Transcript Drosophila Lab: Exploring Genetics

Drosophila Lab: Exploring
Genetics
AP recommended lab
Two Tasks to Complete
1. Pre-lab Questions from 12 Recomm. Labs
(link from my website)
2. Computer Simulated Lab: “Gene Pool” drive
***Answer Questions on a separate paper.
To Access the Lab Simulation for
Drosophila
• Click the “START” and choose “My Computer”
• Type in the following:
\\trhs_math_lang\genepool$
• Choose the “Drosophila folder” and double click
the “Neo” application.
• Follow the instructions and answer the guiding
questions listed on the front page of your lab.
Key Parts for Drosophila Lab
•
•
•
•
Stages of Drosophila
Main Characteristics to observe (4)
Determining Male vs. Female (3)
Examine 3 Modes of Inheritance:
Monohybrid:
Dihybrid:
Sex-Linked:
Red Eyes x Sepia Eyes
Eye color, Wing
White eyed-female x Red eyed Male
(X? X ? )
•
(X ? y )
Observed Values
• Table 7.2: F2 Generation
-78 red-eyed females
-62 white-eyed females
-69 red-eyed males
-73 white eyed males
Expected Results: Complete #3 (both Tables)
Do a Chi-square analysis.
**Note: Critical values are listed in Table 7.5 on
the bottom of Page 86.
Crosses to Complete for Lab #6
1) Table 7.1: F1 Generation Data
Phenotype and Symbol
Red-eyed
White-eyed
Females
Males
all XRXr
all XrY
F2 Generation: Sex-Linked trait
Phenotype and Symbol
Females
Males
Red-Eyed (XR)
78 XRXr
69 XRY
White-Eyed (Xr)
62 XrXr
73 XrY
Assume that the following Data was obtained and determine if it is
significant or not by calculating a Chi-Square value.
Answer for First Cross
X2 = (78-72) 2 + (69-71)2 + (62-71)2 + (73-71)2
71
71
71
71
X2 = 0.69 + 0.06 + 1.14 + 0.06
X2 = 1.94
Degrees of freedom: (4 categories)
3
Critical Value: see Table7.3 (pg.85)
7.82
The chi-squared value is less than 7.82
Therefore:Our null hypothesis is accepted: That there is not a
significant difference between the observed value and
expected value. We must then accept that our results
follows the expected (theoretical value).
nd
2
•
•
•
•
•
•
Genetic Cross
Red-Eyed: Dominant
Sepia eyes: Recessive
Parental cross:
F1 Cross:
F1:
F2:
S
s
SS X ss
Ss X Ss
All Ss
3:1 (red:sepia)
Observed Values for #7 (table)
Phenotype
Red-Eyed
sepia
Total:
# Observed
140
60
200 offspring
Complete Questions #6 & 7
# Expected
calc. value
calc. Value
Data for Second Cross
Phenotype
# observed (o)
# Expected (e)
(o-e)
(o-e)2
(o-e)2
e
Red
140
Sepia
60
Other Crosses to do
• Pg 86: Green & Albino seedlings
• Pg.88: Long & short winged flies
**complete and calculate Chi-Square values to
determine if the results are significant and
acceptable (statistically valid)