Deck 9: Extranuclear Inheritance

Question 1

Which of the following organelles are involved in the general category of organelle heredity?

A) mitochondria and chloroplasts
B) golgi and nuclei
C) lysosomes and peroxisomes
D) factors and episomes
E) golgi and rough endoplasmic reticulum

Answer 1

A

Question 2

The maternal effect in Lymnaea is such that the genotype of the egg determines the direction of shell coiling regardless of the genotype of the offspring.Apparently,the cause of this spectacular maternal effect results from ________.

A) orientation of the spindle apparatus in early cleavage
B) genophores present in the egg cytoplasm
C) the F factor exerting its influence on the centrosome
D) colicins "poisoning" one of the cleavage centers
E) allelic substitution as demonstrated from RNA injection experiments

Answer 2

A

Question 3

Through the study of mitochondrial disorders,scientists have suggested a link between the decline of mitochondrial function and aging.What process appears to be involved in this suspected phenomenon?

A) accumulation of sporadic mutations in the nuclear genome
B) decline of mutations in the nuclear genome
C) accumulation of mutations in the mtDNA
D) recombination of mtDNA and nuclear DNA
E) recombination among mtDNAs of different mitochondria

Answer 3

C

Question 4

List three organisms that provide examples of organelle heredity.

Question 5

Forms of inheritance that do not follow typical Mendelian patterns and that appear to be more influenced by the parent contributing the most cytoplasm to the embryo are grouped under the general heading of ________.

A) sex-linked inheritance
B) neo-Mendelian inheritance
C) extrachromosomal inheritance
D) suppressive inheritance
E) dominance and/or recessiveness

Question 6

Why is variegation in four o'clock plants determined by the phenotype of the ovule source?

Question 7

In what way do mitochondrial mutations influence phenotype?

Question 8

Approximately one in5000 humans either have a mitochondrial DNA disorder or are at risk for developing such a disorder.What future approach involving nuclear transplantation might be available to treat mtDNA-based human disorders?

A) nuclear disintegration
B) mitochondrial swapping
C) nuclear activation
D) mitochondrial activation
E) mitochondrial suppression

Question 9

The inheritance of the petite phenotype in yeast is complicated by an interaction of mitochondrial and nuclear genes.What are these complications? Which three categories of petites are commonly described?

Question 10

Direction of shell coiling in Lymnaea peregra is strongly and most directly influenced by_______.

A) the genotype of the mother
B) the genotype of the father
C) the phenotype of the mother
D) the phenotype of the father
E) the genotype of the embryo itself

Question 11

What is the expression pattern of dominant-negative mutations in petite strains of yeast?

A) Expression of wild-type mitochondria is enhanced.
B) Expression of mutant mitochondria resembles expression of wild-type mitochondria.
C) Mitochondria show enhanced capacity of oxidative phosphorylation.
D) The function of wild-type mitochondria is suppressed.
E) Mitochondrial membranes become hyperpolarized.

Question 12

Which three classes of macromolecules are encoded by mtDNA?

Question 13

To which of the following does the term heteroplasmy refer?

A) cells with a variable mixture of normal and abnormal organelles
B) heterozygous individuals with more than one gene pair involved
C) conditions in which the germ plasm is a mixture of dominant and recessive genes
D) a circumstance that is homologous to incomplete dominance
E) various stages of development of mitochondria and chloroplasts

Question 14

In what way do chloroplast mutations influence phenotype?

Question 15

How are reciprocal crosses used to identify cases of extrachromosomal inheritance? What criteria would one use to state that a particular mode of inheritance is extrachromosomal?

Question 16

One explanation for organelle inheritance is that ________.

A) mitochondria and chloroplasts lack DNA and are therefore dependent on the maternal cytoplasmic contributions
B) mitochondria and chloroplasts have DNA that is subject to mutation
C) organelles such as mitochondria are always wild type
D) chloroplasts, for example, are completely dependent on the nuclear genome for components
E) None of the answers listed are correct.

Question 17

Researchers in the late 1950s isolated multiple antibiotic-resistant strains of the bacterium Shigella,which causes dysentery.Such resistance was caused by nonchromosomal R factors that originated in E.coli.Which of the following forms of extrachromosomal heredity-maternal effect,organelle heredity,infectious heredity-would you consider most closely related to the transfer bacterial antibiotic-resistant strains?

Question 18

Direction of shell coiling in the snail Lymnaea peregra is conditioned by a form of extrachromosomal inheritance known as ________.

A) sex-linked inheritance
B) heteroplasmy
C) maternal effect
D) independent assortment
E) epistasis

Question 19

What is the name of a form of extrachromosomal inheritance that is due to transmission of symbiotic or parasitic microorganisms?

Question 20

How do mitochondria and chloroplasts determine phenotypes? Which characteristics of mitochondria and chloroplasts allow such phenotypes to be inherited? Provide specific examples to illustrate your response.

Question 21

Describe the molecular and transmission characteristics of Leber's hereditary optic neuropathy (LHON).

Question 22

Kearns-Sayre syndrome (KSS)results in progressive loss of vision and hearing,as well as heart defects.What is the genetic basis for this disease?

Question 23

Poky strains in yeast result from suppressive mutations in chloroplast DNA.

Question 24

List three criteria indicating that a human disorder may be attributable to genetically altered mitochondria.

Question 25

Maternal-effect patterns result when nuclear gene products controlled by the maternal genotype condition the egg and influence early development.Give two examples of maternal effects.

Question 26

An example of organelle heredity involves pigmentation in Mirabilis jalapa.

Question 27

The genes for light eyes (lt; light)and straw bristles (stw; straw)are tightly linked on chromosome 2 in Drosophila melanogaster.The Malpighian tubes of lt larvae and adults are maternally affected in that Malpighian tubes of lt/lt organisms,whose mothers were lt⁺/ˡᵗ and have more yellow pigment than those from lt/lt mothers.There is no maternal effect associated with the straw locus.Give the phenotypes of the offspring from the following crosses.
Female Male
Cross #1: lt stw/lt stw lt⁺stw⁺/lt stw
Cross #2: lt⁺ stw/lt stw lt stw⁺/lt stw
Cross #3: lt⁺ stw⁺/lt stw lt stw/lt stw

Question 28

Inheritance of the green and white patches phenotype in Mirabilis jalapa (four o'clocks)is an example of maternal influence.

Question 29

What is the meaning of the term endosymbiotic theory?

Question 30

Molecular/structural orientations (gradients)in an egg are thought to play a significant role in development.What is the origin of such gradients? What evidence indicates that the maternal genotype is involved in providing such gradients?

Question 31

It appears as if the direction of shell coiling in Lymnaea peregra is influenced by the orientation of the first cleavage division.

Question 32

Name two human disorders that appear to be transmitted extrachromosomally.

Question 33

Direction of shell coiling in Lymnaea peregra is influenced by a maternal effect.

Question 34

In what way do segregational petite mutations differ from neutral petites?

Question 35

Mitochondrial mutations are passed equally to offspring by both males and females.

Question 36

It is safe to say that a maternal effect is caused by the genotype,not the phenotype,of the parent producing the egg.

Question 37

List two classes of extrachromosomal inheritance and give an example of each.