Hydrocarbons , Macromolecules, lipids

Hydrocarbons

Definition of Hydrocarbons

  • Hydrocarbons are compounds that consist exclusively of carbon (C) and hydrogen (H) atoms.

  • They represent the simplest form of carbon-based compounds but can vary significantly in size, from one or two carbon atoms in the smallest hydrocarbons to thousands in the largest.

Properties of Hydrocarbons

  • The size of hydrocarbon molecules affects their properties, including melting and boiling points.

  • Some hydrocarbons exist as gases at room temperature, while others are liquids or solids.

  • Hydrocarbons are generally nonpolar, lacking oppositely charged sides, which means they do not dissolve in polar compounds like water.

  • Their nonpolar nature leads to applications in products like floor wax that repel water.

Classes of Hydrocarbons

  • Hydrocarbons can be categorized into two classes based on the number of bonds between carbon atoms:

    • Saturated Hydrocarbons: Have single bonds between carbon atoms, maximizing hydrogen attachment (saturated with hydrogen).

    • Unsaturated Hydrocarbons: Feature at least one double or triple bond between carbon atoms, resulting in fewer hydrogen atoms being bonded (unsaturated with hydrogen).

Uses of Hydrocarbons

  • Crucial sources of fuel, including:

    • Gasoline

    • Natural gas

    • Fuel oil, diesel fuel, jet fuel

    • Coal, kerosene, and propane.

  • Important materials for plastic and polyester production.

Sources of Hydrocarbons

  • Predominantly derived from fossil fuels:

    • Formed millions of years ago from the decomposition of dead organisms, which were buried under sediments and subjected to immense pressure.

    • Examples include:

      • Giant ferns in ancient swamps went on to create coal deposits.

      • Dead marine organisms contributed to petroleum and natural gas deposits.

Carbohydrates

Definition and Structure

  • Carbohydrates range from small sugar molecules (monomers) to large polysaccharides.

  • Sugars:

    • Monosaccharides: Single sugar molecules, typically with a formula that is a multiple of CH₂O, containing hydroxyl and carbonyl functional groups.

    • Disaccharides: Formed when two monosaccharides bond through a dehydration reaction.

Dietary Recommendations

  • The FDA suggests that added sugars should account for no more than 10% of daily caloric intake.

  • Research indicates a link between high sugar intake and negative health outcomes.

Types of Carbohydrates

  • Storage Polysaccharides: Starch and glycogen serve as energy reserves.

  • Structural Carbohydrates: Cellulose comprises plant cell walls, while chitin provides structural support in insect and crustacean exoskeletons, as well as in fungal cell walls.

Lipids

Overview

  • Lipids are diverse compounds primarily composed of carbon and hydrogen and are hydrophobic (water-repelling).

  • Fat Types:

    • Triglycerides: Composed of glycerol linked to three fatty acids.

    • Fatty Acids:

      • Unsaturated fatty acids contain one or more double bonds and are typically found in plant oils.

      • Saturated fatty acids have the maximum number of hydrogen atoms and are found in animal fats.

Hydrogenation

  • Hydrogenation is the process of converting unsaturated fats into saturated fats by adding hydrogen, leading to the formation of trans fats.

  • Trans fats are associated with significant health risks.

  • By the early 1900s, partially hydrogenated oils became prevalent in various foods, which has been linked to increasing health risks.

Health Implications of Trans Fats

  • Different types of studies have looked into the risks of trans fats:

    1. Controlled feeding trials comparing saturated, unsaturated, and partially hydrogenated fats.

    2. Observational studies looking at dietary health impacts.

Natural and Anabolic Steroids

  • Natural Steroids: Organic compounds synthesized from cholesterol, including hormones (e.g., cortisol, testosterone, estrogen) that play vital roles in metabolism, immune response, and reproductive functions.

  • Anabolic Steroids: Synthetic substances that mimic testosterone, used medically for conditions like delayed puberty and muscle wasting, but often abused to enhance athletic performance.

  • Health risks of anabolic steroid misuse include liver damage, cardiovascular issues, behavioral changes, and hormonal imbalances, highlighting the importance of understanding both benefits and risks.

Macromolecules

Classes of Biological Macromolecules

  • The four main classes of macromolecules are:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic acids

  • Commonly known as macromolecules due to their large size and polymers as they are constructed from identical or similar building blocks (monomers).

Polymer Formation and Breakdown

  • Monomers bond to form polymers through dehydration reactions.

  • Polymers can be separated via hydrolysis, with both processes facilitated by enzymes that speed up chemical reactions.

Proteins

Functions of Proteins

  • Proteins serve a wide array of functions in the body, including:

    • Acting as enzymes

    • Transporting proteins in cell membranes

    • Defending against pathogens (antibodies)

    • Receiving molecular signals (receptor proteins)

    • Contributing to muscle contraction (contractile proteins)

    • Providing structural support (e.g., collagen)

    • Storing nutrients (storage proteins).

Composition and Structure

  • Proteins consist of varying arrangements of a common set of 20 amino acid monomers.

  • The functions of different protein types rely heavily on their specific shapes.

  • Denaturation: The process by which proteins unravel, lose their specific shape, and consequently lose their function.