Page 189 - Science Course 3 (Book 1)

Mo5-L1a: How are Traits Passed?

How are traits inherited?

An organism passes its traits to its offspring in
one of two ways—through asexual reproduction or
through sexual reproduction.

In asexual reproduction, one organism makes a copy
of its genes and itself.

In sexual reproduction, offspring receive half of their
genes from an egg cell and the other half from a
sperm cell.
Why do scientists study genetics?
Sexual
Scientists began studying genetics to understand
how traits are inherited.

Parent By studying genetics, scientists have learned that
genes control how organisms develop.

Studying genetics can help scientists determine how
organisms are related.

Offspring

Mixture of both parents

Asexual Because the genes
from these organisms
are similar enough to produce normal eyes when
exchanged, scientists suspect that these species
share a common, ancient ancestor

Experiment A

Identical to parent

Key Concept

How are Traits Passed?
Scientists removed the gene that The fruit fly developed
How are Traits Passed? controls eye development from a normal eyes
mouse and inserted it into the
embryo of a fruit fly.
Experiment B

Scientists removed the gene that The frog developed
controls eye development from a normal eyes.
fruit fly and inserted it into a frog
embryo
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