Transcript INHERITED TRAITS

•Inherited Traits-A
characteristic that is
passed from parent
to offspring.
• For example, Corn-Can you thing of inherited traits
it passes on?
kernel color
ear size
plant height
• Heredity-is the passing of these traits
from one generation to the next.
(Heredity applies to all organisms,
including plants, animals, and even
bacteria.)
• Genetics-is the study of how heredity
works.
• Pollination-is the transfer of pollen
grains from the male part of a flower
to the female part of a flower.
–Self-pollination is the pollination of a
flower’s female parts by pollen from
the male parts of the same flower.
–Cross-pollination takes place when
pollen from one flower is transported
to a different flower.
• Purebred-the same form of that trait
is shown in all of its offspring for
several generations.
• Hybrid-is an organism produced by
crossing parents that have two
different forms of the same trait.
• Dominant Traits-the form of the trait
that appears in the hybrid
generation.
• Recessive Traits-the form of the trait
hidden, or masked, in the hybrid
generation.
Gregor Mendel discovered principles
of heredity through gardening.
Gregor Mendel
• He grew up on his family’s farm. As he
learned how to take care of plants and
animals, he became curious about how traits
are passed from one generation to the next.
• Eventually, he became a science teacher and a
monk. He lived in a monastery and was in
charge of the gardens there.
• He began conducting controlled experiments
at the monastery.
Gregor Mendel made huge advances
in the area of biology.
This is what he did.
He crossed pea plants by taking a
paintbrush and transferred pollen from one
purebred pea flower to another purebred pea
flower. This is referred
to as cross-pollination.
Mendel’s Experiment
• Refer to handout
Traits in Garden Pea Plants Studied by
Mendel
Why did he use pea plants?
• Pea plants have distinct traits, which are easy
to trace from one generation to another.
• Since the pea plant flowers are reproductive
organs, you can see the male and female parts
easily. (Pea plants self-pollinate because male
and female parts are in the same flower.)
• Pea’s offspring grow and mature quickly.
• Easy to gather large amounts of data.
Mendel’s Experiment Concluded
Each tall hybrid in the first offspring
generation carried both tall and short traits.
Dominant traits - the trait in the hybrid generation that
was visible (tallness).
Recessive traits - the trait in the hybrid generation that
was hidden or masked (shortness).
In the second offspring, for every three
dominant traits there was one recessive,
or 3:1.
What is Probability?
• Probability means “how likely it is that
something will happen.
• The probability that something will happen
can be calculated using mathematics.
Example of Probability
• If you had a penny and
tossed it once in the air,
what would be the
probability of getting
heads?
• 50% or one out of two
Now You Try This
What if you toss a
penny 50 times? What
would the outcome
likely be?
25 heads and 25 tails
The greater the number
of trials the closer the
outcome will be to 50%.
Using Probability to Predict Genetic
Outcomes
• This is like tossing two coins at once.
• There are four possible outcomes
Heads-Heads
Tails-Tails
Heads-Tails
Tails-Heads
25%
25%
25%
25%
• The possible outcomes of two coins tossed are
very similar to those of a genetic cross.
• Geneticists use the laws of probability to
predict the results of genetic crosses. Why?
• There are two possible factors for a trait. Each
parent, like a coin, has two factors for a trait.
• Like tossing two coins, two parents give one
factor each for a trait to the offspring.
In the Punnett Square, letters are used
to represent Mendel’s factors for each
trait.
Dominant Factor
• Factor that appears most
often
• Always written with a
CAPITAL LETTER
• If a dominant and recessive
factor are together, you will
see the dominant factor
Recessive Factor
• Factor that appears less
often
• Always written with a
lowercase (“little”) letter
• Only way you see a
recessive factor is if there
are two recessive factors
together
Punnett Square Table is for predicting
outcomes of crossing different traits.
PARENT ONE
• Written across the top
PARENT TWO
• Written along the left side
• One letter per box
• One letter per box
You don’t inherit traits, you inherit
factors for traits.
TIME TO PLAY
Traits Bingo
• Mark the square marked I cross my right
thumb over my left when I clasp my hands if
this describes you.
• Mark the square marked Shared trait-Left if
you have a trait with the person sitting to your
left.
• Mark the square marked Least common trait if
you have a trait that no one else in your group
share.
• Mark the square Attached earlobes if you have
this trait.
• Mark the square Blue eyes if you have this
trait.
• Mark the square or squares naming the
relatives from whom you do not inherit traits.
• Mark the square marked I have allergies if you
have this trait.
• Mark the square marked Trait in commonRight if you and your neighbor to the right
share a common trait.
• Mark the square marked Detached earlobe if
you have this trait.
• Mark the square marked Straight hairline if
you have this trait.
• Mark the square marked Can not roll tongue if
you have this trait.
• Mark the square naming relatives from whom
you do inherit traits.
• Mark the square marked I have a different
trait than the person sitting next to me if this
describes you.
• Mark the square Curly hair if you have this
trait.
• Mark the square marked Freckles if you have
this trait.
• Mark the square marked Dimples if you have
this trait.
• Mark the square marked Cleft chin if you have
this trait.
• Mark the square marked I cross my left thumb
over my right when I clasp my hands if this
describes you.
• Mark the square Brown hair if you have this
trait.
• Have a GREAT day!
• I would like to give special thanks to Mrs. Johnson
for allowing me to be part of your classroom.
• I hope you learned something new and exciting.
• Thank you for allowing me to teach you about
inherited traits.