Hydrogen Bond Formation

Formation

• Hydrogen bonds are formed when a hydrogen atom bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) interacts with another electronegative atom.
• The electronegative atom pulls the shared electrons in the bond closer to itself, creating a partial positive charge on the hydrogen atom.
• This partial positive charge is attracted to a partial negative charge on another electronegative atom, resulting in a weak electrostatic attraction.
• Hydrogen bonds are typically formed between molecules, but can also occur within a molecule.

Strength

• Hydrogen bonds are relatively weak, with bond energies ranging from 5-30 kJ/mol.
• They are stronger than van der Waals forces, but weaker than covalent bonds.
• The strength of a hydrogen bond depends on the electronegativity of the atoms involved and the distance between them.

Types

• Intermolecular hydrogen bonds: formed between two separate molecules.
• Intramolecular hydrogen bonds: formed within a single molecule.
• Hydrogen bonds can also be classified as:
  • Donor hydrogen bonds: when the hydrogen atom is bonded to an electronegative atom that donates its electrons.
  • Acceptor hydrogen bonds: when the electronegative atom accepts the electrons.

Importance in DNA

• Hydrogen bonds play a crucial role in the structure and stability of DNA.
• They are responsible for holding the two strands of DNA together, forming the double helix structure.
• Hydrogen bonds between the nitrogenous bases (adenine, guanine, cytosine, and thymine) on opposite strands of DNA allow for the transmission of genetic information.

Role in Protein Structure

• Hydrogen bonds help stabilize the secondary, tertiary, and quaternary structures of proteins.
• They form between the amino acids and the surrounding solvent, as well as between different parts of the protein itself.
• Hydrogen bonds are important for maintaining the correct conformation of proteins, which is essential for their biological function.

Formation of Hydrogen Bonds

• Hydrogen bonds are formed when a hydrogen atom bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) interacts with another electronegative atom.
• The electronegative atom pulls the shared electrons in the bond closer to itself, creating a partial positive charge on the hydrogen atom.
• This partial positive charge is attracted to a partial negative charge on another electronegative atom, resulting in a weak electrostatic attraction.

Characteristics of Hydrogen Bonds

• Hydrogen bonds are relatively weak, with bond energies ranging from 5-30 kJ/mol.
• They are stronger than van der Waals forces, but weaker than covalent bonds.
• The strength of a hydrogen bond depends on the electronegativity of the atoms involved and the distance between them.

Types of Hydrogen Bonds

• Intermolecular hydrogen bonds: formed between two separate molecules.
• Intramolecular hydrogen bonds: formed within a single molecule.
• Hydrogen bonds can also be classified as:
  • Donor hydrogen bonds: when the hydrogen atom is bonded to an electronegative atom that donates its electrons.
  • Acceptor hydrogen bonds: when the electronegative atom accepts the electrons.

Importance of Hydrogen Bonds in DNA

• Hydrogen bonds play a crucial role in the structure and stability of DNA.
• They are responsible for holding the two strands of DNA together, forming the double helix structure.
• Hydrogen bonds between the nitrogenous bases (adenine, guanine, cytosine, and thymine) on opposite strands of DNA allow for the transmission of genetic information.

Role of Hydrogen Bonds in Protein Structure

• Hydrogen bonds help stabilize the secondary, tertiary, and quaternary structures of proteins.
• They form between the amino acids and the surrounding solvent, as well as between different parts of the protein itself.
• Hydrogen bonds are important for maintaining the correct conformation of proteins, which is essential for their biological function.

Intake of Raw Materials and Elimination of Waste

• The body takes in oxygen, water, and food, and excretes carbon dioxide, urine, and faeces.

Oxygen Intake

• Oxygen is a gas that makes up about 21% of atmospheric air.
• A continuous supply of oxygen is essential for human life.
• Oxygen is needed for chemical reactions that release energy from nutrients.
• The respiratory system carries air between the nose and the lungs during breathing.
• Air passes through the pharynx, larynx, trachea, bronchi, and bronchial passages, ending in alveoli.
• Alveoli are tiny air sacs in the lungs where gas exchange between the lungs and blood takes place.

Nitrogen

• Nitrogen makes up about 80% of atmospheric air but is not used by the body in its gaseous form.
• The body's nitrogen needs are met through protein-containing foods, mainly meat and fish.

Nutrition

• A balanced diet is important for health and provides nutrients.
• Nutrients include water, carbohydrates, proteins, fats, vitamins, and mineral salts.
• Nutrients are required for:
  • Maintaining water balance within the body
  • Energy production, mainly from carbohydrates and fats
  • Synthesis of large and complex molecules, using mineral salts, proteins, fats, carbohydrates, and vitamins
  • Cell building, growth, and repair, especially proteins

Digestion

• The digestive system breaks down complex food into a form the body cells can use.
• The digestive system consists of the alimentary tract and accessory glands.
• The alimentary canal is a tube that begins at the mouth and continues through the pharynx, oesophagus, stomach, small and large intestines, rectum, and anus.
• Accessory glands, including salivary glands, are situated outside the alimentary canal with ducts leading into it.

Learn about the process of hydrogen bond formation, including the role of electronegative atoms and partial charges. Understand the weak electrostatic attraction that forms between hydrogen and other electronegative atoms.