BSC1005 Lecture #4

Science and Biology Overview

Polymers and Plastics

  • Polymers are abundant in biological systems, present as:

    • Proteins

    • DNA

    • RNA

    • Cellulose

  • Nature does not experience long-term accumulation issues associated with synthetic plastics.

  • Inspired by natural processes, scientists are developing plastics that:

    • Are strong when required.

    • Can be programmed to decompose after use.

  • The chemical mechanisms enable materials to degrade responsively without the need for extreme heat or hazardous chemicals.

  • This advancement could revolutionize the production and application of plastics.

Sleep and Cerebrospinal Fluid (CSF)

  • One significant role of sleep involves the management of cerebrospinal fluid, which:

    • Surrounds and cushions the brain.

    • Aids in the removal of waste generated during waking hours.

  • Lack of sleep not only causes fatigue; it can trigger a cleaning process similar to that of sleep while awake, which:

    • Results in decreased attention, as the brain prioritizes self-maintenance over external focus.

Tool Use in Animals

  • Tool use is not confined to all living organisms.

  • Historically, it was believed that tool use was unique to hominids (humans and close ancestors).

  • Recent discoveries show that many animal species use tools in diverse ways, showcasing the evolution of this capability.

Chemistry and Biological Molecules

Chemistry Keywords

  • Element: A fundamental substance that cannot be chemically broken down.

  • Atom: The basic structural unit of matter.

  • Molecule: Composed of two or more atoms (which may be of the same or different elements).

  • Compound: A molecule formed from two or more different elements.

Formation of Chemical Bonds

  • Chemical bonds are attractive forces holding atoms in molecules together:

    • Ionic Bonds: Form between oppositely charged atoms.

    • Covalent Bonds: Form between uncharged atoms and are generally stronger than ionic bonds.

  • Major biological molecules primarily consist of covalently bonded atoms.

Types of Chemical Structures

  • Different ways to diagram chemical bonds include:

    • Structural Formula

    • Ball-and-Stick Model

    • Space-filling Model

  • Example: The chemical structure of methane can be depicted in several formats.

Biological Molecules and their Bonds

  • Biological molecules are mainly composed of covalent bonds:

    • Single Covalent Bond: Example, methane (H-C-H).

    • Double Bond: Example, oxygen gas (O=O).

    • Triple Bond: Example, nitrogen gas (N≡N).

Organic Molecules

  • Four major classes of organic molecules include:

    1. Carbohydrates: Provide short-term energy storage.

    2. Proteins: Function as enzymes, transporters, receptors.

    3. Nucleic Acids: DNA and RNA are involved in data storage.

    4. Lipids: Such as fats, which are involved in energy storage and hormones.

Carbohydrates

  • Functions: Short-term energy storage.

  • Monosaccharides: Simplest form, one sugar molecule (e.g., glucose, fructose), soluble in water, typically sweet-tasting.

  • Disaccharides: Composed of two sugar molecules, e.g., sucrose (glucose + fructose), primarily used for short-term energy storage in plants.

  • Polysaccharides: Complex sugars consisting of three or more sugar molecules, meant for long-term energy storage.

Complex Carbohydrates

  • Types of complex carbohydrates include:

    • Starch: Energy storage in plants.

    • Glycogen: Energy storage in animals, convertible to glucose as needed.

    • Cellulose: The most abundant organic compound on Earth, crucial for plant structure and not digestible by most animals.

    • Chitin: Forms exoskeletons of arthropods.

Structure of Glucose

  • Formula: C₆H₁₂O₆ (monosaccharide structure depiction).

Dehydration Reactions

  • Linking smaller molecules into larger ones through dehydration reactions:

    • For example: Glucose + Fructose = Sucrose (disaccharide formation).

Lactose Intolerance

  • Caused by a mutation affecting lactase production, leading to symptoms like gas, bloating, and diarrhea after dairy consumption.

Hydrolysis Reactions

  • Molecular breakdown processes that divide larger molecules into smaller ones, often involving water.

Dietary Components

  • Starch: Energy storage in plants.

  • Glycogen: Energy storage in animals.

  • Cellulose: Structural component in plants, indigestible by most organisms but digestible by ruminants due to specialized bacteria.

Proteins

Basic Composition

  • Proteins are polymer chains composed of amino acids (20 different kinds with unique functional groups).

  • The sequence of amino acids dictates the specific protein produced.

Types of Proteins

  • Major categories include:

    • Structural Proteins: Provide support/structure.

    • Storage Proteins: Storage of nutrients.

    • Contractile Proteins: Involved in movement.

    • Transport Proteins: Help in the transport of substances.

    • Enzymes: Catalysts for biochemical reactions.

Amino Acids and Their Structure

  • Basic structure of amino acids includes:

    • Amine Group

    • Carboxyl Group

    • Variable “R” Group: This group differentiates each amino acid.

Protein Structure Levels

  1. Primary Structure: Sequence of amino acids in a polypeptide chain.

  2. Secondary Structure: Includes motifs, such as alpha-helices and beta-pleated sheets.

  3. Tertiary Structure: Overall 3D shape formed by further folding and interactions of secondary structures.

  4. Quaternary Structure: Combination of multiple polypeptide chains in a protein.

Sickle Cell Disease

  • A mutation in the hemoglobin protein leads to altered primary structure, causing the formation of abnormal red blood cells that exhibit rigidity and blockage in blood vessels.

Nucleic Acids

  • Composed of nucleotides, nucleic acids are essential for heredity and cellular functions.

  • Two main types include:

    • DNA: Carries genetic information.

    • RNA: Functions in protein synthesis and carries DNA's information to ribosomes.

Nucleotide Structure

  • Composed of a sugar-phosphate backbone and nitrogenous base.

  • Nitrogenous bases include:

    • Pyrimidines: Cytosine (C), Thymine (T), Uracil (U).

    • Purines: Adenine (A), Guanine (G).

DNA Structure

  • Described as a double-helix structure, where specific pairing occurs:

    • A always binds with T; C always pairs with G.

Biological Functional Groups

  • Major biological functions of macromolecules include:

    • Energy storage

    • Structural integrity

    • Information storage

  • Components are essential for forming diverse biological molecules (e.g., carbohydrates, proteins, lipids, nucleic acids).

Lipids

  • Function: Long-term energy storage, cell membrane components, hormones.

  • Characteristics: Mostly composed of carbon and hydrogen; largely insoluble in water due to their nonpolar nature.

  • Types: Oils, fats, waxes, phospholipids, steroids.

Fatty Acids

  • Composed of long hydrocarbon chains with a carboxyl group (-COOH).

  • Fatty acids and glycerol combine to form triglycerides, which store energy.

Saturated vs. Unsaturated Fats

  • Saturated fats: Solid at room temperature; all carbon bonds are single.

  • Unsaturated fats: Liquid at room temperature; contain at least one double bond, resulting in kinks in the fatty acid chains.

Hydrogenation Process

  • Hydrogenation adds hydrogen to unsaturated fats, converting them to saturated fats, which can lead to the formation of trans fats, known to be less healthy than saturated fats.

Phospholipids

  • Unique lipids where one fatty acid is replaced with a phosphate group, leading to amphipathic properties (hydrophilic head and hydrophobic tails), crucial for forming cellular membranes.

Steroids

  • Composed of four fused carbon rings with diverse functional groups; examples include cholesterol and hormones.

Summary Table of Biological Molecules

  • Carbohydrates: Energy sources, with groups including monosaccharides, disaccharides, and polysaccharides.

  • Lipids: Include triglycerides, phospholipids, and steroids, each with essential roles in biological structure/function.

  • Proteins: Serve varied functions from enzymes to structural components.

  • Nucleic Acids: DNA and RNA vital for genetic information and protein synthesis.