2. The basics of cell biology.pdf

The basics of cell biology Aarni Auerniitty Cells  All organisms consist of cells  Smallest organisms are just a single cell (eg. bacteria, archaea, some protists)  Blue whales have approx. 100 000 000 000 000 000 000 000 000 cells  Smaller cell size  higher surface area t...

The basics of cell biology Aarni Auerniitty Cells  All organisms consist of cells  Smallest organisms are just a single cell (eg. bacteria, archaea, some protists)  Blue whales have approx. 100 000 000 000 000 000 000 000 000 cells  Smaller cell size  higher surface area to volume ratio  More efficient transport of substances  Cells live from few days to several decades  Organisms are grouped into prokaryotes and eukaryotes depending if their cells have nucleus or not  Bacteria and archaea belong in prokaryotes Prokaryotes: bacteria  Chromosomes (DNA) are free in the cytoplasm  DNA also in round plasmids  Cell wall protects, cell membrane transports molecules  Photosynthesizing bacteria have thylakoid membranes  Protein synthesis on ribosomes  Flagellum and pilus used for movement  Membrane covered organelles missing Eukaryotes: plants  Nucleus = chromosomes (DNA) surrounded by nuclear envelope  Nucleolus is needed in building ribosomes  Vacuole supports the cell and stores various substances (plant and fungal cells only)  Cell respiration occurs in mitochondria  Chloroplasts take care of photosynthesis (plants and algae only)  Endoplasmic reticulum (ER) takes part in protein and lipid synthesis  Golgi apparatus modifies proteins Eukaryotes: fungi Eukaryotes: animals  Lysosomes break down bacteria and other unwanted substances (animal cells only)  Protein filaments support and move cells  Centrioles are crucial in cell division  No cell wall, chloroplasts or vacuoles Photosynthesis 6CO2 + 6H2O + Light (energy)  C6H12O6 + 6O2  Primary producers (plants, algae, cyanobacteria) synthesize e.g. glucose and other organic molecules from carbon dioxide, water and sunlight.  Oxygen is released as a side product  Photosynthesis is divided into light-dependent and light-independent reactions  Light dependent reactions capture energy from sunlight. The synthesis of organic molecules occurs in light-independent reactions Chloroplast Chemosynthesis  In places where sunlight never reaches, eg. bottom of the oceans or deep in the soil  Bacteria and archaea oxidise inorganic compounds to release energy  Released energy is used to synthesize carbohydrates from hydrogen and carbon dioxide Cell respiration C6H12O6 + 6O2  6CO2 + 6H2O + ATP (energy)  Way for producers, consumers and decomposers to release energy  Requires oxygen, occurs in mitochondria  Some of the energy is released as heat  In anaerobic conditions  alcohol or lactic acid fermentation  Not as effective