Unit 1


Eukaryotic Cells

Eukaryotic cells are in the human body and plants

They have:

  • A nucleus
  • Functionally compartmentalised organelles
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The Nucleus and Nucleolus

The Nucleus

  • Contains the genome: Code that describes what protein factors to produce in the cell
  • Surrounded by a double membrane- Nuclear envelope
  • Biomolecules pass in and out of the nucleus by nuclear pores in the membrane

The Nucleolus

  • Structure within the nucleus
  • Region in the organelle dedicated to building ribosomes (protein builders)
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Rough and Smooth Endoplasmic Reticulum

Rough ER:

  • A highly folded membranous structure with the cystolic face littered with ribosomes
  • It is a folded double membrane extending from the nuclear envelope
  • It is a site of protein synthesis

Smooth ER:

  • Folded membranous extention of the nuclear envelope without ribosomes
  • A site for triglyceride and steroid synthesis
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  • A large multimeric macromolecular protein: RNA complex
  • Dedicated to protein synthesis
  • Messenger RNA (a copy of the DNA gene) passes through the protein complex which scans the RNA and produces protein
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  • A double membranous, bacterium like organelle that has a highly folded inner membrane
  • Mitochondria enable the cell to respire aerobially
  • Uses the energy from the breakdown of food biomolecules in order to respire
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Golgi Apparatus and Vesticles

Golgi Apparatus

  • A folded membranous network that buds off from the endoplasmic reticulum
  • Involved in protein processing and sorting- Biomolecular tags may be added to some proteins
  • Proteins are sorted either for export from the cell or transport within the cell
  • The proteins are released from the golgi apparatus in vesticles to be exported


  • Membrane sacs that contain proteins destined for export from the cell
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Plasma Membrane

  • A lipid bilayer that envelopes the cytoplasm
  • It seperates the cell from the outside environment
  • It regulates the influx and efflux of chemical species
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(Cellulose) Cell Wall

  • Complex bundle of cellulose biopolymer: beta-glucose chains
  • They provide structural support and flexibility to the cell
  • Only found in plant cells
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  • Photosynthetic centres in plant cells only
  • Double membrane with a highly folded internal network of membranes- the thylakois space
  • Rich in photosynthetic proteins- proteins which capture light and use it to drive the synthesis of carbohydrates
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  • A membrane sac of biomolecules
  • Storage for nutrients and waste products
  • Act similarly to lysosomes
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  • Collection of highly dynamic proteins that can assemble and disassemble enabling the cell to morph into different shapes
  • It is involved in the transport of cellular cargo around the cell as the protein chains act like a highway
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  • Consists of the cytosol (an aqueous gel) and all the biomolecules and chemicals involved in cellular activity.
  • The organelles are suspended within the cytosol
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  • Membrane sacs containing degradative enzymes
  • Involved in digesting defective proteins that are no longer required
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