Phenotype plasticity | Heredity | AP Biology | Khan Academy

Summary

The video script discusses the concept of genotype and phenotype through the example of NASA astronauts and identical twins, Mark and Scott Kelly. It explains that despite sharing the same genetic information (genotype), observable characteristics (phenotype) can vary due to environmental influences, a phenomenon known as phenotype plasticity. The script highlights a study where Scott's year-long stay in space resulted in a 7% gene expression difference, illustrating the impact of the space environment on his phenotype, which differed from his twin brother's.

Takeaways

• 🌌 The script discusses two NASA astronauts, Mark and Scott Kelly, who are identical twins.
• 🧬 Genotype refers to the genetic information encoded in an organism's genes, which includes DNA sequences on chromosomes.
• 👤 Phenotype is the observable characteristics of an organism, which can vary even among individuals with the same genotype.
• 🌿 The environment plays a significant role in affecting an individual's phenotype, beyond the influence of their genes.
• 👬 Identical twins Mark and Scott Kelly have the same genotype, but their phenotypes are not identical due to environmental factors.
• 🚀 NASA conducted an experiment to study the effects of space travel on gene expression, focusing on Scott Kelly's extended stay in space.
• 🔍 Before and after Scott's space mission, scientists compared his body's expression of certain characteristics to his twin brother's.
• 🌌 Differences in mitochondria and gene expression were observed in Scott after his time in space, highlighting the impact of the space environment.
• 🔢 A significant 7% difference in gene expression was noted in Scott compared to his twin, demonstrating the extent of phenotype plasticity.
• 🌐 The space environment, characterized by low oxygen and high carbon dioxide levels, was theorized to have influenced Scott's gene expression and phenotype.
• 🧪 The study of the Kelly twins provides insights into how identical genotypes can result in different phenotypes due to environmental influences.

Q & A

Who are the two individuals in the picture mentioned in the script?

The two individuals in the picture are Mark Kelly and Scott Kelly, both NASA astronauts and identical twins.

What is the main focus of the script regarding Mark and Scott Kelly?

The script focuses on the concepts of genotype and phenotype, using Mark and Scott Kelly as examples to illustrate how environmental factors can influence phenotype despite identical genotypes.

What does the term 'genotype' refer to in the context of the script?

Genotype refers to the actual genetic information encoded in an organism's genes, which includes the DNA sequences on chromosomes that code for various proteins and characteristics.

What is meant by 'phenotype' as discussed in the script?

Phenotype refers to the observable characteristics of an organism, which can be influenced by both genetic information (genotype) and environmental factors.

Why might two people with the same genotype not have identical phenotypes?

Two people with the same genotype might not have identical phenotypes because environmental factors can influence how genes are expressed, leading to variations in phenotype.

What is the concept of 'phenotype plasticity' explained in the script?

Phenotype plasticity is the idea that the same genotype can result in variations of phenotype due to different environmental influences on gene expression.

What experiment did NASA conduct involving Scott Kelly to study phenotype plasticity?

NASA conducted an experiment where Scott Kelly spent an extended period in space while his twin brother, Mark, did not, to observe the effects of the space environment on gene expression and phenotype.

What were some of the differences found in Scott Kelly's body after his extended stay in space?

After Scott Kelly's extended stay in space, differences were found in his mitochondria and in the expression of certain genes, with a 7% difference in gene expression compared to before his space mission.

What environmental factors in space might have contributed to the changes in Scott Kelly's phenotype?

The environmental factors in space that might have contributed to the changes in Scott Kelly's phenotype include a low oxygen environment, high levels of carbon dioxide, and stressors associated with space travel.

How did the space environment affect the expression of Scott Kelly's genes, according to the script?

The space environment affected the expression of Scott Kelly's genes by causing changes in mitochondria and gene expression, resulting in a 7% difference in gene expression and demonstrating phenotype plasticity.

What does the comparison between Mark and Scott Kelly demonstrate about the influence of environment on phenotype?

The comparison between Mark and Scott Kelly demonstrates that even with the same genetic information (identical genotype), environmental factors can lead to differences in how genes are expressed, affecting the observable characteristics (phenotype) of an individual.