BIOL 110 Notes Biology the study of life Prokaryote v Eukaryote Characteristics of Life Eukaryotes have a nucleus and membrane bound organelles Prokaryotes lack a nucleus and membrane bound organelles Reproduction mobility metabolism sum total of all chemical reactions in the body growth excreting waste taking in nutrients adapting responding to external environment maintaining homeostasis consists of cells contains hereditary material that can be replicated DNA Viruses living or non living Biologists argue if viruses are living organisms majority believe they are not because they cannot replicate outside of the host cell Natural Selection The process by which an organism can adapt to its environment overtime by changes in successive generations differential reproduction Natural Selection v Evolution Evolution and natural selection are NOT interchangeable Evolution a change in the genetic structure of a population individuals do not evolve evolution is a population level phenomenon During natural selection only organisms with the ideal genetics to fit a specific environment will reproduce there must be genetic variation in the population for N S to occur Evolution Canyons A natural lab for studying evolution Useful because conditions on the North facing slope is different than that of the South facing slope This allows researchers to study species reactions to their environment Evolution and Biodiversity There are approximately 10 100 million species on Earth all of which are composed of Carbon based molecules need water to survive Carbon based molecules lipids carbohydrates nucleic acids and proteins Our understanding has changed dramatically in 200 years Evolutionary processes began 4 5 billion years ago Water Essential to life Some need more water than others but every living species needs some to survive Polar molecule slightly positive Hydrogen side and slightly negative Oxygen side Hydrogen bonds a strong bond that occurs when a Hydrogen atom bonds with Oxygen Nitrogen or Fluorine O N and F are the most electronegative elements on the periodic table Electronegativity the tendency for an atom or molecule to pull another atom towards itself H bonds leads to many of water s special properties cohesion adhesion high heat of vaporization high heat capacity Cohesion occurs when water molecules bond with other water molecules high surface tension at the top insects can walk on water Adhesion occurs when water molecules adhere to other surfaces capillary action in plants water molecules stick to the inside of roots High heat of vaporization water takes a lot of energy to go from the liquid to gas phase when we sweat we release a lot of energy trying to get the excess water in our systems to leave our bodies through evaporation this cools us down High heat capacity water temperature does not fluctuate easily this helps us maintain homeostasis so we always have a constant internal temperature Solid form ice is less dense than its liquid form water because of the H bonds When it is ice the bonds are rigid and do not move allowing a lot of space and air to come in between the separate water molecules This is important because it allows there to be organisms in bodies of water if ice was not less dense when it got cold the whole lake pond or river would freeze and kill the fish and other animals that live there Good solvent because of its polarity nonpolar substances such as waxes fats and oils do not dissolve freely in water they are considered hydrophobic Hydrophobic substances that do not readily dissolve in water or other polar substances water fearing Hydrophilic substances that readily dissolve in water or other polar substances water loving Dehydration Synthesis A process in which molecules are being joined together with the release of water Anabolism building up Endothermic reaction Hydrolysis A process in which molecules are being broken apart by the addition of water Catabolism breaking down Exothermic reaction Carbon Proteins Backbone of biological molecules C s 4 valence electrons allow bonds to form easily it can also form single double or triple bonds this leads to many combinations and 3D structures Carbon based molecules lipids carbohydrates nucleic acids and proteins Monomer single unit amino acid Polymer multiple units polypeptide held together by peptide bonds Function structure Variable R groups Nonpolar hydrophobic Polar hydrophilic Electrically charged acidic or basic hydrophilic Four Levels of Protein Structure Primary the sequence of amino acids beads on a chain with each bead being a different amino acid Secondary because of the H bonds the proteins forms shapes such as the alpha helix or beta pleated sheets Tertiary further folding of polypeptide due to hydrophobic hydrophilic interactions of the variable groups Quaternary two or more polypeptides join together to make a functional protein Lipids Function store energy Three types Dietary fats triglycerides Phospholipids make up cell membrane Steroids send signals within body All are hydrophobic Saturated v Unsaturated A saturated fatty acid has no C double bonds solid at room temperature and is most commonly animal fat An unsaturated fatty acid has at least one C double bond liquid at room temperature and is usually a type of vegetable oil The bent shape that results from the double bond helps the fats to pack in tightly causing it to be a liquid Cholesterol a precursor molecule for steroidal hormones Helps make bile which aids in digestion High density lipoproteins HDL a lipoprotein lipid protein that is more protein and less cholesterol that helps pick up extra cholesterol that gets stuck in the arteries Steroids Low density lipoproteins LDL a lipoprotein that is more cholesterol and less protein which sticks to the arteries causing high blood pressure The Earth The age of the Earth Approximately 4 5 billion years old Life originated 3 5 billion years ago The Earth s surface is dynamic always moving because of the magma core the tectonic plates are always moving Earth s early atmosphere was highly reducing with very little oxygen gas Hard Evidence of Evolution of Life Fossil record sedimentary rocks preserved some animals with skeletons and hard outer coverings most commonly found near water such as lakes swamps and oceans consists of gaps because of bias mainly arthropods like crabs jellyfish or other animals that did not fit the specific criteria would be less likely to be preserved in rock it all