Module 2: The Chemical Level of Organization

Lesson 7: Organic Compounds Essential to Human Functioning: Lipids

Các Hợp Chất Hữu Cơ Cần Thiết Cho Hoạt Động Của Con Người: Lipid

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Dưới đây là danh sách những thuật ngữ Y khoa của module The Chemical Level of Organization.
Khái quát được số lượng thuật ngữ sẽ xuất hiện trong bài đọc và nghe sẽ giúp bạn thoải mái tiêu thụ nội dung hơn. Sau khi hoàn thành nội dung đọc và nghe, bạn hãy quay lại đây và luyện tập (practice) để quen dần các thuật ngữ này. Đừng ép bản thân phải nhớ các thuật ngữ này vội vì bạn sẽ gặp và ôn lại danh sách này trong những bài học (lesson) khác của cùng một module.

Medical Terminology: The Chemical Level of Organization

acid
compound that releases hydrogen ions (H+) in solution
activation energy
amount of energy greater than the energy contained in the reactants, which must be overcome for a reaction to proceed
adenosine triphosphate (ATP)
nucleotide containing ribose and an adenine base that is essential in energy transfer
amino acid
building block of proteins; characterized by an amino and carboxyl functional groups and a variable side-chain
anion
atom with a negative charge
atom
smallest unit of an element that retains the unique properties of that element
atomic number
number of protons in the nucleus of an atom
base
compound that accepts hydrogen ions (H+) in solution
bond
electrical force linking atoms
buffer
solution containing a weak acid or a weak base that opposes wide fluctuations in the pH of body fluids
carbohydrate
class of organic compounds built from sugars, molecules containing carbon, hydrogen, and oxygen in a 1-2-1 ratio
catalyst
substance that increases the rate of a chemical reaction without itself being changed in the process
cation
atom with a positive charge
chemical energy
form of energy that is absorbed as chemical bonds form, stored as they are maintained, and released as they are broken
colloid
liquid mixture in which the solute particles consist of clumps of molecules large enough to scatter light
compound
substance composed of two or more different elements joined by chemical bonds
concentration
number of particles within a given space
covalent bond
chemical bond in which two atoms share electrons, thereby completing their valence shells
decomposition reaction
type of catabolic reaction in which one or more bonds within a larger molecule are broken, resulting in the release of smaller molecules or atoms
denaturation
change in the structure of a molecule through physical or chemical means
deoxyribonucleic acid (DNA)
deoxyribose-containing nucleotide that stores genetic information
disaccharide
pair of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond
disulfide bond
covalent bond formed within a polypeptide between sulfide groups of sulfur-containing amino acids, for example, cysteine
electron
subatomic particle having a negative charge and nearly no mass; found orbiting the atom’s nucleus
electron shell
area of space a given distance from an atom’s nucleus in which electrons are grouped
element
substance that cannot be created or broken down by ordinary chemical means
enzyme
protein or RNA that catalyzes chemical reactions
exchange reaction
type of chemical reaction in which bonds are both formed and broken, resulting in the transfer of components
functional group
group of atoms linked by strong covalent bonds that tends to behave as a distinct unit in chemical reactions with other atoms
hydrogen bond
dipole-dipole bond in which a hydrogen atom covalently bonded to an electronegative atom is weakly attracted to a second electronegative atom
inorganic compound
substance that does not contain both carbon and hydrogen
ion
atom with an overall positive or negative charge
ionic bond
attraction between an anion and a cation
isotope
one of the variations of an element in which the number of neutrons differ from each other
kinetic energy
energy that matter possesses because of its motion
lipid
class of nonpolar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water
macromolecule
large molecule formed by covalent bonding
mass number
sum of the number of protons and neutrons in the nucleus of an atom
matter
physical substance; that which occupies space and has mass
molecule
two or more atoms covalently bonded together
monosaccharide
monomer of carbohydrate; also known as a simple sugar
neutron
heavy subatomic particle having no electrical charge and found in the atom’s nucleus
nucleotide
class of organic compounds composed of one or more phosphate groups, a pentose sugar, and a base
organic compound
substance that contains both carbon and hydrogen
peptide bond
covalent bond formed by dehydration synthesis between two amino acids
periodic table of the elements
arrangement of the elements in a table according to their atomic number; elements having similar properties because of their electron arrangements compose columns in the table, while elements having the same number of valence shells compose rows in the table
pH
negative logarithm of the hydrogen ion (H+) concentration of a solution
phospholipid
a lipid compound in which a phosphate group is combined with a diglyceride
phosphorylation
addition of one or more phosphate groups to an organic compound
polar molecule
molecule with regions that have opposite charges resulting from uneven numbers of electrons in the nuclei of the atoms participating in the covalent bond
polysaccharide
compound consisting of more than two carbohydrate monomers bonded by dehydration synthesis via glycosidic bonds
potential energy
stored energy matter possesses because of the positioning or structure of its components
product
one or more substances produced by a chemical reaction
prostaglandin
lipid compound derived from fatty acid chains and important in regulating several body processes
protein
class of organic compounds that are composed of many amino acids linked together by peptide bonds
proton
heavy subatomic particle having a positive charge and found in the atom’s nucleus
purine
nitrogen-containing base with a double ring structure; adenine and guanine
pyrimidine
nitrogen-containing base with a single ring structure; cytosine, thiamine, and uracil
radioactive isotope
unstable, heavy isotope that gives off subatomic particles, or electromagnetic energy, as it decays; also called radioisotopes
reactant
one or more substances that enter into the reaction
ribonucleic acid (RNA)
ribose-containing nucleotide that helps manifest the genetic code as protein
solution
homogeneous liquid mixture in which a solute is dissolved into molecules within a solvent
steroid
(also, sterol) lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules
substrate
reactant in an enzymatic reaction
suspension
liquid mixture in which particles distributed in the liquid settle out over time
synthesis reaction
type of anabolic reaction in which two or more atoms or molecules bond, resulting in the formation of a larger molecule
triglyceride
lipid compound composed of a glycerol molecule bonded with three fatty acid chains
valence shell
outermost electron shell of an atom
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Dưới đây là các bài văn nằm ở bên trái. Ở bên phải là các bài luyện tập (practice) để đánh giá khả năng đọc hiểu của bạn. Sẽ khó khăn trong thời gian đầu nếu vốn từ vựng của bạn còn hạn chế, đặc biệt là từ vựng Y khoa. Hãy kiên nhẫn và đọc nhiều nhất có kể, lượng kiến thức tích tụ dần sẽ giúp bạn đọc thoải mái hơn.
A lipid is one of a highly diverse group of compounds made up mostly of hydrocarbons. The few oxygen atoms they contain are often at the periphery of the molecule. Their nonpolar hydrocarbons make all lipids hydrophobic. In water, lipids do not form a true solution, but they may form an emulsion, which is the term for a mixture of solutions that do not mix well.
A triglyceride is one of the most common dietary lipid groups, and the type found most abundantly in body tissues. This compound, which is commonly referred to as a fat, is formed from the synthesis of two types of molecules (Figure 1):

  • A glycerol backbone at the core of triglycerides, consists of three carbon atoms.
  • Three fatty acids, long chains of hydrocarbons with a carboxyl group and a methyl group at opposite ends, extend from each of the carbons of the glycerol.

Triglycerides form via dehydration synthesis. Glycerol gives up hydrogen atoms from its hydroxyl groups at each bond, and the carboxyl group on each fatty acid chain gives up a hydroxyl group. A total of three water molecules are thereby released.

Fatty acid chains that have no double carbon bonds anywhere along their length and therefore contain the maximum number of hydrogen atoms are called saturated fatty acids. These straight, rigid chains pack tightly together and are solid or semi-solid at room temperature (Figure 2a). Butter and lard are examples, as is the fat found on a steak or in your own body. In contrast, fatty acids with one double carbon bond are kinked at that bond (Figure 2b). These monounsaturated fatty acids are therefore unable to pack together tightly, and are liquid at room temperature. Polyunsaturated fatty acids contain two or more double carbon bonds, and are also liquid at room temperature. Plant oils such as olive oil typically contain both mono- and polyunsaturated fatty acids.

Whereas a diet high in saturated fatty acids increases the risk of heart disease, a diet high in unsaturated fatty acids is thought to reduce the risk. This is especially true for the omega-3 unsaturated fatty acids found in cold-water fish such as salmon. These fatty acids have their first double carbon bond at the third hydrocarbon from the methyl group (referred to as the omega end of the molecule).

Finally, trans fatty acids found in some processed foods, including some stick and tub margarines, are thought to be even more harmful to the heart and blood vessels than saturated fatty acids. Trans fats are created from unsaturated fatty acids (such as corn oil) when chemically treated to produce partially hydrogenated fats.

As a group, triglycerides are a major fuel source for the body. When you are resting or asleep, a majority of the energy used to keep you alive is derived from triglycerides stored in your fat (adipose) tissues. Triglycerides also fuel long, slow physical activity such as gardening or hiking, and contribute a modest percentage of energy for vigorous physical activity. Dietary fat also assists the absorption and transport of the nonpolar fat-soluble vitamins A, D, E, and K. Additionally, stored body fat protects and cushions the body’s bones and internal organs, and acts as insulation to retain body heat.

Fatty acids are also components of glycolipids, which are sugar-fat compounds found in the cell membrane. Lipoproteins are compounds in which the hydrophobic triglycerides are packaged in protein envelopes for transport in body fluids.
As its name suggests, a phospholipid is a bond between the glycerol component of a lipid and a phosphorous molecule. In fact, phospholipids are similar in structure to triglycerides. However, instead of having three fatty acids, a phospholipid is generated from a diglyceride, a glycerol with just two fatty acid chains (Figure 3). The third binding site on the glycerol is taken up by the phosphate group, which in turn is attached to a polar “head” region of the molecule. Recall that triglycerides are nonpolar and hydrophobic. This still holds for the fatty acid portion of a phospholipid compound. However, the head of a phospholipid contains charges on the phosphate groups, as well as on the nitrogen atom. These charges make the phospholipid head hydrophilic. Therefore, phospholipids are said to have hydrophobic tails, containing the neutral fatty acids, and hydrophilic heads, containing the charged phosphate groups and nitrogen atom.
A steroid compound (referred to as a sterol) has as its foundation a set of four hydrocarbon rings bonded to a variety of other atoms and molecules (see Figure 3b). Although both plants and animals synthesize sterols, the type that makes the most important contribution to human structure and function is cholesterol, which is synthesized by the liver in humans and animals and is also present in most animal-based foods. Like other lipids, cholesterol’s hydrocarbons make it hydrophobic; however, it has a polar hydroxyl head that is hydrophilic. Cholesterol is an important component of bile acids, compounds that help emulsify dietary fats. In fact, the word root chole- refers to bile. Cholesterol is also a building block of many hormones, signaling molecules that the body releases to regulate processes at distant sites. Finally, like phospholipids, cholesterol molecules are found in the cell membrane, where their hydrophobic and hydrophilic regions help regulate the flow of substances into and out of the cell.
Like a hormone, a prostaglandin is one of a group of signaling molecules, but prostaglandins are derived from unsaturated fatty acids (see Figure 3c). One reason that the omega-3 fatty acids found in fish are beneficial is that they stimulate the production of certain prostaglandins that help regulate aspects of blood pressure and inflammation, and thereby reduce the risk for heart disease. Prostaglandins also sensitize nerves to pain. One class of pain-relieving medications called nonsteroidal anti-inflammatory drugs (NSAIDs) works by reducing the effects of prostaglandins.

OpenStax. (2022). Anatomy and Physiology 2e. Rice University. Retrieved June 15, 2023. ISBN-13: 978-1-711494-06-7 (Hardcover) ISBN-13: 978-1-711494-05-0 (Paperback) ISBN-13: 978-1-951693-42-8 (Digital). License: Attribution 4.0 International (CC BY 4.0). Access for free at openstax.org.

Triglycerides are composed of glycerol attached to three fatty acids via dehydration synthesis. Notice that glycerol gives up a hydrogen atom, and the carboxyl groups on the fatty acids each give up a hydroxyl group.

The level of saturation of a fatty acid affects its shape. (a) Saturated fatty acid chains are straight. (b) Unsaturated fatty acid chains are kinked.

(a) Phospholipids are composed of two fatty acids, glycerol, and a phosphate group. (b) Sterols are ring-shaped lipids. Shown here is cholesterol. (c) Prostaglandins are derived from unsaturated fatty acids. Prostaglandin E2 (PGE2) includes hydroxyl and carboxyl groups.

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Dưới đây là video và các luyện tập (practice) của bài này. Nghe là một kĩ năng khó, đặc biệt là khi chúng ta chưa quen nội dung và chưa có nhạy cảm ngôn ngữ. Nhưng cứ đi thật chậm và đừng bỏ cuộc.
Xem video và cảm nhận nội dung bài. Bạn có thể thả trôi, cảm nhận dòng chảy ngôn ngữ và không nhất thiết phải hiểu toàn bộ bài. Bên dưới là script để bạn khái quát nội dụng và tra từ mới.
Script:
  1. Organic compounds essential to human functioning include carbohydrates, lipids, proteins, and nucleotides.
  2. These compounds are said to be organic because they contain both carbon and hydrogen.
  3. Carbon atoms in organic compounds readily share electrons with hydrogen and other atoms, usually oxygen, and sometimes nitrogen.
  4. Carbon atoms also may bond with one or more functional groups such as carboxyls, hydroxyls, aminos, or phosphates.
  5. Monomers are single units of organic compounds.
  6. They bond by dehydration synthesis to form polymers, which can in turn be broken by hydrolysis.
  7. Carbohydrate compounds provide essential body fuel.
  8. Their structural forms include monosaccharides such as glucose, disaccharides such as lactose, and polysaccharides, including starches, glycogen, and fiber.
  9. Starches are polymers of glucose, while glycogen is the storage form of glucose.
  10. All body cells can use glucose for fuel.
  11. It is converted via an oxidation-reduction reaction to ATP.
  12. Lipids are hydrophobic compounds that provide body fuel and are important components of many biological compounds.
  13. Triglycerides are the most abundant lipid in the body, and are composed of a glycerol backbone attached to three fatty acid chains.
  14. Phospholipids are compounds composed of a diglyceride with a phosphate group attached at the molecule’s head.
  15. The result is a molecule with polar and nonpolar regions.
  16. Steroids are lipids formed of four hydrocarbon rings.
  17. The most important is cholesterol.
  18. Prostaglandins are signaling molecules derived from unsaturated fatty acids.
  19. Proteins are critical components of all body tissues.
  20. They are made up of monomers called amino acids, which contain nitrogen, joined by peptide bonds.
  21. Protein shape is critical to its function.
  22. Most body proteins are globular.
  23. An example is enzymes, which catalyze chemical reactions.
  24. Nucleotides are compounds with three building blocks: one or more phosphate groups, a pentose sugar, and a nitrogen-containing base.
  25. DNA and RNA are nucleic acids that function in protein synthesis.
  26. ATP is the body’s fundamental molecule of energy transfer.
  27. Removal or addition of phosphates releases or invests energy.
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