Question

In many organisms, organelles, such as the mitochondria, are transmitted only by the egg. This phenomenon is known as a. biparental inheritance. b. paternal inheritance. c. X-linked inheritance. d. maternal inheritance. e. both c and d.

Short answer

The correct answer is 'd. Maternal inheritance'.

Step-by-step solution

Recognizing the Mode of Inheritance

This exercise asks to identify the inheritance mode where organelles such as mitochondria are transmitted only by the egg. The key point here is that the transmission of mitochondria happens only through the egg.

Analysing the Options

Let's examine the provided options: a. Biparental inheritance: This option suggests that something is inherited from both parents. But in the case process stated, mitochondria are only transmitted through the egg (the mother), not from both parents.b. Paternal inheritance: This refers to something inherited from the father. But again, this doesn't match our scenario as the mitochondria are only transmitted through the egg (the mother).c. X-linked inheritance: Refers to the inheritance of genes located on the X chromosome. This is not the case here as the question is about the inheritance of organelles, not particular genes nor chromosomes.d. Maternal inheritance: This denotes something inherited from the mother. Since the mitochondria are only transmitted through the egg (which comes from the mother), this matches our scenario.e. Both c and d: Since we've already determined c is incorrect, we can rule out e.

Determine the Correct Answer

Based on the information in the question and the analysis of our options, the answer should be option 'd'. Maternal inheritance corresponds to the type of inheritance where the mitochondria (an organelle) are transmitted only by the egg (mother).

Key concepts

Mitochondria

Mitochondria are fascinating organelles found in both plant and animal cells. They are often referred to as the powerhouses of the cell because they provide energy for cellular processes.
The energy is generated through a process called oxidative phosphorylation, producing ATP, which cells use as a source of fuel. What makes mitochondria unique is that they have their own DNA. This mitochondrial DNA (mtDNA) is separate from the DNA contained in the cell nucleus.
Unlike nuclear DNA, which is inherited from both parents, mitochondrial DNA is inherited solely from the mother.

• Mitochondria have a circular DNA structure, similar to that of bacteria.
• They replicate independently within the cell.
• They are critical for energy production, iron-sulfur cluster biogenesis, and controlling the life cycle of cells.

Mitochondria play a crucial role in cellular metabolism and hold vital importance in medical studies related to genetic disorders and inheritance mechanisms.

Organelles

Organelles are specialized structures within a cell that perform distinct functions. They can be thought of as tiny organs working in harmony within the greater system of a cell.
This specialization allows cells to be highly efficient and adaptive to different environments and tasks. Some of the most well-known organelles include:

• Nucleus: The control center of the cell containing most of the cellular DNA.
• Mitochondria: Known for their role in energy production, as already discussed.
• Chloroplasts: Present in plant cells, these organelles conduct photosynthesis.
• Ribosomes: Involved in protein synthesis.

Cells rely on cooperation among various organelles to maintain homeostasis and respond to environmental changes.
Each organelle has a unique role, but they work collaboratively to ensure the cell functions efficiently.

Inheritance Patterns

Inheritance patterns describe how genetic traits or contents are transmitted from parents to offspring. Understanding these patterns helps scientists predict how certain traits or diseases may be passed on.
There are several inheritance patterns to consider:

• Mendelian Inheritance: Traits passed according to dominant and recessive allele interactions, as proposed by Gregor Mendel.
• Non-Mendelian Inheritance:
  • Includes patterns like incomplete dominance, where neither allele is completely dominant.
  • Codominance, where both alleles show their effects.

Maternal inheritance, which is our focus here, is non-Mendelian because it involves the transmission of organelles, like mitochondria, from the mother.
It bypasses the paternal genetic influence when it comes to mitochondrial DNA, leading to unique inheritance patterns in certain conditions.

Egg Transmission

Egg transmission refers to the process by which certain organelles and genetic materials are specifically passed on through the egg of the mother.
This type of transmission is a key aspect of maternal inheritance and is opposed to the genetic transmission through sperm. In most organisms, mitochondria—and thus mitochondrial DNA—are transmitted exclusively through the egg during fertilization.

• Selective Transmission: Only mitochondria from the egg contribute to the offspring, excluding paternal mitochondria.
• Cytoplasmic Factors: Along with mitochondria, other cytoplasmic elements within the egg can influence early development and organ formation.

Egg transmission highlights the critical role mothers play in determining certain aspects of their offspring's genetic makeup.
This mechanism leads to consistent maternal lineage tracking in studies of population genetics and evolutionary biology.