Questions and Answers
Additional hydrogen atoms can be added to saturated fats, a process called hydrogenation.
False
When unsaturated fats are partially hydrogenated industrially, this can produce trans fats which have been linked to elevated levels of low-density lipoprotein (LDL) 'bad cholesterol' and lowered levels of high-density lipoprotein (HDL) 'good cholesterol'.
True
Why are fats excellent energy storage molecules?
They have a relatively high ratio of energy storing C-H bonds.
What are some characteristics of phospholipids?
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How do membranes form spontaneously?
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How does the protein Ras associate with membranes?
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What are some properties of the interior protein network?
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Where do lipids, a class of organic compounds, fit on the hierarchy of biological organization?
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What are characteristics of an ionic bond?
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What are characteristics of a covalent bond?
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What are the 4 most common elements in living organisms?
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What elements are present in trace amounts only?
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What elements are found in greater than trace amounts?
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The atomic number of carbon-13 is ____
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The atomic mass of carbon-13 is ______
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C-12, C-13, and C-14 have the same number of protons but different numbers of neutrons so they are ______.
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Atoms that have gained or lost electrons and are no longer electrically neutral are called _____.
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Describe a single covalent bond.
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Describe an ionic bond.
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Describe a double covalent bond.
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A water molecule is held together by 2 single polar covalent bonds.
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Because oxygen has a greater electronegativity than hydrogen, water molecules are polar with 2 partial negative charges near the oxygen atom and one partial positive charge near each hydrogen atom.
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Atoms differ in their affinity for neutrons, a property called electronegativity.
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In general, electronegativity increases from left to right across each row of the periodic table and also increases down each column.
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In a nonpolar covalent bond, there is an equal sharing of electrons between two atoms while polar covalent bonds involve an unequal sharing of electrons.
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A single molecule of oxygen is held together by 2 double nonpolar covalent bonds.
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A covalent bond is formed when 2 atoms share one or more pairs of electrons.
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Polar molecules are electrically neutral, but the distribution of charge within the molecule is not uniform.
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Although C and H differ slightly in electronegativity, this small difference is negligible, and C-H bonds are considered polar.
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Of the 4 most common elements found in living organisms, nitrogen has the highest electronegativity and therefore, the greatest affinity for electrons.
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A slightly positive hydrogen atom on one water molecule can attract the slightly negative oxygen atom on a different water molecule, leading to the formation of a hydrogen bond.
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What are properties of water?
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As the pH scale increases, the concentration becomes____.
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PH's H+ concentration increases by __.
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When given electronegativity, subtracting the difference between the two molecules will provide you with what information?
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Monosaccharides create what polymer?
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Nucleotides create what polymer?
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Fatty acids, glycerol create what polymer?
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Amino acids create what polymer?
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Describe Dehydration synthesis.
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Describe Denaturation.
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Describe Hydrolysis.
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Describe the primary structure.
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Describe the secondary structure.
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Describe Tertiary structure.
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Describe the quaternary structure.
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What might cause a protein to become nonfunctional?
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What levels of protein would be affected if all hydrogen bonding interactions were prevented?
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What types of bonds link individual amino acids together?
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In the stable form of protein, what is generally oriented to the interior of the protein molecule?
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A protein that has many hydrophobic R-groups pointing to the outside of the protein would be found...
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When proteins are denatured, which type of bond is NOT disturbed?
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If a protein's environment is altered, the protein may change its shape or even unfold completely, a process called dissociation.
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Proteins can denature when the pH, temperature, or ionic concentration of the surrounding solution changes.
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Denatured proteins are usually biologically active.
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When normal environmental conditions are reestablished after protein denaturation, almost all proteins can spontaneously refold back into their natural shape.
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If the 3D structure of a protein depends only on its primary structure and the surrounding environmental conditions, then when the protein is denatured and subsequently returned to its native conditions it will spontaneously refold back into its native structure.
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Proteins have a narrow range of conditions in which they fold properly; outside this range, proteins tend to renature.
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Some proteins require other proteins called chaperones in order to correctly fold into their normal 3D shape.
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Cells use chaperones both to accomplish the original folding of some proteins and to restore the structure of incorrectly folded ones.
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Some diseases may occur because a protein with the correct amino acid sequence fails to correctly fold into its final functional form.
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During a process called dissociation, the polypeptides of a protein with quaternary structure separate and unfold, losing their individual tertiary structure.
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The final 3D shape of a protein is determined entirely by its primary structure.
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What qualities of a chemical reaction are affected by enzymes?
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What might happen if a substance that is not a substrate molecule binds to an enzyme's active site?
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An enzyme may catalyze a reaction by stressing or destabilizing the bonds of substrates. This point in the enzymatic reaction is known as the?
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Sucrase uses _____ to cleave sucrose into 2 monosaccharides.
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When it binds to sucrose, sucrase?
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What can you say about the change in free energy of the cleavage of sucrose into glucose and fructose?
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A mutation occurred in the gene that encodes the enzyme sucrase, resulting in a single amino acid substitution in the active site, whereby a polar amino acid changed to a nonpolar amino acid. The most likely result of this is?
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L-arabinose is a naturally occurring, non-caloric sweetener that acts as a non-competitive inhibitor of the enzyme sucrase. If L-arabinose is consumed, what will happen to the hydrolysis of sucrose?
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Your friend is studying a specific exergonic reaction. Your friend hypothesizes that the addition of enzyme X will reduce the delta-G of this reaction, thus allowing it to proceed spontaneously. What do you think of this?
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What is the structure and function of the Golgi apparatus?
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What is the structure and function of a ribosome?
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What is the structure and function of the smooth ER?
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What is the structure and function of the rough ER?
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What type of cells are in Smooth ER?
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What type of cells are in Rough ER?
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Tay-Sachs disease causes lysosomes to rupture. How would this affect the cell?
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The lysosome contains _____ enzyme.
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You are doing a study on the effects of lysosomal enzymes and want to follow the whole process from the formation of the enzymes to their use in the lysosome. In what location of the cell would you begin this observation?
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What functions do microtubules have?
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What functions do actin have?
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What functions do intermediate filaments have?
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What are the functions of the cytoskeleton?
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What are characteristics of desmosomes?
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What characteristics of plasmodesmata?
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What characteristics of gap junctions?
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What characteristics of a tight junction?
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Suppose a researcher successfully produced a membrane composed of saturated triglycerides rather than from phospholipids. What characteristics would you expect the saturated triglyceride membrane to have?
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What do animal and plant cells have in common?
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A triacylglycerol is composed of 3 glycerol molecules going to a fatty acid.
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The fatty acids of a triglyceride need to be identical, and often they are very different from one another.
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Glycerol is a 3-C alcohol, in which each carbon bears a carboxyl group.
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A fatty acid consists of a hydrocarbon chain joined to a hydroxyl group.
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The hydrocarbon chains of fatty acids vary in length as well as in the number and location of double bonds between the carbon atoms.
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Fatty acids with one double bond in their hydrocarbon chain are called monounsaturated, while those with more than one double bond are called polyunsaturated.
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A saturated fatty acid has the maximum number of oxygen atoms bonded to its hydrocarbon chain.
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Fats containing unsaturated fatty acids have high melting points because their fatty acid chains bend at the double bonds, preventing them from packing closely together.
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Most plant fats contain saturated fatty acids and therefore liquid at room temperature.
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Study Notes
Biological Hierarchy and Elements
- Lipids are a class of organic compounds integral to biological organization.
- The four most common elements in living organisms are carbon, oxygen, hydrogen, and nitrogen.
- Trace elements present in minimal amounts include iodine and zinc, while elements like sodium, chloride, calcium, phosphorus, potassium, sulfur, magnesium, and iron are found in greater quantities.
Atomic Structure
- Carbon-13 has an atomic number of 6 and an atomic mass of 13; it is an isotope alongside C-12 and C-14, which share the same protons but differ in neutron count.
- Ions are defined as atoms that have gained or lost electrons, altering their electrical neutrality.
- Single covalent bonds involve the sharing of two electrons between atoms, while double covalent bonds involve the sharing of four electrons.
Bonding Types
- Ionic bonds arise from strong attractions between atoms with significant electronegativity differences, leading to electron transfer and formation of crystal lattices.
- Covalent bonds can be polar or nonpolar, depending on the electronegativity of the bonded atoms.
- Water is held together by two single polar covalent bonds, contributing to its unique properties.
Water Properties
- Water enables free movement and interaction of substances within cells.
- It maintains stable temperature within living organisms and allows life to persist under frozen lake surfaces due to its unique freezing properties.
pH Scale and Acidity
- As pH increases, the concentration of hydrogen ions decreases; pH changes occur logarithmically, meaning each unit represents a tenfold difference in H+ concentration.
- Understanding electronegativity differences helps determine whether a bond is polar or nonpolar.
Biomolecules and Polymers
- Monosaccharides give rise to carbohydrates, while nucleotides form DNA, and fatty acids combine with glycerol to create triglycerides. Amino acids link to form proteins.
- Dehydration synthesis joins monomers by removing water, while hydrolysis involves adding water to break polymers into simpler molecules.
Protein Structure
- Protein structures:
- Primary: Sequence of amino acids.
- Secondary: Localized 3D structures formed by attractions among amino acids.
- Tertiary: Overall shape influenced by R group interactions.
- Quaternary: Interactions between multiple polypeptide chains.
- Denaturation unfolds proteins without breaking peptide bonds, while hydrolysis breaks them down into amino acids.
Enzyme Functionality
- Enzymes increase reaction speed and lower activation energy without altering the overall free energy change (delta-G).
- Enzyme activity can be inhibited by non-substrate molecules binding to active sites.
Cell Components
- The Golgi apparatus consists of stacked, flat sacs that create vesicles and lysosomes for material secretion and digestion.
- Ribosomes, made of RNA and protein, serve as the site for protein synthesis.
- The endoplasmic reticulum (ER) includes rough ER (with ribosomes) for protein production and smooth ER for lipid synthesis and detoxification.
Cytoskeleton and Cell Structure
- Microtubules aid in intracellular transport; actin filaments enable cell movement; intermediate filaments maintain structural integrity.
- The cytoskeleton provides organization, movement, and shape to the cell.
Cell Junctions
- Desmosomes strengthen tissue by connecting intermediate filaments, while plasmodesmata in plant cells facilitate ion flow.
- Gap junctions allow rapid communication between cells, and tight junctions prevent material movement between cells.
Lipid Characteristics
- Saturated triglycerides do not form bilayers, while phospholipids create membranes with polar heads and hydrophobic tails, critical to cell membrane structure.
- Trans fats result from partial hydrogenation of unsaturated fats, potentially increasing "bad cholesterol".
Protein and Enzyme Interactions
- Enzymatic function can be affected by changes in environmental factors such as pH, temperature, and ionic concentration.
- Chaperone proteins assist in proper protein folding, and any failure in this process can lead to diseases.
General Cell Knowledge
- Animal and plant cells share features, including a phospholipid bilayer and embedded transport proteins.
- Triglycerides provide efficient energy storage due to high C-H bond ratios.
Miscellaneous True/False Statements
- True/False statements cover various facts about proteins, fatty acids, enzymes, and cellular structures, emphasizing concepts such as denaturation, protein folding, and the roles of different biological macromolecules.
Studying That Suits You
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Description
Test your understanding of biological organization and chemical bonds in this quiz based on Chapter 6 of your biology textbook. Topics include the role of lipids and the characteristics of ionic and covalent bonds. Perfect for reinforcing your knowledge in fundamental chemistry within biology.