Lecture 15 Flashcards
What are the basic components of the mitochondria?
Contains DNA that encodes some polypeptides used by the organelle, rRNA, and some tRNAs
Layers: Outer membrane, intermembrane space, inner membrane, matrix, cristae
What is the endosymbiotic theory of the origin of organelles?
1 billion to 1.5 billion years ago, an anaerobic eukaryotic cell engulfed an aerobic eubacterial cell through endocytosis; the aerobic endosymbiont evolved into mitochondria; likewise, endocytosis of a photosynthesizing eubacterium led to the evolution of modern eukaryotic cells with mitochondria and chloroplasts
What is the process of mitochondria segregation?
Uniparental inheritance of ogranelle-encoded traits; animal mtDNA inherited almost exclusively from female parent
What are the basic consequences of mitochondrial DNA mutation?
MERRF syndrome (myoclonic epilepsy with ragged red fibers), LHON (leber’s hereditary optic neuropathy), NARP (neuropathy, ataxia, and retinitis pigmentosa), KSS (kearns-sayre syndrome), CEOP (childhood epilepsy with occipital paroxysms), Leigh syndrome
Explain the concept of pronuclear transfer to eliminate mitochondrial disease and possible risks
You remove the nucleus from a healthy donor egg and replace it with a nucleus taken from the egg cell of a woman who carries a rare neurological disease called Leigh syndrome, leaving the donor’s healthy mitochondria intact; the scientist then fertilized the modified egg with the father’s sperm before implanting it into the mother’s uterus; the resulting baby is born healthy
How do heteroplasmic cells segregate their organelles?
Each cell has hundreds to thousands of oragnelles; these organelles segregate randomly
Describe a prokaryotic cell
Circular DNA, no histones, 70s ribosomes, grow through binary fission
Describe a eukaryotic cell
Linear DNA, histones, 80s ribosomes, grow through mitosis
Describe a mitochondria
Circular DNA, no histones, 70s ribosomes, grow through binary fission
What is MERRF?
Myoclonic epilepsy with ragged red fibers; clumps of diseased mitochondria accumulate in the subsarcolemmal region of the muscle fiber; progressive myoclonic epilepsy, short stature, hearing loss, poor night vision
What is LHON?
Leber’s hereditary optic neuropathy; degeneration of retinal ganglion cells
What is NARP?
Neuropathy, ataxia, and retinitis pigmentosa
What is KSS?
Kearns-Sayre syndrome; progressive external opthalmoplegia, which is weakness or paralysis of the eye muscles
What is CEOP?
Childhood epilepsy with occipital paroxysms
What is Leigh syndrome?
Degeneration of the CNS; rare genetic neurometabolic disorder that is the result of mutations in nuclear or mitochondrial genes that cause loss of function of the mitochondria; symptoms usually begin between the ages of 3 months and 2 years; individuals usually live between a few years to the mid-teens
