Genetics QUIZ
GENETIC CORN LAB
Carolina Biological 1: Pollination
Carolina Biological 1: Pollination FILE
Carolina Biological: 2 Harvesting
Carolina Biological: 2 Harvesting FILE
Carolina Biologica: 3 Preparing the seeds
Carolina Biologica: 3 Preparing the seeds - FILE
Where do seeds
come from?
Tassel
(flower
with
pollen)
Silk (flower with eggs)
1. Describe the corn plants – at least
three facts.
2. Ask at least one question.
3. Write two characteristics – one
inherited, one that is not.
4. Two traits? Phenotypes? 6.Letters?
5. Which phenotypes are recessive
and which – dominant? Explain.
7. COUNT each phenotype. Ratio.
8. Compare to Mendel’s predictions.
Trait 1:
Trait 2:
Phenoty Phenot Phenoty Phenoty
pe 1:
ype 2: pe 1:
pe 2:
Num
ber
of
plant
s:
Rati
o:
Chlorophyll A
Chlorophyll-binding protein
Dwarf
No GA effect
Gibberrelinic acid
(GA)
Normal
GA effect
LAB:
Answer questions 1-8,
including your counts.
1. Describe the corn plants – at least
three facts.
2. Ask at least one question.
3. Write two characteristics – one
inherited, one that is not.
4. Two traits? Phenotypes? 6.Letters?
5. Which phenotypes are recessive
and which – dominant? Explain.
7. COUNT each phenotype. Ratio.
8. Compare to Mendel’s predictions.
Journal:
Two Tall Green corn plants were
crossed, giving rise to the seeds we
had planted.
1. Looking at the seedlings, what
must be the genotypes of the
parents? (Choose the letters)
2. What would be the expected
phenotypic ratio in the children?
Explain.
G g
G GG Gg
g Gg gg
Green: White
¾:¼
T t
T TT Tt
t Tt tt
Tall: Dwarf
¾:¼
G - Green
g - White
T – Tall,
t – Dwarf
For each trait, the
phenotypic ratio is
¾:¼
Is this what your
counts show?
NOTES
Notes: Mendel’s Law of Independent
Assortment
Looking at two traits at a time
“Allele pairs separate independently
of each other during gamete
formation by meiosis.”
When does this law work?
Only when the genes are situated on
different chromosomes (not linked)
Assort Independently:
A and C; B and C
Do NOT assort Independently:
A and B - they are on the same
chromosome.
This will affect the ratios
between the phenotypes
in F2 generation…
Are the two genes, for color and for
height sitting on the same
chromosome?
If they are NOT, and they assort
independently, then we can allow
ourselves to:
A. List ALL the possible gamete
combinations in the punnet sq.
B. Multiply individual probabilities.
GgTt x GgTt
G - Green
g - White
Possible phenotype
T – Tall,
Combinations:
t
–
Dwarf
Green, Tall
Green, Dwarf
White, Tall
White, Dwarf
If the two traits are inherited
independently, what are their expected
ratios?
A. PUNNET SQUARE
G = Green, g = White plant For Corn….
T = Tall, t = Dwarf
GgTt x GgTt
All the possible gametes:
GT
Gt
gT
gt
GT
Step 2: Placing gametes in
Gt the punnet square
gT
gt
What is the expected
phenotypic outcome?
GT
YySs x YySs
GT GGTT
Gt
GGTt
gT
GgTT
gt
GgTt
Gt GGTs
GGtt
GgTt
Ggtt
gT GgTT
gt GgTt
GgTt
ggTT
ggTt
Ggtt
ggTt
ggtt
Expected phenotypic outcome:
Green
Tall
9/16 :
Green
Dwarf
White
Tall
3/16 : 3/16 :
White
Dwarf
1/16
Now, compare these predictions to
your actual counts!
B.
MULTIPLYING
PROBABILITIES
G g
G GG Gg
g Gg gg
G - Green
g - White
T – Tall,
t – Dwarf
Green: White
¾:¼
For each trait, the
T t
phenotypic ratio is ¾ :
T TT Tt
¼
t Tt tt
Is this what your
Tall: Dwarf
counts show?
¾:¼
Are the probabilities of the combined
phenotypes, the products of the
individual chances?
Green, Tall
Green, Dwarf
White, Tall
White, Dwarf
¾ x ¾ = 9/16
¾ x ¼ = 3/16
¼ x ¾ = 3/16
¼ x ¼ = 1/16
Is this what we got in our counts?
9
3
3
1
Expected phenotypic outcome:
Green
Tall
9/16 :
Green
Dwarf
White
Tall
3/16 : 3/16 :
White
Dwarf
1/16
Now, compare these predictions to
your actual counts!
1. Write the possible
gametes in the following
parent: AaBbCc (notice:
one allele per gamete for
each genes: ABC, Abc, …)
2. Repeat your answer
considering the position
of the genes on the
chromosomes:
Assort Independently:
A and C; B and C
Do NOT assort Independently:
A and B - they are on the same
chromosome.
This will affect the ratios
between the phenotypes
in F2 generation…
Assignment: Answer ALL question in
the packet up to 15.
For extra 40 points – continue to
question 19!
(For number 12 – draw the chart,
calculate the ratios, by turning the
largest count into 9, and dividing the
rest by the same factor).
ACTUAL COUNTS?
Draw the following chart for the F2
generation, count the plants and fill
in the numbers you got:
Green
Tall
Green
Dwarf
White
Tall
White
Dwarf
Draw the following chart for the F2
generation, count the plants and fill
in the numbers you got (2 classes):
Green Green White White
Tall
Dwarf
Tall
Dwarf
82
27
30
4
/ 9.11= / 9.11 = / 9.11 = / 9.11 =
9
Complete Lab – Part TWO
Part THREE, looking at the
REAL gene mapping on the
corn chromosomes, can be
done at home, for extra credit!