Eukaryotic Cells

• Nucleus is the site of DNA replication and transcription, containing genetic code for each cell for proteins
• Structure of a Nucleus

  • Nuclear Envelope - double membrane
  • Nuclear Pores
  • Nucleoplasm - granular, jelly-like
  • Chromosomes - protein-bound, linear DNA
  • Nucleolus - site of rRNA production and makes ribosomes
• Endoplasmic Reticulum is the site of protein synthesis (RER) and synthesis and store of lipids and carbohydrates (SER)
• Endoplasmic Reticulum Structure

  • Cisternae - folded membrane
  • Ribosomes (RER) - protein synthesis
• Golgi and Vesicles add carbohydrates to proteins to make glycoproteins, produce secretory enzymes, form lysosomes, and store lipids
• Vesicles transport substances between the cell and the plasma membrane
• Lysosomes hydrolyse phagocytic cells with vesicles of hydrolytic enzymes, breaking down dead cells (autolysis), exocytosis (release enzymes to destroy) and recycle organelles
• Mitochondria is the aerobic site of respiration and production of ATP
• Mitochondria have DNA to code for the enzymes needed in respiration
• Mitochondria Structure

  • Double Membrane
  • Cristae - inner membrane
  • Matrix - fluid centre
  • Mitochondrial DNA
• Ribosomes are the site of protein synthesis
• 80s Ribosomes are large (25nm) and are found in eukaryotic cells
• 70s Ribosomes are smaller found in prokaryotic cells, chloroplasts and mitochondria
• Vaccuoles are a turgid structure for support, temporary stores of sugars and amino acids and are filled with pigment for petal colours
• Vaccuole Structure

  • Fluid-filled
  • Tonoplast - single membrane
• Chloroplasts are the site of photosynthesis and contain chlorophyll
• Chloroplast Structure

  • Double Membrane
  • Granum - made of thylakoid stacks
  • Thylakoid Stacks - folded membranes with chlorophyll
  • Stroma - fluid filled with enzymes
• Cell Walls are the structural strength of a cell made of microfibrils of cellulose or chitin - nitrogen-containing polysaccharides
• Plasma Membranes control the entry/exit of a cell, made of a phospholipid bilayer with proteins, carbohydrates and cholesterol