Cell biology IB HL Biology

• Facilitated diffusion requires carrier proteins that temporarily bind to molecules and help them move across the membrane.
• Exceptions to cell theory:

  • Striated muscle cells: larger than most animal cells, have their own genetic material, and multiple nuclei
  • Acetate fungal hyphae: have many nuclei and branches known as hyphae
  • Giant algae: single-celled organisms resembling plants, up to 100mm in length, photosynthetic but not plants
• Multicellular organisms:

  • Have differentiated cells with specific gene expression
  • Differentiation involves turning on genes for necessary functions and turning off unnecessary genes
• Stem cells:

  • Can be embryonic, cord blood, or adult stem cells
  • Embryonic stem cells have ethical implications but are best for growth and differentiation
  • Cord blood stem cells are easy to obtain but have less differentiation capability
  • Adult stem cells have limited growth and differentiation capacity, are difficult to obtain, and have a lower risk of tumor formation
  • Stem cells can be used to treat diseases like Stargardt's disease (damage to the retina) and leukemia (mutation causing overproduction of white blood cells)
• Prokaryotes:

  • Single-celled organisms without a nucleus or membrane-bound organelles
  • Have ribosomes, cytoplasm, cell wall, cell membrane, and nucleoids containing naked DNA
  • May have flagella or cilia for movement
• Eukaryotic cells:

  • Have a nucleus containing DNA
  • Rough endoplasmic reticulum synthesizes proteins with ribosomes
  • Golgi apparatus processes and packages proteins
  • Lysosomes contain digestive enzymes
  • Mitochondria produce ATP through aerobic cellular respiration
  • Chloroplasts in plant and algae cells perform photosynthesis
  • Vacuoles store water in plant cells and absorb food in animal cells
  • Vesicles are small vacuoles
  • Microtubules and centrioles are involved in mitosis and cell division
  • Cilia and flagella aid in cell movement
• Amphipathic refers to a combination of hydrophobic and hydrophilic properties
• Fluid mosaic model is the modern model of the cell membrane
• Cell membrane consists of hydrophilic and hydrophobic head and tail
• Integral proteins can be part of or the entire membrane
• Peripheral proteins sit on top of the membrane
• Cholesterol in the membrane reduces fluidity and is found in animal cells
• Membrane transport includes endocytosis and exocytosis as examples of active transport
• Endocytosis brings materials into the cell to form a vesicle
• Exocytosis releases materials by fusing the vesicle with the membrane
• Simple diffusion and facilitated diffusion are examples of passive transport
• Osmosis is the diffusion of water
• Hypertonic solution causes water to leave the cell, leading to cell shrinkage
• Hypotonic solution causes water to enter the cell, increasing cell size
• Facilitated diffusion involves ions passing through integral proteins
• Sodium-potassium pump is a specific example of active transport
• Origin of cells by endosymbiosis theory involves mitochondria and chloroplasts
• Mitochondria and chloroplasts were once free-living cells engulfed by larger prokaryotes
• Mitochondria and chloroplasts have their own genes and ribosomes
• Mitochondria and chloroplasts are produced by the division of pre-existing mitochondria and chloroplasts
• Cell division involves mitosis and the cell cycle
• Mitosis stages: prophase, metaphase, anaphase, telophase (PMAT)
• Interphase includes G1 phase, S phase (DNA replication), and G2 phase
• Cytokinesis is the physical separation of cells after mitosis
• Mitotic index is the number of cells in mitosis divided by the total number of cells
• Cancer definitions: mutagens cause gene mutations, oncogenes control cell cycle and division, metastasis is the spread of cancer to other parts of the body
• Mutagens are agents that cause gene mutations
• Oncogenes are involved in the control of the cell cycle and can become cancer-causing after mutations
• Metastasis is when cancer spreads from the primary location to other parts of the body