In the context of recent advances in human reproductive technology, "Pronuclear Transfer" is used for
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- Afertilization of egg in vitro by the donor sperm
- Bgenetic modification of sperm producing cells
- Cdevelopment of stem cells into functional embryos
- Dprevention of mitochondrial diseases in offspring
Show answer
Answer: (D) prevention of mitochondrial diseases in offspring
Pronuclear Transfer is a technique used to prevent mitochondrial diseases from being passed from mother to child.
Here's how it works in simple terms:
Every cell has two types of DNA — nuclear DNA (from both parents) and mitochondrial DNA (only from the mother).
Some mothers carry defective mitochondrial DNA that causes serious diseases.
Pronuclear transfer solves this by:
- Fertilizing the mother's egg with the father's sperm (creating a zygote with the parents' nuclear DNA but defective mitochondrial DNA).
- Separately fertilizing a healthy donor woman's egg with the father's sperm.
- Removing the nuclear DNA from the donor's fertilized egg (keeping only the healthy mitochondria).
- Transferring the parents' nuclear DNA into the donor's egg.
Result: The baby has nuclear DNA from both parents (so it looks like them) but healthy mitochondrial DNA from the donor.
This prevents mitochondrial diseases.
The baby essentially has genetic material from three people — sometimes called "three-parent babies."
Answer: D (Prevention of mitochondrial diseases in offspring).
Key Takeaway: Pronuclear Transfer = preventing mitochondrial diseases = three-parent baby technique.
Pronuclear transfer creates 'three-parent babies' by replacing defective mitochondrial DNA from the mother with healthy mitochondrial DNA from a donor while preserving both parents' nuclear DNA.
The UK became the first country to legalize three-parent IVF techniques in 2015, making mitochondrial replacement therapy a significant international biotechnology development that UPSC began testing.
UPSC is testing whether students can distinguish between different reproductive technologies - fertilization techniques versus genetic disease prevention methods.
Pronuclear Transfer
Science And Technology Pronuclear Transfer
Pronuclear Transfer: Three-Parent Baby Technique
Pronuclear Transfer prevents mitochondrial diseases from mother to child
Creates three-parent babies with nuclear DNA from parents + healthy mitochondrial DNA from donor
Also called Mitochondrial Replacement Therapy (MRT)
First successful case reported in 2016
Pronuclear Transfer is a reproductive technique that prevents serious mitochondrial diseases from being passed from mother to child. The procedure creates embryos with genetic material from three people — earning the nickname 'three-parent babies'.
How Pronuclear Transfer Works
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Fertilization**
Mother's egg fertilized with father's sperm (contains defective mitochondrial DNA)`"]
s2["`**Donor Preparation**
Healthy donor woman's egg fertilized with father's sperm`"]
s3["`**Nuclear DNA Removal**
Nuclear DNA removed from donor's fertilized egg, keeping only healthy mitochondria`"]
s4["`**Transfer**
Parents' nuclear DNA transferred into donor's egg with healthy mitochondria`"]
s5["`**Result**
Baby has parents' nuclear DNA + donor's healthy mitochondrial DNA`"]
s1 --> s2
s2 --> s3
s3 --> s4
s4 --> s5DNA Sources in Pronuclear Transfer
DNA Type | Source | Percentage | Function |
|---|---|---|---|
Nuclear DNA | Both parents | ~99.9% | Physical traits, personality, intelligence |
Mitochondrial DNA | Healthy donor | ~0.1% | Cellular energy production |
This technique directly answers the question by preventing mitochondrial diseases in offspring — not fertilization (Option A), sperm modification (Option B), or stem cell development (Option C).
Trap: Option A sounds like IVF, but pronuclear transfer goes beyond simple fertilization
Trap: Option B mentions genetic modification, but it's not about altering sperm cells
Trap: Option C involves stem cells, but this technique works with fertilized eggs, not stem cell conversion
Mitochondrial Diseases
Science And Technology mitochondrial diseases
Mitochondrial Diseases: Maternal Inheritance Pattern
Mitochondrial diseases pass only from mother to children
Affect cellular energy production leading to organ failure
Examples: Leigh syndrome, MELAS, Leber hereditary optic neuropathy
Cannot be treated by conventional gene therapy
Mitochondrial diseases result from defects in mitochondrial DNA (mtDNA), which is inherited exclusively from the mother. Unlike nuclear DNA, mitochondria have their own small genome that controls energy production in cells.
Key Characteristics
Maternal inheritance: Father's mitochondria are eliminated during fertilization
Energy deficiency: Affects high-energy organs like brain, heart, muscles
Progressive symptoms: Worsen over time as cellular energy decreases
No nuclear gene therapy: Cannot be fixed by modifying nuclear DNA
Common Mitochondrial Diseases
Disease | Primary Symptoms | Organs Affected | Severity |
|---|---|---|---|
Leigh Syndrome | Developmental delays, seizures | Brain, nervous system | Severe |
MELAS | Stroke-like episodes, dementia | Brain, muscles | Progressive |
Leber Neuropathy | Vision loss | Optic nerves | Moderate |
Trap: These diseases follow maternal inheritance, not Mendelian patterns
Trap: Mitochondrial DNA is separate from nuclear DNA — different inheritance rules
Three-Parent Baby Technology
Science And Technology three-parent babies
Three-Parent Baby Technology: Scientific & Ethical Aspects
Baby receives genetic material from three people: mother, father, and mitochondrial donor
UK was first country to legalize this technique
Donor contributes only 0.1% of total genetic material
Alternative technique: Maternal Spindle Transfer
The term 'three-parent babies' refers to children born through mitochondrial replacement therapy. Despite the name, the donor contributes only mitochondrial DNA — less than 0.1% of total genetic material.
Genetic Contributions
# Three-Parent Baby
## Mother
- Nuclear DNA (49.95%)
- Physical traits
- Genetic diseases risk
## Father
- Nuclear DNA (49.95%)
- Y chromosome
- Physical traits
## Donor
- Mitochondrial DNA (0.1%)
- Cellular energy
- Disease preventionMitochondrial Replacement Techniques
Technique | When Performed | Process | Success Rate |
|---|---|---|---|
Pronuclear Transfer | After fertilization | Transfer nuclear DNA between fertilized eggs | Higher |
Maternal Spindle Transfer | Before fertilization | Transfer nuclear DNA between unfertilized eggs | Lower |
Trap: Despite 'three parents', donor contributes minimal genetic material
Trap: Different from surrogacy — genetic modification, not just carrying pregnancy
Assisted Reproductive Technology
Science And Technology fertilization of egg in vitro
Assisted Reproductive Technology: Modern Techniques
IVF is fertilization outside the body in laboratory conditions
ICSI injects single sperm directly into egg
PGD screens embryos for genetic diseases before implantation
Success rates vary by age and technique
Assisted Reproductive Technology (ART) includes all fertility treatments where eggs or embryos are handled outside the body. These techniques help couples overcome various fertility challenges.
Major ART Techniques
Technique | Full Name | Process | Used For |
|---|---|---|---|
IVF | In Vitro Fertilization | Egg + sperm fertilized in lab | Blocked tubes, low sperm count |
ICSI | Intracytoplasmic Sperm Injection | Single sperm injected into egg | Severe male infertility |
PGD | Preimplantation Genetic Diagnosis | Genetic screening of embryos | Hereditary diseases |
Pronuclear Transfer | Mitochondrial Replacement | Three-parent technique | Mitochondrial diseases |
ART Applications
# Assisted Reproductive Technology
## Infertility Treatment
- IVF
- ICSI
- Surrogacy
## Disease Prevention
- PGD
- Pronuclear Transfer
- Genetic Screening
## Research
- Stem Cell Studies
- Embryo Research
- Fertility EnhancementTrap: Option A describes basic IVF, not the specialized pronuclear transfer
Trap: All ART involves lab fertilization — the key is why pronuclear transfer is used