Video Transcript
Following on from Mendel’s work,
some laws of inheritance were written. Which law of inheritance describes
how factors that produce certain traits are separated from each other when gametes,
sex cells, are formed? (A) The law of segregation, (B) the
law of independent assortment, (C) the law of dominance.
Gregor Mendel conducted research on
hereditary and pea plants and used his work to postulate three laws. The first law is the law of
independent assortment. This states that genes segregate
independently during gamete, or sex cell, formation. A gene is a sequence of DNA that
contains the information needed to produce a certain characteristic, for example,
flower color. So, when an offspring inherits the
characteristic of flower color, this is independent of inheriting another
characteristic, like seed color. These two characteristics aren’t
linked.
The second law is the law of
dominance. Here, one trait can conceal another
trait for the same characteristic. So, with the characteristic of
flower color, we can have a plant with two flower color traits, like yellow and
pink. This is caused by two different
versions of the flower color gene. And suppose if we breed these
plants, we only see yellow flower plants as offspring. The gene version for the yellow
flower trait in this case is said to be dominant to the gene version for the pink
flower trait because it conceals its expression.
The third law is the law of
segregation. This states that an organism has
two copies of a gene that are separated when gametes form. This gene can exist as different
versions to make different traits for a characteristic. So, let’s say we have the
characteristic of seed color and two traits, yellow and green seed color. We’ll represent the yellow seed
color version as an uppercase Y and the green seed color version as a lowercase
y.
The organism has two copies of this
gene, one is the uppercase Y and the other is lowercase y. When gametes are produced, each
gamete will receive one copy. So here, we have two gametes being
formed, each with one copy of the gene, either the yellow seed color version or the
green seed color version. So, these different versions of the
gene that produce different traits are separated when gametes are formed.
Therefore, the correct answer is
(A), the law of segregation.
