Download Chapter 8 Lesson 1

Chapter 8
Lesson 1
“Principles of Genetics”
I. Intro Activity
What similarities can you identify about the
fish shown in the following pictures?
II. Origin of Genetics
A. Mendel (1822-1884)
1. History
a. Was a monk in Czechoslovakia
b. Went to school as a science and
math teacher
c. Returned to being a monk
-tended the monastery garden
-experimented with plants
2. Experiments
a. Used common pea plant
b. Characteristics remained the same
-Purple/white, long/short stem
c. Conducted many experiments over
many generations
d. Fig 8-3 “Mendel’s seven traits”
Seed
Shape
Seed
Color
Flower
Color
Flower
Position
Pod
Color
Pod
Shape
Plant
Height
Dominant
Round
Yellow
Purple
Axial
green
Inflated
Long
Recessive
wrinkled
green
white
Terminal
Yellow
constricted
short
3. Results
x
ww
WW
F1
Ww
Ww
Ww
Ww
x
Ww
Ww
F2
WW
Ww
Ww
ww
a. Dominant – the trait that is
expressed. (tall, blue eyes, etc.)
b. Recessive – the trait that is not
expressed. It is carried from
generation to generation.
c. Principle of Dominance – The
dominant trait being carried out instead
of the recessive trait.
4. Hypothesis
a. F1 – no recessive traits are shown
b. F2 – recessive traits appear
c. Traits come from parents ( ½ sperm /
½ egg)
-called characters (genes)
-dominant = capital
-recessive = lower case
d. Punnett Square – chart used to predict
combinations of genes among offspring.
-each square represents a possible
zygote.
Parent #1
Parent #2
Tt
Tt
Tt
Tt
T = tall plant
t = short plant
What is the % chance a tall plant is produced in F1? 100%
5. Terminology
a. Allele – each alternative forms of a
gene. (W (purple) / w (white))
b. Genotype – the combination of
given traits (WW, Ww, ww)
c. Phenotype – the appearance of a
trait (what is dominant) Ww = purple
d. Homozygous – a cell that has 2 of
the same traits. (WW / ww)
e. Heterozygous – a cell that has 2
different traits. (Ww)
6. Two Trait
a. Use the FOIL method
b. Ex: (RrYy) x (RrYy)
-group similar traits
Parent #1 (Rr)
Firsts - RY
Outers - Ry
Inners - rY
Lasts - ry
(Yy)
Parent #2
Same traits as parent #1
Possible
Zygotes
RY
Ry
rY
ry
RY
Ry
rY
ry
RRYY
RRYy
RrYY
RrYy
RRYy
RRyy
RrYy
Rryy
RrYY
RrYy
rrYY
rrYy
RrYy
Rryy
rrYy
rryy
Questions
1. What is the percent chance of the
offspring being green? 25%
2. What is the percent chance of the
offspring being green and wrinkled? 6.25%
3. What is the percent chance of the
offspring being wrinkled? 25%
4. What is the percent chance of the
offspring being yellow and round? 56.25%
5. What is the percent chance of the
offspring being green and round? 18.75%
-Design a two trait Punnett Square.
-Fill it in
-Incorporate 5 questions about the
square and then answer them.
-Make a replica Punnett Square
(don’t fill it in) and write down the 5
questions you previously answered.
**Lab #7  Due Wednesday**