Eukaryotic cell structure

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Eukaryotic cell structure
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Structures External to Cell Wall

• Flagella and cilia
• Flagella
• Cilia
• Both used for motility cilia also used to move
  things across cell surface
• Consist of 92 arrangement of microtubules and
  move in a wavelike manner

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• Cell wall and glycocalyx
• Do not contain peptidoglycan
• Composed of less complex polysaccharides
• Cellulose, chitin, glucan and mannan
• Some eukaryotes lack a cell wall
• Protozoa have a pellicle
• Animal cells are covered by a glycocalyx
• used for identification, cell strengthening and
  attachment
• Carbohydrates are anchored to proteins and lipids
  of cell membrane

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Structures internal to the cell wall

• Plasma membrane
• Similar in function and structure to prokaryotes
• Contain sterols
• Can bring items into the cell by endocytosis
• 2 types
• phagocytosis (uses pseduopods)
• pinocytosis (infolding of membrane)

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Cytoplasm

• Cytosol is the fluid portion
• 80 water with dissolved solutes (salts, glucose,
  proteins)
• Cytoskeleton - complex internal structure
  consisting of exceedingly small rods called
  microfilaments and intermediate filaments and
  cylinders called microtubules
• provides a structural support to the cell
• movement in the cell
• reinforce cell shape, anchor organelles

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• Organelles - Membranous structures with specific
  shapes and specialized functions
• Internal membranes of organelles compartmentalize
  the functions of the cell
• Endomembranous system acts as a cellular factory
  for manufacturing cell products
• increases surface area where reactions can occur
• Some of the enzymes needed to drive reactions are
  part of the membranes
• includes nuclear envelope, endoplasmic
  reticulum, golgi apparatus, lysosomes, vacuoles
  and plasma membrane

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Organelles

• Nucleus - Contains DNA
• Usually the largest structure in the cell
• Has a nuclear envelope and nuclear pores and
  nucleolus where rRNA is synthesized
• DNA is combined with special proteins histones
• Chromatin
• Chromosomes
• Divide by mitosis and meiosis

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Ribosomes

• Eukaryotic ribosome is 80S
• chloroplasts and mitochondria have 70S ribosomes
  like prokaryotic cells
• Ribosome subunits are made in the nucleolus and
  assembled in the cytoplasm
• Free ribosomes synthesize proteins used in the
  cell
• RER ribosomes synthesize secretory and membrane
  proteins

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Endoplasmic Reticulum (ER)

• Network of cisterns, continuous with the nuclear
  envelope
• Rough ER (RER)
• Protein processing occurs inside cisterns
• Smooth ER (SER)
• Lipids are made in SER
• Those in the sex organs produce steroid hormones
  like testosterone
• Involved in muscle contraction
• Detoxification in liver cells
• Liver SER are also involved in carbohydrate
  synthesis

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Golgi Complex

• Composed of stacks of flattened membranous sacs
  called cisterns
• Shipping and receiving department
• finishes, sorts and ships products os SER and RER
  
• Involved in carbohydrate synthesis

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Lysosomes

• Single membrane
• Contains digestive enzymes
• Phagosomes fuse with lysosomes forming
  phagolysosmes
• White blood cells can digest bacteria in their
  phagolysosomes

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Vacuoles

• Single membrane derived from the Golgi complex
• Store nutrients and sequester harmful substances
• Food vacuoles
• Contractile vacuoles
• Central vacuole

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Mitochondria

• Powerhouse of the cell
• Double membrane
• Matrix
• Primary site of ATP production in the cell
• Circular DNA, 70S ribosomes, and divides by
  binary fission

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Plastids

• Group of plant and algal organelles
• Amyloplast (store starch), chromoplasts (color
  providing pigments), chloroplast (contain
  chlorophyll)
• Chloroplasts
• intermembrane space, thylakoid space, and stroma
• Thylakoids stacked in grana contain chlorophyll
  needed for photosynthesis
• Have 70S ribosomes and a circular strand of DNA
  and can reproduce by binary fission

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Endosymbiotic theory

• Eukaryotic cells evolved from symbiotic
  relationships of prokaryotic cells living inside
  other prokaryotic cells
• Evidence for this theory comes from the
  similarities of mitochondria and chloroplasts to
  prokaryotic cells

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Centrosome

• Composed of microtubules
• Important for cellular division
• Forms mitotic spindle which pulls chromosomes
  apart
• Composed of two perpendicular centrioles
• X shaped organelle found adjacent to nucleus

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Intercellular Junctions

• plasmodesmata
• tight junctions
• desmosomes
• gap junctions

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Extracellular Structures
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Intracellular Structures
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Genetic Structures
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Reproductive Processes