A Tour of the Cell
Chapter 6: A Tour of the Cell
Cell fractionation – cells are taken apart using a centrifuge (differential centrifugation) and separated into their sub cellular structures Point of Difference | Eukaryotic | Prokaryotic | Shape/Size | Larger | Smaller | Complexity | Membrane bounded organelles | No membrane bound organelles | Nucleus | Bounded membrane with DNA | DNA in a region (nucleoid) | Kingdom | Plants, animals, fungi, protists | Bacteria and archaea | Reproduction | Sexual reproduction – mitosis | Asexual reproduction – binary fission | * Similarity: plasma membrane, cytosol, chromosomes, ribosomes |
Surface Area to Volume Ratio * Metabolic requirements imposes limits on the size of a practical cell * Cells need a large enough surface area to adequately exchange materials * As any cell increases in size, its volume grows proportionately more than its surface area * Area – n2 * Volume – n2 * Where n = linear dimension * Need for surface area explains the elongated nerve cells * Microvilli – long, thin projections (animal only) that increases SA and not volume
Nucleus
* Contains most of genes (other genes are located in mitochondria and chloroplast) * Nuclear envelope (lipid bilayer, double membrane): encloses nucleus and separates its contents from the cytoplasm * Pore complex: regulates entry/exit of proteins, RNAs and macromolecules * Nucleoplasm: the cytoplasm of the nucleus * Nuclear lamina: a netlike array of protein filaments that maintains the shape of the nucleus * Nuclear matrix: fibres extending throughout the nuclear interior * Nucleolus: rRNA is synthesized from instruction of DNA, proteins imported from the cytoplasm are assembled with rRNA into large and small ribosomal subunits, these subunits exist and assemble into a ribosome
Ribosomes
* Complexes made of rRNA and protein and carry out protein synthesis * Pancreas has a lot of ribosomes because these
Cell fractionation – cells are taken apart using a centrifuge (differential centrifugation) and separated into their sub cellular structures Point of Difference | Eukaryotic | Prokaryotic | Shape/Size | Larger | Smaller | Complexity | Membrane bounded organelles | No membrane bound organelles | Nucleus | Bounded membrane with DNA | DNA in a region (nucleoid) | Kingdom | Plants, animals, fungi, protists | Bacteria and archaea | Reproduction | Sexual reproduction – mitosis | Asexual reproduction – binary fission | * Similarity: plasma membrane, cytosol, chromosomes, ribosomes |
Surface Area to Volume Ratio * Metabolic requirements imposes limits on the size of a practical cell * Cells need a large enough surface area to adequately exchange materials * As any cell increases in size, its volume grows proportionately more than its surface area * Area – n2 * Volume – n2 * Where n = linear dimension * Need for surface area explains the elongated nerve cells * Microvilli – long, thin projections (animal only) that increases SA and not volume
Nucleus
* Contains most of genes (other genes are located in mitochondria and chloroplast) * Nuclear envelope (lipid bilayer, double membrane): encloses nucleus and separates its contents from the cytoplasm * Pore complex: regulates entry/exit of proteins, RNAs and macromolecules * Nucleoplasm: the cytoplasm of the nucleus * Nuclear lamina: a netlike array of protein filaments that maintains the shape of the nucleus * Nuclear matrix: fibres extending throughout the nuclear interior * Nucleolus: rRNA is synthesized from instruction of DNA, proteins imported from the cytoplasm are assembled with rRNA into large and small ribosomal subunits, these subunits exist and assemble into a ribosome
Ribosomes
* Complexes made of rRNA and protein and carry out protein synthesis * Pancreas has a lot of ribosomes because these