- This document outlines a genetics experiment using Drosophila melanogaster to study eye color inheritance.
- Students will set up crosses between fly strains with different eye colors and analyze the results over multiple generations.
- In week 3, chromatography will be used to separate pterin eye pigments from fly strains, which will then be identified under UV light based on their fluorescent colors.
This PPT consists of 24 slides explaining Polygenic Inheritance . Some traits are controlled by two or more genes. These traits differ from Mendelian traits and donot show discrete alternative or contrasting forms and show continuous ranges. Examples of such traits are wheat seed colour, plant height, Human skin colour controlled by at least three genes showing many shades of dark and fare, human height, human eye colour etc
This power point presentation is designed to explain deviation of Mendelian dihybrid ratio due to interaction of genes which may be of following types
1.Two gene pairs affecting same character – 9:3:3:1
2.Epistasis, one gene hides effect of other
a) Recessive Epistasis - 9:3:4
b) Dominant epistasis - 12:3:1
3.Complementary genes - 9:7 ( 2 genes responsible for production of a particular phenotype )
4. Duplicate genes – 15:1 ( same effect given by either of two genes )
5. Polymeric gene action - 9:6:1
6. Inhibitory gene action - 13 : 3
Each interaction is typical in itself and ratios obtained are different
This PPT consists of 24 slides explaining Polygenic Inheritance . Some traits are controlled by two or more genes. These traits differ from Mendelian traits and donot show discrete alternative or contrasting forms and show continuous ranges. Examples of such traits are wheat seed colour, plant height, Human skin colour controlled by at least three genes showing many shades of dark and fare, human height, human eye colour etc
This power point presentation is designed to explain deviation of Mendelian dihybrid ratio due to interaction of genes which may be of following types
1.Two gene pairs affecting same character – 9:3:3:1
2.Epistasis, one gene hides effect of other
a) Recessive Epistasis - 9:3:4
b) Dominant epistasis - 12:3:1
3.Complementary genes - 9:7 ( 2 genes responsible for production of a particular phenotype )
4. Duplicate genes – 15:1 ( same effect given by either of two genes )
5. Polymeric gene action - 9:6:1
6. Inhibitory gene action - 13 : 3
Each interaction is typical in itself and ratios obtained are different
Dihybrid Crosses, Gene Linkage and RecombinationStephen Taylor
For the IB DP Biology course AHL: Genetics unit. To get the editable pptx file, please make a donation to one of my preferred charities. More information at http://sciencevideos.wordpress.com/about/biology4good/
For the IB Biology course. To get the editable pptx file, please make a donation to one of my chosen charities. More information: http://sciencevideos.wordpress.com/about/biology4good/
Basics of Undergraduate/university fellows
Crossing over is exchange of strictly homologous segments of a genome between their
respective non-sister chromatids during cell division, which results in chromosomal
recombinations of linked genes in daughter cells.
it is possible to have more than two allelic forms, i.e., multiple alleles, of one kind of gene.
The best examples of multiple allelic system have been observed in coat colour of rabbits, wings of Drosophila and blood groups in man
allelomorphs, monohybrid cross dihybrid cross mutant alleles
wild type
Changes In Number And Structure Of Chromosomes SMGsajigeorge64
A brief account of the changes in number and structure of chromosomes : Haploidy, Polyploidy, Aneuploidy, Deletion, Duplication, Inversion and Translocation
A cytological technique to detect the nature of adjacent chromosomal regions by using different staining technique assisted with some pre treatment of metaphase chromosomes prepared on the slides
Dihybrid Crosses, Gene Linkage and RecombinationStephen Taylor
For the IB DP Biology course AHL: Genetics unit. To get the editable pptx file, please make a donation to one of my preferred charities. More information at http://sciencevideos.wordpress.com/about/biology4good/
For the IB Biology course. To get the editable pptx file, please make a donation to one of my chosen charities. More information: http://sciencevideos.wordpress.com/about/biology4good/
Basics of Undergraduate/university fellows
Crossing over is exchange of strictly homologous segments of a genome between their
respective non-sister chromatids during cell division, which results in chromosomal
recombinations of linked genes in daughter cells.
it is possible to have more than two allelic forms, i.e., multiple alleles, of one kind of gene.
The best examples of multiple allelic system have been observed in coat colour of rabbits, wings of Drosophila and blood groups in man
allelomorphs, monohybrid cross dihybrid cross mutant alleles
wild type
Changes In Number And Structure Of Chromosomes SMGsajigeorge64
A brief account of the changes in number and structure of chromosomes : Haploidy, Polyploidy, Aneuploidy, Deletion, Duplication, Inversion and Translocation
A cytological technique to detect the nature of adjacent chromosomal regions by using different staining technique assisted with some pre treatment of metaphase chromosomes prepared on the slides
this is all of the information that I have please help Lab 5 In.pdfambikacomputer4301
this is all of the information that I have please help Lab 5 Introduction - Genetic mapping See
figure 5.1 for a schematic of the fly the cross you initially started with, you'll either crosses you
have been working on. Two labs ago, map the distance between the w gene and the m you set up
a pair of reciprocal parental crosses, gene, or between the w gene and the y gene. between mutant
and wild type flies (fig. 5.1a). You had one of two different mutant strains, each with two mutant
phenotypes - either white eyes all F2 individuals will receive only recessive (w) and miniature
wings (m), or white eyes (w) alleles from this parent (fig. 5.1d, orange and and yellow body (y).
The phenotypes of the F1 yellow chromosomes). Because of this, the flies should have indicated
to you that all mutant phenotype of each F2 fly will tell you which phenotypes in question are x-
linked recessive alleles (mutant or WT) were inherited from the (fig. 5.1b). heterozygous female
F1 parent (fig. 5.1d, dark and light blue chromosomes). The first F2 fly Last lab, you used the F1
flies from one of shown in figure 5.1d inherited 'a B' from the your parental crosses to set up an
F1 cross (fig. heterozygous parent and will end up with the consequence. After crossing two pure
breeding this F2, you observe a ABphenotype and parents, F1 offspring will be heterozygous for
therefore know that this fly received 'A B' from nearly all genes in question - the exception is X -
the heterozygous parent. linked genes in the male offspring. Since the Y chromosome is
equivalent to recessive alleles for The goal of genetic mapping is to X-linked genes, these F1
males are recessive for determine the likelihood of cross over between all X-linked genes and act
as a test cross. The two loci/genes. If we score the phenotypes of a heterozygous F1 females and
recessive F1 males large F2 population from our crosses, we can (test cross) can be used to map
the distance determine the recombination frequency of your between the genes causing the two
phenotypes two genes. of your parental mutant female. Depending on
e) F2 phenotype scoring: f) Recombination frequency: Eigure 5.1: Schematic of your Drosophila
crosses, See text of lab 5 intro for description.
For a given F1 gamete for the F2 individual it number of flies, it is easy to calculate the creates),
if no cross over occurs between the two recombinant frequency between your two genes genes in
question, the F2 phenotype will be the (fig. 5.1ef ). same as one of the original parents - either
fully WT or double mutant in this case. In figure 5.1d Recall from last time that a lower
recombinant these have blue chromosomes of a single colour. frequency is observed when
genetic map If a crossover does occur between the two genes, distances are small. When genes
are close to the F2 fly will have a phenotype unlike either of each other, there's a narrow range
on the the parents - a recombinant phenotype (shown chromosome for a random crossover to
land.
INTRODUCTION
ABOUT DROSOPHILA
PHYSICAL APPEARANCE
CELL BIOLOGY OF DROSOPHILA DEVELOPMENT
LIFE CYCLE
THE DROSOPHILA GENOME
UNUSAL FEATURES OF DROSOPHILA
SEX DETERMINATION
GENETIC MARKERS
DEVELOPMENT IN DROSOPHILA
CLEAVAGE
THE ORIGINS OF ANTERIOR-POSTERIOR POLORITY {GENES}
CHROMOSOME ABERRATIONS
CONCLUSIONS
REFERENCES
Running head BIOLOGY LAB PROJECT1BIOLOGY LAB PROJECT 4.docxjoellemurphey
Running head: BIOLOGY LAB PROJECT 1
BIOLOGY LAB PROJECT 4
Introduction
Drosophila melanogaster is a species of fly in the family drosophilidae. The common name for Drosophila melanogaster is fruit fly or vinegar fly (Capy, Gibert & Boussy, 2004). The drosophila is a species widely used for biological research in studies of genetics, physiology, microbial pathogenesis, and life history evolution. It has been used to study genetics for over 100 years. D. melanogaster was one of the first organisms used for genetic analysis and is still widely used today. The drosophila is largely used for research study because it is an insect that is easy to take care of and lays many eggs, which gives us the opportunity to have many flies to study. Also, fruit flies can create a complete generation in about ten days thus allows several generations to be produced and studied within a few weeks (Regan, 2014). The average life of a fruit fly in optimal temperatures is 40 to 50 days. The life of Drosophila melanogaster depends on the weather temperature. For example, D. melanogaster’s lifespan is around 30 days at 29˚ C, 84˚ F and the lifespan decreases with a decrease in temperature. Drosophila’s eggs can hatch after 12–15 hours. The female can mate with the male after 8 to 12 hours after hatching. Nowadays, most genetics scientists prefer to use the Drosophila melanogaster fliesbecause they can study different generations in a short period of time.
In the genetics lab, we determine the mode of inheritance of phenotype mutant and wild type. We cross wild type males with female mutants. Also, we cross mutant males with wild type females to determine the genetic changes in both generations. The wild type flies have red eyes phenotype and long (normal) wings. On the other hand, mutants have white eyes and short wings. These observations are made after observing the first and second generations for both cross and wild type breeds and then comparing the observable change between them. In this course, we make several crosses between flies from wild-type and mutant phenotypes to show the mode of inheritance of the genes in Drosophila Melanogaster.
Methods and Materials
In this lab we used fruit flies and we examined them by putting them under the microscope. We also use FlyNap by to make the flies sleep for a mount of time while we viewing them. In order to use the FlyNap, first we transfer the flies to an empty vial and we do that by place the vial that we want to transfer immediately over the opening of the empty vial, so by this we will not allow the flies to escape from our vial. After they have been transfer to the new vial we place a small FlyNap brush and wait for a while until they all sleep. When they all sleep we put them in a small plate. At this time, we will be able to put them under the microscope and we use a paintbrush to move and look at the flies. Under the microscope we can easily determine the phenotype and the sex for each fly. We careful ...
Experimental Protocols of Cell Divisions and Electrophoresisijtsrd
Mitosis In mitosis, the nucleus of the Eukaryotic cells divides into two, subsequently resulting in the splitting of the parent cells into two daughter cells. Hence, every cell division involves two chief stages Cytokinesis – Cytoplasm division, Karyokinesis – Nucleus division Dr. Rana Taj "Experimental Protocols of Cell Divisions and Electrophoresis" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-5 , August 2021, URL: https://www.ijtsrd.com/papers/ijtsrd46335.pdf Paper URL: https://www.ijtsrd.com/biological-science/zoology/46335/experimental-protocols-of-cell-divisions-and-electrophoresis/dr-rana-taj
Convocatoria-Concurso para la elaboración de material didáctico y/o de divulgación y/o enseñanza de la Genética, que hemos elaborado un grupo de profesores de Genética.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Normal Labour/ Stages of Labour/ Mechanism of LabourWasim Ak
Normal labor is also termed spontaneous labor, defined as the natural physiological process through which the fetus, placenta, and membranes are expelled from the uterus through the birth canal at term (37 to 42 weeks
Normal Labour/ Stages of Labour/ Mechanism of Labour
The genetics eye color drosohila 15 pollock
1. Chapter 15
The Genetics of Eye Color in
Drosophila melanogaster
Carol Pollock
BiologyProgram
Universityof British Columbia
Vancouver, British Columbia V6T 2B1
Carol Pollock is a lecturer in the Biology Laboratory program at the
University of British Columbia.
Note to Instructors:
This exercise has been set up as requiring six weeks. It can be done completely by
students in which case short periods of time are required each week for six weeks.
Alternatively, the crosses could be set up for the students and they could begin the
exercise further along e.g. at Week 3. The two-week chromatography exercise can
be put in anywhere between Week 1 and Week 5. It is assumed that students doing
this exercise will have had some experience with basic Mendelian genetics. If not,
then the exercise can be modified to include basic principlesof meiosis, Mendelian
geneticsand gene/enzymerelationships.
Schedule:
Week 1: set up parentalcrosses
Week 2: remove parents
Week 3: chromatographyof eye pigments
F1self cross
Week 4: remove F1parents
analyze chromatograms
Week 6: analyze F2 data
Week 7: report due
141
3. INTRODUCTION
The purpose of this exercise is to investigate the inheritance of various eye colors in mutant
strains of Drosophila. We will also use these mutants to demonstrate the relationship between the
information carried by the DNA molecule (genotype) and the characteristics of that organism
(phenotype) as well as to demonstrate the way that gene products interact to produce phenotypic
characteristics.
PIGMENT PRODUCING PATHWAYS
There are two separate biochemical pathways leading to the production of eye pigments in
Drosophila. One produces the brown pigments, ommochromes, and the other produces red
pigments, pterins. See Figure 1. In addition to pigment production, the pigment must also be
bound to a granulein the pigment cell of the eye. Failure of this binding process, for example by a
mutation,results in the lack of pigment in the eye regardlessof the pigments produced.
A. Ommochrome pathway (brown pigments):
enz a enz b enz c enz d
tryptophan -----------> Ia -----------> Ib ----------->Ic -----------> xanthommatin
where enz a, enz b, etc. are the enzymes and Ia, Ib,etc.
are the intermediatesof the pathway.
B. Pterin pathway (red pigments):
DROS
enz 1 enz 4
purineriboside ----------------> I1 ----------------> SEP -----------
ISOX
other pathways
KEY:
pigment
binding
enzyme
DROS = drosopterin
SEP = sepiapterin
XAN = xanthopterin
ISOX = isoxanthopterin
where enz 1, enz 2, etc. are the enzymes and I1is an intermediate in the pathway.
pigment
in eye
Figure 1. Pigment production pathways in Drosophila melanogaster. (simplified)
143
4. WEEK 1
Drosophila crosses
Each pair of students will be given a specific cross to follow through three generations: the
parental generation (P), the first generation of offspring (F1) and the second generation of
offspring (F2). For our crosses Drosophila are grown on a cornmeal medium to which dextrose,
agar, yeast extract and a mold inhibitor have been added.
Phenotypes
Examine the flies on demonstration and be sure you can accurately identify each phenotype.
Use the space below for any notes you wish to make on these phenotypes. Each strain differs
from the wild-type in eye color only. Note: there isa "wild" type for all traits; it is the phenotype
that was first observed in wild populations of the organism.
Stocks to be used in crosses:
wild type (+)
scarlet (st)
brown (bw)
white (w)
sepia (se)
Distinguishing the Sex of Adult Flies
In order to set up crosses it is necessary to mate males and females. Therefore it is very
important to be able to distinguish the sexes. Also, some genes are sex-linked and show different
patterns of inheritance in males and females. Therefore, in determining the mode of inheritance of
a genetic trait, it is important to distinguish the sex of the flies and to record the number of flies of
each sex in each phenotype.
Adult males and females can easily be distinguished in a number of ways using the dissecting
microscope (see Figure 2).
1. The abdomen of the female is longer (seven segments) and pointed at the end with several dark
transverse stripes. The male abdomen has only five segments with two narrow dark stripes and a
heavily pigmented tip.
2. The males have a sex comb of about 10 black bristles on the forelegs; females do not have a
sex comb.
3. Males have obvious external genitaliaon the ventral surface; females do not.
Crosses
The following crosses are to be set up:
Cross 1A: brown-eyed female x wild-type male
Cross 1B: wild-type female x brown-eyed male
Cross 2A: scarlet-eyed female x wild-type male
Cross 2B: wild-type female x scarlet-eyed male
144
5. Cross 3A: brown-eyed female x scarlet-eyed male
Cross 3B: scarlet-eyedfemale x brown-eyed male
Cross 4A: white-eyed female x wild-type male
Cross 4B: wild-type female x white-eyed male
Cross 5A: sepia-eyed female x wild-typemale
Cross 5B: wild-type female x sepia-eyed male
Cross 6A: white-eyed female x sepia-eyedmale
Cross 6B: sepia-eyed female x white-eyed male
Note: crosses A and B are reciprocal crosses, i.e. the strains involved in the crosses are the
same but the phenotypeof the female and male parents is reversed.
Figure 2. Distinguishingcharacteristicsof male and femaleDrosophila.
1. Etherize your parental flies for 2-3 min. CAUTION: Ether is flammable. Keep away from all
open flames.
2. Place 5 females and 5 males for each cross in a fresh vial.
3. Indicate your names and cross numberon each vial.
4. Leave the vials on their side until the flies revive.
5. Your vials will be incubated at 25ºC and returned to you next week.
Procedure
145
6. WEEK 2
Drosophila crosses - Removal of Parents
In your culture vials the adults are the original parents. Note the presence of the other stages of
the life cycle (see Figure 3).
Procedure
1. Etherize your flies - do not worry about over-etherizing.
2. Discard your parental flies into the morgue (a soap solution which will kill the flies).
3. Your vials will be incubated at 25ºC and returned to you next week.
WEEK 3
Chromatographyof Pterin Pigments
We will use paper chromatography to separate the pterin pigments which will then be identified
next week on the basis of their fluorescence in ultraviolet light. The ommochrome pigments will
not appear on the chromatograms.
Materials
filter paper, pencil, ruler, glass rod, forceps, beaker with solvent (2:1 n-propanol: 1%
NH4OH)
strains of Drosophila: wild-type (+)
sepia (se)
white (w)
brown (bw)
scarlet (st)
Procedure: Work in pairs.
1. Obtain a piece of filter paper 15 cm x 23 cm and, with a pencil, lightly draw a line 1.5 cm from
the longer edge. This will be the lower edge. Be careful not to get fingerprints on the filter
paper.
2. With a pencil, initial the upper right hand comer.
3. With a forceps, place one white (w) fly on the pencil line 3 cm from the left edge of the paper
(see Figure 4). Holding the fly in place, use a glass rod to crush the head onto the pencil line.
Discard the body of the fly. Label this spot in pencil below the line - see Figure 4. Repeat
with four more white flies. Make sure all the heads are crushed in exactly the same spot.
4. Wash the glass rod and dry it with a paper towel. Place one brown fly 3 cm from the white
flies. Crush the head. Label this spot in pencil below the line - see Figure 4. Repeat with four
more brown flies. Make sure all the heads are crushed in exactly the same spot.
146
7. (look on walls
of vial)
LARVA (1)
4 .
-
-.. ....
in culture medi . . .
. ..
.
-up to 4.5 mm long
1day -after 1st molt
Figure 3. Life cycle of Drosophilamelanogaster.
A.B.
w bw se st +
Figure 4. A chromatogramspotted and labelled.
147
2)-after 2nd molt
8. 5. Repeat step 4 with sepia (se), scarlet (st) and wild-type(+) flies.
6. Allow the spots to dry.
7. Roll your filter paper into a cylinder so that the spots are on the inside. Staple the cylinder so
that the edges are neither touching nor overlapping. (Figure 5).
Figure 5: A chromatogramfolded and stapled, ready for running in solvent.
8. Place this cylinder in a beaker which has approximately1 cm of solvent in it (the solvent must
not come higher than the pencil line). Cover the beaker with foil and let sit for 2 hours 20
minutes or until the solventfront is 1 cm from the top of the paper.
9. Remove the cylinder from the beaker and place your chromatogram where indicated by your
T.A. until next week.
Drosophila crosses - F1self Cross
1. Etherize your flies for 2-3 minutes.
2. Separate into males and females.
3. Note the phenotypeof each sex and record in the space below.
F1females:
F1males:
Do not discard your flies!
4. Check your results with your T.A.
5. Select five males and five femalesand place in a fresh vial.
6. Label the vial with your name and the number of your parental cross.
148
9. 7. Leave the vial on its side until the flies revive.
8. Your vials will be incubated at 25ºC and returned to you next week.
9. Discard any leftover F1 flies into the morgue.
WEEK 4
Drosophila crosses - Removal of F1Parents
1. Etherize your flies in your F1 self vial.
2. Remove all flies from this vial.
3. Discard flies into morgue.
4. Your flies will be returned to you in two weeks.
Analysisof Chromatograms
Introduction
The pathway for the production of the red pigments, the pterins, in Drosophila is outlined in
Figure 1B. Pigments such as drosopterin (DROS), sepiapterin (SEP), xanthopterin (XAN) and
isoxanthopterin, (ISOX) can be identified on the basis of their fluorescence in ultraviolet light.
When ultraviolet light is absorbed by organic compounds, such as pigments, some of the absorbed
energy can be emitted as heat or as light of a longer wavelength, i.e., in the visible range. When
the separated pigments are observed in ultraviolet light, each pigment fluoresces a characteristic
color. This color, as well as its relative position on the chromatogram, can be used to identify the
pigment. None of the brown pigments (ommochromes)will appear on the chromatograrn.
1. Examine your chromatogram in ultraviolet light. CAUTION - Ultraviolet light can be
dangerous. Do not look directly at the source,
2. Compare your results with the sample chromatogram of wild-type pigments on the next page
(Figure 6) and complete Table 1. The pigments may not appear as separate spots but they may
blend into each other. Use the relative distance each pigment has moved from the original
position of the sample to help in your identification.
Results
149
10. Solvent Front Color
SEP yellow-green
XAN green-blue
ISOX violet-blue
DROS orange
original position of sample
Figure 6. Sample chromatogramof wild-typeDrosophila eye pigments
Table1. Resultsof chromatographicseparationof Drosophila eye pigments.
KEY:
- = absent
+ = small amount
++ = moderateamount
+++ = large amount
Strain
+
se
W
bw
st
ISOXDROS XAN SEP
150
11. Analysis of results
If a mutation in
functional, then the
pathway
the DNA occurs such that one enzyme in the biochemical pathway is not
intermediate acted on by that enzyme could accumulate. For example, in the
enz 1 enz 2 enz 3 enz 4
... ----------> ----------> ----------> ---------->I4
if enz 3 is not functional, then I2 could accumulate. If there is a branch in the pathway e.g.
enz 3 I3
enz 1 enz 2
------------> ------------>I2
and the non-functional enzyme occurs after the branch, e.g. enz 3, then I2 could accumulate and/or
extra I4 could be produced (the extra I4 doesn't necessarily accumulate - why?).
Compare the pigments present in each of the mutant strains with the pigments found in the wild
type and by the presence or absence or amount of each and try to determine which enzyme in the
pigment pathways (see Figure 1) could be non-functional. Remember the brown (ommochrome)
pigments do not appear on the chromatogram, therefore you must also consider the phenotype i.e.
the actual eye color of each strain. Xanthommatin is the only ommochrome bound to granules,
therefore if a mutant has no brown pigmentsassume enz d (see Figure 1A)is non-functional.
Remember if one enzyme in the pterin pathway is blocked (excluding the first one), you should
see an increase in at least one of the intermediates or products of the pathway. Also keep in mind
that the pigments must be bound to the granules in the eye for any color to be observed.
Complete the following table:
Strain
W
bw
se
st
Defective enzyme Reasons
I1 I2 I3
I1
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12. WEEK 6
Drosophilacrosses - Analysis of F2
Results
1. Etherize your flies.
2. Separate into males and females.
3. Determine the phenotypesof each sex and the number of each phenotype. Record your results
here and on the blackboard.
PHENOTYPE(S) NUMBER. .
females
males
4. Using the data tables provided, record the resultsof all crosses.
Analysis of Results
For each cross 1 - 6 you must use the results provided to:
1. Decide on the mode of inheritance of each phenotype i.e. how many genes are involved in each
cross, how many alleles of each gene and which alleles are dominant, recessive, linked, etc.
You must provide the reasons for your decision. Use Analysis Table 1 for this part of your
assignment.
2. Do a Chi-Square test: χ2 = Σ(obs - exp)2
exp
to confirm your suggested mode of inheritance. Show all your work, including the calculation
of expected values. If sex-linkage is involved you must do separate Chi-Square tests for males
and for femalesin each of the reciprocalcrosses.
3. Relate the results of each cross to the enzyme defective in each of the parents, the F1 and all the
F2phenotypes observed. If sex-linkage is not involved, you may do either cross A or B. Use
Analysis Table 2 for this part of your assignment.
Remember: Explain all your reasoning and show all your work. Be sure to explain any
abbreviationsor symbols used. Your assignment is due in one week.
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13. Data Table:
(6copies of this table are needed)
Cross:
d. Examine the F1 and F2 data. If sex does not appear to be a factor i.e. results for the F1 and F2
of the reciprocal crosses are similar, then add all the numbers for each F2 phenotype i.e. F2
females cross A + F2 males cross A + F2 females cross B and F2 males cross B. Calculate the
F2 phenotypic ratioon the basis of the combineddata.
a. Parental cross
P female
P male
b. F1 Progeny
F1females
F1 males
c. F2Progeny (from
F1 self) include
numbers of each
phenotype
F2 females
F2 males
number observed:
ratio observed:
Cross A
Phenotype
If sex does appear to be a factor i.e. the results for the F1and F2 of the reciprocal crosses are
not similar, then do not combine your data. Calculate the phenotypic ratio separately for F2
males and F2 females and for crosses A and B.
Cross B
Phenotype
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phenotypes:
14. Analysis Table Thistable has been condensed)
AnalysisTable 2. (6 copies of this table are needed. Also note that this table has been condensed.)
Cross:
15. REFERENCES
Hadorn, E. 1962. Fractionating the Fruit Fly. Sci. Am. Vol. 206, pp 101-110.
Phillips, J. P. and Forrest, H. S. 1980. Ommochromesand Pteridines. The Generics and Biology
of Drosophila. M. Ashburner and T.R.F. Wright, Ed., Academic Press, N.Y. Vol. 2d, pp 541-
623.
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