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Questions and Answers
What is a critical role of phosphorus in living organisms?
Which amino acids contain sulfur as a key component?
What is a common health issue resulting from iodine deficiency?
Which type of bond involves the sharing of electron pairs between atomic nuclei?
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Micronutrients are important because their deficiency can lead to which of the following?
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Which of the following statements about essential elements is true?
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Which group of elements comprises the macronutrients?
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What percentage of an organism’s mass is made up of carbon, hydrogen, oxygen, and nitrogen?
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Which element is essential for cellular respiration as an electron acceptor?
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Which of the following elements is NOT classified as a macronutrient?
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Study Notes
Essential Elements
- Of the 115 elements known, only 19 are essential for human life and are highlighted in purple on the periodic table.
- These elements are found within the first four rows of the periodic table
- An essential element is necessary for life and its absence will result in death.
- A deficiency of an essential element causes abnormal development or functioning and must be prevented by supplementing the precise element.
- Essential elements are either macronutrients (required in large quantities, including carbon, phosphorus, nitrogen, hydrogen, potassium, magnesium, oxygen, calcium, and sulfur) or micronutrients (required in trace amounts, including copper, iron, zinc, boron, manganese, molybdenum, nickel, chlorine).
Biomolecules
- Four elements (carbon, hydrogen, oxygen, and nitrogen) comprise 96% of all living matter.
- Sulfur, phosphorus, calcium, and potassium make up the remaining 4%
- Water constitutes 70% of a cell's mass
- Cells are made up of carbon-based compounds, containing up to 30 carbon atoms.
Carbon
- The foundation of organic chemistry and life.
- Forms the backbone of organic molecules (proteins, carbohydrates, lipids, and nucleic acids).
- Its capacity to form stable bonds with other elements, including itself, allows for the complexity and diversity of life.
Hydrogen
- The most abundant element in the universe
- A key component of essential water (H2O), serving as a solvent and participating in metabolic processes.
- Hydrogen ions (protons) are crucial for cellular respiration and energy production.
Oxygen
- Necessary for cellular respiration, acting as an electron acceptor during the breakdown of organic molecules for energy release.
- A major component of water.
- Plays a role in various biological processes.
Nitrogen
- Essential for proteins and nucleic acids (DNA and RNA).
- Crucial for the structure and function of these biomolecules.
- Obtained by living organisms through the uptake of nitrogen-containing compounds from the environment.
Phosphorus
- A critical component of nucleic acids (DNA and RNA) and ATP (adenosine triphosphate), the primary energy currency in cells.
- Present in phospholipids, crucial for the structure of cell membranes.
Sulfur
- Found in specific amino acids (cysteine and methionine), the building blocks of proteins.
- Plays a role in enzyme activity.
- Involved in the formation of disulfide bonds, which contribute to protein structure and stability.
Trace Elements
- Required by organisms in small quantities.
- Not required by all organisms.
- Examples include iron (Fe, needed by all organisms), iodine (I, needed by vertebrates).
- Iodine is essential in the hormone produced by the thyroid gland.
- A deficiency in iodine leads to goiter, a condition where the thyroid gland grows abnormally.
Chemical Bonds
- Attractive forces between atoms, strong enough to allow the combination of atoms to function as a unit.
- Originate due to electron and atomic nuclei attraction (Coulumbic interactions).
- Two main types: covalent and non-covalent.
Covalent Bonds
- Involve electron sharing between two atomic nuclei.
- These shared electrons are known as bonding pairs.
- Localized within the region of the two nuclei.
- Single covalent bond involves two shared electrons, a double bond has four shared electrons, and a triple bond has six shared electrons.
- Hydrophobic interactions occur either between nonpolar molecules or between nonpolar parts of amphipathic molecules.
- These molecules have no affinity for water and are repelled by it.
- Many biomolecules, such as proteins and sterols, exhibit hydrophobic interactions.
Van der Waal’s Interactions
- Intermolecular forces responsible for weak attractions between the partial positive and partial negative charges between molecules.
- Affected by the distance between molecules.
- Three types:
- London Dispersion Forces: The weakest Van der Waals force, occurring between any two atoms in a molecule. It's temporary.
- Dipole-Dipole Interactions: Occur between the positive end of one polar molecule and the negative end of another polar molecule.
- Hydrogen Bonding: The strongest of the Van der Waals forces and occurs between hydrogen atoms and highly electronegative atoms (oxygen and nitrogen).
Forces Stabilizing Protein Structures
- Five main forces:
- Salt Linkages (Ionic Bonds): Result from interactions between positively and negatively charged groups on the side chains of amino acids.
- Hydrogen Bonding: An electrostatic attraction between a hydrogen atom, covalently linked to a highly electronegative atom (Oxygen or Nitrogen), to another electronegative atom of the same or different molecule in its vicinity.
- Disulfide Linkages: Formed by the oxidation of two highly reactive sulfhydryl (-SH) groups of cysteine residues, resulting in a disulfide bridge.
- Hydrophobic Interactions: Driven by the tendency of nonpolar amino acid groups to cluster together inside, avoiding contact with water.
- Van der Waals' Forces: Extremely weak forces, acting only over short distances. They involve both attraction between induced dipoles and repulsion when atoms get too close.
Structure and Properties of Water
- Water appears light blue due to the selective absorption and scattering of white light.
- Transparency allows sunlight to pass through it, necessary for photosynthesis in water plants and organisms.
- Water's unique chemical structure accounts for its remarkable properties:
- Polarity: Water is a polar molecule, with an unequal distribution of charge.
- Solvency: Water is an excellent solvent, dissolving many substances. It's known as the universal solvent because many polar substances dissolve well in it.
- Cohesion: Water molecules strongly attract each other due to hydrogen bonds. This contributes to surface tension.
- Surface Tension: Cohesive forces cause water's resistance to rupture when under tension or stress.
- Adhesion: The attraction between water molecules and other substances, vital in processes like seed germination and capillary action.
- Capillary Action: Water's adhesive properties create a grip-like characteristic enabling the upward movement of water in narrow spaces.
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Description
Test your knowledge about the essential elements necessary for human life and their roles in biomolecules. This quiz covers key macronutrients and micronutrients, as well as the composition of living matter and the significance of water in cellular structure. Perfect for students of biology and health sciences.
