3.2.1.1 Structure of eukaryotic cells

• All living organisms are made of

  cells — have the same basic features in common— suggests that all living things evolved from the same common ancestor
• Two main types of organism

  ● eukaryotes● prokaryotes
• Prokaryotic organisms


  are prokaryotic cells — they’re single-celled
• Eukaryotic organisms are made up of


  eukaryotic cells
• Both Prokaryotic and Eukaryotic cells contain

  organelles
• Prokaryotic cells are

  smaller and simpler
• Eukayotic cells are


  complex
• Organelles are

  parts of cells — Each one has specific function — If you examine cell through an electron microscope can see organelles and the internal structure of most of them
• Eukaryotic cells are


  generally bit more complicated than prokaryotic cells— have more organelles — e.g Animal, plant, algal and fungal cells
• Organelles found in Animal Cells

  ● cell surface (plasma) membrane● lysosome ● rough endoplasmic reticulum● nucleolus● nucleus ● smooth endoplasmic reticulum● ribosome ● nuclear envelope ● golgi apparatus ● cytoplasm ● mitochondrion

  
• Plant cells have the same organelles as animal cells but with a few added extras

  ● A cellulose cell wall with plasmodesmata — channels for exchanging substances between adjacent cells ● vacuole — fluid filled compartment ● chloroplasts — organelles involved in photosynthesis

  
• Organelles found in Plant Cells

  ● cell surface (plasma) membrane● rough endoplasmic reticulum● nucleolus● nucleus ● smooth endoplasmic reticulum● ribosome ● nuclear envelope ● golgi apparatus ● cytoplasm ● mitochondrion● cellulose cell wall● vacuole● chloroplasts

  
• Algal cells can

  ● carry out photosynthesis — like plants● be unicellular e.g. Chlorella or multicellular e.g. seaweed — unlike plants

  
• Algal cells are a lot like plant cells,


  they have all the same organelles — including cellulose cell wall and chloroplasts

  
• Chloroplasts in many algal cells are

  a different shape and size to plant chloroplasts— e.g some algae have one large chloroplast rather than several smaller chloroplasts

  
• Organelles found in Algal Cells

  ● cell surface (plasma) membrane● rough endoplasmic reticulum● nucleolus● nucleus ● smooth endoplasmic reticulum● ribosome ● nuclear envelope ● golgi apparatus ● cytoplasm ● mitochondrion● cellulose cell wall● vacuole● chloroplasts

  
• You might also see starch grains in plant cells because


  ● although they're not organells● Plants use them to store excess sugars
• Fungi can be

  ● multicellular — e.g. mushrooms or● unicellular — e.g. yeast
• Fungal cells are also lot like plant cells but with two key differences

  ● their cell walls are made with chitin — not cellulose ● they don't have chloroplasts — because they don't photosynthesise

  
• Organelles found in Fungal Cells

  ● ribosome● cell-surface membrane ● rough endoplasmic recticulum ● nucleolus● mitochondrion ● golgi apparatus ● smooth endoplasmic reticulum● nucleus ● cytoplasm ● chitin cell wall ● nuclear envelope● vacuole

  
• The plural of nucleus is

  nuclei
• The plural of nucleolus is

  nucleoli
• Cell surface membrane (plasma membrane)


  ● The membrane found on the surface of animal cells and inside the cell wall of other cells ● It's made mainly lipids and protein

  
• Function of the Cell surface membrane

  
• Nucleus


  ● A large organelle surrounded by nuclear envelope (double membrane) which contains many pores ● The nucleus contains chromosomes — made from protein bound linear DNA and one or more structure (s) called a nucleolus

  
• Nucleus Function

  ● controls the cell's activities by controlling the transcription of DNA — DNA contains instructions to make protiens● The pores allow substances (e.g. RNA) — to move between the nucleus and the cytoplasm — the nucleolus makes ribosomes

  
• Mitochondrion

  ● usually oval - shaped ● have a double membrane — the inner one is folded to form structures called cristae— inside is the matrix which contains enzymes involved in respiration

  
• Mitochondrion Function

  ● The site of aerobic respiration ● Aerobic respiration produces ATP — common energy source in the cell ● Mitochondria found in large numbers in cells that are very active and require a lot of energy

  
• Chloroplast

  ● small flattened structure● found in plant cells and algal cells● surrounded by double membrane — also has membranes inside called thylakoid membranes● These membranes are stacked up in some parts of the chloroplast to form grana ● Grana are linked together by lamellae — thin, flat pieces of thylakoid membrane

  
• Lamellae


  thin, flat pieces of thylakoid membrane
• Chloroplast Function

  ● The site where photosynthesis takes place — Some parts of photosynthesis happen in the grana and other parts happen in the stroma

  
• Stroma


  thick fluid found in chloroplasts
• Golgi apparatus


  ● A group of fluid filled membrane-bound flattened sacs ● Vesicles are often seen at the edges of the sacs

  
• Golgi apparatus Function

  ● It processes and packages new lipids and proteins● also makes lysosomes

  
• Golgi vesicle


  ● small fluid-filled sac in the cytoplasm● surrounded by a membrane ● produced by the Golgi apparatus

  
• Golgi vesicle Function

  ● Stores lipids and proteins made by the Golgi apparatus● transports them out of the cell — via the cell surface membrane

  
• Lysosome


  ● round organelle surrounded by a membrane with no clear internal structure ● a type of Golgi vesicle

  
• Lysosome Function

  ● Contains digestive enzymes — called lysozymes ● These are kept separate from the cytoplasm by the surrounding membrane and can be used— to digest invading cells or — to break down worn out components of the cell

  
• Ribosome


  ● A very small organelle that floats free in the cytoplasm or● is attached to the rough endoplasmic reticulum ● It's made up of proteins and RNA ● It's not surrounded by a membrane

  
• Ribosome Function

  The site where proteins are made