Structure of eukaryotic cells

• Cell membrane structure


  phospholipid bilayer

  
• Cell membrane function


  - Selectively permeable barrier

  - controls passage of substances in and out the cell barrier

  - between internal and external cell environments
• Nucleus structure


  - Nuclear pores

  - nucleolus

  - DNA

  - nuclear envelope

  
• Nucleus function


  - Site of transcription & pre mRNA splicing - mRNA production

  - site of DNA replication

  - nucleolus makes ribosomes

  - nuclear pore allows movement of substances to/from cytoplasm
• Mitochondria structure


  - Double membrane with inner membrane folded into cristae

  - 70S ribosomes in matrix

  - small, circular DNA

  - enzymes in matrix

  
• Mitochondrial function


  - Site of aerobic respiration

  - produces ATP
• Chloroplast structure


  - Thylakoid membranes stacked to form grana, linked by lamellae

  - stroma contains enzymes

  - contains starch granules, small circular DNA and 70S ribosomes

  
• Chloroplast function


  - Chlorophyll absorbs light for photosynthesis to produce organic molecules (glucose)
• Organisms containing chloroplasts


  - plants

  - algae
• Golgi apparatus structure


  - Fluid-filled, membrane-bound sacs (horseshoe shaped)

  - vesicles at edge

  
• Golgi apparatus function


  -Modifies proteins received from RER

  - packages them into vesicles to transport to cell membrane for exocytosis

  - makes lysosomes
• Lysosome structure


  - Type of Golgi vesicle containing digestive enzyme

  
• Lysosome function


  - Contains digestive enzymes

  - e.g lysozymes to hydrolyse pathogens/cell waste products
• Cell wall structure


  - In plant, fungal and bacterial cells

  - plants - made of microfibrils of cellulose

  - fungi - made of chitin

  - bacteria - murein
• Cell wall function


  - Provides structural strength, rigidity and support to cell

  - helps resist osmotic pressures
• Ribosome structure


  - Small and large subunit

  - made of protein and rRNA

  - free floating in cytoplasm & bound to RER - 70S in prokaryotes, mitochondria and chloroplasts

  - 80S in eukaryotes
• Ribosome function


  - Site of translation in protein synthesis
• Rough endoplasmic reticulum structure


  - System of membranes with bound ribosomes

  - continuous with nucleus

  
• Rough endoplasmic reticulum function


  - Site of protein synthesis

  - folds polypeptides to secondary & tertiary structures

  - packaging into vesicles to transport to Golgi
• Smooth endoplasmic reticulum structure


  - System of membranes with no bound ribosomes

  
• Smooth endoplasmic reticulum function


  - Synthesises and processes lipids
• Cell vacuole structure


  - Fluid-filled

  - surrounded by a single membrane called a tonoplast

  
• Cell vacuole function


  - Makes cells turgid - structural support

  - temporary store of sugars, amino acids

  - coloured pigments attract pollinators