Mitochondria Flashcards
What is the structure of the mitochondria?
Outer membrane
Intermembrane space
Inner membrane
Matrix
What is produced as a result of the inner membrane invaginating?
Cristae
What is the matrix?
A gel-like material which is enclosed in the inner membrane and is the site of the krebs cycle
Mitochondria have their own DNA. True or false?
True
What is the function of the mitochondria?
Generate energy in the form of ATP
Where are mitochondria most commonly found? Give an example
Close to sites of high energy utilization
Example = in myofibrils with contract and relax in order to pump cardiac muscle
What is required in order to regenerate ATP?
Energy from another source
Explain the process in which energy is generated in order to regenerate ATP.
- ATP is generated in reactions such as; sugar to pyruvate in the cytoplasm, fats to fatty acids and glycerol in the cytoplasm and fatty acids to acetyl CoA in peroxisomes
- Compounds produced in these reactions are transported to the mitochondrial matrix
- In the matrix these compounds are converted to acetyl CoA which is oxidised in the krebs cycle
- Energy is generated in the form of GTP, NADH and FADH2
Explain what happens in the electron transport chain during oxidative phosphorylation.
- NADH and FAH2 are generated in the cytoplasm and in the krebs cycle
- NADH and FADH2 donate an electron each which enters the transport chain
- Electrons move between complexes on the inner membrane due to each complex having a higher affinity for electrons than the previous one
- The final electron acceptor is oxygen
What form does NADH take once it has donated an electron?
NAD + H + 2e
What form does FADH2 take once it has donated an electron?
FAD + 2H + 2e
What is the first complex on the ETC?
NADH dehydrogenase complex
What is the third complex on the ETC?
Cytochrome b-c1 complex
What is the fourth complex on the ETC?
Cytochrome oxidase complex
What is the equation for oxygen accepting an electron at the end of the ETC?
O + 2H + 2e = H20
Explain how an electrochemical gradient is maintained within the mitochondria.
- Energy is released from electrons moving in the ETC
- This energy is used to pump H+ out of the matrix into the intermembrane space
- The pumping of H+ generates an electrochemical gradient across the membrane
- high H+ concentration in the intermembrane space (low pH)
- low H+ concentration in the matrix (high pH)
Explain proton motive force.
- ATP synthase sits in the inner membrane of the mitochondria forming a hydrophilic pathway
- The flow of H+ through ATP synthase causes the rotation of the transmembranous rotor domain
- This causes an attached stalk to rotate
- Mechanical energy is generated as the stalk grinds against an enzymatic head (held still by an arm attached to the membrane)
- The mechanical energy is converted into chemical energy (ADP + Pi = ATP)
How many ATP molecules are produced from one NADH molecule?
2.5
How many ATP molecules are produced from one FADH2 molecule?
1.5
How do molecules travels through the outer membrane of the mitochondria?
Through porins - large pores made of proteins
How does oxygen and carbon dioxide travel through the inner membrane of the mitochondria?
Passive diffusion
How do most compounds travel through the inner membrane of the mitochondria? Give an example.
Active transport - driven by the electrochemical gradient across the membrane
Example = pyruvate and inorganic phosphate are co-transported in the same direction (symport)
How do ATP and ADP travel through the inner membrane of the mitochondria?
ATP is transported out whilst ADP is co-transported in
Why is ATP transported out of the mitochondrial matrix?
Because it is attracted to the positively charged intermembrane space
What does human mitochondrial DNA code for?
2 rRNA
22 tRNA
13 peptides
Where does protein synthesis occur within the mitochondria?
In the matrix
What is the theory of how the mitochondria originated? Give 2 pieces of evidence that back up the theory.
It originates from a bacteria which entered a symbiotic relationship with a cell
- mitochondria have their own DNA
- mitochondria are not synthesised like other organelles = they grow and divide
