Midterm Study Guide_ Bio (1)

Structures of Macromolecules

• Categories of Macromolecules: Essential molecules divided into four primary groups: nucleic acids, lipids, proteins, carbohydrates.

  • DNA (Deoxyribonucleic Acid):

    • Structure: Double-stranded helix made of nucleotides (deoxyribose sugar, phosphate group, nitrogenous bases A, T, C, G).

    • Function: Stores genetic information, codes for proteins.

    • Example: Found in chromosomes of all living organisms.

  • RNA (Ribonucleic Acid):

    • Structure: Single-stranded, composed of nucleotides (ribose sugar, phosphate, nitrogenous bases A, U, C, G).

    • Function: Transfers genetic information from DNA to ribosomes for protein synthesis.

    • Types:

      • mRNA (Messenger RNA): Carries genetic code.

      • tRNA (Transfer RNA): Brings amino acids to ribosome.

      • rRNA (Ribosomal RNA): Component of ribosome.

    • Example: Present in ribosomes, cytoplasm.

  • Lipids:

    • Structure: Composed of glycerol and fatty acids.

    • Function: Energy storage, formation of cell membranes.

    • Types:

      • Phospholipids: Hydrophilic head & hydrophobic tail (form cell membranes).

      • Triglycerides: Glycerol + 3 fatty acids (energy storage).

      • Steroids: Cholesterol, hormones.

    • Example: Fats, oils, cholesterol.

  • Proteins:

    • Structure: Made up of amino acids linked by peptide bonds.

    • Function: Structural components, enzymes, signaling molecules.

    • Levels of Structure:

      • Primary Structure: Unique sequence of amino acids in a polypeptide chain.

      • Secondary Structure: Folding patterns (alpha-helices, beta-pleated sheets).

      • Tertiary Structure: Complete 3D shape of a single polypeptide.

      • Quaternary Structure: Interaction of multiple polypeptide chains (e.g., hemoglobin).

    • Example: Enzymes, hemoglobin, antibodies.

Carbohydrates

• Structure: Composed of carbon, hydrogen, and oxygen (CH2O)n.

• Function: Quick energy source and structural support.

• Types:

  • Monosaccharides: Simple sugars (e.g. glucose, fructose).

  • Disaccharides: Two sugars (e.g. sucrose, lactose).

  • Polysaccharides: Complex sugars (e.g. starch, glycogen, cellulose).

• Example: Glucose (energy), cellulose (plant cell walls).

Monomers and Polymers

• Definitions:

  • Monomer: Single unit (small molecule).

  • Polymer: Many monomers linked together.

• Examples:

  • Proteins:

    • Monomer: Amino acids

    • Polymer: Polypeptide (enzymes, keratin)

  • Carbohydrates:

    • Monomer: Monosaccharides

    • Polymer: Polysaccharides (starch, glycogen)

  • Lipids:

    • Monomer: Fatty acids & glycerol

    • Polymer: Triglycerides, phospholipids (fats, oils, cell membranes)

  • Nucleic Acids:

    • Monomer: Nucleotides

    • Polymer: DNA, RNA (Genetic material)

Functional Groups

1. Alcohol (-OH)

   • Structure: Hydroxyl group (-OH)

   • Properties:

     • Polar and hydrophilic (water-soluble).

   • Biological Importance:

     • Present in sugars (carbohydrates).

2. Amino (-NH₂)

   • Structure: Nitrogen atom bonded to two hydrogen atoms.

   • Properties:

     • Basic and hydrophilic.

   • Biological Importance:

     • Found in amino acids, key for protein structure.

3. Carboxyl (-COOH)

   • Structure: Carbonyl group (C=O) + hydroxyl.

   • Properties:

     • Acidic and polar.

   • Biological Importance:

     • Involved in protein synthesis.

4. Ester (-COO-)

   • Structure: Carbonyl group linked to an oxygen atom.

   • Properties:

     • Nonpolar and slightly polar.

   • Biological Importance:

     • Found in lipids, essential for energy storage.

Bonds in Biological Molecules

• Ionic Bond:

  • Type: Electron transfer (strong in solid form, weak in water).

  • Example: NaCl (salt)

• Covalent Bond:

  • Type: Electron sharing (strongest bond).

  • Example: H₂O (water), DNA.

• Hydrogen Bond:

  • Type: Attraction between partial charges (weak but essential).

  • Example: DNA base pairing, water properties.

Stains in Microbiology

• Simple Stain: Highlights cell shape and structure with one dye.

• Gram Stain: Differentiates bacteria:

  • Gram-Positive: Purple (thick peptidoglycan layer).

  • Gram-Negative: Pink (thin peptidoglycan, outer membrane).

• Acid-Fast Stain: Identifies bacteria with mycolic acid (e.g., Mycobacterium tuberculosis).

• Negative Stain: Stains background, leaving the cell unstained.

Microscopes & Differences

Cell Transport & Arrangement

• Simple Diffusion: Movement from high to low concentration.

• Active Transport: Requires ATP to move against gradient.

• Passive Transport: No energy required.

• Osmosis:

  • Hypotonic: Water enters cell.

  • Hypertonic: Water leaves cell.

  • Isotonic: No net movement.

Endospores & Glycocalyx

• Endospores: Dormant, resistant structures (e.g., Bacillus anthracis) formed to survive extreme conditions.

• Glycocalyx: Sugar-rich outer layer on bacteria.

  • Function: Adhesion, immune evasion, biofilm formation.

Energy Sources in Microorganisms

Cellular Respiration & Fermentation

• Aerobic Respiration:

  • Reactants: Glucose (C₆H₁₂O₆), Oxygen (O₂).

  • Products: CO₂, H₂O, ATP (36-38).

  • Steps: Glycolysis, Krebs Cycle, Electron Transport Chain.

• Anaerobic Respiration:

  • Reactants: Glucose (C₆H₁₂O₆), alternative electron acceptors.

  • Products: ATP (~2-30), CO₂, reduced byproducts.

• Fermentation: Anaerobic process regenerating NAD⁺ for glycolysis.

Electron Transport Chain (ETC)

• Located in the inner mitochondrial membrane (eukaryotes) or plasma membrane (prokaryotes).

• Steps:

  • Electrons from NADH & FADH₂ travel through ETC.

  • Creates a proton gradient, using oxygen as the final electron acceptor.

  • Produces ATP via ATP synthase.

Bacterial Growth & Classification

• Growth Curve:

  • Lag, Log, Stationary, Death phases.

• Temperature Adaptations:

  • Psychrophiles, Mesophiles, Thermophiles, Hyperthermophiles.

Physical Conditions Required for Bacterial Growth

• Temperature: Varies by categories (psychrophiles, mesophiles, etc.).

• pH: Acidophiles, neutrophiles, alkaliphiles.

• Oxygen Requirements: Obligate aerobes, facultative anaerobes, etc.

• Osmotic Pressure: Halophiles, osmotolerant organisms.

Microbial Control Terminology

• Bacteriostatic: Inhibits growth.

• Germicide: Kills microbes.

• Virucide: Kills viruses.

• Sterilant: Eliminates all microbial forms.

• Fungicide: Kills fungi.

• Disinfectant: Kills pathogens on objects.

• Antiseptic: Reduces microbes on skin.

Autoclave and Its Function

• Process: Uses moist heat under pressure (121°C, 15 psi) for sterilization.

Microbial Control Methods

• Lyophilization: Preserves microbes.

• Radiation: Damages DNA.

• Freezing: Slows metabolism.

• Pasteurization: Kills pathogens without damaging food.

Enzymes in Replication and Transcription

• DNA Replication:

  • Enzymes: Helicase, DNA Polymerase, Ligase, Gyrase.

• Transcription:

  • Enzyme: RNA Polymerase.

Genetic Transfer in Bacteria

• Transduction, Transformation, Mutation, Conjugation: Methods of genetic material transfer.

Restriction Enzymes & PCR

• Restriction Enzymes: Cut specific DNA sequences.

• PCR: Amplifies DNA through denaturation, annealing, and extension.

Steps to Make a Human Gene Product in Biotechnology

1. Isolate gene of interest.

2. Insert into a vector.

3. Transform bacteria.

4. Induce gene expression.

5. Purify and test the product.

DNA Fingerprinting

• Used in forensics, paternity testing, and microbial strain identification using restriction enzymes and gel electrophoresis.

Open-Ended Responses

1. Physical and Chemical Factors for Microbial Growth:

   • Temperature, pH, osmotic pressure, oxygen levels, and essential nutrients.

2. Energy Exchange in Cells (Metabolism):

   • Metabolism includes respiration and fermentation.

3. Endosymbiotic Theory:

   • Explains origins of mitochondria and chloroplasts from engulfed bacteria.

4. Antibiotic Resistance:

   • Factors affecting resistance, genetic changes, and prevention strategies.