Transcript Tongue-Rolling Phenotypes

Scholars Biology 3
Genetics Lab Report
Searching for Correlations
Between Phenotypes
Refer to your syllabus for a
more detailed description of
items to be included in the lab
report.
Components of the Lab Report
•Purpose
•Methods
•Results
•Discussion
•Literature Cited
Purpose
•Describe why the experiment was
done
•Identify the hypotheses being tested
--1 hypothesis for simple inheritance
--1 hypothesis for complex inheritance
--2 hypotheses for taste perception
Hypothesis for
Simple Inheritance
Choose any trait (EXCEPT short index finger)
and determine whether the alleles are
present in equal frequencies. (See p. 95 for details.)
If the dominant and
recessive alleles are
present in equal
frequencies, this
Punnett square
represents the ratio of
expected offspring for
the whole population.
E
e
E
e
EE
Ee
Ee
ee
75% free earlobes
25% attached earlobes
Hypothesis for
Complex Inheritance
Multigenic Traits often show a range of phenotypes
that approaches a normal distribution for numbers
of individuals with each phenotype.
For our experiment: Determine whether we see a
normal distribution of heights with different central
values for males and females.
Hypotheses for
Taste Perception
Determine whether there is a relationship
between
1. Supertaster and PTC-tasting phenotypes
2. Supertaster phenotypes and any ONE of the
following: Gender
Preference for Brussels sprouts
Preference for Cheese
Preference for Black coffee
Preference for Dark chocolate
Methods
Provide a brief description of the techniques,
materials and/or equipment used in the
experiment.
Emphasize how the methods accomplish
the purpose given in the previous section.
Focus on the determination of the
phenotypes that are represented in your
hypotheses, rather than all the traits tested.
DO NOT write this section as a step-bystep guide for repeating the experiment.
DO write it as a summary of the
experimental procedure in past tense.
Results
• Present your experimental data in this
section.
• Introduce the reader to the data with a brief
description that refers to the content of
specific figures or tables.
• Choose the most appropriate format for
each type of data presented.
– Simple Inheritance: Table or Histogram
– Complex Inheritance: Line Graph
– Taste Perception: Table or Histogram
Results
• Essential elements of a
line graph or histogram
– Put a label and specify the units on each axis
– Make the plotted points or bars clearly visible
– Connect related points by a best-fit line
– Include a key to identify different lines, bars
– Provide a caption BENEATH the graph or
histogram
• Brief description
• Title
– Number consecutively from Figure 1
Graphing the Data for Complex Inheritance
9
8
7
6
5
4
3
2
1
0
Males
Females
Class
Male Average
<1
49
15
515
9
16
516
9
17
517
9
18
518
9
19
519
9
Female Average
Class Average
Height (cm)
Figure 1: Distribution of Heights in a Scholars’ Biology 3
Class During Fall Semester 2003. Heights of 25 students
were grouped into the size categories shown.
Displaying Data in a Histogram
0.8
0.7
0.6
0.5
Rolling
0.4
Can't Roll
0.3
0.2
0.1
0
1
Tongue-Rolling
Phenotypes
Figure 2: Frequency of Tongue-Rolling Trait in a Scholars’
Biology 3 Class During Fall Semester 2003. Phenotypes of
25 students were determined by visual observation.
Results
• Essential elements of a table
– Provide a caption ABOVE the table
• Title
• Brief description
– Present the data in clearly labeled
columns and rows
– Provide labels and units of measure if
applicable
– Number consecutively from Table 1
Displaying Data in a Table
Table 1: Frequency of Mid-Digital Hair in a
Scholars’ Biology 3 Class During Fall
Semester 2003. Phenotypes of 25 students
were determined by visual observation.
Phenotype
Percentage
Mid-digital Hair
0.44
No Hairy Digits
0.56
Discussion
 Present your interpretation of the results in
this section.
 Draw conclusions that are based on the
experimental evidence.
 Discuss whether or not the original
hypotheses were supported by the data.
 Explain any discrepancies in your data.
 Elaborate on the biological implications of
the results.*
 Relate your results to existing scientific
knowledge.*
*See Dr. Colavito’s Other Links Web Page
for more information on Supertasters.
Literature Cited
 Include ONLY references cited in your
report.
 To cite references in the text, use the
format (Author, year).
 In the literature cited section, use the
following format:
 For journal: Author, year, Title, Journal
Name, volume number and pages
 For book: Author, year, Title, Publisher
and City of publication
 For Web Page: URL and Date Accessed
Length of
Each Section





Purpose: 1-2 paragraphs
Methods: 1 page
Results: 1 page + figures and tables
Discussion 1-2 pages
TOTAL LENGTH: 3-5 pages of written
material
 Figures and tables should be included
on additional pages.