Download GENETICS

GENETICS
How are traits passed from parents to offspring?
CO Science Standard
Organisms reproduce and transmit genetic
information (genes) to offspring, which
influences individuals' traits in the next
generation.
Warm-up
1. Answer the "Inquiry" questions on page 668.
2. Complete the "What do you think" activity
on page 669.
Objective
Explain how Mendelian traits are inherited.
Human traits
The traits listed below are based on heredity...but not
necessarily simple Mendelian genetics.
Trait
Phenotype 1
Phenotype 2
Dimples
Yes
No
Thumbs
Curved
Straight
Earlobes
Unattached
Attached
Tongue roller
Yes
No
Interlacing fingers
Left thumb over right
Right thumb over left
Widow's peak
Yes
No
Objective
Summarize Mendel's work and how it increased
our knowledge of genetics.
Warm-up (Copy)
● Gregor Mendel
Austrian
Monk
mid 1800's
genetic experiments
involving pea plants
○ disproved blending
inheritance
○ "father of genetics"
○
○
○
○
● Vocabulary
Trait characteristic of an
organism
Phenotype - how a
trait is expressed
●
●
Guiding Questions
● Why did Mendel use pea plants in his
experiments?
● What is the difference between a dominant
traits and recessive traits?
Assignment
Part I
Part II
Use the textbook (pages
672-677) and notes to write
a lab report for Mendel's
genetics experiments.
Include the following:
● Testable question
● Materials
● Procedure
● Results
● Conclusion
Section Review (p. 678)
Numbers 7,8,9
Objective
Predict the outcome of genetic crosses
Warm-up
Explain the following experiments. Use the
terms true-breeding, hybrid, dominant, and
recessive.
Experiment 1.
A purple flower is cross-pollinated with a
white flower and all of the offspring are
purple.
Experiment 2.
A purple flower is cross-pollinated with a
purple flower and some of the offspring are
white.
Notes
● Two genes per trait, one from each parent
● Dominant genes represented by CAPITAL
letter (B)
● Recessive gene represented by lower case
letter (b)
● Use same letter for same trait
● Homozygous dominant (BB)
● Homozygous recessive (bb)
● Heterozygous (Bb)
Examples
See pea plant genetics guide
1.
2.
3.
4.
5.
Homozygous dominant tall = TT
Homozygous recessive wrinkled = rr
Heterozygous purple flower = Pp
Yellow seed = yy
Heterozygous round seeds = Rr
With partners
Create 3 examples of your own and have your
partner try to answer them.
Check for understanding Use your pea plant genetics guide
1. Rr
2. tt
3. PP
Punnett Square
Punnett Square basics
1.
2.
3.
4.
5.
Place genes of one parent on top.
Place genes of other parent on left side.
Copy genes across each row.
Copy genes down each column.
Always write dominant gene first.
Examples
1. If two white flower pea plants are crossed,
what is the predicted outcome?
2. If two pea plants that are homozygous for
yellow seeds are crossed, what is the
3. If a pea plant heterozygous for round seeds is
crossed with a pea plant with wrinkled seeds,
what is the predicted outcome?
4. If two pea plants heterozygous for purple
flowers are crossed, what is the predicted
outcome?
Practice
1. If two plants are homozygous for rounds
seeds, what is the expected outcome?
2. If a heterozygous tall pea plant is crossed
with a dwarf pea plant, what is the expected
outcome?
3. Using a Punnett Square, show how two plants
with purple flowers can produce offspring with
white flowers.
With a partner
Write your own genetics problem and give to a
partner to solve.
DOL
In humans, dark eye color (D) is dominant over
light eye color (d). Use a Punnett Square to
show how two parents with dark eyes can have
a child with light eyes.