Part 1

Question 1

The mitochondria have their own genome and protein synthetic machinery. TRUE OR FALSE?

Answer 1

TRUE

Question 2

Mitochondria consists of an outer mitochondrial membrane, an inner membrane space and inner mitochondrial membrane. TRUE OR FALSE?

Answer 2

TRUE

Question 3

Where does mitochondrial DNA replication and transcription take place?

Answer 3

In the matrix

Question 4

Mitochondria are not exported except during apoptosis. TRUE OR FALSE?

Answer 4

TRUE

Question 5

Many copies of mtDNA per organelle is not influenced by degree of organelle fragmentation. TRUE OR FALSE?

Answer 5

FALSE

Question 6

Replication mtDNA is limited to S-phase. TRUE OR FALSE?

Answer 6

FALSE

Question 7

Individual mtDNA replicate at random, some more than others and some not at all. TRUE OR FALSE?

Answer 7

TRUE

Question 8

The process of mtDNA replication is regulated to ensure that each daughter cells receives the correct complement of mitochondria. TRUE OR FALSE?

Answer 8

TRUE

Question 9

How is mitochondrial DNA distributed?

Answer 9

In clusters known as nucleiods

Question 10

Human mitochondrial is very large compared to the rest of genome. TRUE OR FALSE?

Answer 10

FALSE

Question 11

What does the Endosymbiotic theory describe?

Answer 11

It tells us that mitochondria is originally prokaryotic and it came from one ancestor.

Question 12

Most mitochondrial genes are transferred to the nucleus. TRUE O FALSE?

Answer 12

TRUE

Question 13

What does mtDNA have to adapt to?

Answer 13

Nuclear transcription
Cytoplasmic translation
Signal sequence

Question 14

Nuclear genes coding mitochondrial proteins resemble bacterial genes. TRUE OR FALSE?

Answer 14

TRUE

Question 15

Both mtDNA are transcribed at the same rate using mitochondrial RNA polymerase. TRUE OR FALSE?

Answer 15

TRUE

Question 16

The nucleiod is the unit of mtDNA transmission and inheritance. TRUE OR FALSE?

Answer 16

TRUE

Question 17

Which line of mitochondrial DNA is inherited, maternal or paternal?

Answer 17

Maternal

Question 18

Mitochondrial DNA is non medelian, it is a cytoplasmic inheritance. TRUE OR FALSE?

Answer 18

TRUE

Question 19

What is the reason for inheriting maternal mtDNA?

Answer 19

Eggs contribute more to the zygote

Question 20

What is the reason for having low paternal mtDNA?

Answer 20

This is because they get destroyed before cell division

Question 21

What is the process for mitotic mtDNA segregation?

Answer 21

Stochastic process

Question 22

Mitochondria are not split into daughter cells randomly, one daughter cell can obtain more wild type than mutant type. TRUE OR FALSE?

Answer 22

FALSE

Question 23

What is heteroplasmy?

Answer 23

A mix of mitochondria that are both wild type and mutant type

Question 24

What is homoplasmy?

Answer 24

Can only be entirely mutant type or entirely mild type

Question 25

What are mitochondrial diseases and what are the two types of mitochondrial diseases?

Answer 25

Mitochondrial diseases affects the function of the mitochondria and the two types can be inherited damage to nuclear genome) or acquired which is damage to mtDNA or the protein

Question 26

Diseases of mtDNA does not affect OXPHOS, which does not cause impaired energy ATP production. TRUE OR FALSE?

Answer 26

FALSE

Question 27

What are the four different types of mtDNA mutations?

Answer 27

1. Missense mutation - nucleotide substitution AA substitution 2. Protein synthesis mutation 3. Insertion and deletion mutations - amount of mutation increases with ageing 4. Mutation that causes a change in the amount of mitochondrial genome

Question 28

What are the common symptoms of mtDNA diseases?

Answer 28

Poor growth Muscle weaknesses Visual or hearing problems Heart, liver and Kidney failure

Question 29

What is mitochondrial myopathies and give examples of symptoms?

Answer 29

It is a muscular disease due to mitochondrial abnormalities | Cramps, spams and muscle weakness

Question 30

What does RFF stand for and provide function?

Answer 30

Red ragged fibres - which is the accumulation of glycogen and lipids

Question 31

What does MELAS, MERF, KSS and CPEO stand for and provide detail on disease.

Answer 31

MELAS - mitochondrial encephalomyopathy - which causes lactic acidosis and stroke like syndrome MERF - Myoclonic epilepsy and ragged red fibres KSS- Keanis sayre syndrome - which is progressive myopathy, opthalmopedia CPEO - Chronic progressive external opthamoplegia

Question 32

What type of mutation causes MELAS , MERF , KSS AND CPEO?

Answer 32

MELAS and MERF are caused by mutations | KSS and CPEO are caused by single and large scale deletion

Question 33

How are mtDNA diseases diagnosed?

Answer 33

1. Maternal inheritance 2. Recognition of classic syndromea e.g MELAS 3. Involvement of many organ systems 4. Specific combinations of symptoms 5. Abnormal clinical or laboratory investigation - e.g Lactic acidosis

Question 34

Describe the ways in which mtDNA diseases can be managed

Answer 34

1. There is no cure, treatment reduces symptoms 2. Antioxidants such vitamin E and C 3. Excerise may influence mtDNA level 4. Allotropic expression - which is expression of a gene in a different cellular compartment to its target location. such as mtDNA gene being expressed in the nucleus 5. Nuclear transfer techniques - Nuclear chromosome from an oocyte that contains mutated mtDNA can be transferred to an enucleated oocyte with normal mtDNA.

Question 35

Oxygen does not have a strong affinity for electrons. TRUE OR FALSE?

Answer 35

FALSE

Question 36

An addition of a single electron to oxygen atom will lead to formation of a super oxide; which is a very reactive species. TRUE OR FALSE?

Answer 36

TRUE

Question 37

Oxygen does not bind to COX until it takes up 4 electrons. TRUE OR FALSE?

Answer 37

FALSE

Question 38

Where are super oxides mostly generated?

Answer 38

In the mitochondria

Question 39

What is hydrogen peroxide (H2O2) converted into in the presence of iron?

Answer 39

Hydroxyl radical (.OH)

Question 40

A hydroxyl radical is the most reactive oxygen species known. TRUE OR FALSE?

Answer 40

TRUE

Question 41

Name the two steps that leads to formation of a hydroxyl radical

Answer 41

Step 1: Haber weiss reaction | Step 2: Fenton reaction

Question 42

Describe the vicious cycle hypothesis in relations to mitochondrial damage and ageing

Answer 42

1. Oxidation damage 2. mtDNA mutations accumulate 2. Accelerated rate of oxidation errors

Question 43

What occurs when there is a decrease in mtDNA polymerase?

Answer 43

There is a decrease in the mtDNA polymerase proofreading ability which leads to the accumulation of mtDNA mutations, leading to ageing

Question 44

What are the three possible mechanism by which problems with mitochondria DNA can lead to diabetes?

Answer 44

1. Defect in gene glucokinase - leads to low ATP 2. Mutation in mtDNA coding for LEU and Lys - affects ATP levels 3. Nicotinamide nucleotide transhydrogenase defective - increase ROS , which leads to low production of ATP

Question 45

Around 90 nuclear genes code proteins to serve mtDNA replication , transcription and translation. TRUE OR FALSE?

Answer 45

TRUE