9 EXTRACHROMOSOMAL INHERITANCE Flashcards
Extrachromosomal inheritance also known as?
cytoplasmic inheritance or extranuclear inheritance
- the inheritance of traits that are not controlled by chromosome genes
extrachromosomal inheritance
- this form of inheritance occurs in the cytoplasm of cells and involves genes present in cytoplasmic organelles
- the extrachromosomal hereditary factors have the ability to____ and can be transmitted sexually or asexually
self-replicate
extrachromosomal inheritance is discovered by?
Boris Ephrussi
Criteria of Extrachromosomal Inheritance
- ____ follow the typical Mendelian Inheritance pattern
- inheritance of extrachromosomal factors is ____ of genes located within the cell nucleus
- in some cases, extrachromosomal traits are inherited exclusively from the ____.
- extrachromosomal inheritance can lead to characteristic phenotypic changes that are not inherited in a Mendelian pattern
- extrachromosomal genes can exhibit ____ which is rare in nuclear genes
does not
independent
mother
(This is because the egg contributes more cytoplasm to the zygote compared to the male parent)
vegetative (somatic) segregation
(random distribution of cytoplasmic elements during cell division in asexual reproduction)
types of exrachromosomal inheritance
chloroplast inheritance
mitochondrial inheritance
Possesses own DNA of chloroplast and mitochondria is called
cpDNA
mtDNA
who discovered chloroplast inheritance
Carl Correns and Erwin Baur in 1909
Correns conducted a study on?
and how?
Mirabilis jalapa (four o’clock)
he observed that the transmission of leaf color was strictly maternal, determined by the color of the ovule’s source
Baur experimented on?
and how?
geranium
(Pelargonium zonale)
chloroplast genes can also be inherited from both parents or from the male parent only, resulting in variegated plants
- Recent research conducted at the Max Planck Institute of Molecular Plant Physiology with ____ plants presents new evidence that challenges the commonly held belief that chloroplasts are solely inherited from the mother plant
tobacco
- The researchers discovered that ____, chloroplasts from the father can also be passed on to the offspring
under specific environmental conditions
mtDNA is main form of EI in?
animals
2 characteristics of mtDNA
- circular and
- encodes 37 genes on 16.5kb of DNA
kb - kilobase
who discovered mtDNA?
Margit and Sylvan Nass 1963
- Mitochondria are primarily inherited ____
uniparentally, mostly maternally.
The zygote receives mitochondria exclusively from the mother, while the paternal contribution of mitochondria is minimal or negligible
In biparental inheritance (mtDNA), children can inherit mtDNA from their fathers by?
mitochondrial DNA fragments can migrate into the nucleus and integrate with the chromosomes
- These mitochondrial DNA fragments are inherited alongside the nuclear chromosomes but the primary inheritance of mitochondrial DNA still occurs from the mother
- Mode of inheritance where genetic material or traits are inherited from a single parent, either the mother or the father
Uniparental Inheritance
- The genomes of extrachromosomal organelles are maternally inherited in most ____
eukaryotes
example of uniparental inheritance
- Carl Correns’ experiments with four o’clock plants also demonstrated uniparental inheritance of chloroplast DNA, specifically through the maternal parent
- Less common form of extrachromosomal inheritance where genetic material from both parents contributes to the traits encoded by the extrachromosomal organelles
Biparental Inheritance
example of biparental inheritance
- Baur, 1909, observed the inheritance of leaf phenotypes in Pelargonium cultivars, describing the transmission of chloroplasts through biparental inheritance
- Involves the random distribution of cytoplasmic elements during cell division in asexual reproduction
vegetative segregation
in vegetative segregation, extrachromosomal DNA within the cytoplasm is ____ into daughter cells, resulting in ____ distribution of cytoplasmic content
randomly segregated
unequal
5 Significance of Extrachromosomal Inheritance
- Understand Evolutionary process
- Trace maternal lineages
- Understand inherited disorders
- Forensic identification (act as fingerprint for ID purposes)
- Mapping cp and mt genomes
4 Challenges in Studying Extrachromosomal Inheritance
- Studying inheritance pattern
- Complexity of EI
- Exact characteristics and components are unclear
- Extrachromosomal hereditary factors could be lost through selection
