Biology Chapter on Proteins and Molecules
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Questions and Answers

What are the monomers of proteins called?

  • Fatty Acids
  • Nucleotides
  • Glucose
  • Amino Acids (correct)

    • A structure composed of two amino acids is called a peptide.

    True

    What type of bond links amino acids together in proteins?

    Peptide bond

    Structures containing 21 to 199 amino acids are referred to as ______.

    <p>polypeptides</p> Signup and view all the answers

    Match the types of amino acids with their categories:

    <p>Nonpolar = Hydrophobic Polar = Hydrophilic Charged = Ionized at physiological pH Special characteristics = Contain unique side chains</p> Signup and view all the answers

    Which of the following is an example of a molecular compound?

    <p>Carbon Dioxide (CO2)</p> Signup and view all the answers

    Which of the following is a common cation found in the human body?

    <p>Na⁺</p> Signup and view all the answers

    A molecular formula provides information about the arrangement of atoms within a molecule.

    <p>False</p> Signup and view all the answers

    What term is used to describe molecules that have the same molecular formula but different structural arrangements?

    <p>isomers</p> Signup and view all the answers

    Ionic bonds can form between two cations.

    <p>False</p> Signup and view all the answers

    The molecular formula for carbonic acid is ______.

    <p>H2CO3</p> Signup and view all the answers

    What is a molecular formula?

    <p>A molecular formula shows the types and numbers of atoms in a molecule.</p> Signup and view all the answers

    The four most common elements in the human body are _____ , _____ , _____ , and _____ .

    <p>carbon, hydrogen, oxygen, nitrogen</p> Signup and view all the answers

    Match the following examples with their corresponding formulas:

    <p>Carbonic acid = H2CO3 Carbon dioxide = CO2 Glucose = C6H12O6 Oxygen = O2</p> Signup and view all the answers

    Match the type of bond to its definition:

    <p>Single covalent bond = Sharing one pair of electrons Double covalent bond = Sharing two pairs of electrons Triple covalent bond = Sharing three pairs of electrons Polar covalent bond = Unequal sharing of electrons</p> Signup and view all the answers

    Which category of amino acids contains R groups with hydrogen or hydrocarbons?

    <p>Nonpolar amino acids</p> Signup and view all the answers

    Charged amino acids participate in ionic bonds with other charged amino acids.

    <p>True</p> Signup and view all the answers

    What is the primary structure of a protein?

    <p>Linear sequence of amino acids</p> Signup and view all the answers

    The ________ structure of a protein refers to its three-dimensional shape.

    <p>tertiary</p> Signup and view all the answers

    Match the type of amino acid to its characteristic:

    <p>Nonpolar amino acids = Hydrophobic interactions Polar amino acids = Hydrophilic Charged amino acids = Ionic bonds Amino acids with special functions = Unique properties like disulfide bonds</p> Signup and view all the answers

    Which of the following amino acids is known for forming disulfide bonds?

    <p>Cysteine</p> Signup and view all the answers

    Denaturation of a protein can be caused by high temperature and changes in pH.

    <p>True</p> Signup and view all the answers

    Name the two types of secondary structures in proteins.

    <p>Alpha helix and beta sheet</p> Signup and view all the answers

    Proline can cause a __________ in the protein chain.

    <p>bend</p> Signup and view all the answers

    Match the levels of protein structure with their descriptions:

    <p>Primary structure = Linear sequence of amino acids Secondary structure = Patterns that may repeat Tertiary structure = Three-dimensional shape of a single peptide Quaternary structure = Association of multiple polypeptide chains</p> Signup and view all the answers

    What type of bonds exist between negative and positive R groups of amino acids?

    <p>Ionic bonds</p> Signup and view all the answers

    Globular proteins have a compact shape, while fibrous proteins are long and thread-like.

    <p>True</p> Signup and view all the answers

    What are prosthetic groups?

    <p>Nonprotein structures covalently bonded to proteins</p> Signup and view all the answers

    Ionic bonds are a result of interactions between ________ charged amino acids.

    <p>negatively and positively</p> Signup and view all the answers

    What is the primary element that composes water?

    <p>Oxygen</p> Signup and view all the answers

    Water is a nonpolar molecule.

    <p>False</p> Signup and view all the answers

    How many hydrogen atoms are bonded to one oxygen atom in a water molecule?

    <p>Two</p> Signup and view all the answers

    Water can form up to ___ hydrogen bonds with adjacent molecules.

    <p>four</p> Signup and view all the answers

    Which of the following correctly describes water's cohesive properties?

    <p>Water molecules attract to each other through hydrogen bonding.</p> Signup and view all the answers

    Sweating cools the body by utilizing the high heat of vaporization of water.

    <p>True</p> Signup and view all the answers

    Define hydrophilic.

    <p>Water-loving substances.</p> Signup and view all the answers

    Substances that do not dissolve in water are called ___ molecules.

    <p>nonpolar</p> Signup and view all the answers

    What term describes the process of water molecules forcing out nonpolar substances?

    <p>Hydrophobic exclusion</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Hydrophilic = Water-loving substances Hydrophobic = Water-fearing substances Amphipathic = Contains both polar and nonpolar regions Cohesion = Attraction between water molecules</p> Signup and view all the answers

    What happens to the cohesiveness of water at the surface?

    <p>It creates surface tension.</p> Signup and view all the answers

    Water is referred to as the universal solvent because most substances can dissolve in it.

    <p>True</p> Signup and view all the answers

    The amount of energy required to increase the temperature of 1 gram of a substance by 1 degree Celsius is called specific ___.

    <p>heat</p> Signup and view all the answers

    Which substance dissociates into ions in water?

    <p>Sodium chloride (NaCl)</p> Signup and view all the answers

    What is the role of surfactant in the lungs?

    <p>Prevents collapse of moist sacs.</p> Signup and view all the answers

    What is the molecular formula for fructose?

    <p>C6H12O6</p> Signup and view all the answers

    Isomers have the same arrangement of atoms?

    <p>False</p> Signup and view all the answers

    How many covalent bonds can carbon form?

    <p>four</p> Signup and view all the answers

    A _____ covalent bond involves two pairs of electrons being shared.

    <p>double</p> Signup and view all the answers

    Which type of bond involves three pairs of electrons shared?

    <p>Triple covalent bond</p> Signup and view all the answers

    Electronegativity decreases from left to right across a period in the periodic table.

    <p>False</p> Signup and view all the answers

    What does a polar covalent bond result from?

    <p>unequal sharing of electrons</p> Signup and view all the answers

    In a nonpolar covalent bond, electrons are shared _____ between atoms.

    <p>equally</p> Signup and view all the answers

    What type of molecule is characterized by having both polar and nonpolar regions?

    <p>Amphipathic molecules</p> Signup and view all the answers

    Match the following types of covalent bonds with their characteristics:

    <p>Single covalent bond = One pair of electrons shared Double covalent bond = Two pairs of electrons shared Triple covalent bond = Three pairs of electrons shared</p> Signup and view all the answers

    Hydrogen bonds are strong attractions between nonpolar molecules.

    <p>False</p> Signup and view all the answers

    What type of interaction occurs when nonpolar molecules are placed in polar substances?

    <p>hydrophobic interactions</p> Signup and view all the answers

    Carbon's four electrons allow it to form _____ bonds.

    <p>covalent</p> Signup and view all the answers

    Which of the following atoms forms three covalent bonds?

    <p>Nitrogen</p> Signup and view all the answers

    What kind of bond occurs between two atoms of the same element?

    <p>nonpolar covalent bond</p> Signup and view all the answers

    Electrons have a _____ charge.

    <p>negative</p> Signup and view all the answers

    Study Notes

    Chapter 2 Lecture Outline

    •  This chapter covers learning objectives related to atomic structure, isotopes, chemical stability, and the structure and properties of water.
    •  It also includes a look at ions and ionic compounds, molecules and molecular compounds, and discusses the action of a buffer, acidic and basic solutions.
    •  The information is for a university level course on general chemistry or biology, focusing on chemistry.

    2.1 Atomic Structure

    • Matter has mass and occupies space.
    • The three states of matter are solid, liquid, and gas.
    • An atom is the smallest particle exhibiting the chemical properties of an element.
    • Atoms are made of three subatomic particles: neutrons, protons, and electrons.
    • Neutrons are neutral with a mass of one atomic mass unit (amu).
    • Protons have a positive charge with a mass of one amu.
    • Electrons have a negative charge and are 1/1800th the mass of a proton or neutron
    • Electrons are located in electron shells at varying distances from the nucleus.
    • The number of protons equals the atomic number of an element.
    • The atomic number determines the arrangement of elements in the periodic table.
    • The average atomic mass is the mass of both protons and neutrons.
    • Isotopes are different atoms of the same element with the same number of protons and electrons but different number of neutrons.
    • Radioisotopes are unstable isotopes that lose nuclear components in the form of high-energy radiation (alpha particles, beta particles, gamma rays).
    • Each element has a characteristic half-life.
    • Radioisotopes are commonly used in medical procedures, such as thyroid gland imaging using radioactive iodine.
    • The octet rule states that elements tend to gain, lose, or share electrons to reach a stable electron configuration with eight electrons in their outer shell.

    2.1a Matter, Atoms, Elements, and the Periodic Table

    • Matter exists in three forms: solid, liquid and gas..
    • Atoms are the basic unit of an element, each with a unique number of protons.
    • Atoms make up elements which are categorized into rows in the periodic table.
    • Elements in the periodic table are arranged by atomic number.
    • The element's atomic number is displayed above the chemical symbol.
    • The element's average atomic mass is shown below its symbol.
    • Subatomic particles (protons, neutrons, and electrons) determine an atom's mass and charge.

    2.1b Isotopes

    • Isotopes are atoms of the same element with the same number of protons and electrons, but different numbers of neutrons.
    • Different isotopes of an element share identical chemical characteristics but have different atomic masses.
    • Isotopes are identified with a "mass number".
    • Radioisotopes, a special type of isotope, are unstable.
    • Radioactive materials have physical and biological half-lives.
    • The radioactive half-life of an isotope is the time it takes for half of the atoms in a sample to decay.

    2.1c Chemical Stability and the Octet Rule

    • Elements in the periodic table are organized by the number of electrons in their outermost shell (valence shell).
    • Column IA elements have one valence electron.
    • Column VIIA elements have a full valence shell (eight electrons), which results in chemical stability.

    2.2 Ions and Ionic Compounds

    • Ions are atoms with a positive or negative charge created by gaining or losing electrons.
    • Cations are positively charged ions.
    • Anions are negatively charged ions.
    • Ionic compounds are formed by the electrostatic attraction between oppositely charged ions, forming a crystalline lattice structure.
    • Examples of ionic compounds include table salt (NaCl) and other common salts.

    2.2a Ions

    • Atoms can gain or lose electrons to achieve a stable electron configuration and form ions.
    • The number of electrons in the outer shell (valence shell) is crucial in determining how atoms form ions.
    • Common ions in the body, such as K(+) and other electrolytes, have important physiological functions like regulating nerve impulses, maintaining water balance, etc
    • Ions with positive charges are called cations, and ions with negative charges are called anions

    2.2b Ionic Bonds

    • Ionic bonds form between oppositely charged ions (cations and anions) due to electrostatic attraction.
    • Ionic bonds create ionic compounds, which often form salts.
    • Formation of salts occurs when an electron is transferred from a metal's outer shell to a nonmetal's outer shell.

    2.3 Molecules and Molecular Compounds

    •  Molecular compounds are formed when atoms share electrons through covalent bonds.
    •  Molecular formulas indicate the number and type of atoms in a molecule.
    • Structural formulas depict the arrangement of atoms and bonds within a molecule.
    •  Isomers have the same molecular formula but different structural formulas.
    • Common elements in the human body include hydrogen, oxygen, nitrogen, and carbon.
    • Single, double and triple covalent bonds exist based on the number of shared electron pairs.
    • In covalent bonding, multiple bonds can form between atoms
    •  Polar molecules have uneven distribution of charges due to uneven sharing of electrons between atoms.
    •  Nonpolar molecules have an even distribution of charges.
    • Amphipathic molecules have both polar and nonpolar regions.

    2.3a Chemical Formulas: Molecular and Structural

    • Molecular formulas indicate the number and type of atoms in a molecule (e.g., H2O).
    • Structural formulas show how atoms are arranged in a molecule and how they are bonded (e.g., OCO).
    •  Structural formulas help differentiate isomers.

    2.3b Covalent Bonds

    • Covalent bonds form when atoms share electrons to complete their outer electron shells.
    •  The number of covalent bonds formed depends on the number of electrons needed to complete the outer shell.

    2.3c Nonpolar, Polar, and Amphipathic Molecules

    • Nonpolar molecules contain nonpolar covalent bonds (equal sharing of electrons).
    • Polar molecules contain polar covalent bonds (unequal sharing).
    • Amphipathic molecules contain both polar and nonpolar regions.

    2.3d Intermolecular Attractions

    • Intermolecular forces are weak attractions between molecules.
    • Hydrogen bonds are attractions between a partially positive hydrogen atom of one molecule and a partially negative atom of another molecule.
    • Examples of intermolecular forces include van der Waals forces and hydrophobic interactions.

    2.4 Molecular Structure and Properties of Water

    • Water molecules are polar, meaning there is an uneven distribution of charge.
    • Water molecules can form hydrogen bonds.
    •  Water has several unique properties: high specific heat, high heat of vaporization, cohesion, adhesion, surface tension, and acting as a universal solvent.
    • These properties are vital for many biological processes.

    2.4a Molecular Structure of Water

    • Water is composed of two hydrogen atoms and one oxygen atom.
    • The oxygen atom has a slightly negative charge, and the hydrogen atoms have slightly positive charges.
    • These charges make water a polar molecule.
    • Water molecules can form hydrogen bonds with each other.

    2.4b Properties of Water

    • Water's high specific heat capacity means it can absorb significant heat energy without a large temperature change.
    • Water’s high heat of vaporization is necessary for sweating to take place
    • Water's cohesive and adhesive properties affect its surface tension.
    •  These properties are crucial to many bodily functions like temperature regulation

    2.4c Water as the Universal Solvent

    • Water dissolves many substances because of its polarity.
    • Polar molecules and ions dissolve readily in water. Some substances only dissolve, but stay intact.
    • Nonpolar molecules do not dissolve in water.
    • Some molecules are amphipathic which means they have polar and nonpolar regions and can dissolve in water partially.
    • The solubility properties of molecules determine how they interact with water and are relevant to biological systems

    2.5 Acidic and Basic Solutions, pH, and Buffers

    • Water molecules spontaneously dissociate into hydrogen ions (H+) and hydroxide ions (OH–).
    • Acidity and basicity measure the concentration of H+ in a solution, which influences many cellular processes.
    • Buffers help maintain a stable pH in living organisms.

    2.5a Water: A Neutral Solvent

    • Water dissociates into equal numbers of H+ and OH– ions in neutral solutions.

    2.5b Acids and Bases

    • Acids release hydrogen ions (H+) when dissolved in water, increasing the H+ concentration.
    • Bases accept hydrogen ions (H+) from a solution reducing the H+ concentration
    •  Strong acids and bases readily dissociate in water, while weak ones do not.

    2.5c pH, Neutralization, and the Action of Buffers

    • pH is a measure of the H+ concentration in a solution.
    • Neutral solutions have a pH of 7.
    • Acidic solutions have a pH below 7.
    • Basic (alkaline) solutions have a pH above 7.
    • Acids and bases can neutralize each other in a chemical reaction, returning the solution to a neutral state.
    • Buffers are chemical substances that help prevent drastic changes in pH by absorbing or releasing hydrogen ions (H+).

    2.6 Water Mixtures

    • Mixtures result from combining two or more substances without chemical changes.
    • Types of water mixtures include suspensions, colloids, solutions, and emulsions
    • Suspensions contain larger particles than solutions, the mixtures don't remain mixed unless in motion.
    • Examples of suspensions include blood cells in plasma, or sand in water.
    • Colloids contain smaller particles than suspensions, but they still remain mixed when not in motion.
    • Emulsions are a special type of suspension having one polar and one nonpolar liquid in a mixture.
    • Examples of colloids include fluid in cell cytosol, and fluid in blood plasma, or oil & vinegar dressing.
    • Solutions contain very small particles and remain mixed whether in motion or not.
    • Examples include sugar water or salt water.

    2.7 Macromolecules

    •  Macromolecules are large organic molecules produced by living organisms, serving diverse biological functions.
    • Carbohydrates, lipids, proteins, and nucleic acids are major classes.

    2.7a Biological Macromolecules: General Characteristics

    • Biological macromolecules contain C, H, & O
    • Many contain N, P, or S.
    • They are made up of smaller repeating units called monomers.
    •  Monomers are linked together through dehydration synthesis.
    • Hydrolysis, the opposite process, breaks these bonds in water.

    2.7b Lipids

    • Lipids are diverse, water-insoluble molecules that store energy.
    • Triglycerides are primary energy storage lipids.
    • Phospholipids are a primary component in cell membranes and have polar and nonpolar regions.
    • Steroids are multi-ringed structures including hormones, cholesterol, and bile salts.
    • Eicosanoids are hormones that affect inflammation and nervous system activity

    2.7c Carbohydrates

    • Carbohydrates store, provide, and regulate energy for cells.
    • Monosaccharides are single sugar units, disaccharides are two, and polysaccharides are many.
    • Glucose is a significant monosaccharide.
    • Glycogen is a stored form of glucose in animals.
    • Starch and cellulose are polysaccharides in plants, but not readily digested by humans.

    2.7d Nucleic Acids

    • Nucleic acids store and transfer genetic information (genetic code).
    •  The two primary types are DNA and RNA; both are polymers of nucleotides.
    • Nucleotides have three components: a sugar, a phosphate group, and a nitrogenous base
    • DNA is double-stranded and contains deoxyribose, phosphate groups, and four nitrogenous bases (adenine, guanine, cytosine, thymine).
    • RNA is single-stranded and contains ribose, phosphate groups, and four nitrogenous bases (adenine, guanine, cytosine, uracil)

    2.7e Proteins

    • Proteins are polymers of amino acids, having a wide range of functions.
    • The sequence of amino acids determines the protein's structure and function.
    •  Protein structure involves primary, secondary, tertiary, and quaternary structural hierarchies.
    • The shape of a protein is determined by interactions among amino acids.
    • Some proteins also have non-protein components (prosthetic groups).
    • Denaturation is a change in a protein's shape, losing function.

    2.8 Protein Structure

    •  Different categories of amino acids exist (nonpolar, polar, and charged).
    • Proteins have several levels of structural organization (primary, secondary, tertiary, and quaternary).
    • Intramolecular attractions, such as hydrogen bonds, hydrophobic interactions, and disulfide bonds, determine a protein's three-dimensional shape and function.
    •  Denaturation is the loss of a protein's three-dimensional shape, often due to changes in temperature or pH.

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    Test your understanding of proteins, amino acids, and molecular compounds in this quiz. From peptide bonds to molecular formulas, explore the foundational concepts of biology. Perfect for students studying biochemistry or related fields.

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