>> WELL, WELCOME BACK. ENTERING CHAPTER 2 NOW, WE'RE GOING TO TALK ABOUT CHEMISTRY AND THE HUMAN BODY. NOW, THIS IS NOT MEANT TO BE A CHEMISTRY COURSE. SOME OF YOU MAY HAVE HAD CHEMISTRY IN HIGH SCHOOL, MANY OF YOU DID NOT. I WANT YOU TO GET SOME BASIC UNDERSTANDING, ESPECIALLY WITH THE TERMINOLOGY OF WHAT THAT PART OF CHEMISTRY THAT'S IMPORTANT TO EVERYTHING FROM DIGESTION TO HORMONE CONTROL, AND IDENTIFYING WHO AND WHAT WE ARE. SO AS WE GO THROUGH THIS CHAPTER, DON'T SWEAT IT, DON'T THINK YOU HAVE TO BECOME A CHEMIST. THAT'S NOT THE INTENT. IT IS MOSTLY SO THAT YOU REALLY TRULY BECOME COMFORTABLE WITH SOME OF THE TERMS IN THIS PARTICULAR CHAPTER. FIRSTLY, MATTER IS SOMETHING THAT HAS WEIGHT AND TAKES UP SPACE. THE MOST AND TINIEST PART OF MATTER IS SOMETHING CALLED AN "ATOM." CHEMISTRY IS THE SCIENCE THAT DEALS WITH THE COMPOSITION OF MATTER-- HOW IT'S ALL PUT TOGETHER FROM ITS MOST MINUSCULE ATOMIC LEVEL ON UP TO THE HUMAN ORGANISM. IT'S A BUILDING PROCESS. WE START WITH VERY SMALL ITEMS, WE PUT THEM TOGETHER, THEY START TO INTERACT WITH ONE ANOTHER. WE ARE GONNA TALK ABOUT SOME OF THE DIFFERENT TERMS OF CHEMISTRY. THE ATOM-- MOST OF YOU HAD THIS IN FOURTH GRADE, TRULY. IN MICHIGAN EDUCATION TRACK, THAT'S ABOUT WHEN IT'S INTRODUCED, IN FOURTH OR FIFTH GRADE-- AN ATOM IS INVISIBLE. YOU CANNOT LOOK AT YOUR SKIN AND SAY, "OH, YEAH, "I SEE MY ATOMS OF MY SKIN"-- NO, THAT'S NOT POSSIBLE. IT'S INVISIBLE. WE CAN LOOK AT ITS ACTIVITY, BELIEVE IT OR NOT, WITH SOMETHING THAT WE USE IN THE HOSPITAL CALLED AN "M.R.I. MACHINE," BECAUSE THE ATOM HAS A CENTRAL NUCLEUS, WHICH IS MADE UP OF POSITIVELY-CHARGED PROTONS AND NEUTRONS, AND THEN CIRCULATING AROUND IT, SIMILAR TO MOONS AROUND THE EARTH OR TO OUR PLANETS AROUND THE SUN, WE HAVE SMALL NEGATIVELY-CHARGED PARTICLES CALLED "ELECTRONS." AND THESE NEGATIVELY-CHARGED ITEMS ACTUALLY, AS WE PROGRESS IN THE CHAPTER, INTERACT WITH ONE ANOTHER TO COMBINE ATOMS OF DIFFERENT ELEMENTS TO MAKE UP, THEN, MOLECULES, COMPOUNDS, WHICH EVENTUALLY BECOME PARTS OF OUR VERY MICROSCOPIC CELLS. SO AGAIN, THE ATOM IS INVISIBLE. THE NUCLEUS IS MADE UP OF POSITIVELY-CHARGED PROTONS AND NEUTRONS. AND ELECTRONS ARE NEGATIVE CHARGES THAT ORBIT AROUND THE NUCLEUS AT DIFFERENT DISTANCES ALSO. A MOLECULE IS A CHEMICAL COMBINATION OF TWO OR MORE ATOMS, THE SAME CHEMICAL OR COMBINATION OF CHEMICALS. SO YOU COULD HAVE A MOLECULE OF OXYGEN, AND YOU COULD HAVE A MOLECULE OF WATER, WHICH WOULD BE A CHEMICAL COMBINATION OF MORE THAN ONE PARTICULAR TYPE OF ELEMENT. A COMPOUND IS SUBSTANCES WHOSE MOLECULES HAVE MORE THAN ONE ELEMENT, AND WE USE FORMULAS TO DESCRIBE THE DIFFERENT ELEMENTS WITHIN CERTAIN COMPOUNDS. SO FOR EXAMPLE, SUGAR IS "C," WHICH IS CARBON-- SIX CARBONS-- "H," WE HAVE 12 OF THOSE. SO WE HAVE C-6, H-12, O-6. AND I APOLOGIZE-- THOSE SHOULD BE SUBSCRIPTED, BUT THIS PARTICULAR FONT WILL NOT DO THAT. IN YOUR TEXT, YOU CAN SEE THE PROPER SUBSCRIPT OF THOSE NUMBER OF ATOMS OF CERTAIN ELEMENTS IN THOSE COMPOUNDS. SO FORMULAS DESCRIBE WHICH ATOMS ARE PRESENT IN A COMPOUND, AND THEN WE DESCRIBE THEM BASED ON THE NUMBERS IN THAT PARTICULAR COMBINATION. SO YOU'VE HEARD OF H2O. WELL, H2 WOULD BE TWO OF HYDROGEN AND ONE OF OXYGEN, SO THAT'S WHAT MAKES UP WATER. NOW, CHEMICALS WILL BOND OR ELEMENTS BOND AND ATOMS BOND, AND THEY DO THIS TO MAKE THEIR COMBINATION OR THEIR INITIAL ATOM MORE STABLE. AS I MENTIONED, ELECTRONS MOVE AROUND THE NUCLEUS IN ORBITALS AT DIFFERENT DISTANCES FROM THAT NUCLEUS. AND DEPENDING UPON THAT DISTANCE, THERE ARE DIFFERENT ENERGY LEVELS. SOME OF THESE ENERGY LEVELS, OR "SHELLS" AS THEY'RE ALSO CALLED, ARE ABLE TO SHARE, DONATE, OR BORROW ELECTRONS UNTIL THE OUTERMOST ENERGY LEVEL IS FULL, WHICH IS WHEN IT'S MOST STABLE. AN ION IS AN ELECTRICALLY CHARGED ATOM OR MOLECULE WHICH HAS AVAILABLE ORBITING ELECTRONS. AN IONIC BOND IS A COMMON TYPE OF BOND, WHERE ONE ATOM THAT NEEDS ADDITIONAL ELECTRONS TO COMPLETE ITS OUTER SHELL RECEIVES FROM ANOTHER ATOM THOSE PARTICULAR ELECTRONS, AND YOUR BOOK DESCRIBES THIS IN A LITTLE BIT BIGGER DETAIL, MORE STEPS OF DETAIL, AND YOU'RE WELCOME TO READ THAT. SODIUM CHLORIDE IS A GOOD EXAMPLE OF AN IONIC BOND. IT'S ALSO A GOOD EXAMPLE OF SOMETHING WE CALL AN "ELECTROLYTE," BECAUSE AN ELECTROLYTE IS WHEN YOU TAKE SOMETHING LIKE SODIUM CHLORIDE, WHICH IS IONICALLY BOUND, INTO SOLUTIONS SUCH AS WATER, IT WILL SEPARATE INTO CHARGED PARTICLES, "CHARGED" MEANING THAT IT EITHER STILL HAS AN EXTRA ELECTRON TO OFFER OR IT'S MINUS AN ELECTRON IN ITS OUTER SHELL. SOME ELECTROLYTES THAT WE'RE GOING TO BE TALKING ABOUT IN REFERENCE TO THE HUMAN BODY INCLUDE THOSE LIKE SODIUM, WHICH IS "NA," POTASSIUM CHLORIDE, CO2 OR CARBON DIOXIDE, HC03, WHICH IS BICARBONATE, WHICH IS ACTUALLY A BUFFER. WE'RE GOING TO TALK A LOT ABOUT OUR HOMEOSTASIS AND HOW IMPORTANT IT IS THAT CERTAIN OF THESE ELECTROLYTES-- AND IF YOU THINK OF THE WORD "ELECTROLYTE" CONTRIBUTING TO THE ELECTRICITY OF OUR BODY, WHEN WE START TALKING ABOUT HOW MUSCLES CONTRACT, HOW NERVES IMPULSE, IT WILL HOPEFULLY START TO BRING YOU BACK TO THAT TERM "ELECTROLYTE," AND GET YOU THINKING, "HMM, FOR THAT CHARGE, "THAT CHARGED PARTICLE TO MOVE TO MAKE THINGS HAPPEN, "OH YEAH, THAT'S ELECTROLYTE, THAT'S ELECTRICITY." KINDA START PUTTING THOSE TERMS TOGETHER IN YOUR HEAD, BECAUSE TRULY, A MUCH MORE COMPLEX-- BUT I'M INTRODUCING THIS VERY SIMPLISTICALLY-- OUR ENTIRE BODY DEPENDS ON OUR ELECTROLYTES FOR THE MOVEMENT OF ELECTROCHEMICAL IMPULSE FROM ONE PART OF OUR BODY TO ANOTHER, AND ESPECIALLY IN THE NERVOUS SYSTEM. COVALENT BONDS. ATOMS THAT SHARE ELECTRONS IN THEIR OUTER SHELL, SUCH AS H2, ARE COVALENTLY BONDED. AND THIS BOND IS A TIGHT ONE. IT DOESN'T USUALLY DISSOCIATE IN WATER, THEY ARE NOT EASILY BROKEN, AND THEY FORM ALL THE MAJOR ORGANIC COMPOUNDS THAT ARE IN OUR BODIES. HYDROGEN BOND IS ANOTHER TYPE OF BOND, AND IT DOES NOT CREATE NEW MOLECULES, BUT INSTEAD, IT'S A WEAK BOND BETWEEN NEIGHBORING MOLECULES. EXAMPLES ARE DNA-- AND I APOLOGIZE, I JUST SAW A TYPO IN HERE. IT SHOULD BE "WATER." I DON'T KNOW WHY THAT DIDN'T SPELL CHECK, BUT OBVIOUSLY "WARE" IS A REAL WORD, BUT THIS SHOULD BE-- EXAMPLES ARE WATER, DNA, AND PROTEINS. NOW, INORGANIC CHEMISTRY IS THE STUDY OF NONLIVING MATTER, AND ORGANIC CHEMISTRY IS THE STUDY OF LIVING MATTER. WATER IS KNOWN AS THE UNIVERSAL SOLVENT. WE KNOW THAT WATER IS STABLE AT ROOM TEMPERATURE, AND IT PARTICIPATES IN MANY CHEMICAL REACTIONS. ALL BODILY FUNCTIONS LEAD A THE BREAKDOWN OF PARTICLES THAT DISSOLVE IN THIS WATER. WE JUST GAVE AN EXAMPLE OF THAT AS WE TALKED ABOUT ELECTROLYTES. AND THEN, THEY BECOME TRANSPORTED FROM CELL TO CELL AND ORGAN TO ORGAN. THERE ARE A NUMBER OF DIFFERENT CHEMICAL REACTIONS, AND ONCE AGAIN, THIS IS NOT A CHEMISTRY COURSE. THOSE OF YOU WHO HAVE HAD INORGANIC CHEMISTRY OR EVEN ORGANIC CHEMISTRY KNOW THAT YOU SPEND AN ENTIRE YEAR LEARNING ABOUT HOW DIFFERENT CHEMICALS REACT WITH ONE ANOTHER BASED ON THEIR PROPERTIES. ONE TYPE OF REACTION THAT'S DESCRIBED IN YOUR TEXT IS BOTH DEHYDRATION SYNTHESIS AND HYDROLYSIS, AND THAT HAS TO DO WITH THE UTILIZATION OF WATER IN THE REACTION, AND I DO ENCOURAGE YOU TO READ THAT PORTION IN YOUR TEXT SO THAT YOU'RE FAMILIAR WITH THE TERMS. AN IMPORTANT PART ABOUT CHEMICAL REACTIONS, ESPECIALLY IN THE HUMAN BODY, IS THEY DO INVOLVE SOME TYPE OF ENERGY TRANSFER, AND IN THE PROCESS OF TRANSFERRING THAT ENERGY, SINCE ENERGY CAN BE NEITHER CREATED NOR DESTROYED, IT'S TRANSFERRED. AND WHEN WE SAY "TRANSFERRED," WE MEAN IT IS SENT INTO A DIFFERENT REACTION OR INTO A DIFFERENT MECHANISM WITHIN THE HUMAN BODY. ONE ELEMENT IN THE BODY-- IT'S NOT REALLY AN ELEMENT, IT'S A COMBINATION. IT'S ACTUALLY A FUNCTIONAL PROTEIN THAT IS IN OUR BODY THAT IS REALLY IMPORTANT IN CHEMICAL REACTIONS THAT ARE TAKING PLACE AT ALL LEVELS OF HUMAN PHYSIOLOGY ARE ENZYMES. ENZYMES ARE THAT WHICH SPEED UP CHEMICAL REACTIONS, PARTICIPATE IN THE REACTION, BUT THEY THEMSELVES ARE NOT CHANGED. AND YOUR BOOK DOES GIVE YOU A DESCRIPTION OF HOW SOMETIMES THEY ACT LIKE A KEY TO FACILITATE AN END PRODUCT. WE HAVE ENZYMES THAT ARE UTILIZED FOR DIGESTION, WE HAVE ENZYMES THAT ARE UTILIZED FOR THE PRODUCTION OF OTHER SUBSTANCES WITHIN OUR BODIES. ENZYMATIC ACTIVITY IS VERY IMPORTANT IN HOMEOSTASIS, AS MANY OF THESE CHEMICAL REACTIONS ARE. AND THIS IS IN THE HUMAN VERSION OF ENZYMATIC APPLICATION. YOU PROBABLY HAVE MAYBE WATCHED A TV COMMERCIAL WHERE THEY'LL TALK ABOUT CERTAIN TYPES OF CLEANING PRODUCTS THAT HAVE CERTAIN TYPES OF ENZYMES THAT WILL MAKE THINGS WORK EVEN BETTER. SO AGAIN, AN ENZYME WILL SPEED UP A CHEMICAL REACTION, PARTICIPATE IN THE REACTION, BUT THE ENZYME ITSELF IS NOT CHANGED. SOME OF THE COMMON ELEMENTS YOU WILL WANT TO BECOME FAMILIAR WITH INCLUDE "H," WHICH IS HYDROGEN, "NA," WHICH IS SODIUM-- AND BY THE WAY, THESE PLUSES ARE THAT WHICH ARE CHARGES, AN EXTRA POSITIVE CHARGE. "N," WHICH IS NITROGEN, "K+," WHICH IS POTASSIUM, "FE" IS IRON, "C" IS CARBON, "O" IS OXYGEN, "CL" IS CHLORIDE, "HC03" IS CARBONIC ACID, AND "NACL" IS SALT, WHICH I THINK YOU GUYS HAVE PROBABLY BEEN MORE THAN FAMILIAR WITH THROUGHOUT YOUR HIGH SCHOOL AND MIDDLE SCHOOL EDUCATIONS. NOW, WHEN WE LOOK AT HOMEOSTASIS, ANOTHER VERY IMPORTANT TERM THAT YOU NEED TO BECOME FAMILIAR WITH AND HAVE A BASIC UNDERSTANDING OF IS ACID-BASED RELATIONSHIPS IN OUR BODY. WE HAVE, AS I MENTIONED, COMBINATIONS WHERE WE HAVE DIFFERENT MOLECULES AND DIFFERENT COMPOUNDS THAT INTERACT WITH ONE ANOTHER. WE HAVE A REPRESENTATION OF THE AMOUNT OF HYDROGEN THAT IS ACTUALLY PRESENT IN A SOLUTION. THE AMOUNT OF HYDROGEN IN THAT SOLUTION IS GIVEN A NUMBER AND A TERM CALLED THE "pH"-- THE "P," THE LITTLE BABY "P," AND THE "H." THE "H" STANDS FOR HYDROGEN. AND THE MORE HYDROGEN PRESENT, THE MORE ACIDIC THAT PARTICULAR SOLUTION IS. OUR BODIES WILL NOT FUNCTION WELL IF OUR pH IS OUT OF BALANCE. OUR CHEMICAL COMBINATIONS WILL NOT WORK WELL, OUR BRAINS WILL NOT WORK WELL, OUR HORMONES WILL NOT WORK WELL. NOTHING WORKS WELL IN AN OTHER-THAN-NORMAL TOTAL pH FOR OUR BLOOD AND OUR CELLULAR OR INTRA-CELLULAR pH. NORMAL pH FOR THE HUMAN BODY IS 7.35 TO 7.45. 7.35 TO 7.45. TO MAINTAIN A NORMAL pH, THERE HAS TO BE AN INTERACTION AND A BALANCE BETWEEN THE ACIDS IN OUR SYSTEM AND THE BASES IN OUR SYSTEM. THERE SHOULD BE BUFFERS FOR EXCESSIVE AMOUNTS OF ACID ON A REGULAR BASIS TO MAINTAIN OUR pH IN THAT NORMAL RANGE. IN DISEASE PROCESS, FOR EXAMPLE, IF WE DO NOT BREATHE AND WE START TO RETAIN THE ACIDS THAT ARE LEFT OVER BECAUSE OF THE FACT WE'RE NOT GETTING RID OF THE EXCESS WASTE, AND/OR IF OUR KIDNEYS DO NOT WORK WELL, EITHER SIDE OF THAT PICTURE WILL LEAVE US IN AN ALTERED pH STATE AND USUALLY ACIDIC. NOW, YOU NEED TO MEMORIZE THAT ACIDS HAVE A SOLUTION NUMBER, OR pH NUMBER, BELOW 7.0, AND BASES HAVE A pH NUMBER THAT IS ABOVE 7.0. SO THE NORMAL HUMAN pH IS 7.35 TO 7.45. IT'S A SLIGHTLY BASIC. THE HUMAN BODY IS JUST ABOUT READY TO BE UNABLE TO SUSTAIN ITSELF FOR LIFE WHEN THE pH FALLS BELOW 6.9. YOU CAN RESUSCITATE AT THAT POINT, BUT THERE'S A LOT OF DAMAGE THAT'S BEEN DONE. SO WE KNOW THAT'S A VERY NARROW RANGE OF ACID-BASED BALANCE TO MAINTAIN THE HUMAN BODY WITHIN A NORMAL pH. IN YOUR TEXTBOOK, THERE IS A SCALE THAT SHOWS YOU THE pH OF DIFFERENT TYPES OF PRODUCTS, INCLUDING STOMACH ACID, ORANGE JUICE, COFFEE, PANCREATIC JUICE, AND HOUSEHOLD PNEUMONIA-- ER, NOT "PNEUMONIA," I'M SORRY. AMMONIA. AND THE FURTHER YOU GET TOWARDS THE HIGHER pH, THE MORE BASIC THE PRODUCT IS. SO IF YOU LOOK AT SOMETHING LIKE STOMACH ACID, IT HAS AN EXTREMELY LOW pH OR AN EXTREMELY HIGHLY ACIDIC COMBINATION... STOMACH ACID BEING 0.8 FOR THE pH, ON THE pH SCALE. AND WE KNOW THAT WE LIKE TO KEEP OUR INTRACELLULAR AS WELL AS OUR VASCULAR BEDS-- MEANING OUR BLOODSTREAM-- FLOWING VOLUME. IN FACT, NORMAL RANGE IS 7.35 TO 7.45. WHEN THINGS ARE BASIC, THEY'RE ALSO CALLED "ALKALINE." WHEN WE HAVE AN EXTREME ALKALINE PRODUCT EXPOSED TO SOMETHING LIKE SKIN. SO FOR EXAMPLE, ONCE AGAIN, IF YOU LOOK AT HOUSEHOLD AMMONIA, YOU KNOW THAT IF YOU POUR AMMONIA ON YOUR SKIN, IT DOESN'T FEEL REALLY GOOD. WE KNOW THAT EVEN YOUR SKIN LIKES TO MAINTAIN A RELATIVELY NORMAL pH. ANYTHING TOO HIGH OR TOO LOW FROM THAT NUMBER WILL BE EXTREMELY IRRITATING. WE'LL TALK A LOT MORE ABOUT pH WHEN WE TALK ABOUT THE SYSTEMS OF TRANSPORTATION AS WELL AS THE RENAL SYSTEM, BECAUSE BOTH THE CARDIOVASCULAR SYSTEM AS WELL AS THE RENAL SYSTEM IS IMPORTANT FOR THE MAINTENANCE OF A NORMAL pH IN OUR SERUM. ANOTHER TERM YOU SHOULD BE FAMILIAR WITH IS "LIPID." LIPIDS ARE FATS AND/OR OILS, AND IN OUR BODY, WE HAVE CERTAIN KINDS OF LIPIDS-- YOU'VE PROBABLY HEARD A LOT ABOUT, YOU KNOW, "YOU'VE GOT TO KEEP YOUR CHOLESTEROL LEVELS LOW "AND YOU'VE GOT TO KEEP YOUR TRIGLYCERIDES LOW," BUT WE SURELY DON'T HAVE TO KEEP THEM ZERO, BECAUSE LIPIDS ARE ALSO ESSENTIAL AS FATTY ACIDS FOR THE PRODUCTION OF CERTAIN HORMONES AND FOR THE REGULATION OF CERTAIN CHEMISTRIES IN OUR BODY, AS WELL AS FOR THE INTEGRITY OF THE CELL MEMBRANE. NOW, TRIGLYCERIDES ARE THOSE LIPIDS THAT ARE VERY HELPFUL IN STORING ENERGY. PHOSPHOLIPIDS ARE PRODUCTS THAT ARE A FAT BUT THEY HAVE SOMETHING CALLED A HEAD AND A TAIL, AND IF YOU LOOK IN YOUR TEXT, YOU CAN ACTUALLY SEE THE PICTURE OF THE CELL MEMBRANE, AND THEY DESCRIBE BOTH THE HEAD AND THE TAIL IN THAT PICTORIAL. AND THE HEAD ATTRACTS WATER AND THE TAIL REPELS WATER. THOSE PHOSPHOLIPIDS HELP TO MAKE UP OUR CELL MEMBRANES AND TO STABILIZE THAT CELL MEMBRANE OR CELL WALL. WE ALSO HAVE TO HAVE A CERTAIN AMOUNT OF CHOLESTEROL. WE ALSO NEED CHOLESTEROL AVAILABLE, WHICH WE GET VIA OUR DIET, TO MAKE STEROID HORMONES IN OUR BODY, AND THERE'S A NUMBER OF THOSE THAT WE'LL ALSO BE TALKING ABOUT IN THE ENDOCRINE SYSTEM. PROTEINS ARE ANOTHER ELEMENT IN OUR BODY, AND THEY ARE LARGE MOLECULES. AND THE BASIC UNIT OF THE PROTEIN IS SOMETHING CALLED AN "AMINO ACID," AND IN THE AMINO ACID, THE BASE PART OF THAT STRUCTURE IS NITROGEN. NOW, THE SEQUENCE OF AMINO ACIDS ARE HELD TOGETHER BY A BOND CALLED A "PEPTIDE BOND." THE SHAPE OF PROTEINS CONTRIBUTE TO THEIR ROLE AS EITHER BEING STRUCTURAL OR FUNCTIONAL. YOUR BOOK DESCRIBES THIS A LITTLE BIT MORE IN DETAIL, AS WE DISCUSSED THINGS LIKE COLLAGEN VERSUS SOMETHING FUNCTIONAL LIKE AN ENZYME. AS WE MENTIONED BEFORE, AN ENZYME IS A FUNCTIONAL PROTEIN. NUCLEIC ACIDS ARE A COMBINATION OF CHEMICALS THAT ARE ESSENTIAL FOR THE STRUCTURAL FORMATION OF THAT WHICH WE'VE HEARD ABOUT SO MUCH IN DIFFERENT TV SHOWS AND THE REST, WHICH IS DNA AND RNA. NUCLEOTIDES MAKE UP DNA AND RNA, AND THEY DETERMINE AN INDIVIDUAL'S IDENTITY. A NUCLEOTIDE CONSISTS OF A PHOSPHATE UNIT, A SUGAR IN THE FORM OF RIBOSE, AND A NITROGEN BASE. IN YOUR TEXT, THEY DETAIL THE NAMES OF THE NITROGEN BASES. THEY ARE ARRANGED IN A CERTAIN SEQUENCE, AND WHEN YOU GET A DNA PROBE STUDY DONE ON A PARTICULAR PATIENT, WHAT YOU'RE ACTUALLY FINDING IS HOW THOSE CHEMICALS ARE ACTUALLY SEQUENCED IN THAT PARTICULAR INDIVIDUAL, AND BASED ON THE SEQUENCE OF THOSE CHEMICALS, IT DETERMINES WHO AND WHAT SPECIFICS ARE TO THAT PARTICULAR INDIVIDUAL AND THEIR EACH AND EVERY INDIVIDUAL CELLS. SO EVEN, YOU KNOW, THAT YOU MIGHT HAVE SOME SHARED DNA, BECAUSE YOU'RE HALF YOUR MOM, YOU WILL HAVE A SEQUENCE THAT MAY BE SIMILAR TO HERS, BUT IT WILL NOT BE IDENTICAL. SO WE'LL TALK ABOUT THE INHERITANCE PATTERNS LATER IN THE VERY END OF THE SEMESTER, WHEN IT COMES TO COMBINATIONS OF DNA AND RNA AND HOW WE EXPRESS OURSELVES AS INDIVIDUALS AND HOW THAT DETERMINES THE BEHAVIOR OF EVERY CELL WITHIN THE BODY. THAT ENDS THE VERY SHORT AND SWEET-- OR MAYBE NOT SO SWEET TO YOU-- BUT THE VERY SHORT INTRODUCTION TO CHEMISTRY. MOST IMPORTANTLY, BECOME FAMILIAR WITH THE TERMS. IF YOU CAN ALSO SOMEWHAT UNDERSTAND THE BASIC NATURE OF WHAT THOSE TERMS ARE IMPLYING, THAT ALSO HELPS TREMENDOUSLY AS WE MOVE FORWARD, AND ESPECIALLY IN DIGESTION AND, ONCE AGAIN, IN THE VERY END WHEN WE TALK ABOUT SOME OF THE GENETICS OF THE HUMAN BODY. SO THIS ENDS THE ONLINE CHAPTER 2 REVIEW ON THE POWERPOINT, AND OUR NEXT ONE WILL SPEAK TO THE ANATOMY AND PHYSIOLOGY OF THE CELL.