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• Carbohydrates = type of molecule that can be small and singular or much larger 

• Monosaccharide = monomer of carbohydrates, a single unit of sugar/carb

Carbohydrates exist in many forms, ranging from syrups and sugars to complex starches and fibers. The monomers of carbohydrates are called monosaccharides (glucose, fructose, galactose, etc) which can then bond through dehydration synthesis to form longer, more complex polysaccharides. Honey is a mixture of glucose and fructose monosaccharides. 

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• Glucose = common monosaccharide that has multiple hydroxyl groups and one carbonyl group

The molecular formulas of carbohydrates are all usually some form of CH₂O, multiplied to various scales. For example the molecular formula of glucose is C₆H₁₂O₆, where it can be seen to have both hydroxyl and carbonyl groups. 

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• Fructose = another common monosaccharide with hydroxyl (3) and carbonyl groups (1) as well

As an isomer to glucose, fructose also has the molecular formula of C₆H₁₂O₆, however its carbonyl group is placed differently, which gives it different reactive properties (also tastes sweeter). All monosaccharides have between 3-7 carbons (glucose and fructose have 6), and the five-carbon sugars called pentoses and six-carbon sugars called hexoses are the most common forms of monosaccharides. (most sugars end with -ose, most enzymes end with -ase)

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Although the sugars exist in linear form, when in aqueous solutions, they take on a circular structure. To do this, carbon 1 bonds to the oxygen of carbon 5, forming a circular shape and leaving carbon 6 to exist above the main circular structure. With carbons at each corner of the resulting shape, the structural formula can be abbreviated by implying the carbons at these bends. The different thickness in the lines show that the ring is mostly 2D → flat surface, and it also shows that atoms are also below or above it. Further simplification turns a glucose molecule into a ring with a simple O in its top right corner. 

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Carbohydrates act at the primary fuel source for all cellular activity. When glucose is broken down by the cell in an aqueous solution, it releases energy, which can be exploited to help repair tissue (especially for sick people through a water and glucose solution called dextrose that is injected). Additionally, after breaking down carbohydrates, the carbon skeletons left behind can be used to create amino acids or fatty acids. Sugar is both an energy and construction resource. 

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• Disaccharide = two bonded monosaccharides

To form a disaccharide such as maltose, dehydration synthesis is used to form the glycosidic bonds between two glucose monosaccharides. First, one of the hydroxyl of one monomer must be removed. Then the hydrogen of the hydroxyl group of another monomer is removed as well. This forms the byproduct of H₂O, and also allows the remaining O of that monomer to bond to the C of the other, creating the disaccharide. Although maltose is used to make beer, candy, and whiskey, sucrose is he most common disaccharide, as it is the sugar transported through a plant’s veins to provide energy and other materials. Humans get table sugar from the sucrose in cane sugars. 

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There is clear overconsumption of sugar throughout the US, as the recommended daily intake is 6 teaspoons–making up only 5% of one’s daily caloric intake. However the average American not only consumes about 5 pounds of sugar a week, but also has an average of 22 teaspoons of sugar per day (one can of soda exceeds the limit, and processed foods can add any amount of sugar into their products to maximize taste). 

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The consequences of such overconsumption clearly present as dental issues and obesity risk (health hazards of obesity are type 2 diabetes, high blood pressure, etc). Already, the average rate of obesity in the US has reached 36.5% and 17%  in children. New research also points to the connection of obesity (average caloric percentage of 25% from daily calories) and cardiovascular dangers, high cholesterol, diabetes, etc). This study was performed through two-year intervals that showed people with these higher sugar consumption rates to be three times as likely to die from cardiovascular issues. The FDA proposed the update of nutrition labels to solve the problem, however many companies loss touch with this movement because of their misleading advertisements. 

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• Polysaccharide = macromolecule of hundreds to thousands of monomers bonded by dehydration synthesis 

• Starch = stores energy of plants through long chains of bonded glucose monomers

With lengths of many, many monomers long, polysaccharides are considered to be macromolecules, and they can act as storing or structural compounds with a cell. Starch is one type of polysaccharide that involves a chain of many glucose molecules bonded together  that is twisted into a helical shape, sometimes remaining singular and sometimes branching. Starches serve as the plant’s carbohydrate ‘bank’ or reserve of energy and building materials it can easily access. Capable of hydrolyzing starch (with the right enzymes), humans can consume forms of starch–rice, potatoes, corn, etc, and gain energy from it. 

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• Glycogen = polysaccharide that also stores glucose (energy/resources) that can be accessed when needed

Stored in the liver and muscle cells where it can be easily broken down (hydrolyzed), glycogen acts as the animal form of a carbohydrate reserved, and is also formed by helical chains of glucose, however they are more branched than starch.  

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• Cellulose = a polysaccharide that makes up the cell walls of plant cells

As it is present in all plants (helps make up the cell walls), cellulose is the most abundant organic compound. It is also formed through chains of glucose molecules, however the monosaccharides are flipped, alternating with its O at the top then bottom (in contrast starch and glycogen’s glucose are all oriented the same way). This allows hydrogen bonds to form between the OH and H’s, which arranges each glucose chain parallel to one another. This forms microfibrils with then become the strong structures in trees and lumber (with the help of other polymers). All animals (except some animals–cows and termites, bacteria, and fungi that recycle the cellulose back into the environment) lack the enzymes to hydrolyze cellulose, so humans are therefore unable to digest it and absorb cellulose’s nutrients. However, as insoluble fiber, cellulose helps with digestion (in nuts, vegetables, fruits, etc). 

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• Chitin = another type of polysaccharide involved in an organism’s structures

Chitin is used by animals like insects and crustaceans to make their hard exoskeletons. The cell walls of fungi also have chitin. Most carbohydrates are hydrophilic because of the many hydroxyl groups present in the monosaccharides of its polymers. For example, cotton towels are very water absorbent because their cellulose is hydrophilic. This does not apply to all biological molecules.

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• Lipids = type of biological molecule classified together for their hydrophobic properties

• Hydrophobic = water-fearing (nonpolar, so pushed away by cohesive water forces)

Lipids are distinguished from the other biological molecules not only because they are hydrophobic, but also because they are not polymers made of many repeated similar/identical monomers, or because they are macromolecules. There are four types of lipids, fats, phospholipids, steroids, and waxes.

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• Fat = lipid of one glycerol and three fatty acid molecules

• Triglyceride = synonym for fat

• Glycerol = three carbons, each with a hydroxyl group

• Fatty acid = carboxyl group with 16-18 long hydrocarbon chain

Fats are hydrophobic because some of their monomers are hydrophobic. The singular glycerol molecule (three carbons with corresponding hydroxyl groups) itself is not hydrophobic. In fact its OH’s make it polar. However through dehydration synthesis with each hydroxyl of the glycerol and a fatty acid (acidic because of carboxyl group), totalling as three fatty acids, the hydrocarbon tail of these fatty acids have nonpolar bonds, making it hydrophobic. 

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• Unsaturated fatty acid = a fatty acid with one or more double bonds between carbons (does not need as many hydrogens → unsaturated with hydrogens)

• Saturated fatty acid = a fatty acid with no double bonds (has as many hydrogens as possible → saturated with hydrogens)

• Trans fat = type of fat associated with certain health risks

When a double bond forms between the carbons in the hydrocarbon chain of a fatty acid, it creates a bend in that respective tail. This also means that the one less hydrogen (proportionate to how many double bonds) is present in the fat. As a result, when compacted, the kinks make it harder to stack onto each other, which keeps unsaturated fats liquid at room temperature. However, when there are no double bonds, the fatty acid is called a saturated fat because it has the most possible hydrogens. Additionally, as it has no bends from a double bond, saturated fatty acids can easily stack on top of one another, making it solid at room temperature. Unsaturated fats are found in fishes and plants while saturated fats are found in animal fat. ‘Partially hydrogenated fats’ refer to the addition of hydrogens to an unsaturated fat, causing it to become saturated. This process creates trans fats as well, which are harmful to the human body. 

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• Adipose cell = type of cell that stores fat

Fats are used to efficiently store long-term energy in the body. It stores three times as much energy as polysaccharides. Animals enterprise this compacted nature of fats, as they move around, and store most of their energy as fat. In contrast, plants use only starch to store their energy, as the additional room does not affect their nonmotile lives. Fats are stored in adipose cells, which increase and decrease in size as fat enters or exits it. It is also harder to use the energy in fat because it is so densely energized/packed. However fat is not only important for energy reserves, as it also helps to insulate the body and protect and cushion vital organs. 

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Partially hydrogenated fats, produced by adding hydrogens to unsaturated fat, were first invented in the 1890s as a supposedly healthier alternative to saturated fats, which research had linked to several health risks. It was thought that this new type of fat, in addition to unsaturated fat, were the best options. This then launched the market for partially hydrogenated fats to replace saturated fats, as they also kept for longer, and were also able to be heated multiple times (for example, frying things–margarine is a type of partially hydrogenated fat). But as new research showed, the ubiquity of the trans fat resulting from the partial hydrogenation process in 1990 seemed to be damaging public health even more than saturated fats had (for example, cutting out trans fats stopped one in five heart attacks). At first, the FDA required producers to list the presence of trans fats on their nutrient labels, then escalating to cities and states banning trans fats from restaurants and schools. Finally, in 2015 the FDA stated that all trans fats must be removed from food within three years, as it was not safe for the public. 

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The research involved in establishing the effect of trans fats was done in two ways. The first–experimental, studied active participants with varying dietary levels of saturated, unsaturated, and trans fats and the changes in cardiovascular health. The projection was that an increase in trans fats would worsen such health. For ethical purposes, relatively fit people were studied, and only the cholesterol or intermediary risk factors were measured as to not actually give the participants a heart attack. 

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The second way of conducting research is through observational studies. Observation allows a more comprehensive set of data to be collected over a longer period of time, including both disease and risk factors, as well as a more representative population. There are two types of observational studies, the first being retrospective. This looks into the past, where people have documented their current health status and then also add their past eating habits. Some of the data may not be accurate due to misremembered data and the fact that those who died of heart attacks are not included. The second way–prospective, looks into the future, as it has their participants progressively update their physical health, allowing data to be taken about lifestyle, including diet, habits, and also risk factors and disease. 

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The Nurses’ Health Study was one of the major prospective studies that revealed the danger of trans fat. It began in 1997, overall recording the data of 120,000 female nurses. From 1980-1994 about 80,000 women were studied, where risk of coronary heart disease was estimated from consumption of varying forms of fat. Risk begins at a factor of 1, which shows no connection between the type of fat and coronary heart disease. Subsequently, any recorded value less than one means the risk decreases, and any value greater than one means the risk increases. For monounsaturated and polyunsaturated fats, risk of heart disease decreased with every 5% increase. 5% increases in saturated fats only had an increased risk of 17%. In contrast, trans fats have a 93% increased risk for every 2% intake increase, demonstrating how much of a threat trans fats poses. From advertising trans fat as a healthier alternative to saturated fat, the government has banned trans fat. This is an example of how a broadened understanding had revised and completely changed the policy.

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• Phospholipid = polymer of one glycerol molecule, phosphate group, and two fatty acids

Phospholipids are different from fats because instead of having a third fatty acid, phospholipids have a phosphate group attached. Also, the second fatty acid is unsaturated as it has a double bond.

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When in an aqueous solution or surrounded by water, lipids form a double layered membrane, as its hydrophobic tail (hydrocarbon chains), which clusters together with other phospholipids away from the water, and the hydrophilic heads (the glycerol, phosphate, and r group) face out towards the water. Some types of proteins are involved with the membrane that forms from phospholipids. 

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• Steroids = lipids formed by four fused rings of carbon (3 6-carbon and 1 5-carbon)

• Cholesterol = a type of steroid that is found in animal cell membranes, contributing to production of other hormones (sex hormones)

Steroids are another type of lipid, however they are not made of glycerol or fatty acids; instead every steroid molecule shares the same basic carbon skeleton of four fused rings–the attached chemical groups are responsible for variation among steroids. Cholesterol, for example, has hydroxyl and carbonyl functional groups as well as a hydrocarbon chain attached. Cholesterol is a steroid in animals (in cell membranes) used to help produce important hormones.

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• Anabolic steroids = synthetic steroids that have similar structures to testosterone

• Anabolism = process of body making substances

Because anabolic steroids have a similar shape to testosterone–a steroid hormone that increases muscle and bone growth (mainly during puberty) and also produces masculine characteristics, so too, do anabolic steroids have similar effects on muscle building. Medically, it is used to treat anemia and muscle-destroying diseases.

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Athletes can use anabolic steroids to increase the rate of muscle growth and performance. However, there are many side effects that include mood swings, depression, impact liver health, and reduce male sex hormone production. As a result, that also causes more consequences. For women, use of steroids can give rise to pronounced masculine traits and disruption of their menstrual cycles. The US congress, professional authorities, and school athlete programs have banned the use of synthetic steroids, using drug testing and punishment to maintain the health and fairness of competitors. However many trainers, coaches, etc continue to give their athletes anabolic steroids.  

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• Proteins = polymers of bonded amino acids

As a result of their wide variation and diversity, proteins participate and regulate almost all dynamic functions in the body. Enzymes are vital to the body’s chemical reactions because they are catalysts (for example, lactase, maltase, and sucrase help make and break down those carbs). Signaling proteins, or hormones, help to control the rate of body activities by acting as messengers–these messages are then received by receptor proteins in the cell membrane that implement or pass on the hormone’s information. Transport proteins also in the cell membrane bring nutrients and sugar into the cell. Defensive proteins patrolling your bloodstreams (like antibodies) defend against antigens. Contractile proteins make up most of your muscle mass, and structural proteins form the ligaments and tendons that keep your joints and muscles operational. For example collagen, a type of structural protein, makes up about 40% of the body’s protein because it is connective tissue. 

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A protein’s function is tied directly to its structure, as its particular shape allows it to complete its specific function. Proteins are mostly carbon, hydrogen, nitrogen, and oxygen. However the sulfur bonds present, although few, form stabilizing bonds within the protein. Most enzymes and other proteins have a globular shape (rounded, compact). Fibrous proteins are longer and thinner, and are the structural proteins (hair, connective tissue, etc). Classification of proteins with globular and fibrous labels are quite general, as each protein also has its own unique shape. The specific way the protein is folded creates grooves and structures that allow it to attach to the molecule it needs to accomplish its function. Most proteins need this recognition system because they operate based on recognizing and binding to a specific molecule. 

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• Denaturation = process of a protein unfolding

When a protein denatures, its specific folding and therefore shape is lost, also removing its ability to function. This shows how important structure is to function, especially for proteins. Without the ability to operate, misshapen proteins can damage the body in the forms of degenerative diseases like Alzhimer’s, mad cow disease, etc. This usually happens because the amino acid chain making up the protein was not folded properly during its immediate arrangement after being made. Infectious proteins that have been mis-folded in such a way are called prions. They are infectious because they cause similar proteins to also mis-fold/become misshapen. It is key to recognize that the three dimensional structure of proteins is the only way they are able to fulfill their functions. 

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• Amino acid = monomer of protein

Amino acids are made up of an amino group (NH₂), carboxyl group (COOH) which gives an amino acid its acidic properties, a central carbon atom, where a hydrogen is attached above and a variable R group is attached below. The R group is an umbrella term for the various arrangements and combinations of carbon atoms and functional groups (glycine only has one H for its R group) that distinguish each amino acid from the other. As a result, the amino and carboxyl group, central carbon, and additional hydrogen all make up the amino acid’s backbone. 

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These R groups are so significant because they determine if the amino acid is hydrophobic or hydrophilic. All of these depend on the end atoms of the R group. Hydrophobic amino acids have nonpolar C–H bonds at the end of the R group. The R groups of hydrophilic amino acids have either polar or charged. OH groups have polar covalent bonds, and any negatively charged O at the end of carboxyl groups are acidic because they have released their H+ ion (increases the acidity. Alternatively, and the NH₂ groups in basic amio acids are able to accept an additional proton (just H+ ion), giving it a negative charge. This turns the NH₂ into a NH₃, although it depends on how many bonds the nitrogen already has. A nitrogen atom have make three covalent bonds, however this acceptance of an additional proton is done through the pair of electrons not involved in covalent bonds. Also, the backbone of an amino acid is usually portrayed in its ionized form, where the carbozyl group has lost its H+ ion, and the amino group has accepted it. 

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• Peptide bond = the bond connecting two amion acids through dehydration synthesis (results in a dipeptide)

• Polypeptide = chain of 100-1,000 amio acids

Amino acids link to each other through dehydration synthesis, bonding the C of a cayboxyl group of one amino acid to the N of a amino group of another amino acid. Two bonded amion acids are called a dipeptide, and the continuation of adding amion acids forms a polypeptide. Despite the fact that there are only 20 different types of amio acids, there are countless types of polypeptide chains (eventaully form unique proteins) because any variation in the seuqence of the amino acids creates a different polypeptide. Also, each chain is at least 100 amino acids long, so there is a lot of variation between just these 20 amino acids. 

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• Disulfide bridge = specific name in some proteins for a covalent bond between two sulfur atoms

There is a key distinction between polypeptide chains and a protein, because a polypeptide must first be elaborately folded so it can form into a protein. This folding process is where the R groups come in, because the hydrophobic or hydrophilic properties it gives to the amion acids. Those hydrophobic amino acids will gather together in the interior of a protein, away from the external water. Conversely the hydrophilic amino acids arrange themselves outside, allowing the protein to be dissolved as a result. Additionally, ionic and hydrogen bonds that form between hydrophilic amino acids also determine a protein’s shape. A type of covalent bond between sulfur atoms also affects the protein’s shape, called a disulfide bridge. 

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• Primary structure = specific sequence of amino acids within one polypeptide chain

• Secondary structure = folding/coiling of the polypeptide chain into particular pattern

• Tertiary structure = the folded, three dimensional shape of the secondary structure

• Quaternary structure = two or more tertiary structures arranged together

First, protein structure begins with a singular polypeptide chain, which, according to its sequence of amino acids and how hydrogen bonds form within its backbone, will form on of two secondary structures (alpha helix or beta pleated sheet). The tertiary structure involves the influence of the R group, and hydrophobic/hydrophilic interactions. This results in a particular folded polypeptide, including its alpha helices/beta pleated sheets. Hydrogen, ionic, and covalent (disulfide bridges) also create the specific folding in tertiary structures.  Finally, the quaternary structure invovles multiple tertiary structures, which are also influenced by hydrogen bonding, resulting in the protein’s final, unique shape. (Stage where protein becomes fully functional, though some proteins can operate as a tertiary structure).