Biochemistry Basics and Key Concepts

Posted on Jun 28, 2024 in Biology

1. Cellular Respiration

Glycolysis

  • Formula: C6H12O6 + 2 NAD+ + 2 ADP + 2 Pi → 2 C3H4O3 (pyruvate) + 2 NADH + 2 ATP + 2 H2O + 2 H+
  • Key Points:
    • Occurs in the cytoplasm.
    • Glucose (6C) → 2 Pyruvate (3C).
    • Net gain of 2 ATP and 2 NADH.

Citric Acid Cycle (Krebs Cycle)

  • Formula: Acetyl-CoA + 3 NAD+ + FAD + ADP + Pi + 2 H2O → 2 CO2 + 3 NADH + 3 H+ + FADH2 + ATP + CoA
  • Key Points:
    • Occurs in the mitochondrial matrix.
    • For each Acetyl-CoA, 2 CO2, 3 NADH, 1 FADH2, and 1 ATP are produced.

Electron Transport Chain (ETC) and Oxidative Phosphorylation

  • Overall Reaction: 10 NADH + 2 FADH2 + 6 O2 + 34 ADP + 34 Pi → 10 NAD+ + 2 FAD + 12 H2O + 34 ATP
  • Key Points:
    • Occurs in the inner mitochondrial membrane.
    • Creates a proton gradient to drive ATP synthesis.
    • Oxygen is the final electron acceptor, forming water.

2. Photosynthesis

Light Reactions

  • Formula: 2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light energy → O2 + 2 NADPH + 3 ATP
  • Key Points:
    • Occurs in the thylakoid membranes.
    • Produces ATP, NADPH, and O2.

Calvin Cycle

  • Overall Reaction: 6 CO2 + 18 ATP + 12 NADPH + H2O → C6H12O6 + 18 ADP + 18 Pi + 12 NADP+
  • Key Points:
    • Occurs in the stroma of the chloroplasts.
    • Converts CO2 into glucose using ATP and NADPH.

3. Amino Acids and Carboxyl Groups

General Structure of Amino Acids

  • Formula: H2N-CHR-COOH
    • H2N (Amino Group)
    • R (Side Chain, varies among different amino acids)
    • COOH (Carboxyl Group)

Important Biochemical Reactions

Peptide Bond Formation:

  • Reaction: Amino acid 1 + Amino acid 2 → Dipeptide + H2O
  • Formula: H2N-CHR-COOH + H2N-CHR’-COOH → H2N-CHR-CO-NH-CHR’-COOH + H2O

4. Structure of Glucose

Linear Form

  • Formula: C6H12O6
    • Structure: H-(C=O)-(CHOH)4-CH2OH

Ring Form

  • Formula: C6H12O6
    • Structure: Forms a six-membered ring (pyranose).
    • Alpha Glucose: -OH on C1 below the plane.
    • Beta Glucose: -OH on C1 above the plane.

5. Nervous System

Central Nervous System (CNS)

  • Brain:
    • Cerebrum: Thought, memory, voluntary movement.
    • Cerebellum: Coordination, balance.
    • Brainstem: Involuntary functions.
  • Spinal Cord: Signal transmission, reflex actions.

Peripheral Nervous System (PNS)

  • Sensory (Afferent) Division: Sensory input to CNS.
  • Motor (Efferent) Division: Motor output from CNS.
    • Somatic Nervous System: Voluntary control.
    • Autonomic Nervous System: Involuntary control.
      • Sympathetic Division: “Fight or flight”.
      • Parasympathetic Division: “Rest and digest”.

6. Homeostasis

Negative Feedback

  • Example: Body Temperature Regulation.
    • Increase in temperature → Sweat production → Cooling → Temperature decreases.
    • Decrease in temperature → Shivering → Heat production → Temperature increases.

Positive Feedback

  • Example: Blood Clotting.
    • Injury → Platelets release chemicals → Attract more platelets → Clot formation.

Biochemistry Formulas and Concepts

ATP (Adenosine Triphosphate)

  • Formula: C10H16N5O13P3
  • Hydrolysis Reaction: ATP + H2O → ADP + Pi + energy

NAD+ / NADH and FAD / FADH2

  • NAD+ Reduction: NAD+ + 2H+ + 2e– → NADH + H+
  • FAD Reduction: FAD + 2H+ + 2e– → FADH2

Enzymes

  • General Reaction: Substrate + Enzyme → Enzyme-Substrate Complex → Product + Enzyme
  • Example: Catalase breaking down hydrogen peroxide.
    • Reaction: 2 H2O2 → 2 H2O + O2

Carbohydrates

  • General Formula: (CH2O)n
    • Glucose: C6H12O6

Lipids

  • Triglyceride Formation:
    • Reaction: Glycerol + 3 Fatty Acids → Triglyceride + 3 H2O
    • Formula: C3H8O3 + 3 CnH2n+1COOH → C3H5(OCnH2n+1COO)3 + 3 H2O

Additional Concepts for Exam

  • Osmosis and Diffusion:
    • Osmosis: Movement of water across a semipermeable membrane from low to high solute concentration.
    • Diffusion: Movement of molecules from high to low concentration.
  • Genetics:
    • DNA Structure: Double helix, composed of nucleotides (Adenine-Thymine, Cytosine-Guanine).
    • Transcription and Translation:
      • Transcription: DNA → mRNA.
      • Translation: mRNA → Protein.
    • Mendelian Genetics:
      • Law of Segregation: Alleles segregate during gamete formation.
      • Law of Independent Assortment: Genes for different traits can segregate independently during gamete formation.