Mitochondria

Question 1

What causes differentiation in cristae structure?

Answer 1

• cristae take on dif structures based on where mito sit within certain cells

Question 2

What are 5 functions of mito?

Answer 2

1. bioenergetics
2. Apoptosis –> intrinsic pathway of cell death (when cytochrome c appear in cytoplasm)
3. calcium homeostasis (mito-ER interactions)
4. biogenesis –> to meet energy demands of cells
5. oxygen sensors

Question 3

distinguishing what cell types will have the most/least number of mito?

Answer 3

• based on whether or not cells live in anaerobic vs. aerobic environment
• do cells require large amounts of energy to perform functions

Question 4

general properties of mito

Answer 4

• tissues of high energy have higher numbers of mito
• maternally inherited (diseases can be tracked)
• mito positioning is influenced by cytoskeleton & demand for ATP (pattern of microtubule & mito distribution similar)

Question 5

What is the relationship between mito and the basal side of cells within striated ducts and kidney tubules?

Answer 5

• mito more concentrated on basal side
• ATP needed to pump Na+ out of cell to maintain gradient –> ATP not easily diffusible within cell
• PM has infolding at basal side to increase SA, mito interdigitate between infolds (almost looks like striations)

Question 6

What role do mitochondria play within the cells of striated ducts?

Answer 6

• product in initial lumen is dif than product found at final location
• secretion being “remodeled” (isotonic in lumen but hypotonic in saliva)
• ions being taken up in ductal system –> need ATP to pump ions out of cells to maintain conc gradient

Question 7

What don’t Na+/K+ pumps migrate to apical or lateral-basal surfaces of ductal cells?

Answer 7

• tight junctions prevent movement of lipids/proteins from one side of membrane to other side?

Question 8

Why does cytoplasm of striated duct cells stain eosinophilic?

Answer 8

• have lots of mito

- mito is location of electron transport chain, which contains highly basic proteins

Question 9

Which cells stain very eosinophilic due to mitochondria content?

Answer 9

• striated ducts
• parietal cells (stomach
• oxyphil (parathyroid)

Question 10

How do different muscle fibers stain using immunohistochemistry?

Answer 10

• smaller, darker staining fibers are slow oxidative fibers

- large, lighter staining fibers are fast glycolytic fibers

Question 11

What don’t neutrophil stain very eosinophilic in the cytoplasm?

Answer 11

• contain few functional mito

- don’t need energy aerobically

Question 12

How does material move across the inner membrane of the mito?

Answer 12

• inner membrane very impermeable

- transport systems used to bring things into inner matrix

Question 13

What accounts for the impermeability of the mito inner membrane?

Answer 13

• when looking a PM lipid composition, cardiolipin is highly restricted to the inner membrane of mito
• allows for membrane to be highly impermeable

Question 14

How do mitochondria play a role in apoptosis?

Answer 14

• cytochrome c is a protein found within the intermembrane space of mito –> used in electron transport system
• when cyt c moves from mito into cytoplasm, it facilitates apoptosis

Question 15

What are proteins destined for nucleus, mito, or peroxisomes made?

Answer 15

• proteins destined for mito/nucleus/peroxisomes are made on free ribosomes

Question 16

How do cells get proteins to go to right location (mito)?

Answer 16

• signal sequences target proteins to mito

- use motifs that drive proteins made in cytoplasm to specific receptor complexes in mito

Question 17

Where are proteins destined for outside the cell made?

Answer 17

• synthesized in ER, move in vesicle to PM, fuse with PM and are released outside cell
• N-linked glycosylations, GPI-linkages, etc

Question 18

What does the mito genome encode for?

Answer 18

• 13 polypeptide chains
• encodes for its complete set of tRNA
• when number of damaged mito gets too high, start seeing disease states

Question 19

What are some differences between nuclear and mito DNA?

Answer 19

• nuclear genome contains introns, mito genome does not
• nuclear encoded mRNA involves capping and is polyadenylated, mito encoded mRNA does not involve capping but is polyadenylated

Question 20

What affects can antibiotics have on mito?

Answer 20

• in high enough amounts, antibiotics can disrupt mito transcriptional/translational processes

Question 21

How do mito multiply? What is an advantage of this?

Answer 21

• energy of daughter cells must be maintained
• mito divide by fission, equal distribution of mito into daughter cells
• in opposite direction, two mito can come together in fusion
• if damage and normal mito fuse, damaged mito DNA is diluted out