Syllabus

Unit –III The interaction of animal kingdom in their ecosystems. Integration of biology with chemistry.

The interaction of animals within ecosystems is a key part of ecological dynamics, explaining how species coexist, compete, and contribute to the environment. These interactions can be categorized into several types:

1. Predation:

This is when one species (predator) hunts and eats another (prey). Predators help control prey populations, preventing overgrazing or overpopulation that could destabilize ecosystems. 2. Competition:

Species compete for the same resources, such as food, water, or territory. This competition can occur between members of the same species (intraspecific competition) or between different species (interspecific competition). This drives natural selection and adaptation. 3. Symbiosis:

This involves close, long-term interactions between species, which can take different forms: - Mutualism: Both species benefit (e.g., bees and flowers, where bees get nectar, and flowers are pollinated). - Commensalism: One species benefits, and the other is unaffected (e.g., birds nesting in trees). - Parasitism: One species benefits at the expense of another (e.g., ticks feeding on mammals). 4. Herbivory:

Herbivores consume plants, which in turn shapes plant communities and promotes biodiversity. Herbivores may also be prey for carnivores, linking different levels of the food chain. 5. Decomposition:

Decomposers like fungi, bacteria, and some insects break down dead organic matter, recycling nutrients back into the soil, which supports plant growth and maintains soil health. 6. Trophic Levels:

Animals occupy different positions in the food chain (producers, consumers, and decomposers). Producers (plants) are eaten by primary consumers (herbivores), which are prey for secondary consumers (carnivores), and so on. The energy flow through these levels shapes ecosystem structure. These interactions maintain ecological balance, promote biodiversity, and drive the evolution and adaptation of species within ecosystems.

The integration of biology with chemistry, often referred to as biochemistry, is fundamental to understanding life at the molecular level. This interdisciplinary field combines principles from both sciences to explain how chemical processes support the functions of living organisms. Let’s explore the integration in detail:

1. Biomolecules and Their Chemistry

Living organisms are made up of four main classes of biomolecules: carbohydrates, lipids, proteins, and nucleic acids. The structure and function of these molecules are determined by chemical principles.

• Carbohydrates: These are sugars and starches, composed of carbon, hydrogen, and oxygen atoms. They provide energy (glucose) and serve as structural components (e.g., cellulose in plants). The chemical bonds in carbohydrates store energy, which is released during metabolism. - Lipids: Lipids (fats, oils, waxes) are hydrophobic molecules made primarily of long hydrocarbon chains. They are crucial for storing energy, making up cell membranes (phospholipids), and signaling between cells (steroid hormones).
• Proteins: Proteins are made of amino acids linked by peptide bonds, and their structure is critical to their function. Enzymes, for example, are proteins that catalyze biochemical reactions, lowering the activation energy and allowing life-sustaining processes to occur at body temperature.
• Nucleic Acids: DNA and RNA are nucleic acids that store and transmit genetic information. The chemical structure of these molecules allows them to replicate and code for the synthesis of proteins, connecting genetic inheritance to cellular functions.

2. Metabolism: Chemical Reactions in Biology

Metabolism refers to all the chemical reactions that occur within living organisms to maintain life. These reactions are divided into catabolism (breaking down molecules to release energy) and anabolism (building complex molecules from simpler ones).

• ATP (Adenosine Triphosphate): ATP is the energy currency of the cell, linking the chemical reactions of metabolism. It stores energy in high-energy phosphate bonds, which are broken to release energy when needed for cellular processes.
• Cellular Respiration: This is a key metabolic pathway where glucose and oxygen are converted into carbon dioxide, water, and ATP. It involves complex chemical reactions in the mitochondria, including glycolysis, the citric acid cycle, and the electron transport chain. Each step is regulated by enzymes, showcasing the chemistry behind energy production in cells.
• Photosynthesis: In plants, photosynthesis converts light energy into chemical energy stored in glucose. This process involves a series of chemical reactions where carbon dioxide and water are transformed into glucose and oxygen, driven by the light-absorbing pigment chlorophyll.

3. Enzyme Catalysis

Enzymes are biological catalysts that accelerate chemical reactions in living organisms. The active site of an enzyme binds to specific substrates, lowering the activation energy required for reactions to occur. Without enzymes, many biochemical processes would be too slow to sustain life.

• Lock and Key Model: The enzyme’s active site has a specific shape that fits its substrate like a lock and key. Once bound, the enzyme catalyzes the chemical reaction and releases the product. - Allosteric Regulation: Many enzymes are regulated by molecules that bind to sites other than the active site, altering the enzyme's shape and activity. This is crucial in controlling metabolic pathways.

4. Genetic Information and Molecular BiologyBiology and chemistry merge in the study of how genetic information is stored, replicated, and expressed in living organisms.

• DNA Replication: The chemical structure of DNA allows it to replicate before cell division. Enzymes like DNA polymerase help in copying the DNA by matching complementary nucleotides (adenine pairs with thymine, and guanine with cytosine). - Transcription and Translation: DNA is transcribed into messenger RNA (mRNA), which is then translated into proteins by ribosomes. The chemistry of base pairing (A-U, G-C in RNA) and peptide bond formation in proteins is central to this process.

5. Cell Membrane and Chemical TransportThe cell membrane is a lipid bilayer with embedded proteins that control the movement of substances into and out of the cell. This regulation is based on chemical principles:

• Diffusion and Osmosis: Molecules move from areas of high concentration to low concentration. This passive transport allows cells to maintain balance in their internal environment. - Active Transport: Some molecules require energy (ATP) to move across membranes against concentration gradients. Transport proteins, which change shape to shuttle molecules, are crucial for processes like nerve signaling and muscle contraction.

6. Chemical SignalingCells communicate using chemical signals (hormones, neurotransmitters) that bind to specific receptors on target cells. This triggers a cascade of chemical reactions inside the cell, leading to a response, such as gene expression or enzyme activation.

• Neurotransmitters: Chemicals like dopamine or serotonin transmit signals across neurons in the nervous system. The binding of these molecules to receptors triggers ion flow and changes in cell voltage, allowing for signal transmission.
• Hormonal Signaling: Hormones like insulin regulate processes like glucose uptake by cells. The binding of insulin to its receptor activates a series of chemical reactions that lead to the cell absorbing glucose from the blood.

7. Biotechnology: Applying Chemistry in BiologyAdvances in molecular biology and biochemistry have led to powerful biotechnological applications:

• Genetic Engineering: Scientists can manipulate the chemical structure of DNA to alter genetic traits. Techniques like CRISPR allow precise editing of genes for applications in medicine, agriculture, and research. - Pharmacology: Drugs are designed based on their chemical interactions with biological molecules. For example, antibiotics target bacterial enzymes, while chemotherapy drugs disrupt the chemical processes involved in cancer cell division.

ConclusionThe integration of biology and chemistry provides a deeper understanding of life’s molecular mechanisms. From the chemical structure of biomolecules to the regulation of metabolic pathways, this interdisciplinary approach is essential for exploring everything from basic cellular functions to modern applications like drug development and genetic engineering. Through biochemistry, scientists can unravel the chemical basis of life and apply this knowledge to improve health, agriculture, and environmental sustainability.