Exam 19: Cytoplasmic Inheritance and the Evolution of Organelle Genomes

In a cross between a petite yeast mutant and a wild-type strain,results showed some petite and some wild-type outcomes.Which of these statements must be true of this petite mutation?

When a cell divides,chloroplasts are randomly distributed.What is this called?

The noncoding regions of mammalian mitochondrial genomes have few to no repair mechanisms,but no real selective pressure.Which of the following are consequences of this condition?

Allan Wilson showed that the mtDNA of Africans is more diverse than that of other human populations.Does this finding provide evidence for the multiregional (MRE)model or the recent African origin (RAO)model?

In Leber's disease (LHON),degeneration of the optic nerve results in blindness due to a defect in NADH dehydrogenase affecting electron transport.If this is due to a mutation in a mitochondrial gene,which combination of effects would you expect to see when doing a pedigree analysis of a family with LHON? i. variable expressivity Ii. incomplete penetrance Iii. progressive blindness over time Iv. maternal inheritance V. diminished muscle mass

The following is a hypothetical pedigree for a family,some of whose members have symptoms of Leigh syndrome,caused by an mtDNA mutation that reduces ATPase activity. Which of the following in the youngest generation might transmit the condition in future?

Suppose there is (hypothetical)evidence that a gene in mice produces a substance that induces twitchiness in hind leg muscles.A female mouse of a true-breeding twitchy strain is mated with a male of a true-breeding non-twitchy strain.All progeny are twitchy.Which of these procedures would you use to provide evidence for your hypothesis that twitchiness is due to mtDNA?

In certain Latin American countries where,during periods of political volatility,children were removed from their families and the parents murdered (then referred to as the "disappeared"),the best possibility of restoring the children to members of their larger family have used mtDNA matching.Why and how?

What are the closest "relatives" of chloroplasts still found as free-living organisms today?

In 1918,the tsar and tsarina of Russia and their five children were presumably assassinated and buried in an unmarked grave.Later,several women came forward and claimed that they were in fact Anastasia,one of the daughters whose bones had not been found.More recently,forensic scientists have extracted DNA,including mtDNA,from the skeletal remains.Which of the following samples of mtDNA had to be analyzed to discern which,if any,of the claimants was Anastasia?

Among the discoveries that Correns and Bauer (1908)made in plants was that,sometimes,reciprocal crosses resulted in what phenotype only?

What name is given to the alteration of an RNA sequence after transcription?

What number of membranes is typical of both mitochondria and chloroplasts,and which of them anchors the organelle's genome?

Organisms have been created by nuclear transfer cloning,in which a diploid nucleus from a somatic cell of an adult animal is injected into an enucleated egg cell to create an embryo.Among the many species thus cloned,there has been a prevalence of mitochondrial defects.Which of the following is a most likely explanation?

Variation in numbers of mutated chloroplast genomes can give rise to green,white,or variegated leaves.What color leaves do you expect in offspring of pollen from a white-leafed plant and ovules from a green-leafed plant?

In the 1950s,mitochondrial genomes were discovered by differential staining for ________.

In one or two words,give two characteristics of mitochondrial genomes.

The direction of shell coiling in snails such as Limnea peregra is determined by the egg's genotype,which affects orientation of the spindle in early cleavage divisions.How could the egg genotype cause the directional orientation of a spindle in the embryo?

Mitochondrial mutations in mammals are passed to the offspring by the ________ parent.

DNA transfer has occurred many times between organelle and nuclear genomes.Two pairs of sequences are analyzed.Pair A has more similarities than pair B.Which of these is the most ancient transfer?