cell biology - biology

• Organelles


  Also called subcellular structures, the parts that make up a cell like the nucleus, ribosomes, and mitochondria
• Organelles


  • Each individual organelle has a specific role to play
  • When combined, multiple organelles will form a single cell
• Cells


  Come in all sorts of shapes and sizes and contain different combinations and numbers of organelles
• Specialized cells


  Different types of cells like epithelial cells, muscle cells, and glandular cells
• Tissues


  A group of similar cells that work together to carry out a particular function
• Tissues


  • Epithelial tissue
  • Muscle tissue
  • Glandular tissue
• Organs


  A group of different tissues that work together to perform a particular function
• Organs


  • Stomach
  • Pancreas
  • Liver
• Multicellular eukaryotic organisms require a continuous supply of new cells for growth, development and repair
• The process through which these cells are generated is known as the cell cycle
• Cell cycle


  1. Growth

  2. DNA replication

  3. Mitosis and division (cytokinesis)
• DNA


  When a cell is not dividing, it is spread out in long strings; when preparing for division, it condenses into chromosomes
• Chromosomes


  • Packets of condensed DNA
  • Each chromosome contains a large number of genes that control the development of different characteristics
• Eukaryotic cells have two copies of each chromosome, one from the mother and one from the father
• Humans have 23 pairs of chromosomes, for a total of 46 chromosomes
• Chromosome duplication


  Each chromosome duplicates, with the duplicate staying attached to the original chromosome, forming an X-shape
• Cell division


  1. Chromosomes line up at the center of the cell

  2. Fibers from either side of the cell attach to the respective halves of each chromosome and pull them to opposite sides

  3. Cell membrane and cytoplasm pull apart, forming two daughter cells with identical DNA
• The resulting daughter cells can then contribute to growth, development or repair and undergo the cell cycle all over again
• Surface area : volume ratio

  The surface area to volume ratio of an organism affects how easily substances can be exchanged between it, and its environment
• Substances do not have to travel very far to get where they are needed in bacterial cells, so transport by diffusion, osmosis or active transport alone is sufficient for the cell to meet its needs
• Unicellular organisms can exchange materials directly with their environment
• Calculating surface area to volume ratios

  1. Model the effect of increasing size on surface: volume ratio using simple cubes

  2. As the size of an organism increases, surface area: volume ratio decreases
• Larger organisms with smaller surface area: volume ratios need exchange surfaces and transport systems to ensure their cells obtain the materials they need
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