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Questions and Answers
Which type of fat is considered 'good' cholesterol?
What is the primary structural difference between steroids and fats?
How many amino acids can the human body synthesize?
What is one function of phospholipids in the body?
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Which of the following is considered a bad cholesterol?
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Which amino acid group includes those that must be obtained from food?
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Which action can elevate levels of low density lipoproteins (LDL) in the body?
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What distinguishes hydrophobic amino acids from hydrophilic ones?
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What is the primary structure of a protein?
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What effect can a slight change in the primary structure of hemoglobin have?
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What happens to proteins when they undergo denaturation?
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Which of the following is NOT a function of proteins?
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What structural component does RNA have that DNA does not?
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What is the role of ATP in cells?
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How do changes in pH affect enzyme activity?
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What defines the quaternary structure of a protein?
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Which of the following pairs of bases correctly pairs in DNA?
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What role do transport proteins play in the body?
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How does the shape of molecules relate to their function in biological systems?
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Which type of molecule is known for being hydrophobic?
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What is the main characteristic of a polar molecule like water?
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Which statement correctly describes carbohydrates?
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Which molecule is primarily responsible for buffering pH levels in biological systems?
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What is the difference between saturated and unsaturated fatty acids?
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Which of the following groups is found in amino acids?
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How do antibodies function in relation to antigens?
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Which of the following is a major type of macromolecule in biological systems?
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What is a distinguishing feature of oligosaccharides?
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In terms of biological molecules, organic molecules contain which of the following?
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What is the pH level that is considered neutral?
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Which biological macromolecule is primarily used for energy storage?
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Which type of carbohydrates are complex carbohydrates formed by many sugar units?
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Study Notes
Molecular Shape and Function
- Molecules have specific shapes that determine their functions in living organisms.
- Receptors and ligands interact based on their shapes, allowing for specific binding.
- Antibodies recognize and neutralize antigens based on their shapes.
Water
- Water is a polar molecule, with a V shape due to the positive hydrogen atoms and the negative oxygen atom.
- Water molecules are held together by hydrogen bonds.
- Water is an excellent solvent, dissolving hydrophilic substances and repelling hydrophobic substances.
Importance of Hydrogen Compounds
- The concentration of hydrogen ions (protons) determines the pH of a solution, impacting the function of molecules.
- Acids donate protons, while bases accept protons.
- A pH of 7 is neutral, while values below 7 are acidic and values above 7 are alkaline.
Biological Molecules
- Biological molecules are organic molecules containing carbon.
- Each type of organic molecule has a unique three-dimensional shape that defines its function.
- The unique properties of an organic compound depend on its carbon skeleton and the functional groups attached to it.
Functional Groups
- Hydroxyl groups are found in alcohols and sugars.
- Carbonyl groups are found in sugars.
- Amino groups are found in amino acids and urea.
- Carboxyl groups are found in amino acids, fatty acids, and some vitamins.
Giant Molecules from Smaller Building Blocks
- Biologists refer to large, complex molecules as macromolecules.
- Macromolecules are assembled from smaller subunits, forming giant structures like DNA and carbohydrates.
Biological Macromolecules
- There are four categories of large molecules in cells: carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates
- Carbohydrates are important for energy storage and structural support.
- They are made up of sugar molecules.
- Monosaccharides are single sugar units, such as glucose and fructose.
- Disaccharides consist of two sugar units, such as sucrose.
- Oligosaccharides consist of three to ten sugar units.
- Polysaccharides are complex carbohydrates consisting of long chains of sugar units, such as starch, cellulose, and glycogen.
Lipids
- Lipids are insoluble in water and have essential functions in the human body, including energy storage, cushioning, and insulation.
- Triglycerides are energy storage molecules composed of glycerol and fatty acids.
- Phospholipids are structural components of cell membranes.
- Steroids are carbon-based ring structures, with cholesterol being a key component.
Proteins
- Proteins are made up of amino acids, with 20 different types of amino acids commonly found in proteins.
- Each amino acid has a central carbon atom bonded to four covalent partners: an amino group, a carboxyl group, a side group, and a hydrogen atom.
- Human bodies can synthesize 11 amino acids but obtain 9 from food.
- Proteins have complex structures, including:
- Primary structure: the linear sequence of amino acids.
- Secondary structure: the orientation of the polypeptide chain in space, such as alpha helices and beta sheets.
- Tertiary structure: the three-dimensional shape of the protein formed by interactions between side chains.
- Quaternary structure: the association of two or more polypeptide chains.
- Proteins have several functions in the body, including:
- Enzymatic catalysis: proteins that speed up chemical reactions.
- Transportation and storage: proteins that transport molecules or store substances.
- Coordinated motion: proteins involved in muscle contraction.
- Mechanical support: proteins that provide structural support for tissues and organs.
Nucleic Acids
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Nucleic acids store genetic information and provide instructions for making proteins.
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They are made up of nucleotides, which consist of a phosphate group, a sugar, and a nitrogenous base.
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DNA is a double helix composed of two associated strands of nucleic acids.
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RNA is a single-stranded molecule.
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Both DNA and RNA contain the nitrogenous bases adenine, guanine, cytosine, and thymine (DNA) or uracil (RNA).
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ATP produces energy for the cell and is derived from food or the body's stored glycogen or fat.
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The average American consumes about 64 kg of sugar per year.
Cholesterol Types
- Chylomicron is a lipoprotein that is high in triglycerides and low in protein.
- Low-density lipoprotein (LDL) is high in cholesterol and low in protein, often referred to as "bad cholesterol."
- High-density lipoprotein (HDL) is high in protein and low in cholesterol, often referred to as "good cholesterol."
Lipid Transport
- LDL can lead to heart disease.
- Cells obtain cholesterol from LDL.
- HDL helps remove cholesterol from the body.
- High LDL levels are associated with a greater risk of heart disease, while high HDL levels are beneficial.
Protein Structure
- A protein's shape is influenced by its surrounding environment.
- Temperature and pH changes can cause a protein to denature, losing its functional shape.
- Enzyme function is dependent upon several factors including temperature, pH, ion concentration, and the presence of inhibitors.
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