Transcript Whose got Genes? - Miss White`s Science Class

Traits & Dominance
ISN p. 31
What is GENETICS?
The study of how traits are
inherited through the interactions
of genes.
What is HEREDITY?
The passing of traits from parent to
offspring.
Review: What is an ALLELE?
The different forms of a
trait that a gene may have
Define TRAIT
A feature or characteristic
about an organism
Inherited Traits
Traits that you inherit from your
mom and dad – they are in your
DNA.
Eye color
Hair color
Height
Can you think of others??
Acquired Traits
Traits that you have to learn
from your environment
Riding a bike
Reading
Writing
Can you think of others??
Describe DOMINANT
A trait that covers over, or
dominates, another form of that trait
Trait that always shows up, even when
only one of the two alleles is in the
dominant form
Shown by a capital letter
Ex: Brown hair, B
Describe RECESSIVE
A trait that is covered up, or
dominated, by another form of that
trait and seems to disappear.
Hidden when the other copy of the
gene contains the dominant allele.
A recessive allele shows up only when
there is no dominant allele present
Shown with a lower-case letter
Ex: Blonde hair, b
CODOMINANCE
When two dominant alleles
occur together, they make
something half-way in between
the two traits.
Ex: In flowers, red is
dominant (R), white is also
dominant (W)
When they appear together,
RW = pink flowers
What is HOMOZYGOUS?
Both alleles are the same
When offspring inherit two
dominant genes, (one dominant
gene from each parent) they are
said to be homozygous dominant
(BB)
When offspring inherit two
recessive genes, (one recessive
gene from each parent) they are
said to be homozygous recessive
(bb)
What is HETEROZYGOUS?
When offspring inherit one dominant
gene and one recessive gene, they are
said to be heterozygous
Since the dominant gene will always be
expressed, they are said to be
heterozygous dominant
When offspring are heterozygous, they
are said to be a CARRIER of the
recessive trait
Hair color Bb, dominant allele is brown hair
Person is a carrier for blonde hair
In your ISN p. 30
Make a T-chart and list 10 of your
acquired traits and 15 inherited
traits. Be specific!
Summary: (5 sentence minimum)
Describe the difference between
dominant and recessive genes. Of
your inherited traits, which ones do
you THINK are dominant and which
are recessive? (It’s ok to guess!)