mitochondria

• What is the main aim of Lecture 13 on mitochondrial structure?

  To describe key characteristics of mitochondria
• What are the key characteristics of mitochondria that should be described?

  Size, location, number, and attributes
• What attributes do mitochondria possess?

  Contain DNA, can undergo fusion and fission
• Where are mitochondria located in cells?

  In the cytoplasm of nearly all eukaryotic cells
• Which types of cells do not contain mitochondria?

  Red blood cells
• How much of the cytoplasm's volume can mitochondria occupy?

  Up to 25%
• What is the approximate length of mitochondria?

  1. 10 µm
• How does the number of mitochondria vary among cells?

  Varies between organism and tissue type
• What correlates with the number of mitochondria in a cell?

  The cell's level of metabolic activity

  
• Which types of cells have more mitochondria?

  Motile or contractile cells
• What percentage of cone cells is made up of mitochondria?

  80%
• What is the relationship between energy needs and mitochondria?

  Cells needing more energy have more mitochondria
• Are mitochondria part of the endomembrane system?

  No, they are not part of it
• What type of membranes do mitochondria have?

  Two phospholipid membranes
• What is the main protein in the outer mitochondrial membrane?

  Porin
• What does porin do in the outer mitochondrial membrane?

  Permits diffusion of small molecules
• What is the protein to lipid ratio in the outer mitochondrial membrane?

  1. 1 ratio
• What is the protein composition of the inner mitochondrial membrane?

  ~80% protein by mass
• What are the key participants in cellular respiration found in the inner mitochondrial membrane?

  ATP synthase and transport proteins

  
• What is the permeability of the inner mitochondrial membrane?

  Permeable to small uncharged molecules
• How does the surface area of the inner mitochondrial membrane compare to the outer membrane?

  Five times larger in live cells

  
• What does the matrix of mitochondria contain?

  DNA, ribosomes, and enzymes

  
• What are some functions of mitochondria besides energy production?

  Cell signaling, calcium storage, apoptosis

  
• What is the typical structure of mitochondrial DNA?

  Closed, circular DNA

  
• How many copies of mtDNA does each mitochondrion possess?

  1. 10 copies
• Why does mtDNA come predominantly from the mother?

  Due to simple dilution from egg and sperm
• What is the length of the human mitochondrial genome?

  16,569 base pairs
• What types of genes are found in the mitochondrial genome?

  13 proteins, 22 tRNAs, 2 rRNAs
• What is the role of mtDNA in mitochondrial function?

  Codes for some polypeptides and tRNAs
• What are the four large multiprotein complexes in the electron transport chain (ETC)?

  Complex I, II, III, and IV
• Which complex in the ETC is NADH-CoQ reductase?

  Complex I
• How do electrons from NADH flow in the ETC?

  From complexes I to III to IV

  
• What is the significance of mtDNA in mitochondrial protein synthesis?

  Provides tRNA and RNA for ribosomes
• What is the main function of mitochondria?

  Convert energy to usable forms for cells
• What are the functions of mitochondria?

  • Cellular respiration (Kreb’s cycle, oxidative phosphorylation)
  • Cell signaling
  • Storage of calcium ions
  • Regulation of apoptosis
  • Regulation of membrane potential
  • Regulation of cell proliferation
  • Regulation of cell metabolism
  • Role in steroid synthesis

  
• What is the structure of mitochondria?

  • Double membrane: outer (smooth) and inner (folded into cristae)
  • Intermembrane space and matrix
  • Contains unique proteins and ribosomes
  • Mitochondrial DNA (mtDNA) is circular

  
• What is the significance of mitochondrial DNA (mtDNA)?

  • Encodes for 13 proteins
  • Contains tRNA and rRNA
  • Replicates independently of the cell
  • Mostly inherited from the mother
• What are the components of the electron transport chain (ETC)?

  • Complex I: NADH-CoQ reductase
  • Complex II: Succinate-CoQ reductase
  • Complex III: CoQH2-cytochrome c reductase
  • Complex IV: Cytochrome c oxidase

  
• What is the role of the inner mitochondrial membrane in ATP production?

  • Contains ATP synthase
  • Highly folded into cristae to increase surface area
  • Permeable to small uncharged molecules

  
• How do mitochondria demonstrate dynamic behavior?

  • Can move and change shape
  • Undergo fusion and fission
  • Create tubular networks