Biology 1201

Biology 1201 - Biology 1201 Exam 1: Thursday Jan 31 review...

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Biology 1201 Exam 1: Thursday Jan 31 – review sessions: Mon 5:30-7:00 & Tues 4:30-6:00 Jan 28-29 5:30 A101 Life sciences Ionic bonds - Weak bond - Transfer of electron from one atom to another. - Figure 2.13 Covalent bonds - Strong bonds - Sharing of electrons to complete the valence shell - Figure 2.12 Polar bonds - Unequal sharing of electrons - Partial + and partial – regions - No net charge Hydrogen Bonds - Weak (non-covalent bonds) - Between partial positive and partial negative bonds. - The major categories of bonds are not based on the number of electrons involved. Polar bonds result from the transfer of electrons between atoms- false Water - 70 to 90 % of weight of most life forms
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- Sets the lower temperature limit for life - Sets the upper temperature limit? (Probably not) - Important role in structures and properties of biological molecules - Water is a biological molecule The unusual properties of water - Result of hydrogen bonding - Water behaves as a much larger molecule Bonds - Covalent: H-O 110 kcal per mole - Weak (hydrogen bond): 4.5 kcal/mol - -H bonding effectively makes water a larger molecule - In ice a water molecule interacts with exactly 4 other water molecules - In liquid water, on average 3.6 or fewer other molecules (can be made and broken very quickly) - Figure 3.5x1a Water, 3.5x1c steam Small molecules- a comparison of properties - Water- H2O - Ammonia- NH3 - Ethanol- CH3Ch2 Properties - Water- boils at 100 degrees C - Ammonia- 35 degrees C
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- Ethanol: 78.5 degrees C - Ice melts at 0 - Ammonia melts at -77 - Ethanol melts at -117.3 Unusual properties of water 1. High heat capacity - Amount of heat to raise temperature of 1g of water by one degree - 1 cal per g of water 2. High heat of vaporization - Amount of heat to vaporize 1 g of water - 540 cal per g at 100 degrees C 3. High heat of fusion - Amount of heat removed to freeze 1 g of water - 80 cal per g 4. Most dense at 4 degrees C - Because of the hydrogen bonding structure, ice is lighter than water 5. High dielectric - Good solvent
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6. Capillary action and surface - Due to hydrogen bonding 7. Ionization - Dissociation into acid (hydronium ion) - And base (hydroxyl ion) pH- a review - pH= log [1/H+] = -log [H+] - actually activity of H+ pH scale - log base 10 - as pH decreases, concentration increases - the difference between pH 3 and pH 4 is a 10-fold difference in the concentration of H+ - the difference pH 3 and pH 5 is a 100 fold diff in the concentration - pH of 7 is neutral - pH below 7 is acidic pH above 7 is basic Biological Molecules - water - carbohydrates - liquids - proteins
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- nucleic acids Functional Groups - hydroxyl – alcohols - Carbonyl- aldehydes (terminal carbon) and Ketones - Carboxyl- Acid group - Amino- Amines - Sulfhydryl- Thiols - Phosphate- Organic Phosphates - Figure 4.5 variations in carbon skeletons Each carbon require 4 covalent bonds to fill its outer shell Biological Molecules - Large molecules constructed from smaller molecules - Polymers
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Biology 1201 - Biology 1201 Exam 1: Thursday Jan 31 review...

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