6.2 Mitochondrial DNA

Question 1

What are the three extracellular ways DNA can be transmitted to organisms?

Answer 1

1. organelle heredity
2. infectious heredity
3. maternal affect

Question 2

What is organelle heredity?

Answer 2

DNA transmitted from chloroplasts or mitochondria

Question 3

What is infectious heredity?

Answer 3

associated with a parasitic or symbiotic microorganism

Question 4

What is the maternal effect?

Answer 4

nuclear gene products are present in the egg and are transmitted through the ooplasm to cells of the developing embryo

Question 5

What is extranuclear inheritance?

Answer 5

extracellular means of DNA being transmitted to an organism

Question 6

What is mtDNA?

Answer 6

Mitochondrial DNA

Question 7

How are Mitochondrial mutations transmitted?

Answer 7

via the cytoplasm during reproduction

Question 8

What does mtDNA look similar to?

Answer 8

that of bacteria

Question 9

What is the endosymbiotic theory?

Answer 9

free-living primitive bacteria were engulfed by larger eukaryotic cells giving them the ability to perform aerobic respiration

Question 10

What does mtDNA of most eukaryotes look like?

Answer 10

double stranded circular DNA

Question 11

What has the smallest and largest amount of mtDNA?

Answer 11

smallest = humans
largest = plants

Question 12

What are organisms with a small amount of mtDNA usually lacking?

Answer 12

introns

Question 13

Do mitochondria have there own set of ribosomes?

Answer 13

yes

Question 14

How many genes are encoded in human mtDNA?

Answer 14

37 genes

Question 15

What do the genes of mitochondria generally encode for?

Answer 15

proteins that are necessary for cellular respiration

Question 16

What do mutations of mtDNA affect?

Answer 16

organisms ability to supply critical energy to every physiological system

Question 17

Why is mtDNA susceptible to mutations?

Answer 17

1. exists alone and has no external structural protection from histone proteins that wrap around nuclear DNA
2. repair mechanisms are much weaker
3. process of cellular respiration creates highly concentrated levels of ROS

Question 18

What are ROS?

Answer 18

reactive oxygen species

Question 19

What are ROS harmful to?

Answer 19

proteins, lipids and DNA

Question 20

In order for a human genetic disorder to be attributed to mutations in the mitochondria what are the criteria it must meet?

Answer 20

1. inheritance pattern must be maternal and not mendelian
2. disorder must be directly caused by a deficiency in the bioenergtic function of mitochondria
3. must be at least one mutation detected in Mitochondrial genes