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Page 1: Chemistry of Life

Chemistry of Life

Life’s chemistry is based largely on Organic Molecules.--molecules must contain both C and H--can contain more than just C and H--those that contain only C and H are called Hydrocarbons.

Example of a hydrocarbonis methane, aka biogas or gut gas. It is made from 1 C and 4 H. Methane is emitted from the Bacteriaof ruminant animalsand those found in ricepatties. It is also emitted byhumans as a gas coming out either end.

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Most of the important molecules in living organisms have long chains of carbon molecules forming a backbone for other atoms to attach to.These carbon atoms can also attach to carbon atoms of othermolecules to form very large, or macro molecules.

Dehydration Synthesis:-used to build largemolecules from smallones.-a single water moleculeis removed from thetwo large molecules…anH+ from one and OH-from the other.-they join at this point-this example shows aminoacids joining to form a protein

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Molecules can also be broken down. To do this, reverse theprocess used during dehydration synthesis…instead of takinga water molecule away, add one!!This process is called Hydrolysis and it is used to break a largemolecule into many smaller one that can be used to build with.

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4 Major Groups of Macromolecules Play an Important Role in Living Organisms.

1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids

Carbohydrates:-Mainly C, H, and O in a 1:2:1 ratio.-General chemical formula is (CH2O)n with n = any #-Source of “quick energy” for the body-Found in many foods we consume like pasta, bread,

cakes, cookies, pizza, sugared drinks, beerMonosaccharides = simple sugars

-simplest class of carbs-sugars such as glucose (blood sugar) and fructose(fruit sugar)

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Disaccharides = two sugars-two monosaccharides joined by dehydration synthesis-most common disaccharide is sucrose = glucose + fructose“table sugar” made from sugar cane or sugar beets.-lactose = glucose + galactose…”milk sugar” found in all dairy products. Some people lack the enzyme to helpbreak down lactose in their body and are called “lactoseintolerant.”-maltose = glucose + glucose…”malt sugar” found in malted milk balls, malt for milk shakes, and brews.

Polysaccharides = many sugars-long chains (100’s to 1000’s) of monosaccharides


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Starch- plant storage sugar.-plants make sugars in leaves and transport to storage area like roots or fruits or grains.-pastas and breads are considered “high starch” foods

Glycogen- animal storage sugar.-animals store in liver until needed and then convert it to glucose

Cellulose- “fiber”-forms cell walls of plants-largely indigestible…provides fiber for most

organisms and helps keep them “regular”-ruminants can digest cellulose because they have an extra stomach, the “rumen,” which contains

microorganisms that break down the cell walls of plants. When the plant cells pass into the next stomach, digestion occurs as normal.

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Cows and





Notice howlarge therumen is

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Chitin = outer shell of insects, crabs, lobster, crayfish, etc.these organisms lack a skeletal system and use thechitin shell for support and protection.

When you step on a bug and it goes “crack” you have crushedsome chitin!!

Chitin is non-biodegradable meaning it does not break down inthe ground over time like most parts of organisms.This characteristic is important in the manufacturing of suturingthread used to put stitches in you when you cut yourself.Think about it…it is strong and won’t break down over time during the healing process so it allows the skin to heal and thenyou can remove it.Next time you get stitches, ask the doctor if he is using the traditional “cat gut” or if he is using “chitin.”

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Lipids:-mainly C and H. Contain very little O.-source of long term energy storage for the body-lipids have 6x as much energy as carbs but are muchharder for the body to break down.-also serve as protective layers (think whale blubber) and precursors of larger molecules-are hydrophobic…meaning they fear water.

Fats—-class of lipids found in many foods we consume-consist of one fatty acid and three glycerols joined bydehydration synthesis. (triglyceride)-see Figure 3.15, pg. 42 -two classes of fats…

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Saturated Fats— -have all C atoms completely covered with H atoms. The molecule is “saturated” and is not easily broken

down.-are solids at room temperature. When in fridge, they become “bricks” and are hard to use-main source is animal fats such as lard and real butter-tend to build up in arteries as plaque because they arenot broken down. Lead to “arthrosclerosis” or plugged arteries.

Heart pumps sameamount of bloodthrough blocked artery but works much harder andheart attack occurs

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Unsaturated Fats—-C atoms are not completely covered by H atoms. Somedouble bonds can readily bond with other atoms toallow hydrolysis to occur.-still not good to consume in large amounts-found mostly in plant products…peanut oil, sunfloweroil, vegetable oil, corn oil, canola oil-generally liquid at room temperature…will not freeze.-reindeer in artic have pockets of unsaturated fats in their hooves to prevent them from freezing

What about Hydrogenated Vegetable Oil? Where do you find it at? Is it good for you?

-most “spreadable” butters are plant oils that have beenhydrogenated…-makes them more aesetic to use at the table but lesshealthy for your body.

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Waxes—-protective coverings for plants and animals-where do we find them?-what do they protect against?

Phospholipids—-important components of the cell membrane-learn more about them in the next unit


-have ring shape instead of linear shape -classified as lipids because they are hydrophobic

-Cholesterol is important to body as part of cell membraneand ingredient in sex hormones estrogen and testosterone

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Anabolic steroids— “not from the body”-variants of male testosterone.-build up bone and muscle mass-cost is great…many side effects…”roid rage” common-can suffer liver damage-build manly muscles in women-reduced testicle size in men

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Proteins:-mainly C, H, O, and N-building blocks are amino acids (20 common aa’s build aninfinite number of proteins)-protein shape determines function-seven different classes of proteins do many different jobs

Classes of Proteins:

-structural proteinsused for support…hair and spider webs,

horns and feathers, tendons and ligaments are all strong

-contractile proteinsfound in muscles and are like elastic…allow muscleto expand and contract without losing shape

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-transport proteinsfound many places to transport materials throughoutthe body…hemoglobin is an example and transportsoxygen from your lungs throughout your body

Signal proteins--relay messages from one part of the body to another.-hormones are a good example…they help start and stop processes in the body by their release

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Storage proteins--store amino acids to be used for development of youngorganisms…such as a seed or an egg.

Defense proteins--antibodies in your immune system -each antibody will be specific for a different “bug”-will only attack what it is programmed to-flu, tetanus, hepatitis vaccines all have relatively “harmless”versions of the “bugs” that are introduced into your body tohelp build up an antibody army against it so when you comeinto contact with the real thing your body is ready to fight!

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Enzymes—-very important class of protein -govern virtually every system in the body-speed up chemical reactions without becoming part of thereaction…thus, one enzyme can speed up thousands ofchemical reactions.-called “catalysts”-lower the “activation energy” or the amount of energy that is needed to start a reaction.

When a protein undergoes a shape change, it loses its abilityto function properly. This is called DENATURING.

These eggs do not havethe same function afterheat is added to them.I doubt cooked eggs canproduce a baby chick!!

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Nucleic Acids:-information storage molecules

most common are DNA and RNA, ATP-contain “directions” for building proteins, supply cell energyDNA-located in the nucleus of the cell-made up of nucleotides

3 part molecule:PhosphateSugar (2)

Deoxyribose in DNARibose in RNA

Nitrogen Base (4)Adenine ~ ThymineCytosine ~ Guanine

-all genetic information written in 4 letter alphabetA, T, C, G

RNA-messages carried to cytoplasm, amino acids connected to make protein by different RNA types.

ATP- located throughout the cell where energy processes take place.some cells have more ATP than others based on activity.