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Questions and Answers
What characterizes HDL (high-density lipoprotein) compared to LDL (low-density lipoprotein)?
Which term describes a molecule composed of two amino acids?
What is the main structural difference between amino acids?
What process forms a peptide bond between amino acids?
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Which type of cholesterol is primarily associated with an increased risk of cardiovascular disease?
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What type of energy is described as energy stored in an object that is not currently doing work?
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Which chemical reaction involves breaking down a large molecule into smaller ones?
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In an exchange reaction, what happens to the molecules involved?
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In a synthesis reaction, what is the outcome of the reaction?
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Which of the following is a type of potential energy that is specifically related to molecular bonds?
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What does a chemical equation represent?
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What is the main characteristic of kinetic energy?
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Which of the following is an example of an exchange reaction?
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What property of water allows it to cling to membranes, reducing friction around organs?
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What is the term used to describe water's ability to stabilize internal temperature?
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What does a pH of less than 7 indicate?
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How does a change of one number on the pH scale affect H+ concentration?
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What role do buffers play in biological systems?
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Which of the following statements is true regarding hydrogen ions in an acid?
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What is the relationship between surface tension and water's cohesive property?
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What does the term 'hydrolysis' refer to in the context of chemical reactions involving water?
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What is the general formula for carbohydrates?
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Which of the following is a monosaccharide?
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Which combination of monosaccharides forms lactose?
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Which polysaccharide is primarily used for energy storage in plants?
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What is the primary role of cellulose in plants?
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Which of the following disaccharides is commonly known as table sugar?
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What is a function of glycoproteins in the human body?
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What is the main composition of glycogen?
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What term describes the extreme conformational change in proteins that destroys their function?
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Which structure of a protein is determined by the sequence of amino acids?
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Which of the following statements about secondary protein structure is true?
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What causes a protein to reversibly change its conformation?
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Which of the following structures is NOT considered a level of protein complexity?
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Study Notes
Properties of Water
- Water is a versatile solvent due to its polarity.
- Water participates in chemical reactions, ionizing itself and other substances.
- Water's high heat capacity stabilizes internal temperatures through hydrogen bonds.
- Cohesion refers to the tendency of molecules of the same substance to cling to each other.
- This cohesion is due to hydrogen bonds and results in surface tension.
- Adhesion refers to the tendency of one substance sticking to another, reducing friction in organs.
- Water is highly cohesive due to its hydrogen bonds.
Acids, Bases, and pH
- Acids are proton donors, releasing H+ ions in water.
- Bases are proton acceptors, accepting H+ ions or releasing OH- ions in water.
- The pH scale measures acidity and is derived from the molarity of H+.
- pH 7.0 is neutral (H+ = OH-).
- pH less than 7 is acidic (H+ > OH-).
- pH greater than 7 is basic (OH- > H+).
Energy and Work
- Energy is defined as the capacity to do work.
- Potential energy is stored energy not currently doing work, like water behind a dam.
- Kinetic energy is the energy of motion, energy doing work.
- Chemical energy is a type of potential energy stored in molecular bonds.
- Free energy is the potential energy available in a system to do work.
Chemical Reactions
- A chemical reaction is a process representing the formation or breaking of a covalent or ionic bond.
- A chemical equation symbolizes the course of a chemical reaction, with reactants on the left and products on the right.
- Decomposition reactions involve the breakdown of a large molecule into smaller ones.
- Synthesis reactions involve the combination of small molecules to form a larger one.
- Exchange reactions involve the exchange of atoms or groups of atoms between two molecules.
Carbohydrates
- Carbohydrates (sugars and starches) are hydrophilic organic molecules.
- The general formula is (CH2O)n, with n representing the number of carbon atoms.
- Carbohydrates have a 2:1 ratio of hydrogen to oxygen.
- Monosaccharides are the simplest carbohydrates, the monomers of larger carbohydrates.
- Important monosaccharides include glucose (blood sugar), galactose, and fructose.
- All three monosaccharides have the same molecular formula (C6H12O6), making them isomers.
- Ribosome and deoxyribose are also monomers, part of RNA and DNA respectively.
- Disaccharides are sugars made of two monosaccharides bonded together.
- Important examples include:
- Sucrose (table sugar): glucose + fructose
- Lactose (milk sugar): glucose + galactose
- Maltose (sugar in grain products): glucose + glucose
- Polysaccharides are long chains of monosaccharides.
- Important examples include:
- Glycogen: energy storage in liver, muscle, brain, uterus, and vagina cells.
- Starch: energy storage in plants, digestible by humans.
- Cellulose: structural molecule in plants, important for human dietary fiber but indigestible.
Lipids
- Lipids are hydrophobic organic molecules.
- Triglycerides: most common type of fat; three fatty acids linked to glycerol.
- Phospholipids: make up cell membranes; contain a phosphate group, glycerol, and two fatty acid tails.
- Steroids: complex ring structures used for various functions, including hormone production and membrane structure.
- Cholesterol: helps in the production of steroid hormones, bile salts, and vitamin D.
Proteins
- Proteins are polymers of amino acids.
- Amino acids have a central carbon with an amino group (-NH2), carboxyl group (-COOH), and R (radical) group.
- The 20 amino acids differ in their R groups, determining their properties.
- A peptide is formed by joining two or more amino acids with peptide bonds.
- Peptide bonds are formed through dehydration synthesis.
- Peptides are named based on the number of amino acids they contain:
- Dipeptides: 2 amino acids
- Tripeptides: 3 amino acids
- Oligopeptides: fewer than 10 to 15 amino acids
- Polypeptides: larger than 15 amino acids
- Protein structure is complex and crucial for function.
- Primary structure: the sequence of amino acids in a protein chain.
- Secondary structure: the coiling or folding of the primary structure into alpha helices and beta sheets, stabilized by hydrogen bonds.
- Tertiary structure: the three-dimensional shape of the protein, formed by interactions between R groups, including hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.
- Quaternary structure: the arrangement of multiple polypeptide chains into a functional protein complex.
- Denaturation: loss of a protein's normal shape, causing loss of function.
- Denaturation can be caused by extreme heat or pH changes, which can be reversible or irreversible.
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Description
Test your knowledge on the properties of water, acids, bases, and the pH scale. This quiz covers how water's unique characteristics affect its role as a solvent and its interactions in chemical reactions. Additionally, explore the definitions and examples of acids and bases, including their relevance to pH.
