Cell theory

  1. All organisms are composed of one (Unicellular) or more cells (Multicellular)
  2. The cell is the basic unit of organization of organisms
  3. All cells come from pre-existing cells

<aside> 🗣 The technological development of the microscope contributes a lot to the discovery of cells and cell theory

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Function

Name of Cell Structure Structure Function
Cell wall (only in plant cells) • Outside the cell membrane
• Thick and tough
• Made of cellulose (carbohydrate)
***• Contains large holes
• Permeability: freely permeable*** • Keeps the shape of the cell and protects inner structure
Cell membrane • Thin and elastic
***• Tiny pores
• Permeability: selectively permeable*** • Controls movement of substances into and out of a cell
Cytoplasm • Jelly-like
• Contains mainly water
• Contains organelles • Most chemical reactions take place
Vacuole (sometimes found in animal cells) • Large, central space
• Filled with cell sap (watery liquid)
• Much smaller in animal cells • Storage of various substances
Nucleus • Largest organelle in the animal cell
• Not present in red blood cell • Controls activities of the cell
• Contains chromosomes (carrier of genes)
Mitochondrion • Muscle cells have more mitochondria than other body cells • Involved in the release of energy in anaerobic respiration
Chloroplast • Contains chlorophyll (green pigment)
X root hair cell • Absorbs light energy in photosynthesis and making food
Ribosome • Tiny structures in the cytoplasm • Site of protein synthesis

Similarities

  1. Cell membrane surrounding the cytoplasm
  2. Nucleus
  3. Contain mitochondria

Differences

Animal cell Plant cell
Smaller in size Larger in size
Irregular shape Regular shape
No cell wall Cell wall presented
Small/ absented vacuole, nucleus at the centre Large vacuole

<aside> 🗣 Compare & contrast = 50% differences + 50% similarities

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Organelle Cell Tissue Organ Organ system Organism
Specialized subunit of a cell Specific function
different sizes/shapes Cells with similar functions grouped Different tissues grouped Different organ grouped Different organ systems grouped
muscle cells, nerve cells, blood cells bones, muscles, nerves, blood heart, skin, eyes, ears, liver, stem digestive system, breathing system, reproduction system human