Biomolecules: A. How are polymers made from and broken down into monomers? Polymers are made through dehydration reactions where two monomers bon

Biomolecules

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A. How are polymers made from and broken down into monomers?

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Polymers are made when two monomers bond together and lose a water molecule in a reaction called a dehydration reaction.1 Polymers are broken down when a water molecule is added to break the bond between monomers in a reaction called a hydrolysis reaction.1 Enzymes are special macromolecules that can speed up these chemical reactions.1

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B. What are the four types of biomolecules?

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The four classes of biomolecules are:

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Lipids2

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Carbohydrates2

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Proteins3

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Nucleic Acids3

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C. The three types of lipids (chemical structure, chemical properties, and biological function)

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Triglycerides

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Structure: Made from one glycerol and three fatty acids.4

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Properties: Nonpolar and hydrophobic.45

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Fatty acids can be saturated or unsaturated, depending on the presence of double bonds.5

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Saturated fats have the maximum number of hydrogens and are solid at room temperature.5

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Unsaturated fats have fewer hydrogens and are liquid at room temperature.5

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Function: Important for brain development and function, fat-soluble vitamin absorption, insulation, energy storage, and satiety.6

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Phospholipids

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Structure: Have a hydrophilic head (phosphate group) and a hydrophobic tail (fatty acids).7

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Properties: Amphiphilic, meaning they have both hydrophobic and hydrophilic regions.7

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Function: Form the lipid bilayer that surrounds all cells, called the plasma membrane.8

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Steroids

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Structure: Have a fused ring structure with four linked carbon rings.8

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Properties: Cholesterol contributes to the maintenance of plasma membrane fluidity.6

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Function: The most common steroid in our bodies is cholesterol, which is used to make reproductive hormones (estradiol, testosterone, progesterone), stress hormones (cortisol), other hormones (aldosterone), vitamin D3 (cholecalciferol), and bile salts.8

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D. Meaning of hydrophobic, hydrophilic, and amphiphilic

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Hydrophobic: "Water-fearing" - molecules that do not dissolve in water.4

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Hydrophilic: "Water-loving" - molecules that dissolve in water.7

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Amphiphilic: Molecules that have both hydrophobic and hydrophilic regions.7

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E. Types of carbohydrates and their structures (mono-, di-, and polysaccharides)

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Monosaccharides: The simplest carbohydrate monomers. Glucose is an important energy source for cells.9

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Disaccharides: Two monosaccharides joined together by a glycosidic bond in a dehydration reaction. Common examples include:9

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Maltose (glucose + glucose)

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Sucrose (glucose + fructose)

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Lactose (glucose + galactose)

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Polysaccharides: Long chains of monosaccharides linked by glycosidic bonds.9 Examples include:

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Starch: How plants store glucose. Can be either amylose (straight chain) or amylopectin (branched).10

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Glycogen: How animals store glucose (branched).10

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Cellulose: Maintains plant cell walls.10 It is a type of fiber, which may protect against colon cancer.10

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F. Building blocks of proteins (how they differ from one another)

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Amino acids are the building blocks of proteins. There are 20 different amino acid monomers.3 Amino acids are linked together through peptide bonds.11 They differ from one another in their side chains (R groups).3 Differences in the side chains give each amino acid its unique chemical properties.3 Some of these properties are:

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Polar vs. non-polar3

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Charged vs. uncharged3

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Positive vs. negative charge3

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Small vs. large3

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Some amino acids are essential, meaning they cannot be made by the body and must be consumed in the diet.3

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G. What are the four levels of protein structure?

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Primary Structure: The sequence of amino acids in a polypeptide chain.11 This is like the order of letters in a word.11

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Secondary Structure: The coils and folds that result from hydrogen bonds between the repeating parts of the polypeptide backbone.11 Common secondary structures include the alpha helix and the beta pleated sheet.12

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Tertiary Structure: The overall three-dimensional shape of a polypeptide.12 This is determined by interactions between R groups, including hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions.12 Strong covalent bonds called disulfide bridges may further strengthen the structure.12

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Quaternary Structure: Results when two or more polypeptide chains form one macromolecule.12 Hemoglobin is an example of a protein with quaternary structure.13

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H. Naming conventions for the start and end of polypeptides and the start and end of nucleic acids

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Polypeptides:

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N-terminus: The amino end of a polypeptide chain.11

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C-terminus: The carboxyl end of a polypeptide chain.11

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Nucleic Acids:

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5' end: The end of a nucleic acid strand with a free phosphate group attached to the 5' carbon of the sugar.1415

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3' end: The end of a nucleic acid strand with a free hydroxyl group attached to the 3' carbon of the sugar.1415

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I. General structure for the building blocks for nucleic acids and how these subunits differ for different types of nucleic acids

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The building blocks of nucleic acids are nucleotides.1617 Each nucleotide consists of:17

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A pentose sugar (deoxyribose in DNA and ribose in RNA)17

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A phosphate group17

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A nitrogenous base17

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There are two families of nitrogenous bases:17

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Pyrimidines (cytosine, thymine, and uracil)

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Purines (adenine and guanine)

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DNA contains adenine (A), guanine (G), cytosine (C), and thymine (T).14 RNA contains adenine (A), guanine (G), cytosine (C), and uracil (U).17

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J. How nucleotides are assembled into larger molecules

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Nucleotides are linked together by phosphodiester bonds to form a sugar-phosphate backbone.1418 A phosphodiester bond is created through a dehydration reaction.1415 Nucleic acids are linear and have directionality, forming in the 5' to 3' direction.1415

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K. Differences between RNA and DNA

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Sugar: DNA uses deoxyribose, while RNA uses ribose.17

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Bases: DNA contains thymine (T), while RNA contains uracil (U).1417

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Structure: DNA is usually double-stranded, forming a double helix.14 The two strands of DNA run in opposite directions (antiparallel).19 RNA is usually single-stranded, but can fold into complex 3D structures through complementary base pairing.1920

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L. Complementary base pairing

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In DNA, adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G) through hydrogen bonding.14 This is called complementary base pairing, and it is what holds the two strands of DNA together.21 Complementary base pairing is also important in RNA, allowing it to form 3D structures.1920

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