Chapter 2 A & P

Describe what is formed when when water dissociates. What does dissociation mean in this case?

ions form when water dissociates. It means dissociation?

Define an amphipathic molecule (LOOK AT FIGURE 2.10)

molecules that contain both nonpolar and polar components are called amphipathic molecules. ex: phospholipid

Compare and Contrast the 3 different types of water mixtures. Define emulsion (FIGURE 2.16 IN JOURNAL)

*Suspension*: a suspension is a mixture composed of particles that are relatively large. These types of mixtures do not remain mixed together unless the mixture is in motion. The large solutes or cells settle out of a suspension when it is not in motion. EX: sand in water and blood cells within the plasma ( the liquid portion of the blood *Colloid*: A colloid is a mixture composed of smaller particles than those in a suspension (but larger than those in a solution). It remains mixed when not in motion. EX: gelatin and agar media *Solution*: A solution is a homogeneous mixture in which the dissolved substance is very small. The water is the solvent, and the dissolved substance is the solute. Solutes are not visible, do not scatter lights, and not settle if the solution is not in motion EX: salt water and sugar water Emulsion: An emulsion is composed specifically of water and a nonpolar ( hydrophobic) liquid substance such as vegetable oil, which does not mix unless shaken or agitated. Emulsions are classified as a type of colloid EX: Breast Milk

Describe the molecular structure of water and how water molecules form four hydrogen bonds. (FIGURE 2.12) :)

*Water* is a polar molecule composed of one oxygen atom bonded to two hydrogen atoms. It exhibits polarity bc there is an unequal sharing of electrons between the oxygen atom and each of the two hydrogen atoms Every water molecule has the ability to form 4 hydrogen bonds with adjacent water molecules. This is because each of the 2 hydrogen atoms forms one hydrogen bond, and each oxygen atom forms 2 hydrogen bonds Water is a polar molecule due to unequal sharing of electrons Hydrogen bonds form between water molecules

Describe the role of water in both dehydration and hydrolysis reactions in altering biomolecules (FIGURE 2.17)

- During the synthesis of complex molecules from simpler subunits, one specific subunit *loses* an -H, and the other subunit *loses* an -OH, to form a water molecule (which is released) as a new covalent bond is produced. This type of reaction is called *dehydration synthesis* or condensation bc the equivalent of a water molecule is "lost" from the original structure - During the breakdown of complex molecules, H2O molecules are split. An -H is *added* to one subunit, and an -OH is *added* to another subunit in the complex molecule, and the chemical bond is broken between them. Because the equivalent of water is added to break a bond within the molecule, the process is referred to as *hydrolysis* or a hydrolysis reaction

List the general functions of proteins and provide examples of each ( TABLE 2.6 IN JOURNAL) ( Figure 2.23)

- Serve as *catalysts* (enzymes) in most metabolic reactions of the body - Act in *defense* , which occurs, for example, when immunoglobulins (antibodies) attach to foreign substances for their elimination - Aid in *transport*, as when hemoglobin molecules transport respiratory gases within the blood - *Contribute to structural support*, such as collagen, a major component of ligaments and tendons - Cause *movement* , when myosin and act in proteins interact during concentration of muscle tissue - Perform *regulation* as occurs when insulin helps control blood glucose levels - Provide *storage*, such as ferritin, which stores iron in liver cells

Describe the chemical interactions of nonpolar substances and water :)

-substances that don't dissolve in water ( Nonpolar Molecules) - nonpolar molecules do not dissolve in water, and so they are called *hydrophobic* (meaning water fearing) - the hydrogen bonds between water molecules cause the water molecules to be cohesive (stick to each other) and attract each other; at the same time, they exclude, or "force out" the nonpolar molecules by a process called *hydrophobic exclusion* (you can observe that when oil contacts water) - the interaction between the molecules of the excluded nonpolar substance is termed hydrophobic interaction because it appears that these molecules are avoiding water - hydrophobic substances: triglycerides (fats) and cholesterol (can't dissolve in water) - Nonpolar molecules are hydrophobic; "hydro-" means water and "-phobic" means fear. Nonpolar molecule are water fearing and do not easily dissolve in water. These molecules have nonpolar covalent bonds or polar covalent bonds, both of which share their electrons equally between the bonded elements

Describe the structure of a nucleotide(LOOK AT FIGURE 2.21 IN JOURNAL)

A nucleotide has: - a sugar (deoxyribose for DNA or Ribose for RNA) ,the sugar is a five carbon pentose sugar - a phosphate functional group, attached at a carbon #5 - a nitrogenous base, attached to the same sugar but at a carbon #1. Has either a single ring or double ring structure that contains both carbon and nitrogen within the ring Single-Ring Nitrogenous bases (pyrimidines) >Cytosine (C) DNA & RNA >Uracil (U) UNIQUE TO RNA >Thymine (T) UNIQUE TO DNA Double-RIng nitrogenous bases (purines) >Adenine (A) DNA & RNA >Guanine (G) DNA & RNA

Explain the difference between an acid and a base

Acid: a substance that dissociates in water to produce H^+ and an anion - Because H^+ is a proton, an acid is also called a *proton donor*. The proton donor increases concentration of free H^+ - More dissociation of H^+ with stronger acids - Less dissociation H^+ with weaker acids, e.g., carbonic acid in the blood - Equation: Substance A (an acid in water) -> H^+ + anion Base: accepts H^+ when added to solution -Proton acceptor, decreases concentration of free H^+ - More absorption of H^+ with stronger bases - Less absorption of H^+ with weak bases, e.g., bicarbonate in blood - Equation: Substance B (a base in water) + H^+ -> B-H

Explain how amphipathic molecules interact in water to form chemical barriers (FIGURE 2.14) :)

Amphipathic molecules have both polar and nonpolar regions. They do not completely dissolve, nor are they completely excluded when placed into water. Instead the polar portion dissolves in water (hydrophilic), and the nonpolar portion is repelled by water (hydrophobic) Recall that phospholipid molecules are amphipathic molecules, The polar heads of these molecules are hydrophilic and have contact with water, but their non-polar tails are hydrophobic and group together, limiting their contact with water. This results in bilayers (two layers) of phospholipids that form chemical barriers within the body. A bilayer of phospholipid molecules composes membranes of a cell (e.g. the plasma membrane which forms the outside barrier of a cell)

Describe ATP and explain why it is called the "energy currency" of a cell :)

An important nucleotide is adenosine triphosphate or *ATP*. - composed of the nitrogenous base (A)denine, a ribose sugar and 3 phosphate groups - ATP is the central molecule in the transfer of chemical energy within cells - Biologists often refer to this molecule as the *"energy currency"* of a cell. The covalent phosphate bond linkages between the last two phosphate groups are unique, energy-rich bonds.

Define atom and element. Diagram the structure of an atom ;)

Atom: the smallest particle that exhibits the chemical properties of an element Figure 2.2 in Journal composed of neutrons, protons and electrons

Describe the general chemical composition of biomolecules :)

Biological Macromolecules are organized into 4 primary classes that include: lipids, carbohydrates, nucleic acids, and proteins. Biological macromolecules are large organic molecules that are synthesized by the human body. These molecules always contain the elements carbon, hydrogen and oxygen. Some biological macromolecules may also have one or more of the following: -Nitrogen (N) -Phosphorus (P) -Sulfur (S) (CHON P.S.) Biological macromolecules are not simply hydrocarbons ( involve only carbon and hydrogen molecules) because these molecules also contain functional groups (two or more atoms that when present together on a molecule always exhibit the same specific chemical characteristics) (TABLE 2.3) such as hydroxyl, carboxyl, amine, and phosphate

Describe the distinguishing characteristics of carbohydrates. (FIGURE 2.19)

Carbohydrate means hydrated carbon. -H and -OH are usually attached to every carbon Chemical formula: (CH2O) n , n = # of carbon atoms in a molecule The least complex carbohydrates are simple sugar monomers called *monosaccharides* Carbohydrates that are dimers formed from two monosaccharides are *disaccharides* , and those with many monosaccharides are *polysaccharides* . Polysaccharides formed from nay monosaccharides, ( e.g. glycogen ) animal storage, stach (plant storage), cellulose (structure of plant)

Differentiate between cations and anions. Describe how charges are assigned to ions. pg 37

Cations: Ions with a positive charge (lose electrons) Anions: Ions with a negative charge (gaining electrons) do this and gain stability. Cations are positively charged because electrons are lost, and anions, which have a negative charge because electrons are gained.

List the different properties of water and provide an example of the importance of each property within the body.

Cohesion: is the attraction between water molecules. They are inclined to "stick together" because hydrogen bonds form between these molecules Surface Tension: is the inward pulling of cohesive forces at the surface of water. This inward attraction occurs because water molecules at the surface are pulled by hydrogen bonds in only 3 directions, whereas water molecules that are internal in the liquid are pulled by hydrogen bonds in 4 directions. Adhesion: is the attraction between water molecules and a substance other than water. This occurs when hydrogen bonds form between water molecules and the molecules that compose those other substances Two properties of water influence water temperature: Its specific heat and the heat of vaporization Temperature: the measure of kinetic heat Specific Heat: is the amount of energy (measured in calories) required to increase the temperature of 1 gram of a substance by 1 degree celsius (C) - waters value extremely high due to energy needed to break hydrogen bonds - contributed to keeping body temperature constant Heat of Vaporization: is the energy required for the release of molecules from a liquid phase into the gaseous phase for 1 gram of a substance - waters value very high due to hydrogen bonding -sweating cools body

Distinguish between DNA and RNA :)

DNA: # of strands:2, double stranded Sugar: deoxyribose sugar Nitrogenous base: uses (T)hymine base. (T)hymine:(A)denine & (G)uanine:(C)ytosine Location : nucleus, mitochondria RNA- # of stands: single stranded Sugar: ribose sugar Nitrogenous base: uses (U)racil base. (U)racil:(A)denine & (G)uanine:(C)ytosine Location : nucleus, cytoplasm - (G)uanine is the complementary base of (C)ytosine - (A)denine is the complementary base of (T)hymine in DNA and of (U)racil in RNA

Distinguish between electrolytes and nonelectrolytes

Electrolytes: substances that both dissolve and dissociate in water, such as salts, acids, and bases, can readily conduct an electric current. Nonelectrolytes: In contrast, substances that remain intact when introduced into water, such as glucose, do not conduct an electric current

Name some monosaccharide, disaccharides, and polysaccharides found in living systems :)

FIGURE 2.20 IN JOURNAL AND PG 57 Monosaccharides contain one saccharide molecule. 6-carbon sugars also known as hexose sugars are FOR EXAMPLE galactose and fructose. 5-carbon sugars also known as pentose sugars are FOR EXAMPLE ribose and deoxyribose (both are sugar molecules of the nucleic acids). Disaccharides are dimers composed of two monosaccharides/saccharides bonded together. EXAMPLES are: sucrose (table sugar), lactose (milk sugar), and maltose (malt sugar, found in sprouting grains). All 3 disaccharides contain a glucose monosaccharide bonded to a 2nd hexose monosaccharide. Polysaccharides are composed of 3 or more monosaccharides / saccharides. FOR EXAMPLE: *glycogen*, which is the storage form of glucose within liver and muscle cells of animals. Polysaccharides in plants include *starch* and *cellulose*

Describe the general structure of a nucleic acid :)

FIGURE 2.21 *Nucleic Acids* are biological macromolecules within cells that store and transfer genetic, or hereditary, information. Composed of nucleotide monomers linked by a covalent bond called a phosphodiester bond. Originally discovered within the cell nucleus , nucleic acids ultimately determine the types of proteins synthesized within cells. The two classes of nucleic acid are DNA and RNA. Both DNA and RNA are polymers composed of *nucleotide* monomers. These monomers are linked together through covalent bonds between one nucleotide monomer and an adjacent nucleotide monomer. RNA: - # of strands: 1 - Sugar: Ribose - Nitrogenous base : (U)racil DNA: - # of strands: 2 - Sugar: Deoxyribose - Nitrogenous base : (T)hymine This covalent bond between the phosphate of one nucleotide and the sugar of the adjacent nucleotide is called a *phosphodiester bond* A nucleotide has 3 components: a sugar, a phosphate group and nitrogenous base 5 different nitrogenous bases occur in nucleic acids. Single-ring nitrogenous bases are called *pyrimidines*: - (C)ytosine - (U)racil - (T)thymine Double-Ring nitrogenous bases are called *purines* - (A)denine - (G)uanine

Describe the general structure of amino acids and proteins :)

FIGURE 2.23a & 2.23c Proteins are polymers composed of one or more linear strands of *amino acid* monomers. (Amino Acids are the monomers of Proteins) Each amino acid has both amine (-NH2) functional group and carboxylic acid (-COOH) functional group. The other two covalent bonds are a hydrogen (-H) and side train structures known as R(Remainder) Group. The ends of a polymer protein are distinguished as the N-terminal end, which has a free amine group, and the C-terminal end, which has a free carboxyl group. If more than 200 amino acids are linked, the structure is called a *protein*

Distinguish between the four structural hierarchy levels of proteins and describe each level :)

FIGURE 2.26 *Primary Structure*: Linear sequence of amino acids that are bonded together through peptide bonds. - The Primary structure of a protein is forced into its initial shape as hydrophobic exclusion "tucks" amino acids with nonpolar R groups into a more central location, limiting their contact with water. *Secondary Structure*: Structural patterns within a protein that result from hydrogen bonds formed between amino acids. Two different secondary structures are - a spiral coil, called an *alpha helix* . Alpha helix gives some elasticity to fibrous proteins that are located, for example, in skin or hair. - a planar pleat arrangement, called a *beta sheet* (it looks zigzag). Beta sheets give some degree of flexibility to many globular proteins (e.g. enzymes) *Tertiary Structure*: Final 3-dimensional shape of a protein, which contains repeating secondary structures(alpha helix's and beta sheets). Tertiary structure is the final 3-dimensional shape exhibited by one complete protein chain. Two categories of proteins are either *globular proteins* or *fibrous proteins*. - *globular proteins* fold into a compact, often nearly spherical shape such as enzymes, hormones, antibodies - *fibrous proteins* are extended linear molecules that are constituents of ligaments and tendons and contractile proteins within muscle cells *Quaternary Structure*: Molecule composed of 2 or more separate proteins. The quaternary structure of a protein is present only in those proteins with *two or more* protein strands. - The protein hemoglobin is an example because it is composed of four protein chains. -Only when the four separate strands associate through intermolecular attractions to form the quaternary structure does the biological molecule of hemoglobin become active

Define and ion. Recognize examples of ions. List some common ions in the body :)

Ion: ions are either individual atoms or groups of atoms that have a positive or negative charge. An ion can have either a positive charge from the loss of one or more electrons or a negative charge from the gain of more electrons. Examples of Ions: - Sodium ion (Na^+) - Chlorine ion (Cl^-) - Bicarbonate ion (CHO3^- ) Common Ions (Table 2.1) pg 36: Common Cations (positively charged ions) - Sodium ion (Na^+) - Potassium ion (K^+) - Calcium ion (Ca2^+) - Magnesium ion (Mg2^+) - Hydrogen ion (H^+) Common Anions (negatively charged ions) - Chloride ion ( Cl^-) - Bicarbonate ion (HCO3^-) - Phosphate ion (PO4^3-)

Define and ionic bond. Describe the formation of the ionic compound, NaCl. List other examples of ionic compounds. :)

Ionic bond: positively charged cations and negatively charged anions may bind together by electrostatic interactions. Usually formed by salt. AKA electrostatic attractions between cations and anions (transfer of electrons) FIGURE 2.5 sodium atom loses one outer shell electron to a chlorine atom. the sodium atom then becomes a sodium ion (Na^+), and the chlorine atom becomes a chloride ion (Cl^-) . The oppositely charged Nat^+ and Cl^- ions are held together by ionic bonds in a precise, lattice crystal structure composing an *ionic compound* OTHER EXAMPLE - Magnesium Chloride (MgCl2). The chemical formula contains one magnesium and two chloride ions. This is because magnesium, has two electrons in its outer shell. It becomes stable by losing one electron to each of the chlorine atoms - Sodium Bicarbonate (NaHCO3), and the most common ionic compound in the body, calcium phosphate Ca3(PO4)2, which helps harden bones and teeth

Describe an isotope. Explain how radioisotopes differ from other types of isotopes

Isotope: atom with the same number of protons and electrons, but differing numbers of neutrons. Radioisotopes: unstable Isotopes with their nuclei containing excess number of neutrons.

Identify the 4 types of lipids and their physiologic roles

LOOK AT FIGURE 2.18 & TABLE 2.4 in Journal and Packet and book (P)hospholipids (E)icosanoids (T)riglycerides (S)teroids

Explain the relationship between glucose and glycogen :)

LOOK AT FIGURE 2.19 AND PG 56 *Glucose* is a six-carbon (hexose) carbohydrate that is the most common monosaccharide. It is shown here in the ring form. Glucose is crucial to life processes because it is the primary nutrient supplying energy to cells. Liver and skeletal muscle tissue absorb the excess glucose-and then bind the glucose monomers together to form a polysaccharide (many monosaccharides (monomer of carbs)) called *glycogen* by a process called *glycogenesis*. When blood glucose levels drop between meals, the liver hydrolyzes some of the glycogen into glucose and releases it into the blood. The process is called *glycogenolysis*. Thus the liver serves the role of a "glucose bank" by storing glycogen, them breaking down glycogen to release glucose. Nutrient storage and release are important in the endocrine regulation of nutrient blood levels of both triglycerides and glucose. Note: the liver can also form glucose from noncarbohydrate sources (ex: fats, proteins) through a process called *gluconeogenesis*.

Describe the general characteristics of a lipid ;)

Lipids are a very diverse group of fatty water-insoluble (hydrophobic) molecules that function as stored energy, components of cellular membranes, and hormones. 4 classes of lipids: Triglycerides (neutral fats), phospholipids, steroids, and eicosanoids (P)hospholipids (E)icosanoids (T)riglycerides (S)teroids Lipids are not polymers because they are not formed from repeating monomers. (TABLE 2.4)

Identify the most common elements of the human body ;)

Oxygen (O) Carbon (C) Hydrogen (H) Nitrogen (N) Calcium (Ca) Phosphorus (P)

Explain the arrangement of elements in the periodic table based on atomic number and valence number/ electronegativity. State the octet rule (LOOK IN SECTIONS 2.1a and 2.1C)

Look at figure 2.1 and 2.4 the periodic table is organized into rows based on atomic number. The atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom It is also organized into columns based on the number of electrons in the outer shell, or what is referred to as the *valence shell*. Each consecutive column thereafter has one additional electron in its outer shell for each element in that column. This allows us to make predictions about the chemical characteristics of a given element Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. Octet Rule: rule stating every atom wants to have 8 valence electrons in its outermost shell to be chemically stable

explain the relationship between monomers and polymers :)

Many important biological macromolecules are polymers. *Polymers* are molecules that are made up of repeating subunits called *monomers* , and each monomers is either identical or similar in its chemical structure. Some important carbs ( ex; glycogen, starch) , nucleic acids, and proteins are polymers , whereas lipids *are not* made up of monomers -Carbohydrate polymers contain sugar monomers -nucleic acids have nucleotide monomers - proteins are composed of amino acid monomers - lipids are not composed of monomers two monomers bonded together are called a dimer

Define Matter, and list its 3 forms

Matter: a substance that has mass and occupies space. Solid (bone) Liquid (blood) Gas (oxygen and CO2)

Describe hydrogen bonding between polar molecules :)

Molecules sometimes have weak chemical attractions called *intermolecular attractions*. One important intermolecular attraction is called a hydrogen bond. A hydrogen bond forms between polar molecules, It is a weak attraction between partially positive (S+) hydrogen atom within a polar molecule and a partially negative (S-) atom within a polar molecule. (figure 2.11) occurs between partially positively charged hydrogen ions and partially negatively charged atom of polar molecules Hydrogen bonds are important for shape of complex molecules; individually weak, collectively strong a dotted or broken line

Define neutralization, and describe how the neutralization of both an acid and a base occur

Neutralization: Neutralization occurs when a solution that is either acidic or basic becomes neutral (pH of 7). The neutralization of an acidic solution is accomplished by adding a base, whereas a basic solution is neutralized by adding an acid.

Differentiate the charge, mass, and relative location of: electrons, protons, and neutrons :)

Proton: - charge : +1 - Mass (amu) : 1 - location : nucleus Neutron: - charge: 0 - Mass (amu) : 1 - location : nucleus Electron: - charge : -1 - Mass (amu) : 0 - location: orbitals

Describe a structural formula, and explain its use in differentiating isomers

Structural formula: the structural formula of a molecule is complementary to its molecular formula and exhibits not only the numbers and types of atoms but also their special arrangements within the molecule. The molecular formula for carbon dioxide (CO2) thus is complemented by its structural formula (O=C=O) Structural formulas provide a means for differentiating *isomers*, which are molecules composed of the same number and types of elements but arranged differently in space. LOOK AT FIGURE 2.6

Compare substances that dissolve in water with those that both dissolve and dissociate in water (FIGURE 2.13)

Substances that dissolve in water: polar molecules and ions - both polar molecules (ex: glucose) and ions (ex:Na^+, HCO3^-) favorably interact with water molecules to disperse or *dissolve* within water. For this reason they are appropriately called hydrophilic (meaning water loving) - an important characteristic of ionic compounds is that they both dissolve and dissociate (separate) when placed in water. Ex: NaCl salt - Substances that both dissolve and dissociate in water, such as salts, acids, and bases , can readily conduct an electric current

Define pH, and explain the relative pH values of acids and bases. (FIGURE 2.15)

The *pH* of a solution is a measure of the relative amounts of H^+ it contains; it is expressed as a number between 0 and 14.

Explain what is meant by denaturation and list factors that can cause it (FIGURE 2.26)

The biological activity of a protein is usually disturbed or terminated when its conformation (or structure) is changed. This change in protein conformation is called *denaturation*. The tertiary structure of the protein is disrupted if the protein is heated or chemically altered - Conformational change to a protein - Disturbs protein activity - Usually irreversible - May occur due to *increased temperature* or in response to *changes in pH*

Define atomic number and average atomic mass :)

atomic number : of an element indicates the number of protons in an atom of the element and is located above its symbol atomic mass: indicates the mass of both protons and neutrons in the nucleus, and it reflects the "heaviness" of an elements atoms relative to other atoms

Describe a covalent bond and explain its formation :)

covalent bond: bond that is formed when atoms share electrons A covalent bond forms when both atoms require electrons to become stable. This takes place when the participating atoms that form the chemical bond have 4,5,6 or 7 electrons in the outer shell. The 4 most common elements that form covalent bonds are (H) Hydrogen (O) Oxygen (N) Nitrogen (C) Carbon There can be (figure 2.7 in journal) : single covalent bonds: one pair of electrons shared between two atoms double covalent bonds: two pairs of electrons shared between two atoms triple covalent bonds ( imagine shown) : three pairs of electrons shared between two atoms

Describe the action of a buffer

helps prevent neutralization if acid or base is added -a buffer is either a single type of molecule or two or more different types of molecules that helps prevent pH changes if excess acid or base is added - Buffers act to accept H^+ from excess acid or donate H^+ to neutralize added base; the reaction is *reversible* -EX: carbonic acid (weak acid) and bicarbonate acid - It is critical to maintain acid-base balance because small changes in pH can be fatal - Thinking of buffers as H^+ sponges may be helpful. If acid is added, the buffer "absorbs" the H^+ , and if a base is added, the buffer releases H^+. IN either case, this helps maintain the H^+ in solution, thus helping prevent changes in pH

Explain polar and nonpolar covalent bonding :)

nonpolar covalent bond a covalent bond in which the electrons are shared equally by two atoms of the same element . EX: C-H (only exception) , H-H , O-O , C-C nonpolar covalent bonds formed between the same elements (O-O), by C-H bonds, or both -same atom, attraction same polar covalent bond A covalent bond in which electrons are not shared equally due to differences in an atoms electronegativity EX: H-O - different atom, stronger attraction to electron. So for example in O-H , Oxygen would have a stronger pull because oxygen has more protons. C-O, N-H, and N-O. One exception to the pattern exists: a molecule containing polar covalent bonds that extend in opposite directions can be nonpolar because the partial charges cancel each other. Carbon dioxide (O=C=O)

Differentiate between an organic molecule and an inorganic molecule

organic molecule: always contain carbon, hydrogen,oxygen and also may contain nitrogen and phosphorus, or sulfur (CHON P.S.) inorganic molecule: Inorganic molecules are generally simple and are not normally found in living things. Although all organic substances contain carbon, some substances containing carbon, such as diamonds, are considered inorganic. organic means that a molecule has a carbon backbone with some hydrogen thrown in for good measure. Living creatures are made of various kinds of organic compounds. Inorganic molecules are composed of other elements. They can contain hydrogen or carbon, but if they have both, they are organic

Distinguish between the four structural hierarchy levels of proteins and describe each level (FIGURE 2.26)

primary structure: linear sequence of amino acids - The *primary structure* of a protein is forced into its initial shape as a hydrophobic exclusion "Tucks" amino acids with nonpolar R groups into a more central location, limiting their contact with water - Higher levels of protein organization result from folding. The *secondary structure* is a pattern within a protein that may repeat several times. The two distinctive secondary structures are a spiral coil, called an *alpha helix*, and a planar pleat arrangement , called a *beta sheet*. Alpha helix gives some elasticity to fibrous proteins that are located, for example, in skin or hair. In contrast, beta sheets give some degree of flexibility to many globular proteins (ex: enzymes) - *Tertiary structure* is the final 3-dimensional shape exhibited by one completed protein chain. Two categories of proteins-either globular or fibrous- are distinguished by their molecular shape *globular proteins* fold into a compact, often nearly spherical shape such as enzymes, antibodies, and some hormones In comparison, *fibrous proteins* are extended linear molecules that are constituents of ligaments and tendons and contractile proteins within muscle cells - The *quaternary structure* of a protein present only in those proteins with 2 or more protein strands (ex: hemoglobin w/ its 4 polypeptide chain)

Molecular Formula

the molecular formula is the number and types of atoms composing a molecule . An example of a molecular formula would be H2CO3 representing carbonic acid, where the molecule contains two hydrogen atoms, one carbon atom, and three oxygen atoms

Define Solute, Solvent and Solution

water is the solvent of the body, and substances that dissolve in water are called solutes. Water is called the universal solvent Solute: Substance dissolving in a solvent Solvent: Substance (ex: water) holding a solute in solution Solution: A homogeneous mixture composed of a solvent and a solute