7.2 Cytoplasmic Inheritance SV - Tagged

Cytoplasmic Inheritance

Overview

• Cytoplasmic inheritance refers to the genetic material that is not located in the nucleus of a cell.

Genetic Material in Cytoplasm

• Mitochondria and chloroplasts have their own genomes that are found in the cytoplasm.

Characteristics of Cytoplasmic Inheritance

Inheritance Patterns

• Genes undergoing cytoplasmic inheritance are:

  • Present in both males and females.

  • Exclusively inherited from the maternal parent.

  • Exhibit variability in phenotype within a cell and within an individual due to the lack of a mechanism like mitosis or meiosis for equal segregation of cytoplasmic genes/alleles.

Mitochondrial Genome Details

Features of Mitochondrial DNA

• Mitochondria possess their own genome consisting of:

  • 16,569 nucleotides

  • 37 genes

  • Thousands of mitochondria are present per cell.

  • Each mitochondrion contains 2-10 copies of the mitochondrial genome.

  • Mitochondria segregate randomly during cell division, leading to significant variation within a single cell and across all cells in an organism.

Random Segregation of Mitochondria

Process During Cell Division

• Mitochondria segregate randomly during cell division, resulting in progeny cells with varying numbers of mitochondria having wild-type (normal) genes (red) and mutated genes (blue).

  • This random segregation leads to discrepancies in gene expression and phenotypic outcomes in daughter cells.

Example of Cytoplasmic Inheritance

Experimental Methods

• Method involves crossing flowers from:

  • White branches

  • Green branches

  • Variegated branches

  • All combinations of pollen plants used as male contributors.

Results Observed

• The results of these crosses yield different phenotypes, including:

  • White

  • Green

  • Variegated

• The distribution showcases the range of color expressions resulting from cytoplasmic inheritance.