Chem test

Biochemistry: Proteins, Carbohydrates, and Fats

Biochemistry Overview

  • Biochemistry: Study of chemistry involved in living organisms and life processes.

  • Cell: Basic structural unit of all living organisms. The largest structure within a cell is the nucleus, which contains DNA.

Nutrients

  • Categories of Nutrients:

    • Macronutrients: Required in large amounts (e.g., proteins, carbohydrates, fats).

    • Micronutrients: Required in smaller amounts (e.g., vitamins, minerals).

Proteins as Critical Nutrients

  • Proteins: Polymers made of amino acids bonded by peptide bonds.

  • Each amino acid has a three-letter designation. Examples include:

    • Valine: Val (V)

    • Leucine: Leu (L)

    • Tryptophan: Trp (W)

    • Lysine: Lys (K)

    • Glycine: Gly (G)

    • Cysteine: Cys (C)

  • To represent amino acids using one-letter abbreviations: Trp-Gly-Leu-Val-Cys becomes W-G-L-V-C.

Essential vs. Non-Essential Amino Acids

  • Essential Amino Acids: Cannot be produced by the human body; must be ingested (different lists for children and adults).

  • Non-Essential Amino Acids: Can be synthesized by the body.

  • Unique structure for each amino acid indicated by areas that differentiate them.

Protein Structure and Folding

  • Globular Proteins: Fold and curl into complex shapes affecting their function.

  • Protein shapes are determined by amino acid sequences and interactions (e.g., disulfide bonds).

  • Protein Shapes:

    • Primary Structure: Order of amino acids.

    • Secondary Structure: Folding into structures like alpha helices.

    • Tertiary Structure: 3D folding pattern of a protein.

    • Quaternary Structure: Multi-unit structures.

Functions of Proteins

  • Enzymes: Catalyze biochemical reactions.

  • Hormones: Serve as chemical messengers.

  • Antibodies: Fight infections.

  • Hemoglobin/Myoglobin: Store and carry oxygen.

  • Types of Proteins:

    • Globular Proteins: Functions include enzymes and hormones.

    • Structural Proteins: Provide mechanical support (e.g., skin, muscles).

How Proteins Are Made

  • Role of DNA in Protein Synthesis: DNA contains genetic instructions for protein creation, residing within chromosomes in the cell nucleus.

  • DNA Structure:

    • Composed of nucleotide units that form two strands connected by base pairs (A-T, C-G) using hydrogen bonds.

    • DNA strands run in opposite directions (5-prime to 3-prime).

Transcription and Translation

  • Transcription: Process where DNA is copied into RNA.

  • Translation: Process of decoding RNA to synthesize proteins, where each triplet of nucleotides corresponds to a specific amino acid.

Carbohydrates Overview

  • Carbohydrates: Polymers made of saccharides.

    • Monosaccharides: Simple sugars (one unit).

    • Disaccharides: Two monosaccharides linked together (e.g., sucrose).

    • Polysaccharides: Many units linked together (e.g., starch, cellulose).

Types of Carbohydrates

  • Digestible Polysaccharides: Starch (chain of glucose).

  • Indigestible Fiber: Cellulose (long chain of glucose polymers).

Fats and Lipids

  • Fats: Non-polymers composed of long hydrocarbon chains.

    • Fatty Acids: Contain a long nonpolar chain and a polar carboxylic group; classified as saturated or unsaturated.

  • Saturated Fats: Solid at room temperature; straight chains.

  • Unsaturated Fats: Liquid at room temperature; contain double bonds.

  • Triglycerides: Formation of three fatty acids and glycerol; serve functions such as energy storage and insulation.

Nutrition Overview

Fats & Food

  • Protein Sources:

    • Found in meat and dairy products.

    • Vegetarian sources include beans, legumes, soy, and nuts.

    • Insects can also be a good protein source when traditional sources are scarce.

  • Complete Proteins:

    • A diet must include a source of complete protein containing all essential amino acids in adequate quantities.

    • Complete proteins include most meats, dairy products, eggs, quinoa, and soy.

    • Most plant-based foods are considered incomplete proteins.

Proteins

  • Essential Amino Acids:

    • There are nine essential amino acids:

    • Isoleucine, lysine, phenylalanine, tryptophan, leucine, methionine, threonine, arginine, and valine.

    • Must be included in the diet for growth and repair of body tissues.

  • Daily Requirement:

    • Recommended daily protein intake is 0.8 g per kilogram of body weight.

Dietary Guidelines

  • Changing Habits:

    • U.S. dietary habits are shifting, leading to obesity increases.

  • USDA and HHS Guidelines:

    • Following nutritional guidelines can promote healthy eating, as illustrated by the old food pyramid and new MyPlate model.

Carbohydrates

  • Complex Carbohydrates:

    • Grains mostly consist of polysaccharides.

    • Whole grains are intact and unprocessed, containing bran, germ, and endosperm.

    • Bran and germ help maintain a healthy digestive tract.

    • Refined grains contain only the endosperm.

  • Sugar Requirement:

    • Simple sugars (C6H12O6) supply energy to the body, especially in the form of glucose.

    • Glucose is the only energy source for red blood cells and is preferred by the brain, placenta, and fetus.

    • Natural sugars come from milk, fruits, vegetables, grains, but added sugars are widespread and problematic.

Excessive Sugar Consumption

  • Health Risks:

    • High sugar intake can replace more nutritious foods, promote weight gain, cause dental cavities, and lead to excessive insulin production.

    • Names for added sugars include High Fructose Corn Syrup (HFCS), sucrose, fructose, ect.

Ingredient Labels

  • Reading Ingredients:

    • Ingredients are ordered by concentration; avoid foods with sugar listed as one of the top ingredients.

High Fructose Corn Syrup

  • Overview:

    • HFCS is a concentrated carbohydrate solution, sweeter than conventional corn syrup.

  • Properties:

    • High solubility, hygroscopic, high osmotic pressure, and cheaper due to subsidies.

  • Health Effects:

    • Can inhibit leptin's ability to signal satiation, leading to overeating.

Artificial Sweeteners

  • Types:

    • Saccharin, aspartame, sucralose, and stevia.

  • Pros and Cons:

    • Provide low or no calories but safety concerns remain.

    • Saccharin has been associated with a cancer risk; aspartame is widely used but controversial.

Sugar Replacers

  • Sugar Alcohols:

    • Found naturally in fruits and vegetables, provide fewer calories than sugar, but can cause gastrointestinal issues.

    • Examples: sorbitol, mannitol, xylitol.

Fats

  • Energy Storage:

    • Fats are essential nutrients; excess consumption leads to obesity and chronic health issues.

  • Types of Fatty Acids:

    • Saturated vs. unsaturated; unsaturated fats are healthier and less likely to clog arteries.

Cholesterol and Fatty Acids

  • Health Risks:

    • Saturated fats can raise LDL cholesterol (bad cholesterol), while HDL carries cholesterol away from arteries.

  • Triglycerides:

    • Comprised of three fatty acids and glycerol; serve as energy storage.

Trans Fats

  • Dangers:

    • Altered fats have increased health risks for heart disease.

    • Found in margarine and used for extended shelf life.

Vitamins and Minerals

  • Essential Nutrients:

    • Iodine, iron, calcium, phosphorus, sodium, chloride, and vitamins (fat-soluble vs water-soluble).

  • Daily Intake Recommendations:

    • Various nutrients have specific daily requirements for optimal health.

Fiber and Water

  • Importance of Fiber:

    • No calories but helps maintain fullness and digestive health.

  • Hydration:

    • Recommended water intake is about 1.0-1.5L a day; avoid sugar-laden drinks as substitutes.

Food Additives and Safety

  • Additives:

    • Over 3000 substances are approved for food use in the U.S.

    • Common additives include sugar, salt, citric acid, and preservatives.

  • Risks:

    • Some additives may have associated health risks, such as sodium nitrite related to meat preservation.

Food Safety Issues

  • Natural Toxins:

    • Examples include toxic oxalic acid in rhubarb leaves, psoralens in celery, and toxins in puffer fish.

  • Carcinogens:

    • Natural carcinogens exist in many foods like char-broiled steak and peanuts, necessitating limits set by the FDA for safety.

Forensic Chemistry and Crime Labs

What is Forensic Science?

  • Definition: Application of science to criminal and civil laws enforced by police agencies in a criminal justice system.

Organization of Crime Labs

  • Major federal crime labs include:

    • Federal Bureau of Investigation (FBI)

    • Drug Enforcement Administration (DEA) Laboratories

    • Bureau of Alcohol, Tobacco, and Firearms (ATF)

    • U.S. Postal Inspection Service

Application of Sciences in Forensic Science

  • Forensic science applies multiple scientific disciplines, including:

    • Chemistry

    • Biology

    • Physics

    • Geology

  • Places physical evidence into a professional discipline tied to civil and criminal law.

Crime Lab Units

  • Standard units involved in crime investigation:

    • Physical Science

    • Biology

    • Firearms

    • Document Examination

    • Photography

  • Optional units include:

    • Toxicology

    • Fingerprints

    • Polygraph

    • Voice Print

Functions of a Forensic Scientist

  • Key responsibilities include:

    • Applying natural and physical sciences to analyze evidence from crime scenes.

    • Providing expert testimony in court.

    • Training law enforcement on evidence recognition, collection, and preservation.

Basic Services of Full-Service Crime Laboratories

  • Physical Science Unit:

    • Applies Chemistry, Physics, Geology techniques for evidential comparison.

  • Biology Unit:

    • Identifies dried blood and body fluids; compares hair/fibers; conducts DNA analysis.

  • Firearms Unit:

    • Examines firearms, discharged bullets, cartridge cases, and shotgun shells.

  • Document Examination Unit:

    • Analyzes handwriting, documents, and paper.

  • Photography Unit:

    • Examines and records crime scene evidence.

Optional Services of Crime Labs

  • Toxicology Unit:

    • Examines body fluids and organs for drugs and poisons.

  • Latent Fingerprint Unit:

    • Processes evidence for latent fingerprints on surfaces.

  • Polygraph Unit:

    • Involves lie detection but not core forensic analysis.

  • Voiceprint Analysis Unit:

    • Analyzes recorded voice threats to link to suspects.

  • Evidence-Collection Unit:

    • Integrates evidence collection within forensic service.

Forensic Chemistry

  • Characterization of Evidence:

    • Explosives/Arson Analysis, Illicit Drug Analysis, Toxicology, Trace Analysis (hair, fiber, glass, firearms, soil).

  • Significance of Physical Evidence:

    • Identification Test: Identifies physical or chemical identity (e.g., accelerant residues).

    • Comparison Test: Determines if specimens have a common origin (e.g., hair, paint chips).

    • Individual vs. Class Characteristics:

    • Individual Characteristics: High probability attribution to common source.

    • Class Characteristics: Association with a group, not a specific source.

Explosives

  • Definition:

    • Substances undergoing rapid oxidation producing large gas quantities.

    • Explosions result from sudden gas pressure buildup.

  • Classification:

    • Low Explosives: Rapid decomposition but less destructive (e.g., black powder, smokeless powder).

    • High Explosives:

    • Primary Explosives: Sensitive to heat/shock (e.g., blasting caps).

    • Secondary Explosives: Insensitive, must be detonated (e.g., ANFO, RDX).

Collection and Analysis

  • Systematic search for evidence after an explosion, focusing on:

    • Trace of detonating mechanisms.

    • Items near the explosion's origin.

  • Collection Techniques:

    • Use ion mobility spectrometry (IMS) for on-site screening.

    • Ensure materials are sealed in air-tight containers to avoid contamination.

  • Laboratory Analysis Methods:

    • Microscopy for unconsumed explosive particles, combined with chromatography techniques for identification.

    • Advanced methods: IR-spectrophotometry, gas chromatography–mass spectrometry, X-ray diffraction.

In-Depth Notes on Illicit Drug Testing and Substance Effects

Illicit Drug Testing

  • Screening Tests:

    • Preliminary tests to reduce the number of possible identities of an unknown substance.

    • Types include color tests and microcrystalline tests.

  • Confirmation Tests:

    • A single test that specifically identifies a substance.

  • Identification of Drugs:

    • Qualitative: Descriptive, e.g., an unknown sample may be determined to contain heroin and quinine.

    • Quantitative: Amount, e.g., a sample may contain 10% heroin and 90% quinine.

Analysis Considerations

  1. Legal Description

  2. Weight

  3. Confirmation of drug identity

  4. Purity

  5. Cutting Agents

Color Tests

  • Characteristic colors produced when mixed with specific reagents.

  • Useful for field investigators as screening tests only.

  • Examples of Color Tests:

    • Marquis: heroin, morphine, opium derivatives, amphetamines

    • Dille-Koppanyi: barbiturates

    • Duquenois-Levine: marijuana

    • Van Urk: LSD

    • Scott test: cocaine

Microcrystalline Tests

  • Identifies specific substances based on the color and shape of crystals formed with reagents.

Chromatography

  • An analytical technique used to separate components of a mixture for identification and quantification.

  • Process Components:

    • Stationary Phase: Solid substance that adsorbs components of a mixture.

    • Mobile Phase: Liquid or gas flowing through the stationary phase.

    • Components separate based on their speed through the stationary phase which depends on their attraction to mobile and stationary phases.

Thin-Layer Chromatography (TLC)

  • Utilizes a solid (silica gel/aluminum oxide) coated on a plate, immersed in a liquid solvent.

  • As the solvent moves up, components of a mixture travel at different speeds.

  • Unknown substances can be compared to reference samples.

Gas Chromatography (GC)

  • Uses a solid stationary phase and gaseous mobile phase.

  • Analyzes complex mixtures and provides quantitative results.

  • Stationary phase is a thin film of liquid inside a column, allowing separation of components.

Spectrophotometry

  • Uses UV, visible, and infrared light to analyze unknown substances.

  • Substances either absorb, reflect, or transmit various wavelengths of light, aiding in the identification or quantification.

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

  • Examples: Aspirin, Ibuprofen, Naproxen.

  • Relieve minor aches and reduce fever.

  • Inhibit production of prostaglandins that send pain messages to the brain.

  • Risks: stomach pain and excess bleeding with large doses.

Narcotics

  • Derived from opium; includes Morphine (discovered in 1805) and Heroin (developed by Bayer in 1874).

  • Heroin effects brain faster than morphine due to its chemical structure.

  • Related drugs: Oxycodone, Hydrocodone, Methadone (for addiction treatment).

Anesthetics

  • Substances that cause lack of feeling or awareness.

  • Historical examples include Diethyl ether (1840s), Nitrous oxide, and Chloroform (1847).

  • Current anesthetics include Isoflurane, Desflurane, and Sevoflurane.

Psychotropic Drugs

  • Affect the human mind and categorized into three classes:

    1. Stimulants: e.g., cocaine, amphetamines (increase alertness).

    2. Depressants: e.g., alcohol, opiates, barbiturates (reduce consciousness).

    3. Hallucinogens: e.g., LSD (alters perception).

Stimulant Drugs

  • Amphetamine: inexpensive, widely abused, previously a diet drug.

  • Methamphetamine: made from antihistamines; long-term effects include mental problems and dental issues.

  • Cocaine: derived from Andean shrubs, quick intake effects when smoked.

  • Caffeine: mild stimulant; effective dose ~200mg.

  • Nicotine: found in tobacco, highly toxic.

Hallucinogenic Drugs

  • LSD: powerful hallucinogen; typical dosage is very small (10-100ug).

  • Marijuana: contains THC; effects include euphoria and altered time perception; used in medical contexts.

Depressant Drugs

  • Ethanol: alcohol depresses mental and physical activity.

  • Evidence suggests moderate drinking may extend lifespan, despite alcoholism shortening life span by 10-12 years.

  • Barbiturates: risk of mild sedation to death, highly addictive.

  • Example: Phenobarbital as an anticonvulsant.

  • Key Takeaways:

    • The use of various testing methods is crucial for identifying and confirming illicit drugs.

    • Understanding drug categories can aid in both legal and health-related discussions regarding drug effects.