THE BEAN LAB:
ALLELE
FREQUENCY
THE BEAN ALLELE FREQUENCY LAB
Purpose: The following pictures are a guide to show
one example of how the allele frequency could
change in a population due to a genetic disorder.
Setup: The three types of beans (red [RR], pinto [Rr]
and white [rr]) will be used to represent a population of
individuals with a certain trait. If an individual has the
recessive phenotype (rr) then there is a 50% chance of
surviving to reproduce. Being a carrier of the trait (Rr)
has no bearing on mortality.
The 2012-13 class has gone through the lab and
developed a set of instructions to go along with the
following pictures to help walk you through how to do the
lab.
Slide #1
White, rr
(16)
Red, RR
(16)
Pinto, Rr
(32)
R and r frequency =
16 + 16 + 32
64 +64
Slide #2
White, rr
(8)
Red, RR
(16)
Pinto, Rr
(32)
Slide #3
The Dating Game
Slide #4
Who got married
to who from this
Parent Generation
(P)
Slide #5
The offspring
of those
couple, now
known as the
First
Generation
(F1).
How did we
get these
numbers of
beans?
How did we
get these
numbers of
beans?
Slide #6
Red, RR (37)
Pinto, Rr (54)
White, rr (21)
Slide #7
Red, RR (37)
Pinto, Rr (54)
White, rr (11)
Slide #8
Slide #9
Slide #10
Slide #11
Red, RR (82)
Pinto, Rr (92)
White, rr (30)
Slide #12
Red, RR (82)
Pinto, Rr (92)
White, rr (15)
Slide #13
Slide #14
Slide #15
Slide #16
Red, RR (172)
Pinto, Rr (166)
White, rr (38)
IF WE CONTINUED ON
THIS PATH, WHAT
SHOULD THE NEXT
SLIDE SHOW?
Slide #17
Red, RR (172)
Pinto, Rr (166)
White, rr (19)
DATA ANALYSIS
Bean Population Growth
4 Generations of Beans
400
Bean Populaiton
350
300
250
200
150
100
50
0
0
2
4
6
8
Days
10
12
14
16
Growth of Bean Population
(10 Generations)
Total Population of Beans
60000
50000
40000
30000
20000
10000
0
0
10
20
30
40
Days
10 Generation Forecast
50
60
What is happening to the overall bean population?
Why is this happening to the OVERALL bean
population?
Could we expect this pattern to continue
indefinitely?
What factors could stop this pattern?
Growth and Decline of R/r Frequencies
Percentage of the Population
100
90
80
70
60
R Frequency
50
r Frequency
40
30
20
10
0
0
5
10
Days
4 generagtions of Beans
15
Allele Frequency over Generations
100
Perentage of Alleles
90
80
70
60
50
R Frequency
40
r Frequency
30
20
10
0
0
10
20
30
40
Days
10 Generation Forecast
50
60
OTHER QUESTIONS ON
BEAN EVOLUTION
* Will the white beans ever completely disappear at
this rate?
* What are some scenarios that could happen to
cause the white beans to completely disappear?
* The mechanism of evolution that this lab
demonstrates is ______ because of ________.
OTHER MECHANISMS THAT
COULD AFFECT ALLELE
FREQUENCY
MIGRATION
(GENE FLOW)
New First Generation
Reproduction Populations
Original Population
MATE SELECTION
Original Parent Pairs
New Parent Pairs
SMALL POPULATION + CHANCE EVENT – DANGEROUS MUTATION
Original Population
Reproduction Population
INTRODUCTION OF A PREDATOR
Original Population
Fire Breathing Dragon who
eats red beans for lunch