molecular structure

Cis-Trans Isomers

• Definition: Cis-trans isomers are structural isomers where the orientation of functional groups relative to a double bond differs.

• Structure:

  • Cis Isomers: Functional groups are on the same side of the double bond.

  • Trans Isomers: Functional groups are on opposite sides of the double bond.

Trans Fats

• Cis Fats vs. Trans Fats:

  • Cis Fats: Involves hydrocarbons where the functional groups of the fat molecules are on the same side of the double bond.

  • Trans Fats: Involves hydrocarbons where the functional groups are on opposite sides of the double bond.

• Health Implications:

  • Trans fats are harmful as they are not easily digested by the human body due to their unnatural formation.

  • Since trans fats do not require the same metabolic processes as cis fats, they can lead to negative health effects.

Functional Groups

• Definition: Functional groups are specific groups of atoms within molecules that have distinct chemical properties.

• Examples of Functional Groups:

  • Methyl Group (C-CH₃):

    • Simplest hydrocarbon functional group; non-polar due to low electronegativity.

  • Amino Group (NH₂):

    • Basic functional group, acts as a base in biological systems.

  • Carboxyl Group (COOH):

    • Contains both a carbonyl (C=O) and a hydroxyl (–OH) group, acidic in nature.

  • Sulfhydryl Group (–SH):

    • Contains sulfur; can form disulfide bonds in proteins.

  • Phosphate Groups (PO₄³⁻):

    • Highly electronegative, can repel each other due to similar charges. Important in biological energy transfer (e.g., ATP).

• Preparation Techniques for Studying:

  • Utilize flashcards for memorization.

  • Draw molecular structures including functional groups for better understanding.

  • Create molecules by combining functional groups and practicing by naming them.

Properties of Functional Groups

• Electronegativity:

  • A key factor in defining how atoms interact with each other.

  • Influences the polarity of molecules and their solubility in water.

  • Polar vs. Non-Polar:

    • Polar molecules have partial positive and negative charges due to uneven distribution of electrons (e.g., water).

    • Methyl group (low electronegativity) is non-polar and does not form dipole moments.

    • Hydroxyl group (–OH) has polar characteristics due to the electronegativity of oxygen, leading to dipole moments and solubility in water.

Understanding Carbon's Importance in Biology

• Atomic Structure and Reactivity:

  • Understanding valence electrons and their roles in bonding patterns leads to diverse molecular shapes and reactivity.

• Geometries from Bonding Patterns:

  • Open valence shells lead to varied geometries that are critical for biological function, particularly in protein structure and functionality.

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