Eukaryotic cell structure

Eukaryotic cell structure

1. Nucleus

   • Nuclear envelope
     • Double membrane surrounding the nucleus. Controls the entry and exit of materials.
   • Nuclear Pores
     • Allows passage of large molecules.
   • Nucleoplasm
     • Jelly-like material that makes up the bulk of the nucleus.
   • Chromosomes
     • Protein bound linear DNA
   • Nucleolus
     • Manufactures ribosomal RNA and assembles the ribosomes.

2. Mitochondrion

   • Double membrane
     • Controls the exit and entry of materials.
   • Cristae
     • Extensions of the inner membrane. Provide a large surface area for the attachment of enzymes during respiration.
   • Matrix
     • Contains proteins, lipids, ribosomes and DNA.

3. Chloroplasts

   • Chloroplast Envelope
     • Controls the exit and entry of materials.
   • Grana
     • Stacks of up to 100 disc like structures called Thylakoids. Where the first stage of photosynthesis takes place.
   • Thylakoids
     • Where chlorophyll is located.
   • Stroma
     • Fluid-filled matrix where the second stage of photosynthesis takes place.

4. Endoplasmic Reticulum

   • Rough Endoplasmic Reticulum
     • Has ribosomes on its outer surface.
     • Provides a large surface area for the synthesis of protiens.
     • Provides a pathway for the transport of materials through the cell.
   • Smooth Endoplasmic Reticulum
     • Has no ribosomes
     • Synthesises, stores and transports lipids.
     • Synthesises, stores and transports carbohydrates.

5. Golgi Apparatus

   • Cisternae
     • Stack of membranes which make up flattened sacks.
   • Vesicles
     • Small round hollow structures. Transports modified proteins to the cell surface to be released outside.
   • Modifies proteins by adding carbohydrates and labels them so they can be sorted.
   • Produces secretorty enzymes.
   • Forms lysosomes.

6. Ribosomes

   • 80S
     • 25nm in diameter
   • Site of protein synthesis
   • One large one small sub unit.

7. Cell Wall

   • Consist of a number of polysaccharides
   • Middle Lamella
     • Thin layer which marks the boundry between cells and joins them together.
   • Provides mechanical strength to prevent the cell from bursting.
   • Gives strength to the plant as a whole.
   • Allows water to pass along it and contributes to the movement of water through the plant.

8. Vacuoles

   • Tonoplast
     • Single membrane surrounding the vacuole.
   • Contains mineral salts, sugars, amino acids, wastes and pigments.
   • Support plants by making them more turgid
   • Sugars and amino acids act as a temporary food store

9. Lysosomes

   • Vesicles which contain the enzymes lysozymes
   • Hydrolyse the cell wall of certain bacteria
   • Hydrolyse material ingested by phagocytic cells
   • Release enzymes outside of the cell to destroy material around the cell
   • Digest worn out organelles so the chemicals can be reused.
   • Break down cells after they have died.

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