Lab Report
Lab Report
Molecular Evolution Laboratory
Answer the following questions about the results of this lab activity. Record your answers in the
boxes and after the numbered questions. It is important to give complete answers and accurate
descriptions of the leaf and flower images viewed.
Send your completed lab report to your instructor. Don’t forget to save your lab report to your
computer!
Activity 1 – Testing mutagen effectiveness
Background:
Scientists study molecular evolution by investigating mutations that cause significant changes to
an organism’s characteristics. In Activity 1, you were asked to add different amounts of the
mutagen ethyl methanesulfonate (EMS) to the plant cultures. This process is needed to
determine the concentration of mutagen needed to produce the most abundant mutations that
have value for the investigation.
Note: Use the diagram below as a guide for recording data and answering questions in Activity 1.
Record the number and types of mutations found at the different segments of DNA studied.
Figure of mutation analysis: silent mutations cause no measurable change, effect
mutations can be advantageous or detrimental, unknown mutations may or may not
affect the organism.
Data
Culture
1
2
3
4
5
6
Number of
mutations
Types of mutations
Most common mutation
1. Explain how the concentration of EMS affected the number of
mutations in the DNA sequence investigated.
2. Explain how the concentration of EMS affected the types of
mutations in DNA sequence investigated.
3. Explain which concentration of EMS (one to six drops added to the
culture) would be optimal for investigating mutations that like have
evolutionary significance.
Activity 2 - Comparing mutations of leaves
Background:
The mutations produced by EMS are the same types of mutations that would naturally
develop in the Arabidopsis plants. Scientists who study evolution typically hypothesize
how changes caused by mutations would affect the organism’s survival and reproductive
success. Culture # 1 is the untreated leaf and all of the leaves in Culture # 2 should be
compared to Culture #1. It is important to pay record any comments about how the
changes in leaf structure could affect the plants ability to carry out photosynthesis.
Data
Sample
Culture # 1
No EMS
treatment
Culture # 2
EMS
Treatment
Sample 1
Culture # 2
EMS
Treatment
Sample 2
Culture # 2
EMS
Treatment
Sample 3
Shape of leaf
Size of leaf
Comments
Culture # 2
EMS
Treatment
Sample 4
1. Discuss how changes to the size of a leaf may affect a plant’s
survival.
2. Discuss how changes to the shape of a leaf may affect a plant’s
survival.
3. Do in internet image search of “wild mustard artificial selection”
and look at the different leaf mutation changes that produced
crops such as cabbage, kale, and kohlrabi. How do the mutations
you observed in Arabidopsis leaves compared to the mustard
artificial selection mutations?
Activity 3- Comparing mutations of flowers
Background:
As mentioned in Activity 2, the mutations produced by EMS are the same types of
mutations that would naturally develop in the Arabidopsis plants. Scientists who study
evolution typically hypothesize how changes caused by mutations would affect the
organism’s survival and reproductive success. Culture # 1 is the untreated leaf and all of
the flowers in Culture # 2 should be compared to Culture #1. It is important to pay
record any comments about how the changes in flower structure could affect the plants
ability to reproduce. Use the image of the Arabidopsis flower below to answer the
questions. You may want to use the internet or a textbook to look up the function of the
different flower parts.
Data
Sample
Culture # 1
No EMS
Shape and size of
petals and sepals
Shape and size of
stigma and stamen
Shape and size of
carpel
Comm
treatment
Culture # 2
EMS
Treatment
Sample 1
Culture # 2
EMS
Treatment
Sample 2
Culture # 2
EMS
Treatment
Sample 3
Culture # 2
EMS
Treatment
Sample 4
1. Discuss how changes to shape and size of petals and sepals may
affect a plant’s ability to reproduce.
2. Discuss how changes to shape and size of stigma and stamen may
affect a plant’s ability to reproduce.
3. Discuss how changes to shape and size of the carpel may affect a
plant’s ability to reproduce.