South 고등학교 2학년 Cells and Metabolism
Chapters: 3
1. Cell structure and function
Carbohydrates and lipids · Nucleic acids and proteins · Organelles · Prokaryotes and eukaryotes · Membranes and transport
- Biomolecules – A cell is mostly water, plus four big families of carbon compounds: proteins, carbohydrates, lipids and nucleic acids. Grinding tissue in acid separates small molecules (acid-soluble pool) from big ones – proteins, polysaccharides and nucleic acids (acid-insoluble pool). Proteins are chains of amino acids folded into four levels of structure. Polysaccharides are chains of sugars; lipids are fatty acids on glycerol; nucleic acids are chains of nucleotides. Enzymes are protein catalysts that bind a substrate at the active site, lower the activation energy, and are affected by temperature, pH, substrate level and inhibitors.
- Cell: The Unit of Life – Every living thing is made of cells, and every new cell comes from an old cell. Prokaryotic cells (bacteria) have no nuclear envelope and no membrane-bound organelles; eukaryotic cells have a true nucleus and many organelles. The membrane is a fluid mosaic of lipids and proteins; plants add a cellulose wall. ER, Golgi, lysosomes and vacuoles form the endomembrane system. Mitochondria and plastids make energy and food, ribosomes make proteins, the cytoskeleton, cilia, flagella and centrioles give shape and movement, and the nucleus holds the DNA.
- Membrane Transport: How Things Get In and Out of a Cell – The cell membrane is a thin double layer of fat-like molecules with proteins in it. It lets some substances through and stops others (selectively permeable). Diffusion moves particles from high to low concentration with no energy. Facilitated diffusion does the same through protein channels. Osmosis is the diffusion of water through a partially permeable membrane. Active transport uses ATP and a protein pump to move particles from low to high concentration. Very large things enter and leave in bubbles (endocytosis and exocytosis).
2. Metabolism and energy
What metabolism is · ATP · Enzymes and their properties · How enzymes work · Enzymes in daily life and industry
- Metabolism: How Cells Build, Break and Use Energy – Metabolism is the full set of chemical reactions inside a living thing. Breaking big molecules into small ones is catabolism; it gives out energy. Building big molecules from small ones is anabolism; it uses energy. ATP carries the energy between the two, like a rechargeable battery. Each reaction is sped up by its own enzyme, and the reactions link into chains called metabolic pathways.
- Biomolecules – A cell is mostly water, plus four big families of carbon compounds: proteins, carbohydrates, lipids and nucleic acids. Grinding tissue in acid separates small molecules (acid-soluble pool) from big ones – proteins, polysaccharides and nucleic acids (acid-insoluble pool). Proteins are chains of amino acids folded into four levels of structure. Polysaccharides are chains of sugars; lipids are fatty acids on glycerol; nucleic acids are chains of nucleotides. Enzymes are protein catalysts that bind a substrate at the active site, lower the activation energy, and are affected by temperature, pH, substrate level and inhibitors.
3. Cellular respiration and photosynthesis
Mitochondria · Stages of cellular respiration · Phosphorylation · Aerobic respiration vs fermentation · Chloroplasts · Light reactions and carbon fixation · Comparing electron transport chains · Historic photosynthesis research
- Respiration in Plants – Respiration breaks food like glucose to release energy stored as ATP. Plants take in O₂ through stomata and lenticels. Glycolysis in the cytoplasm splits glucose into two pyruvates. Without O₂, pyruvate is fermented to ethanol or lactic acid. With O₂, pyruvate enters the mitochondrion, runs the Krebs cycle, and the electron transport system uses O₂ to make most of the ATP: up to 38 per glucose. The same path also builds molecules (amphibolic). RQ = CO₂ given out ÷ O₂ taken in.
- Photosynthesis in Higher Plants – Green plants make sugar from carbon dioxide and water using light. It happens in chloroplasts. The light reaction in the thylakoids splits water, gives out oxygen and makes ATP and NADPH. The Calvin cycle in the stroma uses that ATP and NADPH to fix CO₂ into sugar. C₄ plants add a CO₂ pump that stops the wasteful photorespiration. The slowest factor, such as light, CO₂ or temperature, sets the rate.
- History of Science: How Our Ideas About Nature Changed – Science grew slowly over 5,000 years. Early civilisations watched the sky to make calendars. Greek thinkers asked why things happen and used reason. Indian and Islamic scholars gave us zero, algebra and careful experiments. In the Scientific Revolution, Copernicus, Galileo and Newton replaced the Earth-centred model with a Sun-centred one and tested ideas by experiment. Modern science brought atoms, evolution, relativity and quantum theory. Each step shows the same lesson: good evidence can overturn old ideas.