Biochemistry: Fats and Polymers Quiz

Biology: How Life Works

• This course covers the active lecture slides and content for Chapter 2: The Molecules of Life.
• The authors and contributors are Morris, Hartl, Knoll, Lue, Michael, Heitz, Hens, Lozovsky, Merrill, Phillis, Pires, and Liu.
• The course content is published by Macmillan Learning.

Atoms and Elements

• Atoms are composed of protons, neutrons, and electrons.
• The nucleus of an atom contains protons and neutrons.
• Electrons orbit the nucleus in orbitals.
• Elements consist of only one type of atom.

Atomic Mass

• The atomic number is determined by the number of protons in an atom.
• For instance, an atom with 6 protons is always carbon.
• Atomic mass is the sum of protons and neutrons in an atom.

Isotopes

• Isotopes have the same number of protons but a different number of neutrons, resulting in varying atomic masses.

Orbitals and Shells

• Electrons occupy regions of space called orbitals.
• Atoms with more than two electrons have at least two orbitals.
• The second electron shell consists of four orbitals: a spherical orbital and three dumbbell-shaped orbitals.

Valence Electrons

• Valence electrons are electrons in the outermost electron shell; they participate in chemical reactions and bond formation.

Losing or Gaining Electrons

• Atoms that gain or lose electrons can acquire a positive or negative charge.
• In sodium chloride (salt), sodium loses an electron, taking a positive charge, while chlorine gains an electron, attaining a negative charge.

Chemical Bonds

• Atoms combine to form molecules held together by chemical bonds.
• Valence electrons (electrons in the outermost shell) are involved in bond formation.
• The number of valence electrons affects the number of bonds that can be formed.

Covalent Bonds

• Covalent bonds form when atoms share electrons.
• In a hydrogen molecule, two hydrogen atoms share electrons to form a covalent bond.

Polar Covalent Bonds

• Polar covalent bonds occur when atoms do not share electrons equally, leading to partial charges (δ+ and δ-).
• In a water molecule, oxygen is more electronegative than hydrogen, leading to partial positive charges on hydrogen and a partial negative charge on oxygen.

Nonpolar Covalent Bonds

• Nonpolar covalent bonds form when atoms share electrons equally, resulting in no partial charges.
• This occurs in molecules like hydrogen gas, where the electronegativities are similar, and methane.

Which Option Accurately Describes a Polar Covalent Bond?

• The correct answer is: The unequal sharing of electrons between an atom with a partial positive charge and an atom with a partial negative charge.

The Oxygen and Hydrogen Atoms of a Water Molecule Contain What Type of Bond?

• The correct answer is: polar covalent bond

Ionic Bonds

• Ionic bonds form when the electronegativity difference between atoms is large, and one atom transfers an electron to the other, creating ions and opposite charges that attract.

Why do salts dissolve in water?

• The partial positive charges of hydrogen atoms in water molecules are attracted to the negative ions, and the partial negative charges of oxygen atoms in water molecules are attracted to the positive ions.
• This attraction helps dissolve the ions.

Chemical Reactions

• Chemical reactions involve breaking and forming chemical bonds to transform reactants into products.

Water Chemistry

• Water is a polar molecule.
• Water is a good solvent.
• pH in water is 7. pH is a measurement of the concentration of protons in solution. Different molecules have diverse effects with water.

Hydrogen Bonds in Water

• Hydrogen bonds form between water molecules due to the partial positive charge on hydrogen and the partial negative charge on oxygen.
• These bonds are important for water's unique properties.

Water has Unusual Properties

• Water is less dense when frozen than when liquid.
• Water resists changes in temperature because breaking hydrogen bonds requires energy.

Carbon: Life's Chemical Backbone

• The four major elements in the human body are carbon, oxygen, hydrogen, and nitrogen
• Molecules containing carbon are called organic molecules.

Carbon and Covalent Bonds

• Carbon atoms form four covalent bonds, often allowing organic molecules to have complex structures.

Carbon-Containing Molecules

• Carbon-containing molecules can be diverse in their structure and form a wide array of molecules in living organisms.
• The carbon atoms can form single bonds, double bonds, and more.

Carbon Double Bonds

• Adjacent carbon atoms can form double bonds by sharing two pairs of electrons.

Structure and Function

• Molecules with the same chemical formula, but different structures, are isomers.
• Structural differences affect how molecules interact, leading to different functions.

Organic Molecules

• Please refer to the provided YouTube link.

Proteins

• Proteins are made of amino acid subunits.
• Amino acids have an amino group, a carboxyl group, an α-carbon, and an R group.
• Amino acids link together by peptide bonds to form proteins.

Nucleotides

• Nucleotides are building blocks of nucleic acids (DNA and RNA).
• Nucleotides have three components: phosphate group(s), a five-carbon sugar (ribose or deoxyribose), and a nitrogenous base.

Nucleotide Bases

• Nucleotide bases are divided into pyrimidines (single ring) and purines (double ring) structures.
• Specific bases differentiate DNA and RNA types.

Bonds Between Nucleotides

• Phosphodiester bonds connect nucleotides in nucleic acids.

Structure of DNA

• DNA is a double helix.
• The sugar-phosphate backbone is on the outside, and the bases paired on the inside by hydrogen bonds.

Carbohydrates

• Carbohydrates are monosaccharides (e.g., glucose, galactose, fructose).
• Monosaccharides join to form more complex carbohydrates like polysaccharides.

Types of Sugar Molecules

• Simple sugars are monosaccharides
• Complex sugars are polysaccharides.

Lipids: Fatty Acids

• Lipids are hydrophobic molecules grouped together because of their shared hydrophobic property.
• Fatty acids are long chains of carbon with carboxyl groups.

Lipids: Structure

• Saturated versus unsaturated fatty acids differ in their structure due to the presence or absence of carbon-carbon double bonds.
• Triacylglycerols are uncharged and hydrophobic, often forming oil droplets within cells.

Van der Waals Forces

• Van der Waals forces are weak attractive forces between molecules caused by temporary fluctuations in electron distribution.
• These forces contribute to the properties of lipids and other substances.

Saturated vs. Unsaturated Fats

• Saturated fats lack double bonds, allowing them to stack closely and be solid at room temperature.
• Unsaturated fats have double bonds, introducing kinks and preventing close packing, resulting in a liquid state at room temperature.

Lipids: Steroids

• Steroids are lipids with a characteristic four-ring structure.
• Cholesterol is a steroid found in cell membranes.

Could water vapor, methane, ammonia, and hydrogen gas been the building blocks of life on early Earth?

• This question is explored through an experimental setup (Miller-Urey experiment) where these gases were combined and exposed to energy to see if organic molecules, the building blocks of life, could form naturally.

How did the building blocks of life form macromolecules?

• Clay minerals in volcanic rocks can bind and stabilize nucleotides, helping form polymers.
• Experiments using nucleic acids demonstrated how complementary sequences form double-stranded nucleic acids.