Biochemistry Past Paper PDF

**SHAILA MARIE A. DE GUZMAN** **BSN-1D** **Biochemistry\| L1 TO L3** - **Study of chemical substances and vital processes** in living organisms. - Focuses on the chemistry behind biological processes and the synthesis of biologically active molecules. **Significance and Importance o...

**SHAILA MARIE A. DE GUZMAN** **BSN-1D** **Biochemistry\| L1 TO L3** - **Study of chemical substances and vital processes** in living organisms. - Focuses on the chemistry behind biological processes and the synthesis of biologically active molecules. **Significance and Importance of Biochemistry in Nursing** - **Application in Nursing**: Demonstrates the existence of many therapeutic agents first in lab experiments (e.g., insulin, vitamins). - **Clinical Examples**: - **Galactose Intolerance**: Infant vomiting after milk. - **Jaundice in Infants**: Indicates liver dysfunction. - **Dark Urine in Infants**: Possible amino acid metabolic disorder. **Cell: The Basic Unit of Life** - **Principles of Cell Theory**: - Smallest living unit of structure and function. - All living things are made of cells. - All cells arise from pre-existing cells. **Cell Types** - **Prokaryotic Cell (Unicellular)**: - First cell type on Earth. - Includes Bacteria and Archaea. - No membrane-bound nucleus; nucleoid region of DNA concentration. - Example: Viruses. - **Eukaryotic Cell (Multicellular)**: - Nucleus bound by membrane. - Includes fungi, protists, plant, and animal cells. - Possess many organelles. - Example: Protozoan, humans. **Cell Organelles** - **Plasma Membrane (Cell Membrane)**: - Contains cell contents. - Double layer of phospholipids & proteins. - **Transport Mechanisms**: - **Active Transport**: Needs ATP, moves molecules from high to low concentration. - **Passive Transport**: No ATP needed, moves molecules from low to high concentration (e.g., osmosis, diffusion). - **Cytoplasm**: - All organelles reside here. - Components: Interconnected filaments & fibers, cytosol (fluid), storage substances. - **Mitochondria**: - Powerhouse of the cell, produces ATP. - Involved in cellular respiration. - **Golgi Complex**: - Protein packaging and transport center. - Has incoming and outgoing vesicles. - **Ribosomes**: - Synthesizes proteins. - Present in the cytoplasm and with Rough ER. - **Smooth Endoplasmic Reticulum**: - Transports materials, digests lipids, produces proteins and phospholipids. - **Rough Endoplasmic Reticulum**: - Covered with ribosomes, produces proteins. - Site of synthesis of lysosomal enzymes and proteins for extracellular use. - **Lysosome**: - Breaks down materials for digestion. - Contains hydrolytic enzymes. - **Nucleus**: - Control center of the cell, contains DNA. - **Cell Wall**: - Rigid and strong wall. - Protects and maintains the shape of the cell. - **Chloroplast (Plant Cell Only)**: - Contains chlorophyll, makes plants green. - Uses light energy to make ATP and sugars. - Site of photosynthesis. - **Central Vacuole (Plant Cell Only)**: - Large, fluid-filled structure. - Exerts pressure to push the plasma membrane against the cell wall. **Biomolecules** - Building blocks of cells. - **Water**: Constitutes 50-95% of cell content by weight. - **Ions**: Na+, K+, Ca+ account for another 1%. - **Organic Molecules**: C, H, N, O, P, S. - Infinite variety of molecules contain C. Most bio-molecules considered to be derived from hydrocarbons. - The chemical properties of organic biomolecules are determined by their functional groups. Most bio-molecules have more than one. **Major Classes of Small Bio-molecules** - **Amino Acids**: - Building blocks of proteins. - Contains amino group and carboxyl group functional groups. - R Group (side chains) determines the chemical properties of each amino acid. - Determines protein folding and biological function. - Connected by peptide bonds. - Functions: transport proteins, structural proteins, enzymes, antibodies, cell receptors. - **Sugars**: - Carbohydrates are the most abundant organic molecule in nature. - Synthesized in plants via photosynthesis. - Basic unit: monosaccharides. - Larger molecules: glycogen, plant starch, cellulose. - Glycogen: stored form of glucose. - **Fatty Acids**: - Monocarboxylic acids with even number C atoms. - Types: saturated (C-C single bonds), unsaturated (C-C double bonds). - Components of lipid molecules (e.g., triacylglycerol, steroids). - Functions: energy storage, membrane structures, insulation, hormone synthesis. **Metabolism** - **Anabolism**: Energy-requiring biosynthetic pathways. - **Catabolism**: Degradation of fuel molecules, energy production. - **Primary Functions**: - Acquisition & utilization of energy. - Synthesis of molecules for cell structure and function (proteins, nucleic acids, lipids, CHO). - Removal of waste products. **Frequent Reactions in Biochemical Processes** - **Nucleophilic Substitution**: One atom/group substituted for another. - **Elimination Reactions**: Double bond formed when atoms are removed. - **Addition Reactions**: Two molecules combine to form a single product. - **Hydration Reactions**: Water added to alkene to form alcohol. - **Isomerization Reactions**: Intramolecular shift of atoms/groups. - **Oxidation-Reduction (Redox) Reactions**: Transfer of electrons. - **Hydrolysis Reactions**: Cleavage of double bond by water. **Energy for Cells** - Living cells are inherently unstable. - Constant flow of energy prevents disorganization. - **Synthesis of Bio-molecules**: Provides energy through metabolic pathways. - **Transport Across Membranes**: Cells obtain energy mainly by oxidation of biomolecules. **Cell Movement** - Organized movement is a key characteristic of living cells. - Movement of cell components is essential for sustaining life. **Waste Removal** - Animal cells convert food molecules into CO2, H2O, and NH3. - Proper disposal of waste is crucial to avoid toxicity. **Stages of Cell Cycle** - **Series of events leading to cell division and duplication**. - **Prokaryotes**: Undergo binary fission. - **Eukaryotic Cells**: Two main periods: - **Interphase**: Preparation for mitosis, includes G1, S, and G2 phases. - **G1 Phase**: Growth phase, end of previous M phase to start of DNA synthesis. - **S Phase**: DNA replication, formation of sister chromatids. - **G2 Phase**: Mitochondria divide, spindle fibers synthesized. - **Mitosis (M Phase)**: Division of nucleus into two identical sets. - **Prophase**: Chromosomes condense, spindle fibers form. - **Metaphase**: Chromosomes align at the equator. - **Anaphase**: Chromatids separate to opposite poles. - **Telophase**: Nuclear membranes form around each set of chromosomes. - **Cytokinesis**: Division of cytoplasm, forming two daughter cells. **Meiosis** - **Reduces chromosome number** so each daughter nucleus receives one chromosome from each homologous pair. - **Two divisions (M1 and M2)** with no DNA synthesis between. - **Produces four haploid non-identical cells**. - **Phases**: - **Prophase I**: Crossing over, recombination. - **Metaphase I**: Homologous chromosomes align. - **Anaphase I**: Homologous chromosomes separate. - **Telophase I**: Cleavage furrow forms. - **Interkinesis**: Cells divide, preparing for second division (similar to cytokinesis in mitosis). - **Prophase II, Metaphase II, Anaphase II, Telophase II**: Similar to mitosis but results in four haploid cells. - **Anaphase II**: Centromeres divide, chromosomes (now monads) are pulled to opposite poles. Unlike Anaphase I, sister chromatids are separated. - Total of four cells from the original cell, each containing one haploid set of monad chromosomes. - Sperm and egg cells each have 23 chromosomes. Upon fertilization, they combine to form 46 pairs of chromosomes. **Water: The Medium of Life** - **Essential for all living organisms**. - Cells are 70-95% water, making Earth habitable. - **Properties**: - **Cohesion**: Hydrogen bonds hold water molecules together. - **Adhesion**: Attraction between different substances (e.g., water and plant cell walls). - **Surface Tension**: High due to hydrogen bonding. - **Moderation of Temperature**: Absorbs and releases heat with minimal temperature change. - **High Specific Heat**: Resists temperature changes. - **Evaporative Cooling**: Stabilizes temperatures in organisms and bodies of water. - **Floating of Ice**: Ice is less dense than liquid water, preventing bodies of water from freezing solid. - **Solvent Properties**: Versatile solvent due to polarity.