Chapter 2 - Chemistry of Life PDF

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Summary

Dr. Jef Jaeger. BIO 100 Sec 1002. Chapters based on book "Biology of Humans, Concepts, Applications and Issues – Second Edition Edition for UNLV (based on
Sixth Edition) Authors: Judith Goodenough and Betty McGuire. Pearson/Prentice Hall Publishing"...

Description

1. At the cellular level, chemistry merges with life a. Matter: physical substance that takes up space and has mass Gas, liquid, solid, plasma b. Element: pure form of matter containing one kind of atom c. Atom: smallest particle of an element Cannot be broken down by ordinary chemical processes Earth is made up of less than 100 natural elements, plus some others Subatomic particles 1. Protons a. Positive charge b. Has mass c. Used to determine identity 2. Neutrons a. No charge b. Has mass c. Number can change 3. Electrons a. Negative charge b. Mass is negligible (may have mass, just small, so unimportant) c. Number can change 2. Atoms a. Mostly “empty” space b. Nucleus contains mass 3. Elemental composition of organisms a. CHNOPS (approx. 98% of living organisms):

4. Elements (Periodic Tables) a. 25 elements important to life b. Atomic number = number of protons c. Atomic mass = number of protons and neutrons 5. Isotopes a. Atoms of a particular element all have the same number of protons, but they can differ in number of neutrons b. Example: carbon 6. Electrons a. Orbits around nucleus - shells (energy levels) b. Inner shell may hold 2 electrons

c. Outer shell are known as valence electrons 7. Chemical bonds a. Bonds between atoms are a form of chemical energy b. Atoms form bonds because doing so moves them to a more stable energy state c. Atoms have a propensity to attain complete shells, thus becoming more stables d. Formulas: i. Water = H2O ii. Oxygen gas = O2 iii. Glucose = C6 H12 O6 8. Three types of bonds: covalent, ionic, hydrogen a. Covalent bonds “strongest” i. Sharing of electrons between atoms ii. Law of Conservation of Mass: matter is neither created nor destroyed in chemical reactions b. Hydrogen bond (weakest) i. Bonds between already covalently bonded hydrogen with an electronegative atp, c. Molecule: a group of atoms bonded together i. Polar molecule = different area of the molecule have slightly different charges d. Ionic bonds (strongish) i. Transfer of electrons between atoms ii. In neutral atoms: electrons = protons iii. Lose or gain electrons and an atom takes on an electrical charge (+ or -) iv. Ionic attraction: sodium and chloride ions attract because of opposite charges e. Hydrogen bonding among water molecules f. Hydrophilic i. Water loving 1. Compounds that readily interact with water g. Hydrophobic i. Water hating 1. Compounds that water forms itself around h. Water is critical to life - life first evolved in water i. Vertebrate animals are ~ 70-80% water ii. Terrestrial plants are ~ 90% water i. Unique properties of water i. Solvent 1. Polarity allows water to interact with many substances (main transport for organisms) ii. Cohesive iii. High heat capacity iv. High heat of vaporization 9. Acids and Bases a. Water molecules can dissociate to produce ions b. Acids yield H+ (hydrogen ions)

i. Example: Hydrogen Chloride c. Bases accept H+ i. Example: Sodium Hydroxide d. pH: the concentration of hydrogen ions in a solution (acidity of a solution) i. 0-14 (most acid-most basic) ii. Based on log scale - 10 fold differences e. Buffers i. Substances that keep pH from changing ii. Buffers yield or accept H+ 10. Biological molecules a. Carbohydrates i. Sugars, starches, and fibers ii. Simple carbohydrates (simple sugars) 1. Monosaccharides = 1 sugar a. Glucose or Fructose 2. Disaccharides = 2 sugars a. Lactose iii. Complex carbohydrates - “polysaccharides” = many sugars

iv.

1. Made of repeating units of simple sugars Macromolecules, like complex carbohydrates, are made of repeating units generically called monomers 1. Formed through dehydration synthesis 2. Broken apart through hydrolysis

b. Lipids i. Fats, oils, waxes

ii. iii.

Insoluble in water - nonpolar High ratio of H to O

iv.

Major uses: energy, energy storage, insulation (poor conductor of heat), protection, cellular structure and function

V. Fatty acids

1. Saturated fatty acid 2. Unsaturated fatty acids a. Double bond between carbons change physical shape of the molecule, thus its behavior 3. Triglycerides = 3 fatty acids, bound to glycerin. Most common fat, consumed in food 4. Phospholipids a. Hydrophilic head b. Hydrophilic tails c. Phospholipid bilayer c. Proteins i. Molecules that facilitate biological functions ii. Thousands of different types and functions iii. Types: 1. Enzymes - quickens chemical reactions 2. Transport - moves other molecules 3. Contractile - muscles movement 4. Structural - physical or mechanical support 5. Protective - defends 6. communication iv. Proteins are polymers 1. Peptides - large molecules made up of smaller units 2. Amino acids - building blocks of peptides and proteins a. Number of types - 20 b. Two main types i. Essential = only obtained by humans from food ii. Non-essential = synthesized in body 3. Structure a. Primary - specific sequences of amino acids b. Secondary - bending and coiling of the amino acid chain c. Tertiary - 3D shape of the protein d. Quaternary - assemble subunits d. Enzymes - proteins that speed up chemical reactions

i. Don’t make the impossible happen, just make the unlikely occur ii. Very specific, often only one action iii. Example - lactose → the enzyme lactase breaks down lactose e. Nucleotides - small molecules important for: i. Transfer of energy in cells ii. Store and transmission of genetic information iii. Used in genetic information 1. DNA made of nucleotides, “bases”: a. Adenine b. Guanine c. Cytosine d. Thymine 2. Sequence of bases determines sequence of amino acids in proteins f. Cellular energy transfer i. Breaking and forming of bonds in ATP = release and storage of energy 1. ATP 2. ADP...