Transcript Animal Growth and Heredity

Animal Growth and Heredity
Growth and Development
• All living things start life as a
single cell. One cell divides
into 2, 2 into 4 and so on.
• All living things grow and
most pass through stages.
• The stages an organism
pass through make up a life
cycle.
• A life cycle starts with a
fertilized egg.
Cell Division
• Mitosis is the process by
which most cells divide.
Changes first take place
in the nucleus.
• Chromosomes are the
threadlike structures
found in the nucleus.
• During mitosis a new cell
gets an exact copy of
chromosomes.
How are characteristics inherited?
• An inherited trait is a
characteristic passed
from parents to
offspring.
• In humans, hair, eye
color, skin, freckles,
and the shape of our
earlobes are
inherited.
Gregor Mendel
• In 1857 Mendel began experimenting
with pea plants to learn how traits were
inherited.
• Through experimentation, Mendel
learned that each parent passes one pair
of its factors to an offspring.
• He learned that traits can skip a
generation.
• He also learned that the height of pea
plants depended on the factors they
inherited from their parents.
Dominant & Recessive Traits
• Dominant traits are
strong traits. If an
organism has 1 factor
for a dominant trait,
that trait will appear.
• Recessive traits are
weak traits.
Genes
• A gene is the part of a
chromosome that contains
DNA.
• A combination of about
20,000 different genes that
we inherit from our parents
make us unique.
Instincts
• A behavior that
organisms develop.
• They are passed from
parents to offspring.
• Behaviors for building
homes and caring for
young are usually
instinctive.
• Birds know how to
instinctively build their
nests.
• Instinctively animals know
that they must hunt for
food.
Learned Behaviors
• Some animals instinctively
know that they must hunt.
They must learn how to
hunt.
• A learned behavior is a
behavior obtained through
experience.
• Most behavior is learned
through the teaching by
adults of the same species.
Environmental Influences
• Some behaviors and
characteristics are a
result of environmental
influences.
• All living and nonliving
things that affect an
organism make up its
environment.
• Changes in the
environment can cause
animals to change their
behaviors.
Video
Video
Questions
• How does cell division affect growth?
• What characteristics are inherited?
• What other factors affect characteristics?