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Mitochondria: Structure, function and development

Question 1 of 33

1

This is our learning resource on Mitochondria, in the form of a quiz. There may be more than one correct answer for each question, or equally just one. It is advised that this quiz is used as a consolidation resource, and that lectures have been revised, as well as the content of "Karp, G. C. (2014). Cell Biology. 7th ed. New Jersey: John Wiley." is covered (or any other molecular cell biology text book.

Here is a practice at answering:

Mitochondria are an organelle within the cell. True or False?

Select one of the following:

  • True
  • False

Explanation

Question 2 of 33

2

What does the outer boundary of a mitochondria contain?

Select one or more of the following:

  • Cristae

  • Outer membrane

  • Inner membrane

  • Cytosol

Explanation

Question 3 of 33

2

What is the inner membrane subdivided into?

Select one or more of the following:

  • Inner boundary membrane

  • Thylakoid membrane

  • Cristae

  • ATP synthesising membrane

Explanation

Question 4 of 33

1

Approximately what length is a mitochondrion?

Select one of the following:

  • 1-2μm

  • 0.1- 05μm

  • 3- 5μm

Explanation

Question 5 of 33

1

According to one of the structural models, what structure joins the major domains of the inner membrane?

Select one of the following:

  • Cristae junction

  • Interlinking-tubular connection

  • Connexins

  • Domain-binding protein

Explanation

Question 6 of 33

1

What characteristic makes the outer membrane permeable?

Select one or more of the following:

  • Voltage-gated channels

  • Porins

  • Ligand-gated channels

Explanation

Question 7 of 33

2

Why is the mitochondria termed as 'semi-autonomous'?

Select one or more of the following:

  • It has it's own DNA and therefore replication is not controlled by cell division but most of the proteins it requires are encoded for by the nucleus and without them, the mitochondrion would not be functional.

  • It can only partially carry out its function on its own without the intervention of other organelles to complete a task.

  • It has it's own DNA and ribosomes within the matrix but requires substrates from the cytosol such as pyruvate to carry out its function as it doesn't contain the right enzymes to make the substrates itself.

Explanation

Question 8 of 33

2

How do mitochondria normally exist in cells?

Select one or more of the following:

  • Individually

  • In a syncytium

  • In pairs

  • Separated

Explanation

Question 9 of 33

1

What does fusion of mitochondria result in the mixing of?

Select one or more of the following:

  • The outer membranes only

  • The inner membranes only

  • The outer membranes and contents of the matrix only

  • The outer membranes, inner membranes and the contents of the matrix

Explanation

Question 10 of 33

2

What are 2 important roles of mitochondrial fusion?

Select one or more of the following:

  • For transport of mitochondria

  • To allow communication between organelles

  • For distribution of mitochondria

  • To buffer defects that arise in the mitochondria

Explanation

Question 11 of 33

1

What does mitochondrial division facilitate?

Select one or more of the following:

  • Distribution and transport of mitochondria

  • Communication between organelles

  • The buffering defects that arise in mitochondria

  • Division does not facilitate any processes

Explanation

Question 12 of 33

1

What are the only outer membrane proteins essential for fusion of mitochondria?

Select one or more of the following:

  • Dynamin-related proteins (DRPs)

  • Sodium-potassium pumps

  • Mitofusins

  • No outer membrane proteins are essential for fusion

Explanation

Question 13 of 33

1

What mediate the division events of mitochondria?

Select one or more of the following:

  • Mitofusins

  • Dynamin-related proteins (DRPs)

  • The electron transport chain

  • There are no specific proteins

Explanation

Question 14 of 33

1

The placement of the mitochondrial division site is dependent on an interaction with which other organelle?

Select one or more of the following:

  • Peroxisome

  • ER

  • Nucleus

  • Lysosome

Explanation

Question 15 of 33

1

Mitochondria will elongate and form net-like structures due to?

Select one or more of the following:

  • Loss of mitochondrial division

  • Loss of mitochondrial fusion

  • Loss of mitochondrial division and fusion

  • Too much mitochondrial division

Explanation

Question 16 of 33

1

Which of these is NOT a result of loss of mitochondrial fusion?

Select one or more of the following:

  • Facilitation of cell death in response to apoptotic signals

  • Formation of well-connected networks

  • Slow cell growth

  • Reduced activity of all respiratory complexes

  • Loss of control of mitochondrial shape

Explanation

Question 17 of 33

1

Mitochondria are continually fusing and dividing, they are likely to contain...

Select one or more of the following:

  • Wild-type DNA only

  • Both mutant and wild-type DNA

  • Mutant DNA only

Explanation

Question 18 of 33

1

ATP synthase is embedded into the plasma membrane of the inner membrane of the mitochondria, but which part is this?

Select one or more of the following:

  • Stalk

  • Base

  • Head

Explanation

Question 19 of 33

1

The generation of ATP via the use of a proton gradient is used by which ATP associated complex?

Select one or more of the following:

  • F – Type

  • V – Type

  • C – Type

Explanation

Question 20 of 33

1

The C – subunits are used by protons as a transporter to ‘pass’ through the a – subunit. How many C – subunits are found in the bacterial/plastid ATP synthase complex?

Select one or more of the following:

  • 10 – 15 subunits

  • 8 – 10 subunits

  • 5 – 8 subunits

Explanation

Question 21 of 33

2

True or false: the addition of a proton to the COOH group found on a C – subunit causes the neutralisation of the group which in turn generates the rotation seen in an active complex?

Select one of the following:

  • True
  • False

Explanation

Question 22 of 33

1

The use of opposite charges are used to generate the motion of the C – subunit which drives the rotation of the stalk. The attraction between the COO- group and which amino acid on the Stator causes the motion?

Select one of the following:

  • Lysine

  • Arginine

  • Histidine

Explanation

Question 23 of 33

1

How many α and β subunits are there on the head of each ATP synthase?

Select one of the following:

  • 3 each

  • 4 each

  • 6 each

Explanation

Question 24 of 33

1

What causes the α and β subunits to change from an open to a loose to a tight formation to generate ATP?

Select one of the following:

  • Orientation of the α and β subunits

  • Orientation of the Stator

  • Orientation of the ϒ stalk

Explanation

Question 25 of 33

1

True or false: ATP synthase can associate together, with their stalk regions back to back to form a dimer?

Select one of the following:

  • True
  • False

Explanation

Question 26 of 33

3

The Respirasome is a complex of multiple complexes which are used in the electron transport chain. Which of the following is the make-up of the Respirasome?

Select one of the following:

  • Complex I, Complex II and Complex IV

  • Complex I, Complex III and Complex VI

  • Complex I, Complex III and Complex IV

Explanation

Question 27 of 33

1

The action of Complex I, allows for the translocation of four protons into the intermembrane space, this action is also coupled with which other process?

Select one of the following:

  • The reduction of NADH

  • The reduction of Ubiquinone

  • The addition of sugars

Explanation

Question 28 of 33

1

Which of the following is NOT another name for Complex II?

Select one of the following:

  • Succinate Coenzyme Q reductase

  • Succinate Dehydrogenase

  • Succinate Fumarate reductase

Explanation

Question 29 of 33

1

Complex III contains cytochrome b, cytochrome c, and Fe-S Reiske protein. Which of these structures is encoded for by a mitochondrial gene?

Select one of the following:

  • Cytochrome b

  • Cytochrome c

  • Fe-S Reiske protein

Explanation

Question 30 of 33

1

Complex IV makes use of atmospheric oxygen to generate water. This process is achieved via the creation of what, between haem groups CuB and a3, causing the reduction of oxygen?

Select one or more of the following:

  • An oxide bridge.

  • A peroxide bridge.

  • A Severn Bridge.

Explanation

Question 31 of 33

1

What role does Mitochondria have in regulating the levels of calcium in the cell?

Select one of the following:

  • Mitochondria acts as an intracellular buffer of calcium.

  • The majority of the calcium absorbed by the cell is then absorbed by the mitochondria to avoid precipitation when in contact with phosphate groups.

  • Mitochondria does not play any role in regulating levels of calcium.

Explanation

Question 32 of 33

2

Mitochondria has various functions in the cell apart from oxidative phosphorylation. Which of these is also a mitochondrial function?

Select one of the following:

  • Apoptosis

  • Detoxification of toxic respiratory products

  • Glucose metabolism

Explanation

Question 33 of 33

3

Read this paper:

Xu, Y., Peng, L. and Li, Y. (2005). Impaired development of mitochondria plays a role in the central nervous system defects of fetal alcohol syndrome. Birth Defects Research 73: 83-91.
http://onlinelibrary.wiley.com/doi/10.1002/bdra.20110/full

According to the paper, why is full mitochondrial development important within mammals (3 marks):

Select one or more of the following:

  • It can lead to poorly formed organs and central nervous system.

  • It leads to abnormal cellular metabolism.

  • It is important in homeostasis

  • None of the above

Explanation

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