C-13 C-14 6 Protons 6 Protons 6 Protons 6 Neutrons 7 Neutrons 8 Neutrons 6 Electrons 6 Electrons 6 Electrons Stable Radioactive  Sea Turtle Ecology – Stable Isotopes Where do adolescent sea turtles migrate? – Compare C-13 values in shell to determine the where green sea turtles spend their lost years – 1 – 5 years in open ocean eating live prey Higher ratio of heavy isotopes than vegetarian diet  Compounds Substance consisting of two or more different elements Compound differs from constituent parts. + Sodium Chloride Sodium Chloride  Chemical Bonds Atoms with incomplete valence shells will be attracted to each other – Ionic Bonds – Covalent Bonds – Hydrogen Bonds  Ionic Bonds One element donates an electron to another element – Salt – Complete polarity Cation – Donating ion = positively charged Anion – Recipient ion = negatively charged – Electron orbits do not overlap – What holds the elements together? Electrostatic Interaction  Covalent bonds Elements share electron(s) = molecule Oxygen Oxygen approach each other to complete valence shell Nonpolar bond  Electronegativity Influenced by elements density and fullness of valence shell. – Higher density & Complete Valence Shell = Higher Electronegativity ↑ electronegativity = e- attractor Oxygen Carbon Sulphur Oxygen  Electronegativity, so what? High to low Which is easier to separate? electronegativity – N–H – O>N>C≈H – C–H Which molecule releases the – The larger the differencemost energy when broken? The tighter the grip on – Ammonia (NH3) the shared electron(s) – Methane (CH4)  Electronegativity Electronegativity difference among atoms affects the type chemical bond.  Polar Covalent Bond O H H H H Many covalent bonds are polar when shared electron is more attracted to one of the elements – Attracted to element with Oxygen (-) greater electronegativity – Water Oxygen = negative Hydrogen = positive Hydrogen Hydrogen (+) (+)  Hydrogen Bond Adjacent polar molecules attach from negative to positive polar ends  Van der Waals Forces Continuous movement of electrons can create hotspots (negatively and positively charged areas) in elements and molecules Nonpolar O2 Carbon  Gecko Toe Pad Why can some gecko’s walk on smooth surfaces like glass?