3: Biological Macromolecules Flashcards
Synthesis of Biological Macromolecules, Carbohydrates, Lipids, Proteins, Nucleic Acids
What is a biological macromolecule?
A large molecule necessary for life that is built from smaller organic molecules.
What is dehydration synthesis?
A reaction that links monomer molecules together, releasing a molecule of water for each bond formed. AKA condensation.
What is hydrolysis?
A reaction that causes breakdown of larger molecules into smaller molecules with the utilization of water.
What is a monomer?
The smallest unit of larger molecules called polymers.
What is a polymer?
A chain of monomer residues that is linked by covalent bonds; polymerization is the process of polymer formation from monomers by condensation.
What are the major classes of biological macromolecules?
Carbohydrates, lipids, proteins, and nucleic acids.
How does a dehydration synthesis reaction occur?
The hydrogen of one monomer combines with the hydroxyl group of another monomer, releasing a molecule of water, while also sharing electrons and forming covalent bonds.
What are some of the polymers formed by the glucose monomer?
Starch, glycogen, and cellulose.
How does hydrolysis occur?
A polymer is broken into two components, where one part gains a hydrogen atom (H+) and the other gains a hydroxyl molecule (OH–).
How are dehydration and hydrolysis reactions catalyzed?
They are catalyzed by specific enzymes; dehydration reactions involve the formation of new bonds, requiring energy, while hydrolysis reactions break bonds and release energy.
What are some enzymes that break down carbohydrates?
Amylase, sucrase, lactase, maltase.
What are some enzymes that break down proteins?
Pepsin, peptidase, and hydrochloric acid.
What are some enzymes that break down lipids?
Lipases.
What is a carbohydrate?
A biological macromolecule in which the ratio of carbon to hydrogen and to oxygen is 1:2:1; carbohydrates serve as energy sources and structural support in cells and form the cellular exoskeleton of arthropods.
What is cellulose?
A polysaccharide that makes up the cell wall of plants; provides structural support to the cell.
What is chitin?
A type of carbohydrate that forms the outer skeleton of all arthropods that include crustaceans and insects; it also forms the cell walls of fungi.
What is a disaccharide?
Two sugar monomers that are linked together by a glycosidic bond.
What is glycogen?
Storage carbohydrate in animals.
What is a glycosidic bond?
A bond formed by a dehydration reaction between two monosaccharides with the elimination of a water molecule.
What is a monosaccharide?
A single unit or monomer of carbohydrates.
What is a polysaccharide?
A long chain of monosaccharides; may be branched or unbranched.
How many carbons are usually found in monosaccharides?
Usually from three to seven.
What are some ways in which monosaccharides are classified?
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), or hexoses (six carbons).
What is the chemical formula for glucose?
C6H12O6
How is glucose used by humans?
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).
What is the source of glucose?
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 by humans and other animals that feed on plants.
What are some structural isomers of glucose?
Galactose (part of lactose, or milk sugar) and fructose (found in sucrose, in fruit).
How are glucose, galactose and fructose classified?
They are isomeric monosaccharides (hexoses). Glucose and galactose are aldoses and fructose is a ketose.
Are monosaccharides linear- or ring-shaped?
They can exist as a linear chain or as ring-shaped molecules; in aqueous solutions they are usually found in ring form.
What are the different arrangements of ring-form glucose?
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 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.
What are the types of glycosidic bonds?
Alpha and beta.
What are some common disaccharides?
Lactose, maltose, and sucrose. 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.
How large are polysaccharides?
The molecular weight may be 100,000 daltons or more depending on the number of monomers joined.
How is starch produced?
It 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 needs, is stored as starch in different plant parts, including roots and seeds.
How is starch consumed?
The starch in 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.
How are starch monomers joined?
Starch is made up of glucose monomers that are joined by alpha 1-4 or alpha 1-6 glycosidic bonds, where the numbers refer to the carbon number of the two residues that have joined to form the bond.
How are amylose and amylopectin joined?
Amylose is starch formed by unbranched chains of glucose monomers (only alpha 1-4 linkages), whereas amylopectin is a branched polysaccharide (a 1-6 linkages at the branch points).
How is glycogen stored and used in animals?
Glycogen is highly branched and usually stored in liver and muscle cells. When blood glucose levels decrease, glycogen is broken down to release glucose in a process known as glycogenolysis.
What is the most abundant natural biopolymer?
Cellulose
How are cellulose monomers joined?
Cellulose is made up of glucose monomers that are linked by beta 1-4 glycosidic bonds.
Why does cellulose have high tensile strength?
Every other glucose monomer is flipped over, and the monomers are packed tightly as extended long chains. This gives cellulose its rigidity and high tensile strength, which is important to plant cells.
How is cellulose digested?
The beta 1-4 linkages cannot be broken down by human digestive enzymes, however herbivores such as cows, koalas, buffalos, and horses are able, with the help of specialized flora in their stomach, to digest plant material that is rich in cellulose. 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. 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.
What is chitin made of?
Repeating units of N-acetyl-β-d-glucosamine, a modified sugar.
Where do dietitians work?
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.
How can you become a dietitian?
You need 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).
How many calories are provided by carbohydrates versus fats?
Carbohydrate provides 4.3 Kcal/g compared to 9 Kcal/g in fats.
What is the role of fiber in diet?
Fiber is the insoluble part of carbohydrates and promotes regular bowel movement by adding bulk and regulates the rate of consumption of blood glucose. It 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 the cholesterol exits the body via feces. Fiber-rich diets also have a protective role in reducing the occurrence of colon cancer.
Why should carbohydrates not be eliminated from diet?
Meals containing whole grains and vegetables gives a feeling of fullness. Glucose is broken down to produce ATP, which provides energy. A better way to lose weight is a low-calorie diet that is rich in whole grains, fruits, vegetables, and lean meat, together with exercise and water consumption.
What is starch?
Storage carbohydrate in plants.
What is a lipid?
A macromolecule that is nonpolar and insoluble in water.
What is an omega fat?
A type of polyunsaturated fat that is required by the body; the numbering of the carbon omega starts from the methyl end or the end that is farthest from the carboxylic end.
What is a phospholipid?
A major constituent of the membranes; composed of two fatty acids and a phosphate-containing group attached to a glycerol backbone.
What is a saturated fatty acid?
A long-chain of hydrocarbon with single covalent bonds in the carbon chain; the number of hydrogen atoms attached to the carbon skeleton is maximized.
What is a steroid?
A type of lipid composed of four fused hydrocarbon rings forming a planar structure.
What is a trans fat?
A fat formed artificially by hydrogenating oils, leading to a different arrangement of double bond(s) than those found in naturally occurring lipids.
What is a triglyceride / triacylglycerol?
A fat molecule; consists of three fatty acids linked to a glycerol molecule.
What is an unsaturated fatty acid?
A long-chain hydrocarbon that has one or more double bonds in the hydrocarbon chain.
What is a wax?
A lipid made of a long-chain fatty acid that is esterified to a long-chain alcohol; serves as a protective coating on some feathers, aquatic mammal fur, and leaves.
What are some uses of lipids?
Cells store energy for long-term use in the form of fats. Lipids also provide insulation from the environment for plants and animals. They help to keep aquatic birds and mammals dry when forming a protective layer over fur or feathers because of their water-repellant hydrophobic nature. They are also the building blocks of many hormones and are an important constituent of cellular membranes.
What are the different types of lipids?
Fats, oils, waxes, phospholipids, and steroids.
What are triglycerides made of?
Glycerol and fatty acids. The fatty acids are attached to each of the three carbons of the glycerol molecule with an ester bond through an oxygen atom. The three fatty acids in the triacylglycerol may be similar or dissimilar.
What is glycerol?
Glycerol is an organic compound (alcohol) with three carbons, five hydrogens, and three hydroxyl (OH) groups.
What is a fatty acid?
Fatty acids have a long chain of hydrocarbons to which a carboxyl group is attached, hence the name “fatty acid”. The number of carbons in the fatty acid may range from 4 to 36; most common are those containing 12 to 18 carbons.
What happens during the ester bond formation of triglycerides?
Three water molecules are released.
What are some examples of fatty acids?
Palmitic acid, a saturated fatty acid, is derived from the palm tree. Arachidic acid is derived from Arachis hypogea, the scientific name for groundnuts or peanuts.
What is an example of a saturated and unsaturated fatty acid?
Stearic acid is a saturated fatty acid, and oleic acid is an unsaturated fatty acid.
How are unsaturated fatty acids classified?
If there is one double bond, it is known as a monounsaturated fat, and if there is more than one, it is known as a polyunsaturated fat.
What is an example of a monounsaturated and a polyunsaturated fat?
Olive oil is monounsaturated, and canola oil is polyunsaturated.
What are some examples of food products containing saturated fats?
Animal fats with stearic acid and palmitic acid (common in meat) and the fat with butyric acid (common in butter).
Where are fats stored in plants and animals?
Mammals store fats in specialized cells called adipocytes, where globules of fat occupy most of the cell’s volume. In plants, fat or oil is stored in many seeds and is used as a source of energy during seedling development.
What is the source of unsaturated fats or oils?
They are usually of plant origin and contain cis unsaturated fatty acids.
What is the difference between cis and trans fats?
Cis and trans indicate the configuration of the molecule around the double bond. If hydrogens are present in the same plane, it is referred to as a cis fat; if the hydrogen atoms are on two different planes, it is referred to as a trans fat. The cis double bond causes a bend or a “kink” that prevents the fatty acids from packing tightly, keeping them liquid at room temperature.
What are some examples of unsaturated fats?
Olive oil, corn oil, canola oil, and cod liver oil.
What is the impact of fat consumption in human diet?
Unsaturated fats help to lower blood cholesterol levels whereas saturated fats contribute to plaque formation in the arteries.
How are oils artificially hydrogenated in the food industry?
Artificial hydrogenation makes oils semi-solid and of a consistency desirable for many processed food products. Hydrogen gas is bubbled through the oils to solidify them. During this hydrogenation process, double bonds of the cis-conformation in the hydrocarbon chain may be converted to double bonds in the trans-conformation.
What are some food products that may contain artificially hydrogenated trans fats?
Margarine, some types of peanut butter, and shortening.
What is the impact of trans fats in human diet?
An increase in trans fats in the human diet may lead to an increase in levels of low-density lipoproteins (LDL), or “bad” cholesterol, which in turn may lead to plaque deposition in the arteries, resulting in heart disease.
What are essential fatty acids?
Fatty acids that are required but not synthesized by the human body and must be supplemented through diet.
