cell biology

• Bacteria are single-celled prokaryotic organisms
• Subcellular structures common to animal and plant cells


  • Cell membrane
  • Nucleus
  • Cytoplasm
  • Mitochondria
  • Ribosomes
• Plant cells


  • Have a rigid cell wall made of cellulose
  • Contain a permanent vacuole with cell sap
  • Contain chloroplasts for photosynthesis
• Bacterial cells


  • Lack mitochondria and chloroplasts
  • Have a single circular strand of DNA instead of a nucleus
  • May have flagella for movement
  • May have additional small rings of DNA called plasmids
• Bacteria are unicellular, meaning they are single-cell organisms
• Bacterial cells contain a cell membrane, cell wall, ribosomes, and cytoplasm
• Multicellular eukaryotic organisms require a continuous supply of new cells for growth, development and repair
• 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 DNA
  • Each chromosome contains a large number of genes that control the development of different characteristics
• Chromosome duplication


  The right half of each chromosome is a duplicate of the left half
• Cell division


  1. Chromosomes line up along the center of the cell

  2. Fibers from either side of the cell attach to the respective half of each chromosome

  3. Chromosomes are pulled to opposite sides of the cell, breaking them in half

  4. Cell membrane and cytoplasm pull apart, forming two daughter cells
• The resulting daughter cells have the same DNA and are identical to each other and the parent cell
• The daughter cells can then undergo the cell cycle all over again
• mitochondria is where aerobic respiration takes place, it produces ATP by breaking down glucose with oxygen
• chloroplasts contain chlorophyll which absorbs light energy used in photosynthesis
• ribosomes are found floating free in the cytoplasm or attached to the endoplasmic reticulum, they make proteins from amino acids
• the mitochondrion has its own circular DNA which codes for proteins that make up the inner membranes of the organelle