Biology Molecule

Biology Molecule Unit 1 -man is high 50s to 60% water -distribution in body divided into 3 compartments: 1) intracellular – 28 litres 2) intercellular/interstitial fluid – 11 litres – 80% 3) blood plasma – 3 litres – 20% -women contain less water than men -organisms can contain 60-80% water -bacteria have lots of water -fat cells have little -waters properties result from its structure and molecular interactions -water is polar -polar covalent bonds and asymmetrical shape give it opposite charges on opposite sides -electrons spend more time around O giving H a slight positive charge -hydrogen bonds form between the oxygen of one molecule and the hydrogen of another -cohesion: substance being held together by hydrogen bonds -hydrogen bonds are transient yet enough is always held together to give water more structure than almost any other liquid -beads and meniscus formed by cohesion (also helps upward transport of water in plants) -adhesion counteracts downward pull of gravity -water has greater surface tension than most liquids -surface molecules are hydrogen bonded to molecules below and around them -surface tension can hinder life (i.

e. beading in the alveoli of lungs) -makes water “unwettable” -surfactants used to counteract this -water has a high specific heat which allows it to resist extreme temperature changes -has a high heat of vaporization that causes it to require alot of energy to change states -when sweating, heat energy is utilized to change states from liquid to gas, causing a drop in temperature -as a solid water is less dense than as a liquid and will float -charged regions of molecules have an electrical attraction to charged ions -water surrounds ions separating and shielding them from one another -polar compounds are generally soluble -charged regions of water are attracted to oppositely charged regions of other polar molecules -polar molecules are miscible in other polar liquids -most water molecules dont dissociate (~ 1/554 million do) -hydrogen atom in hydrogen bond between the two water molecules may shift from the oxygen atom it is covalently bonded to the unshared orbitals of the oxygen that it is hydrogen bonded to -hydrogen ion is transferred creating a hydronium ion and leaving a hydroxide ion -the solvent is water itself -at equilibrium water is not dissociated -at equilibrium in pure water at 25oC [H+] = [OH-] -pH of this solution is 7 (neutral) -high pH = low acidity -acids are substances that increase the relative [H+] and remove OH- because it tends to combine with H+ to form water – if [H+] * [OH-] , it is acidic and has a pH between 0 and 7 -bases are substances that reduce the relative [H+] in a solution -it may increase the [OH] -if [H+] * [OH-] , it is basic and has a pH greater than 7 -buffers are important in the body to keep the pH range between 6 and 8 -pH of blood is between 7.34 and 7.44 -mustnt shift below 7.

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2 or acidosis will occur -some body zones may have a pH as low as 0.5 or as high as 10 -buffers minimize sudden changes and are a combo of hydrogen donors and hydrogen acceptors -ions are accepted when in excess and donated when in short supply -in biological systems an example is the bicarbonate buffer -in response to a rise in pH, the carbonic acid dissociates to form a carbonate ion and a hydrogen proton -if there is a drop, it is reversed (pH up = to right, pH down = to left) -equilibrium is established but it is always moving to the left or the right -a balance is the optimum pH -other body buffers include protein molecules which donate and accept amino acids to stabilize pH -most of the rest of organisms is made up of carbon based compounds like carbs, lipids, proteins, nucleic acids -carbon compounds are known as organic -vitalism is the belief in a life force outside the control of chemical laws -this has been disproved as water, ammonia, hydrogen and methane have been combined in a lab to form organic substances -C+O+H = carbohydrates -C+H+N = amino acids, urea, proteins, lipids -carbon atoms are the most versatile building blocks -each has 4 valences where bonds can form -carbon chains form the skeleton of most organic molecules -may be straight or branched, long or short, or in closed rings -hydrocarbons contain only hydrogen and carbon -they form when organic matter decomposes and functional groups break off leaving a skeleton -hydrocarbon chains, branches, and rings can be modified by other elements which are joined on in a particular matter -these are components of organic molecules that are often involved in chemical reactions -they replace 1 or more hydrogens in a hydrocarbon Carbohydrates: -sugars and starches -nonsugars: plant starch, animal starch, cellulose, chitin -come from pasta, rice, flour, fruit, syrups -important source of energy, can be oxidized to release energy, improves your mood -contain C, H, and O, with generally 2 times as much H as O -sugar names usually end with -ose, and are named depending on the number of carbons in them (e.g. triose, pentose) -6 carbon sugars, hexoses, are most important -general formula is C6H12O6, and in living systems, the state is aqueous -solids exist in chains, and liquids as rings -the molecular formula is the same for different hexoses, but the structural formula differs -other isomers of glucose can be reorganized by cells into alpha glucose, and then oxidized -glucose is the major nutrient for cells and its carbon skeleton is raw material for the synthesis of other organics Disaccharides: -2 hexose sugars-most common are: sucrose, lactose and maltose -glucose + glucose = maltose + water -glucose + fructose = sucrose + water -glucose + galactose = lactose + water -this process is known as condensation or dehydration synthesis -synthesis of disaccharides doesnt happen in the human body, but usually they are eaten and digested, through a process known as hydrolysis or disaccharidases Polysaccharides: -these are macromolecules that are made by condensation when monosaccharides are joined -general molecular formula isC6H12O5 -common polysaccharides are amylose, amylopectin (plant starch), glycogen (animal starch), cellulose (cell wall material), chitin (leathery covering of invertebrates) -plants use glucose to grow, and extra is stored in the roots in a soluble form which is then reactivated in the spring – this reactivates the growing process year after year -animal starch is stored in special cells (average person has a 24 hour supply) and can readily be converted into glucose for use -cellulose and chitin are structural carbohydrates -amylose is formed when glucose molecules join in a 1-4 linkage pattern -first carbon of one glucose links to the fourth carbon of another -this is a …