Module 4 Extrachromosomal inheritance

Question 1

The characteristics showing ___ still conforms with the principles of chromosomal genetics but sidetracked by the ties of a parent.

Answer 1

delayed inheritance

Question 2

2 important features in the egg resulting to maternal inheritance:

Answer 2

• The orientation of the mitotic spindle axis
• The high cytoplasmic continuity between the egg and the zygote with very little or no contribution from the sperm

Question 3

production of ___ which is involved in pigment synthesis of flour moths.

Answer 3

KYNURENIN

Question 4

Note that while the female gamete contributes all its genome to the zygote, the male gamete only contributes nuclear genome in a ___.

Answer 4

haploid dose

Question 5

___of zygote is derived from the oocyte. A mother will pass it to her children but only her daughter will transmit it to her progeny

Answer 5

Mitochondrial DNA (mtDNA)

Question 6

the presence of a uniform collection of mtDNA; either completely normal mtDNA or completely mutant mtDNA

the presence of some mitochondria that have a mutation
in the mtDNA and some that do not - often associated with a disease

Answer 6

Homoplasmy

Heteroplasmy

Question 7

TRUE or FALSE: conditions that are transmitted via mtDNA vary in terms of severity based on the number of bad mitochondria a cell receives

Answer 7

TRUE

Question 8

Mutation in mitochondrial genome in the yeast, Saccharomyces cerevisiae, produces ____strains which can grow on media
with only non-fermentable carbon sources (ex: glycerol and ethanol) and form small anaerobic colonies

it is concluded that these mutants have a defective aerobic respiratory mechanism

Answer 8

PETITE

Question 9

In fungi, Neurospora crassa, a number of mutations of mitochondria are inherited via the female parent. In Neurospora crassa, ____ has low activity of respiratory enzymes due to defective cytochrome complement in mitochondria.

Cyt a and cyt b are absent and cyt c is excessive.

As a result, this mutant is slow-growing. It is cytoplasmic.

Answer 9

POKY strain

Question 10

• Mutation in Electron Transport Chain proteins, Cytochrome Oxidase and ATPase
• Results to partial or complete blindness from optic nerve degradation

Answer 10

Leber’s hereditary optic neuropathy (LHON)

Question 11

• Neuromuscular defects due to large deletions in mtDNA
• Accumulation of pigments in retina

Answer 11

Kearns-Sayre Syndrome (KSS)

Question 12

TRUE or FALSE: * The rate of mutation in mtDNA is 10 to 17 times higher than nuclear gene.

Answer 12

TRUE

Question 13

Several possible factors that may cause this high mutation rate can include: (3)

Answer 13

➢ insufficient DNA repair system
➢ lack of proteins such as histones
➢ spontaneous error arising during DNA replication

Question 14

As shown in their role as vectors in recombinant DNA technology,___are capable of self-perpetuation and independent transmission and may therefore be considered as genetic units fully equal to those in the chromosomes.

Answer 14

PLASMIDS

Question 15

Criteria for Extrachromosomal Inheritance: (5)

Answer 15

Maternal Inheritance:

Non-Segregation:

Non-Mendelian Segregation:

Indifference to nuclear substitution:

Infection-like transmission: