Full Answer Section

• Teratogens: Agents that can cause birth defects or abnormalities in a developing embryo or fetus.

2. Prior Knowledge of Genetics

Based on my understanding of genetics, I know that:

• Genes are the basic units of heredity that carry genetic information from parent to offspring.
• Genes are located on chromosomes, which are thread-like structures in the nucleus of a cell.
• Genetic information is passed down from generation to generation through the process of meiosis and fertilization.
• Genetic variations can influence physical traits, diseases, and other aspects of an individual’s development.

3. Conception Process from “Life Before Birth”

From the video “Life Before Birth,” I learned that the conception process involves the following steps:

1. Ovulation: A mature egg is released from the ovary.
2. Fertilization: A sperm cell penetrates the egg cell and fertilizes it, forming a zygote.
3. Implantation: The zygote travels through the fallopian tube and implants in the uterine wall.
4. Cell Division: The zygote begins to divide and grow, eventually developing into an embryo.

4. Monozygotic vs. Dizygotic Twins

• Monozygotic twins: Identical twins formed from a single fertilized egg that splits into two separate embryos. They share the same genetic material.
• Dizygotic twins: Fraternal twins formed from the fertilization of two separate eggs by two separate sperm. They are genetically different, like any other siblings.

5. Teratogen Influences Under Maternal Control

Expecting mothers can potentially control the following teratogen influences:

• Alcohol consumption: Avoiding alcohol consumption during pregnancy can significantly reduce the risk of fetal alcohol spectrum disorders.
• Drug use: Abstaining from drug use, including prescription medications, illegal drugs, and over-the-counter medications, can minimize the risk of teratogenic effects.
• Nicotine exposure: Quitting smoking or avoiding secondhand smoke can prevent harm to the developing fetus.
• Diet: Consuming a balanced and nutritious diet can provide essential nutrients for fetal development and reduce the risk of certain birth defects.

6. Teratogen Influences Beyond Maternal Control

Some teratogen influences may be difficult or impossible for expecting mothers to control, including:

• Radiation: Exposure to radiation, such as from X-rays or environmental sources, can increase the risk of birth defects.
• Environmental pollutants: Exposure to certain environmental pollutants, such as lead or mercury, can harm the developing fetus.
• Maternal infections: Certain infections, such as rubella, toxoplasmosis, and Zika virus, can have adverse effects on fetal development.
• Genetic factors: In some cases, genetic factors can contribute to birth defects, even in the absence of other risk factors.

7. Impact of Genes on Human Development

Genes play a significant role in human development, influencing physical traits, cognitive abilities, and susceptibility to diseases. However, it is important to note that environmental factors also interact with genes to shape development. This concept is known as nature versus nurture. Genetic factors can predispose individuals to certain conditions or traits, but environmental factors can influence how those genes are expressed.