Classification of glycosidic anomeric bonds (alpha vs. beta)

Classification of glycosidic anomeric bonds (alpha vs. beta)

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In the process of studying for my upcoming biochemistry exam, I have stumbled over the classification of glycosidic bonds. I want to be able to distinguish $alpha$- from $eta$-glycosidic bonds. Unfortunately, even after reading through this page, I don't really understand how to go about classifying the bonds in e.g. an oligosaccharide.


Now, I am inclined to say that both of these anomeric linkages are of type $alpha$, because the O-glycosidic bond is axial to the respective sugar rings. Is that a correct way of reasoning?

Here's my interpretation, as far as I can get, which agrees with your deduction that both of the O-glycosidic bonds involve α epimers. (If the epimeric carbon has an -OH in the axial direction then this is the α anomer.)

Do you have the name of this compound?

Let's hope that a real glycobiologist comes along.

Supplementary I'm now not sure that it is even possible to assign an anomeric state to the sugar marked as ?. There is no indication in the diagram of the presence of a -CH2OH substituent on the ring - it appears to have a methyl group instead. If that group was a -CH2OH then the putative anomeric C would indeed be in the α form since it is pointing in the opposite direction from the "-CH2OH" (c.f. the two galactose residues). If ? is a deoxy- derivative of a sugar then it may be that the convention still holds.

Carbohydrate Structure

(01) Study the following Fischer projections to answer the questions below.

  1. Is galactose a D-sugar or an L-sugar?
  2. Is mannose a D-sugar or an L-sugar?
  3. Choose either one, and sketch it as it would appear if it was an L-sugar.
  4. Are these two carbohydrates enantiomers? If not, in how many places do they differ?
  5. What is the term to describe the relationship between galactose and mannose?

(02) Are any of the following carbohydrates L-sugars? What makes something an L-sugar as opposed to a D-sugar? Rewrite each structure into an L-sugar if they are not already in that conformation.

(03) Which carbon is considered the anomeric carbon? How do you distinguish between the alpha and beta types of anomers?

(04) Study these Haworth projections to answer the following for each of them.

  1. Is it a furanose or a pyranose?
  2. Is it an alpha or beta anomer?
  3. Circle the anomeric carbon.

(05) Examine the structure of this Fischer projection of D-gulose.

  1. Number each carbon from 1 to 6. What number is the anomeric carbon?
  2. Circle the &ndashOH group that determines whether it is a D- or L-sugar.
  3. Sketch the structure of L-gulose for comparison. Are the two versions of gulose enantiomers of one another or diastereomers?
  4. Now sketch the structure of D-glucose for comparison. Are D-gulose and D-glucose enantiomers or diastereomers?

(06) Examine the following Haworth projections to answer the questions below.

  1. Circle each anomeric carbon
  2. Which of the two is the alpha anomer and which is the beta anomer?
  3. Are these structures considered enantiomers or diastereomers?
  4. Are these monosaccharides reducing sugars? Explain.
  5. Can you convert the alpha anomer to a beta anomer? Explain.

(07) Consult your text and notes for the structure of lactose. Lactose utilizes a beta-1,4 linkage to form a disaccharide. Sketch a hypothetical disaccharide where it instead links the two monosaccharides that form lactose via an alpha-1,6 formation.

(08) Some people cannot digest the disaccharide lactose. The term for this is known as lactose intolerance. Lactose is shown below. Answer the following questions.

1,4 glycosidic bond

The two monosaccharides (monomers, a molecule that can be bonded to other identical molecules to form a polymer) form a disaccharide (2 monomers bound together) and subsequently a polysaccharide (polymers, or many units of sugars). A condensation reaction is when water is eliminated to form a simple molecule. Later hydrolysis by water molecules will reform the two original monosaccharides.

The 1,4 glycosidic bond is formed between the carbon-1 of one monosaccharide and carbon-4 of the other monosaccharide. There are are two types of glycosidic bonds - 1,4 alpha and 1,4 beta glycosidic bonds. 1,4 alpha glycosidic bonds are formed when the OH on the carbon-1 is below the glucose ring while 1,4 beta glycosidic bonds are formed when the OH is above the plane [2] . When two alpha D-glucose molecules join together a more commonly occurring isomer of glucose compared to the L-glucose, form a glycosidic linkage, the term is known as a α-1,4-glycosidic bond [3] .


Lactose is known as milk sugar because it occurs in the milk of humans, cows, and other mammals. In fact, the natural synthesis of lactose occurs only in mammary tissue, whereas most other carbohydrates are plant products. Human milk contains about 7.5% lactose, and cow&rsquos milk contains about 4.5%. This sugar is one of the lowest ranking in terms of sweetness, being about one-sixth as sweet as sucrose. Lactose is produced commercially from whey, a by-product in the manufacture of cheese. It is important as an infant food and in the production of penicillin.

Lactose is a reducing sugar composed of one molecule of D-galactose and one molecule of D-glucose joined by a &beta-1,4-glycosidic bond (the bond from the anomeric carbon of the first monosaccharide unit being directed upward). The two monosaccharides are obtained from lactose by acid hydrolysis or the catalytic action of the enzyme lactase:

Many adults and some children suffer from a deficiency of lactase. These individuals are said to be lactose intolerant because they cannot digest the lactose found in milk. A more serious problem is the genetic disease galactosemia , which results from the absence of an enzyme needed to convert galactose to glucose. Certain bacteria can metabolize lactose, forming lactic acid as one of the products. This reaction is responsible for the &ldquosouring&rdquo of milk.

For this trisaccharide, indicate whether each glycosidic linkage is &alpha or &beta.

The glycosidic linkage between sugars 1 and 2 is &beta because the bond is directed up from the anomeric carbon. The glycosidic linkage between sugars 2 and 3 is &alpha because the bond is directed down from the anomeric carbon.

To Your Health: Lactose Intolerance and Galactosemia

Lactose makes up about 40% of an infant&rsquos diet during the first year of life. Infants and small children have one form of the enzyme lactase in their small intestines and can digest the sugar easily however, adults usually have a less active form of the enzyme, and about 70% of the world&rsquos adult population has some deficiency in its production. As a result, many adults experience a reduction in the ability to hydrolyze lactose to galactose and glucose in their small intestine. For some people the inability to synthesize sufficient enzyme increases with age. Up to 20% of the US population suffers some degree of lactose intolerance.

In people with lactose intolerance, some of the unhydrolyzed lactose passes into the colon, where it tends to draw water from the interstitial fluid into the intestinal lumen by osmosis. At the same time, intestinal bacteria may act on the lactose to produce organic acids and gases. The buildup of water and bacterial decay products leads to abdominal distention, cramps, and diarrhea, which are symptoms of the condition.

The symptoms disappear if milk or other sources of lactose are excluded from the diet or consumed only sparingly. Alternatively, many food stores now carry special brands of milk that have been pretreated with lactase to hydrolyze the lactose. Cooking or fermenting milk causes at least partial hydrolysis of the lactose, so some people with lactose intolerance are still able to enjoy cheese, yogurt, or cooked foods containing milk. The most common treatment for lactose intolerance, however, is the use of lactase preparations (e.g., Lactaid), which are available in liquid and tablet form at drugstores and grocery stores. These are taken orally with dairy foods&mdashor may be added to them directly&mdashto assist in their digestion.

Galactosemia is a condition in which one of the enzymes needed to convert galactose to glucose is missing. Consequently, the blood galactose level is markedly elevated, and galactose is found in the urine. An infant with galactosemia experiences a lack of appetite, weight loss, diarrhea, and jaundice. The disease may result in impaired liver function, cataracts, mental retardation, and even death. If galactosemia is recognized in early infancy, its effects can be prevented by the exclusion of milk and all other sources of galactose from the diet. As a child with galactosemia grows older, he or she usually develops an alternate pathway for metabolizing galactose, so the need to restrict milk is not permanent. The incidence of galactosemia in the United States is 1 in every 65,000 newborn babies.

Breakage of a glycosidic bond by hydrolysis

  • The breakage of a glycosidic bond occurs by the process of hydrolysis by the addition of a water molecule.
  • Hydrolysis of glycosidic bond occurs both in the presence of acid or an alkali.
  • The OH group from the water molecule attacks the carbon atom involved in the glycosidic linkage.
  • In acid-catalyzed hydrolysis, the hydrogen atom binds to the oxygen atom of the ether bond separating the monomeric units.
  • In the case of polysaccharides, hydrolysis results in smaller polysaccharides or disaccharides, or monosaccharides.
  • In the living system, hydrolysis of polysaccharides occurs in the presence of a group of enzymes termed hydrolases that catalyze the hydrolysis process.

Classification of Carbohydrates

Carbohydrates are classified into three different groups based on the degree of polymerization

Carbohydrates/Sugars alpha beta glycosidic bond review?

The anomeric carbon is the carbon that is bonded to the oxygen in the ring and also bonded to an -OH group (which is seen as the glycosidic bond in di- or poly- saccharides). So in your first picture, the anomeric carbon on glucose is C-1. The anomeric carbon on fructose is C-2. The anomeric carbons will ALWAYS be the ones participating in the glycosidic bond.

In the sucrose picture, imagine if you numbered from the other side of the oxygen in the ring. That would make the anomeric carbon C-5, resulting in an alpha 1,5 glycosidic bond. We know this is wrong because we are only ever going to see 1,2 and 1,4 glycosidic bonds (as far as I know). Sucrose is always going to be 1,2 and lactose and maltose are 1,4.

In the lactose picture, we can see that there are two D-sugars (pyranoses). You should be able to recognize that they are D-sugars (the L-sugars will look like the mirror image!) I think the numbering is a little more straightforward here. Just start numbering clockwise from the oxygen in the ring. You can check if your numbers make sense from there. C-1 and C-4 participate in the bond? Checks out! If you numbered from the wrong side, you might get something weird like a 1,3 glycosidic bond.

Let me know if you need more help - I could send some youtube videos from my organic chemistry class that I think explain it pretty well.

Monomers of carbohydrates - monosaccharides

Monomers of carbohydrates, monosaccharides, are the simplest form of 3 types of carbohydrates.

They (mono- = “one” sacchar- = “sweet”) are simple sugars, the most common of which is glucose.

Most monosaccharide names end with the suffix -ose.

  • If the sugar has an aldehyde group (the functional group with the structure R-CHO), it is known as an aldose,
  • if it has a ketone group (the functional group with the structureR-C(=O)-R') , it is known as aketose .

In monosaccharides, the number of carbons usually ranges from three to seven.

Depending on the number of carbons in the sugar, they also may be known as trioses (three carbons), pentoses (five carbons), and hexoses (six carbons).

The two simplest monomers of carbohydrates are:

  • dihydroxyacetone (a triose with a ketone group),
  • glyceraldehyde (a triose with an aldehyde group).

Three common pentose sugars are:

  • ribose (a component of RNA),
  • deoxyribose (a sugar in DNA),
  • ribulose (used in photosynthesis).

Three common hexoses are:

  • glucose (source of energy for all cells),
  • galactose (milk sugar),
  • fructose (fruit sugar).

Although glucose, galactose, and fructose all have the same chemical formula (C6H12O6), they differ structurally and chemically (and are known as isomers) because of the different arrangement of functional groups around the asymmetric carbon all of these monosaccharides have more than one asymmetric carbon.

Monosaccharides can exist as a linear chain or as ring-shaped molecules in aqueous solutions they are usually found in ring forms.

Ring forms of monosaccharides serve as a monomer of carbohydrate polymers.

Ring structure of glucose

When a glucose molecule forms a six-membered ring, there is a 50 percent chance that the hydroxyl group at carbon one will end up below the plane of the ring.

Thus the ring structure of glucose can have two different arrangements of the hydroxyl group (-OH) around the anomeric carbon.

The anomeric carbon - carbon 1 that becomes asymmetric in the process of ring formation, stereocenter.

If the hydroxyl group is below carbon number 1 in the ring structure of glucose, it is said to be in the alpha (α) position, and if it is above the plane, it is said to be in the beta (β) position.

alpha (α) position and beta (β) position of the anomeric carbon of the ring structure of glucose

3.2 Carbohydrates

Most people are familiar with carbohydrates, one type of macromolecule, especially when it comes to what we eat. To lose weight, some individuals adhere to “low-carb” diets. Athletes, in contrast, often “carb-load” before important competitions to ensure that they have enough energy to compete at a high level. Carbohydrates are, in fact, an essential part of our diet grains, fruits, and vegetables are all natural sources of carbohydrates. Carbohydrates provide energy to the body, particularly through glucose, a simple sugar that is a component of starch and an ingredient in many staple foods. Carbohydrates also have other important functions in humans, animals, and plants.

Molecular Structures

Carbohydrates can be represented by the stoichiometric formula (CH2O)n, where n is the number of carbons in the molecule. In other words, the ratio of carbon to hydrogen to oxygen is 1:2:1 in carbohydrate molecules. This formula also explains the origin of the term “carbohydrate”: the components are carbon (“carbo”) and the components of water (hence, “hydrate”). Carbohydrates are classified into three subtypes: monosaccharides, disaccharides, and polysaccharides.


Monosaccharides (mono- = “one” sacchar- = “sweet”) are simple sugars, the most common of which is glucose. In monosaccharides, the number of carbons usually ranges from three to seven. Most monosaccharide names end with the suffix -ose. If the sugar has an aldehyde group (the functional group with the structure R-CHO), it is known as an aldose, and if it has a ketone group (the functional group with the structure RC(=O)R'), it is known as a ketose. Depending on the number of carbons in the sugar, they also may be known as trioses (three carbons), pentoses (five carbons), and or hexoses (six carbons). See Figure 3.4 for an illustration of the monosaccharides.

The chemical formula for glucose is C6H12O6. In humans, glucose is an important source of energy. During cellular respiration, energy is released from glucose, and that energy is used to help make adenosine triphosphate (ATP). Plants synthesize glucose using carbon dioxide and water, and glucose in turn is used for energy requirements for the plant. Excess glucose is often stored as starch that is catabolized (the breakdown of larger molecules by cells) by humans and other animals that feed on plants.

Galactose (part of lactose, or milk sugar) and fructose (found in sucrose, in fruit) are other common monosaccharides. Although glucose, galactose, and fructose all have the same chemical formula (C6H12O6), they differ structurally and chemically (and are known as isomers) because of the different arrangement of functional groups around the asymmetric carbon all of these monosaccharides have more than one asymmetric carbon (Figure 3.5).

Visual Connection

What kind of sugars are these, aldose or ketose?

Glucose, galactose, and fructose are isomeric monosaccharides (hexoses), meaning they have the same chemical formula but have slightly different structures. Glucose and galactose are aldoses, and fructose is a ketose.

Monosaccharides can exist as a linear chain or as ring-shaped molecules in aqueous solutions they are usually found in ring forms (Figure 3.6). Glucose in a ring form can have two different arrangements of the hydroxyl group (OH) around the anomeric carbon (carbon 1 that becomes asymmetric in the process of ring formation). If the hydroxyl group is below carbon number 1 in the sugar, it is said to be in the alpha (α) position, and if it is above the plane, it is said to be in the beta (β) position.


Disaccharides (di- = “two”) form when two monosaccharides undergo a dehydration reaction (also known as a condensation reaction or dehydration synthesis). During this process, the hydroxyl group of one monosaccharide combines with the hydrogen of another monosaccharide, releasing a molecule of water and forming a covalent bond. A covalent bond formed between a carbohydrate molecule and another molecule (in this case, between two monosaccharides) is known as a glycosidic bond (Figure 3.7). Glycosidic bonds (also called glycosidic linkages) can be of the alpha or the beta type.

Common disaccharides include lactose, maltose, and sucrose (Figure 3.8). Lactose is a disaccharide consisting of the monomers glucose and galactose. It is found naturally in milk. Maltose, or malt sugar, is a disaccharide formed by a dehydration reaction between two glucose molecules. The most common disaccharide is sucrose, or table sugar, which is composed of the monomers glucose and fructose.


A long chain of monosaccharides linked by glycosidic bonds is known as a polysaccharide (poly- = “many”). The chain may be branched or unbranched, and it may contain different types of monosaccharides. The molecular weight may be 100,000 daltons or more depending on the number of monomers joined. Starch, glycogen, cellulose, and chitin are primary examples of polysaccharides.

Starch is the stored form of sugars in plants and is made up of a mixture of amylose and amylopectin (both polymers of glucose). Plants are able to synthesize glucose, and the excess glucose, beyond the plant’s immediate energy needs, is stored as starch in different plant parts, including roots and seeds. The starch in the seeds provides food for the embryo as it germinates and can also act as a source of food for humans and animals. The starch that is consumed by humans is broken down by enzymes, such as salivary amylases, into smaller molecules, such as maltose and glucose. The cells can then absorb the glucose.

Starch is made up of glucose monomers that are joined by α 1-4 or α 1-6 glycosidic bonds. The numbers 1-4 and 1-6 refer to the carbon number of the two residues that have joined to form the bond. As illustrated in Figure 3.9, amylose is starch formed by unbranched chains of glucose monomers (only α 1-4 linkages), whereas amylopectin is a branched polysaccharide (α 1-6 linkages at the branch points).

Glycogen is the storage form of glucose in humans and other vertebrates and is made up of monomers of glucose. Glycogen is the animal equivalent of starch and is a highly branched molecule usually stored in liver and muscle cells. Whenever blood glucose levels decrease, glycogen is broken down to release glucose in a process known as glycogenolysis.

Cellulose is the most abundant natural biopolymer. The cell wall of plants is mostly made of cellulose this provides structural support to the cell. Wood and paper are mostly cellulosic in nature. Cellulose is made up of glucose monomers that are linked by β 1-4 glycosidic bonds (Figure 3.10).

As shown in Figure 3.10, every other glucose monomer in cellulose is flipped over, and the monomers are packed tightly as extended long chains. This gives cellulose its rigidity and high tensile strength—which is so important to plant cells. While the β 1-4 linkage cannot be broken down by human digestive enzymes, herbivores such as cows, koalas, and buffalos are able, with the help of the specialized flora in their stomach, to digest plant material that is rich in cellulose and use it as a food source. In these animals, certain species of bacteria and protists reside in the rumen (part of the digestive system of herbivores) and secrete the enzyme cellulase. The appendix of grazing animals also contains bacteria that digest cellulose, giving it an important role in the digestive systems of ruminants. Cellulases can break down cellulose into glucose monomers that can be used as an energy source by the animal. Termites are also able to break down cellulose because of the presence of other organisms in their bodies that secrete cellulases.

Carbohydrates serve various functions in different animals. Arthropods (insects, crustaceans, and others) have an outer skeleton, called the exoskeleton, which protects their internal body parts (as seen in the bee in Figure 3.11). This exoskeleton is made of the biological macromolecule chitin , which is a polysaccharide-containing nitrogen. It is made of repeating units of N-acetyl-β-d-glucosamine, a modified sugar. Chitin is also a major component of fungal cell walls fungi are neither animals nor plants and form a kingdom of their own in the domain Eukarya.

Career Connection

Registered Dietitian

Obesity is a worldwide health concern, and many diseases such as diabetes and heart disease are becoming more prevalent because of obesity. This is one of the reasons why registered dietitians are increasingly sought after for advice. Registered dietitians help plan nutrition programs for individuals in various settings. They often work with patients in health care facilities, designing nutrition plans to treat and prevent diseases. For example, dietitians may teach a patient with diabetes how to manage blood sugar levels by eating the correct types and amounts of carbohydrates. Dietitians may also work in nursing homes, schools, and private practices.

To become a registered dietitian, one needs to earn at least a bachelor’s degree in dietetics, nutrition, food technology, or a related field. In addition, registered dietitians must complete a supervised internship program and pass a national exam. Those who pursue careers in dietetics take courses in nutrition, chemistry, biochemistry, biology, microbiology, and human physiology. Dietitians must become experts in the chemistry and physiology (biological functions) of food (proteins, carbohydrates, and fats).

Benefits of Carbohydrates

Are carbohydrates good for you? People who wish to lose weight are often told that carbohydrates are bad for them and should be avoided. Some diets completely forbid carbohydrate consumption, claiming that a low-carbohydrate diet helps people to lose weight faster. However, carbohydrates have been an important part of the human diet for thousands of years artifacts from ancient civilizations show the presence of wheat, rice, and corn in our ancestors’ storage areas.

Carbohydrates should be supplemented with proteins, vitamins, and fats to be parts of a well-balanced diet. Calorie-wise, a gram of carbohydrate provides 4.3 Kcal. For comparison, fats provide 9 Kcal/g, a less desirable ratio. Carbohydrates contain soluble and insoluble elements the insoluble part is known as fiber, which is mostly cellulose. Fiber has many uses it promotes regular bowel movement by adding bulk, and it regulates the rate of consumption of blood glucose. Fiber also helps to remove excess cholesterol from the body: fiber binds to the cholesterol in the small intestine, then attaches to the cholesterol and prevents the cholesterol particles from entering the bloodstream, and then cholesterol exits the body via the feces. Fiber-rich diets also have a protective role in reducing the occurrence of colon cancer. In addition, a meal containing whole grains and vegetables gives a feeling of fullness. As an immediate source of energy, glucose is broken down during the process of cellular respiration, which produces ATP, the energy currency of the cell. Without the consumption of carbohydrates, the availability of “instant energy” would be reduced. Eliminating carbohydrates from the diet is not the best way to lose weight. A low-calorie diet that is rich in whole grains, fruits, vegetables, and lean meat, together with plenty of exercise and plenty of water, is the more sensible way to lose weight.

Link to Learning

For an additional perspective on carbohydrates, explore “Biomolecules: the Carbohydrates” through this interactive animation.

Differences Between Alpha and Beta Glucose

Glucose is the unit of carbohydrate and show the unique characteristic of the carbohydrate. Glucose is a monosaccharide and reducing sugar which is the main product of photosynthesis in plants. Chlorophylls produce glucose and oxygen using inorganic carbon and water. So, sunlight is fixed into chemical energy through glucose. Then glucose is further converted into starch and stored in plants. In respiration, glucose is broken down to ATP and provides energy to the living organisms resulting carbon dioxide and water as the final product of respiration. Glucose can be found in animals and humans, in their blood stream.

Glucose is six carbon molecule or called hexose. The formula of the glucose is C 6 H 12 O 6 , and this formula is common to other hexoses too.Glucose can be in cyclic chair form and in chain form.

Since glucose has aldehyde, ketone and alcohol functional groups it can be easily converted into straight chain form to cyclic chain form. The tetrahedral geometry of the carbons makes six membered stable ring. Hydroxyl group on the carbon five in the straight chain is linked with carbon one making hemiacetal bond (Mcmurry, 2007). So the carbon one is called anomeric carbon. When glucose is figured into fischer projection, this the hydroxyl group of the asymmetric carbon is drawn in the right and called D- glucose. If the hydroxyl group of the asymmetric carbon is in the left side in the fischer projection, it is L- glucose. D- glucose has two sterioisomers called alpha and beta differing from specific rotation. In a mixture, these two forms can be converting into each other and forms equilibrium. This process is called mutarotation.

Alpha Glucose

The arrangement of the atoms in space of the glucose molecule is important when determining of the chemical nature. Alpha and beta glucose are stereoisomers. The (1-4) glycosidic bond between two α-D-glucose molecules produces a disaccharide called maltase. Bonding large number of α-D-glucose molecules α-(1-4) glycosidic bond starch is formed, which contain amylopectin and amylose. They can be easily broken down by enzymes.

Beta Glucose

Two β-D- glucose molecules are bound with (1-4) glycosidic bond making cellobiose, and further making cellulose which is difficult to broken down by enzymes. The beta form is more stable than the alpha form so in a mixture, amount of β-D- glucose is two third at 20°. Although these two isomeric forms are similar in elementary form, they are not similar in physical and chemical properties.

What is the difference between Alpha Glucose and Beta Glucose?

• They are different in specific rotation, α- D- glucose has [a]D 20 of 112.2°and β-D-glucose has

[a] D 20 of 18.7°.

• The beta form is more stable than the alpha form, so in a mixture amount of β-D- glucose is higher than α-D-glucose.

• The (1-4) glycosidic bond between two α-D-glucose molecules produces a disaccharide called maltase while two β-D-glucose molecules are bound with (1-4) glycosidic bond making cellobiose.

• Starch, which is produced with α-D-glucose, is easily broken down by enzymes, whereas cellulose cannot be easily broken down by enzymes.

• Cellulose, which is a polymer of β-D-glucose, is structural material and starch is the storage food in plants.

Classification of glycosidic anomeric bonds (alpha vs. beta) - Biology

Monomer - the building block that is used to make polymers EX: glucose

Polymer - a large molecule made up of identical or similar building blocks EX: polysaccharides, starches

Enzymes - a macromolecule serving as a catalyst, a chemical agent that changes the rate of a reaction without being consumed by the reaction

Dehydration reaction - a chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule Sugars build through this linkage

Hydrolysis - a chemical process that lyses, or splits, molecules by the addition of water, functioning in disassembly of polymers to monomers

Carbohydrates - composed of C, H, O most names of sugars end in "-ase" contains a carbonyl (C=O) and many hydroxyl (OH) functions: energy and storage EX: sugars, starches, cellulose, chitin

Monosaccharides - simple 1 monomer sugars 5- and 6-Carbon chains energy is stored in the carbon rings (key parts of nucleic acids, ATP)

glucose - Hexose - 6-Carbon rings

fructose - Disaccharide = Glucose+Galactose

deoxyribose - sugar found in DNA. Does not include oxygen

Disaccharides - 2 monomers held together by glycosidic bonds!

sucrose - Glucose + Fructose

lactose - Glucose + Galactose

maltose - Glucose + Glucose

Glycosidic bonds/linkages - chemical linkage between the monosaccharide units of disaccharides, and polysaccharides, which is formed by the removal of a molecule of water (aka condensation reaction) bond forms between the carbon-1 on one sugar and the carbon-4 on the other α-glycosidic bonds are formed when the -OH group on carbon-1 is BELOW the plane of the glucose ring . β-glycosidic bonds bonds are formed when the -OH group on carbon-1 is ABOVE the plane

Polysaccharides - polymers of sugars joined by glycosidic linkages

1) structural polysaccharides - key in forming the structure of an organism

Cellulose - most abundant organic compound on Earth herbivores have evolved a mechanism to digest cellulose (most carnivores have not)

Chitin - found in arthropods EX: insects, spiders, crustaceans, and fungi

2) storage polysaccharides- glycosidic linkages are hydrolyzed to obtain monosaccharides as energy is needed

Starch - amylose - main storage polysaccharide found in plants with a 1-4 glycosidic linkage found in glucose anylopectin found in plants with branching

G lycogen - main storage polysaccharide in animals highly branched primarily in muscle and liver cells and is used when glucose stores are low

Lipids - composed of C, H, O long hydrocarbon chains do NOT form polymers

Fatty Acids - 1 glycerol + 3 fatty acids long HC tail with carboxyl group head Functions: store large amounts of energy and insulation not polymers but assembled from smaller molecules by dehydration synthesis adipose tissue is made primarily of triacylglycerols (fat). Formed by dehydration synthesis between glycertol and a fatty acid..ESTER LINKAGE

Triacyglycerol (fats) - constructed of two kinds of smaller molecules: glycerol and three carbons covalently bound to one another, each with a single hydroxyl group (triose) (same functions as fatty acids)

Saturated vs unsaturated fatty acids -

Saturated - composed of fatty acid chains that contain no double bonds saturated with hydrogen All C bonded to H - no C=C double bonds long, straight chains most animal fats solid at room temp. contributes to cardiovascular disease (atherosclerosis - hardening of the arteries)

Unsaturated - composed of fatty acid chains with double bonds not saturated with hydrogen naturally occurring fatty acid chains are Cis-fats C=C double bonds in fatty acids plant and fish fats, vegetable oils, liquid at room temp liquid at room temp

Phospholipids - double layer-bilayer hydrophilic heads on outside that are in contact with aqueous solution outside of cell and inside of cell hydrophobic tails on inside that form the core of phospholipids - form carrier between cell and external environment Structure: glycerol + 2 fatty acids + PO4 = negatively charged amphipathic, which is when aqueous environments are pushed together while the heads interact with water and each other Found in biological membranes - allows passage through membranes - the proteins imbeded in the phospholipid bilayer that allows polar molecules and ions in and out

Steroids - hydrophobic Structure: 4 fused C rings - different steroids created by attaching different functional groups to rings EX: cholesterol, sex hormones

Cholesterol - make up animal cell membranes and sex hormones

Proteins - EX: Structural: hair, fingernails, feathers (keratin) Storage: egg white (albumin) Transcript: Transport iron in blood (hemoglobin) Hormonal: Regulate blood sugar (insulin) Membrane Proteins: receptors, antigens Movement: muscle contraction (actin and myosin) Defense: antibodies - fight germs Metabolism: enzymes act as catalysts in chemical reactions Toxins: (botulism, diphtheria)

Catalyst - speed up reactions in proteins not consumed by reaction

Polypeptide - (polymer) protein can be one or more polypeptide chains folded and bonded together large and complex molecules complex 3-D shape

Amino Acids - monomer 20 different amino acids central carbon - assymetric carbon (bonded to 4 different molecules) carboxyl group

Peptide bonds - covalent bond between NH2 (amine) of one amino acid and COOH, (carboxyl) of another C-N bond Peptide Bonds!

alpha helix vs beta pleated sheets - (in secondary protein structure) alpha helix held together by Hydrogen bonds between every 4th amino acid (spiral) EX: keratin. beta pleated sheets - strong due to many Hydrogen bonds (logs in a raft) EX: silk

Hydrophobic interactions - (tertiary structure) cytoplasm is water-based nonpolar amino acids cluster away from water Hydrogen bonds and ionic bonds disulfid bridges covalent bonds between sulfurs in sulfhydryls (S-H) anchors 3-D shape

Disulfie bridges - covalent cross links between sulfhydryls stabilizes 3-D structure

Denaturation - unfolding a protein conditions that disrupt H bonds, ionic bonds, disulfide bridges: pH, salt, temperature alter tertiary and quaternary structure (3-D shape) destroys functionality - some proteins can return to their functional shape after denaturation many cannot

Chaperonins - guide protein folding provide shelter for folding polypeptides keep the new proteins segregated from cytoplasmic influences

Nucleic Acids - information flow in cells stores information blueprint for building proteins DNA --> RNA --> Proteins

DNA - deoxyribonucleic acid double helix genetic code contains info that programs cell activity sugar=deoxyribose Nitrogenous bases: A,T,C,G strands run in opposite directions (anitparallel) hydrogen bonds between nitrogenous bases hold sides of ladder together H replaces the -OH on the 2' carbon

RNA - single stranded sugar=ribose nitrogenous bases= A,U,G,C can fold up in 3-D shape has -OH on the 2' carbon

Genes - DNA strands in each of our genes and are identical, create our features and bodily "blueprint"

Nucleotides - nitrogenous base + sugar (ribose in RNA and deoxyribose in DNA) + phosphate group monomer of nucleic acids build polymers

Pyrimidines vs Purines - pyrimidines - 1 ring Cytosine (C), Thymine (T), Uracil (U). Triangle with "CUT". Purines - 2 rings Adenine (A) and Guanine (G). Pure silver --> Ag

Deoxyribose vs Ribose - deoxyribose is the sugar in DNA and ribose is sugar in RNA


Why and how do cells synthesize and break down macromolecules?

>Cells synthesize macromolecules through a process called dehydration synthesis that removes the water molecules from a macromolecule and the H+ ions and OH- ions leave room for synthesis. Macromolecules are broken down through hydrolysis, which is simply the opposite

How are carbohydrates, lipids, nucleic acids, and proteins similar and different in their form and function?

>All are made with the same basic elements, just different configurations to create completely new functions and substances and all have monomers that build to polymers.

How does the level of protein structure affect the function of the protein?

>The different protein structures affect the protein functions by differentiating the 3-D structures and shapes (coiled, rippled, folded)

How can a change in the structure of a protein affect the ability of the protein to function?

>A slight change in DNA sequence can change the entire organism's makeup and is connected by peptide bonds.