Inheritance Explained || How do we inherit features from our parents?

Summary

DNA, Chromosomes, and Genes

DNA is arranged into chromosomes. A gene is a section of DNA containing instructions that can influence a feature, such as hair or eye color.

People generally share the same genes, but genes can have different versions called alleles. Different combinations of alleles contribute to differences between people.

How Genes Are Inherited

Humans typically have 23 pairs of chromosomes. A child inherits one chromosome of each pair from each parent, and therefore two copies—two alleles—of each gene.

When egg and sperm cells form, they each receive 23 chromosomes. Which chromosome from each pair is passed on is random.

Dominant and Recessive Alleles

The video uses uppercase F for the normal allele and lowercase f for the cystic fibrosis allele. In this example, F is dominant and f is recessive. A person with Ff does not have cystic fibrosis, because the dominant allele is expressed, but they can pass the recessive allele to a child.

Cystic Fibrosis Example

Cystic fibrosis can cause sticky mucus in the lungs and digestive system, leading to problems such as lung infections and difficulty with digestion. In the example, a person develops cystic fibrosis after inheriting two recessive f alleles.

When both parents are carriers (Ff), each can pass on either F or f. The four equally likely combinations are FF, Ff, Ff, and ff. For each child, this means:

• 25% chance of having cystic fibrosis (ff)
• 50% chance of being a carrier without the disease (Ff)
• 25% chance of inheriting two normal alleles (FF)

The video concludes that genetic diagrams can be used to calculate inheritance probabilities.

Speaker and Source

The video features one unnamed narrator presenting an educational explanation for Science Sauce.