6.2 Mitochondrial DNA Flashcards
What are the three extracellular ways DNA can be transmitted to organisms?
- organelle heredity
- infectious heredity
- maternal affect
What is organelle heredity?
DNA transmitted from chloroplasts or mitochondria
What is infectious heredity?
associated with a parasitic or symbiotic microorganism
What is the maternal effect?
nuclear gene products are present in the egg and are transmitted through the ooplasm to cells of the developing embryo
What is extranuclear inheritance?
extracellular means of DNA being transmitted to an organism
What is mtDNA?
Mitochondrial DNA
How are Mitochondrial mutations transmitted?
via the cytoplasm during reproduction
What does mtDNA look similar to?
that of bacteria
What is the endosymbiotic theory?
free-living primitive bacteria were engulfed by larger eukaryotic cells giving them the ability to perform aerobic respiration
What does mtDNA of most eukaryotes look like?
double stranded circular DNA
What has the smallest and largest amount of mtDNA?
smallest = humans
largest = plants
What are organisms with a small amount of mtDNA usually lacking?
introns
Do mitochondria have there own set of ribosomes?
yes
How many genes are encoded in human mtDNA?
37 genes
What do the genes of mitochondria generally encode for?
proteins that are necessary for cellular respiration
What do mutations of mtDNA affect?
organisms ability to supply critical energy to every physiological system
Why is mtDNA susceptible to mutations?
- exists alone and has no external structural protection from histone proteins that wrap around nuclear DNA
- repair mechanisms are much weaker
- process of cellular respiration creates highly concentrated levels of ROS
What are ROS?
reactive oxygen species
What are ROS harmful to?
proteins, lipids and DNA
In order for a human genetic disorder to be attributed to mutations in the mitochondria what are the criteria it must meet?
- inheritance pattern must be maternal and not mendelian
- disorder must be directly caused by a deficiency in the bioenergtic function of mitochondria
- must be at least one mutation detected in Mitochondrial genes
