life sciences term 1

Inorganic Compounds

Substances that do not contain both carbon (C) and hydrogen (H) atoms. Examples include water (H2O), mineral salts (like nitrates and phosphates), and gases like oxygen (O2) and carbon dioxide (CO_2).

Organic Compounds

Complex molecules that contain carbon (C) and hydrogen (H) atoms, often found in living organisms. The main groups include:

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids
• Vitamins

Carbohydrates

Organic molecules containing C, H, and O in a ratio of 2:1 (H:O).

• Monosaccharides: Single sugars (e.g., glucose, fructose).
• Disaccharides: Two sugars (e.g., sucrose, maltose).
• Polysaccharides: Long chains (e.g., starch, glycogen, cellulose).

Lipids (Fats and Oils)

Organic molecules containing C, H, and O, but with very little oxygen. They are composed of:

• 1 Glycerol molecule
• 3 Fatty acid molecules
• Functions: Energy storage, insulation, and protection.

Proteins

Organic compounds containing C, H, O, and N (nitrogen). Some also contain sulfur (S) and phosphorus (P).

• Monomers: Amino acids.
• Structure: Sensitive to temperature and pH; high temperatures can cause denaturation.

Enzymes

Biological catalysts (usually proteins) that speed up chemical reactions without being used up. They work according to the Lock and Key model, where the substrate fits into the enzyme's active site.

Nucleic Acids

Large molecules that store genetic information. Two main types:

1. DNA (Deoxyribonucleic acid): Found in the nucleus; contains the genetic code.
2. RNA (Ribonucleic acid): Involved in protein synthesis throughout the cell.

The Cell Theory

The fundamental concept of biology stating:

• All living organisms are made of one or more cells.
• The cell is the basic unit of life.
• All cells come from pre-existing cells.

Nucleus

The control center of the cell containing genetic material (chromatin/chromosomes).

• Roles: Controls metabolic activities and passes on hereditary information.

Mitochondria

The powerhouses of the cell where Cellular Respiration occurs.

• Process: Glucose + O2 \rightarrow CO2 + H_2O + ATP (Energy)
• Structure: Double membrane, inner membrane folded into cristae.

Ribosomes

Small, granular structures found in the cytoplasm or attached to the Endoplasmic Reticulum. Their primary function is Protein Synthesis.

Difference between Plant and Animal Cells

1. Plant Cells:
   • Large central vacuole
   • Rigid Cell Wall (Cellulose)
   • Chloroplasts present
2. Animal Cells:
   • Small, temporary vacuoles
   • No cell wall
   • No chloroplasts
   • Centrioles present (for cell division)