Mitochondrion

1
Mitochondrion

• site of cellular respiration
• enclosed by 2 membranes outer is smooth inner
  is convoluted (cristae)
• between membranes is intermembrane space
• interior is called the matrix
• contains its own DNA ribosomes
• number in cell is related to cells level of
  metabolic activity

2
Chloroplast

• site of photosynthesis
• contains chlorophyll
• found in leaf cells cells of other green organs
• enclosed by 2 membranes with a narrow
  intermembrane space
• interior fluid is called the stroma
• stroma contains stacks of membranous sacs called
  thylakoids (a stack of thylakoids is called a
  granum)
• contains its own DNA ribosomes

3
Peroxisome

• bound by a single layer of phospholipids
• contains enzymes that catalyze oxidation
  reactions producing hydrogen peroxide (H2O2) as a
  by-product
• additional enzymes break down the H2O2 which is
  toxic to the cell

4
Cytoskeleton

• network of fibers extending throughout cytoplasm
• provides mechanical support to the cell
• maintains the shape of the cell
• anchors organelles
• involved in cell movement (cilia flagella)
• may also be involved in the regulation of
  biochemical activities

5
Components of the Cytoskeleton

• microtubules
• shape support the cell
• serve as tracks for the movement of organelles
• separate chromosomes during cell division
• 92 arrangement and dynein arms cause cilia
  flagella to beat
• grow out from centrosome (which includes a pair
  of centrioles in animal cells)

continued
6

• microfilaments (actin filaments)
• built from molecules of actin
• helps cell bear tension (pulling forces)
• play a role in cell motility
• works with myosin to cause muscle cell
  contraction in animals cytoplasmic streaming in
  plant cells
• intermediate filaments
• helps cell bear tension
• reinforces shape of cell
• helps anchor organelles
• make up nuclear lamina (lining on nuclear side of
  nuclear envelope)

7
Cell Wall

• protects maintains shape of plant cell
• prevents excessive uptake of water
• composed primarily of cellulose in plants
  chitin in fungi
• perforated by channels called plasmodesmata that
  connect adjacent cells

8
Extracellular Matrix

• consists primarily of glycoproteins (carbohydrate
  attachments to membrane proteins)
• most abundant glycoprotein is collagen

9
Intercellular Junctions

• Plant Cells
• plasmodesmata cytoplasmic channels between
  adjacent plant cells
• Animal Cells
• tight junctions bind cells tightly together to
  prevent fluid from leaking into surrounding
  tissues
• desmosomes anchoring junctions (fasten cells
  together)
• gap junctions cytoplasmic channels between
  adjacent animal cells