Chapter 13: Biochemistry

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Chapter Overview & SLOs

What is biochemistry? Biochemistry is the branch of science that explores the chemical processes within and related to living organisms. It focuses on biomolecules such as proteins, lipids, nucleic acids, and carbohydrates.

What bond is responsible for linking amino acids in a protein? Amino acids are joined by a peptide bond (a type of amide bond), formed when the amino group (-NH₂) of one molecule reacts with the carboxyl group (-COOH) of another, eliminating a water molecule (condensation reaction).

What are the functions of proteins? Proteins act as enzymes (catalyze reactions), provide structural support (collagen, keratin), transport molecules (hemoglobin), and function as hormones and antibodies. They do NOT store genetic information (that's the role of nucleic acids).

How do lipids facilitate the absorption of vitamins? A diet lacking in lipids decreases the absorption of fat-soluble vitamins (A, D, E, and K) because these vitamins require fats to be properly absorbed into the bloodstream. Vitamins A, D, E, K are non-polar and dissolve in lipids.

What are the specific functions and deficiency symptoms of key vitamins?

| Vitamin | Function | Deficiency | Sources | |---------|----------|------------|---------| | Vitamin A | Vision, immune function, skin health | Night blindness | Carrots, sweet potatoes | | Vitamin C (Ascorbic acid) | Collagen formation, wound healing, antioxidant | Scurvy (bleeding gums, poor wound healing) | Citrus fruits, tomatoes | | Vitamin D | Calcium absorption, bone health | Rickets (soft, weak bones in children) | Sunlight, fish oil | | Vitamin E | Antioxidant, protects cell membranes | Rare (nerve problems) | Nuts, seeds | | Vitamin K | Blood clotting (coagulation) | Excessive bleeding | Leafy greens |

What are nucleic acids? Nucleic acids (DNA and RNA) are the primary information-carrying molecules that determine inherited characteristics. DNA stores genetic information, while RNA helps in protein synthesis.

How does the body synthesize proteins? Protein synthesis occurs in two stages:

1. Transcription: DNA is copied into messenger RNA (mRNA) in the nucleus.
2. Translation: Ribosomes read the mRNA sequence to assemble amino acids into a polypeptide chain.

What is the difference between genetic engineering and gene therapy?

| Feature | Genetic Engineering | Gene Therapy | |---------|--------------------|--------------| | Application | Agriculture, industry, research | Medical treatment in humans | | Purpose | Alter DNA for desired traits (e.g., GMOs) | Treat or cure genetic disorders | | Target | Plants, animals, bacteria | Human cells | | Example | Bt cotton, Golden Rice | Correcting CFTR gene in cystic fibrosis |

What is the biochemical principle behind pregnancy tests? Pregnancy tests use antibodies to detect the hormone human chorionic gonadotropin (hCG) in urine. The binding of hCG to these antibodies triggers a visible color change signal (like a line or plus sign).

What is the difference between gene cloning and therapeutic cloning?

• Gene cloning: Replicating genes for research, pharmaceutical production, or agricultural purposes.
• Therapeutic cloning: Creating stem cells for medicine and regenerative therapy.

Energy storage: Lipids vs Carbohydrates Lipids provide approximately 9 calories per gram, compared to 4 calories per gram for carbohydrates, making them a more concentrated energy source.

These notes are strictly aligned with the Student Learning Outcomes (SLOs) for the FBISE 2026 annual examination.

• How does the body synthesize proteins? Protein synthesis occurs in two stages: transcription, where DNA is copied into mRNA in the nucleus, and translation, where ribosomes read the mRNA sequence to assemble amino acids into a chain.
• What are the specific functions and deficiency symptoms of key vitamins? Vitamin A is essential for vision, while Vitamin C (ascorbic acid) is needed for collagen formation and wound healing (deficiency causes scurvy). Vitamin D aids calcium absorption (deficiency causes rickets), and Vitamin K is critical for blood clotting.
• How do we differentiate between genetic engineering and gene therapy? Genetic engineering involves altering DNA for desired traits in agriculture or industry (e.g., GMOs), whereas gene therapy focuses on modifying genes in humans to treat or cure genetic disorders.
• What is the biochemical principle behind pregnancy tests? These tests use antibodies to detect the hormone human chorionic gonadotropin (hCG) in urine; the binding of hCG to these antibodies triggers a visible color change signal.

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