Experiment 6 PDF

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WEEK 6 EXPERIMENT ANSWER SHEET Please submit to the Week 6 Experiment dropbox no later than Sunday midnight. SUMMARY OF ACTIVITIES FOR WEEK 6 EXPERIMENT ASSIGNMENT   

Experiment 6 Exercise 1 – Monhybrid Crosses Experiment 6 Exercise 2 – Dihybrid Cross Experiment 6 Exercise 3 – Inheritance of Human Traits

Experiment 6 Exercise 1: Monohybrid Crosses You will be conducting monohybrid crosses using fruit flies. Open in the following website: Glencoe-McGraw Hill. No date. Punnett Squares http://glencoe.mcgraw-hill.com/sites/dl/free/0078759864/383934/BL_05.html Procedure A. Open the above website and click on the VCR to listen to the introduction. Close the window when done. B. Click on the Lab Notebook on the lab bench. A breeding scenario will be presented to you that you will need to carry out. Here are the possible phenotypes and genotypes you will using: a. Normal wings (LL or Ll) or vestigial wings (ll) b. Gray body (GG or Gg) or black body (gg) C. Enter the Scenario number in Table 1 below. D. Based on the Scenario, use the down arrows beneath the Parent 1 and Parent 2 boxes to select the appropriate parents. Look carefully at the flies so that you know which ones to select. E. Before proceeding, click on the Check Parents button. If necessary, make corrections. If you are correct, the maternal and paternal alleles will be added to the Punnett Square. F. Next, drag the correct allele combinations and the corresponding fly types to the boxes in the Punnett Square. G. When you are done, click on Check Offspring. If necessary, make corrections. H. Record your data in Table 1 below. An example has been given, but note that the example is not using the genotypes and phenotypes used in this exercise. Updated October 2013

I. Click on Reset. Repeat steps B - H four more times for a total of five crosses. If a scenario is presented that has already been completed, click Reset again. DO NOT REPEAT a given scenario! Note that the scenario number you need to record in the Table below is the number associated with the specific scenario you completed. Table 1. Results of crosses. Parent Genotypes

Offspring Genotypes

Offspring Phenotype

Scenario #

Parent 1

Parent 2

#

%

#

%

Example

Rr

rr

2 Rr 2 rr

50% Rr 50% rr

2 red 2 white

50% red 50% white

ll

2 Ll 2 ll

2 h long winged 2 vestigal winged

50% h long winged 50% vestigal winged

Scenario 7

Ll

50% Ll 50% ll

Scenario 1

Gg

gg

2 Gg 2 gg

50% Gg 50% gg

2 h gray fly 2 black fly

50% h gray fly 50% black fly

Scenario 8

GG

gg

4 Gg

100% Gg

4 black fly

100% black fly

100% ll

4 vestigal winged

100% vestigial winged

25% LL 50% Ll 25% ll

3 vestigal winged fly 1 long winged fly

75% vestigial winged 25% long winged fly

Scenario 3

Scenario 5

LL

Ll

ll

Ll

4 ll

1LL 2 Ll 1ll

Questions 1. Which type of cross gave you the greatest number of genotypes? Was the number of phenotypes the same as the number of genotypes or different? If different, why (2 pts)? LL/GG and ll/gg combo gave us the greatest number of genotypes and yes there was the same number of phenotypes as genotypes. The only time the genotypes was different than the phenotypes was when there was the same 2 parent genotypes like Ll Ll.

Updated October 2013

2. Can the genotype for a gray-bodied fly be determined? If so, how? (3 pts)? Yes, in order to determine the genotype in a fly showing dominant body color it must be cross bred with a fly expressing the recessive trait of being lighter colored. If any offspring express the recessive trait of a lighter body the gray-bodied fly will have a genotype of dominant/recessive carrier alleles ex. Aa. In other words gray-bodied flies would be the dominant and black bodied flies would be recessive. So, the results can only be a homozygous dominant fly (GG) or heterozygous fly (Gg). If you cross that fly with a black bodied fly (gg) and there is a result of some black bodied flies, then you know the original fly was heterozygous. If you result in all gray flies, then it was dominant.

Experiment 6 Exercise 2: Dihybrid Cross We will continue to use flies for our crosses, but this time we will examine the inheritance of TWO different traits: body color (gray or black) and wing type (long or vestigial). As with our first crosses, the gray body color is dominant (GG or Gg) over the black body color (gg). And the long wing type is dominant (LL or Ll) over vestigial (ll). Be sure you have reviewed our online Genetics lecture and this week’s reading before proceeding. An example of a dihybrid cross is shown on p 150 in your book. Recall our flies from the previous exercise. We have the following traits:  

Gray body (GG or Gg) is dominant over black body (gg) Long wings (LL or Li) is dominant over vestigial wings (ll)

We will cross a gray bodied fly with long wings which has the genotype GGLl with a gray bodied fly with long wings with a genotype of GgLl . Note that even though the phenotypes are the same, the genotypes of the two parents are different. Identify the four possible gametes produced by these two individuals. Note that each gamete must consist of two alleles (G or g and L or l): Parent 1

Parent 2

GGLl

GgLl

Parent 1 (GGLl) Gametes: _GL___ Gl____ _GL______ Parent 2 (GgLl) Gametes: _GL______

_Gl_____

Gl_______ (1 pts)

_gL______ __gl_____ (1 pts)

Create a Punnett square to show the outcome of a cross between these two individuals (GGLl and GgLl) using the gametes you identified above (3 pts). Updated October 2013

GL

Parent 2

G L Gl gL gl

Parent 1 Gl GL

Gl

GGLL

GGlL

GGLL

GGlL

GGLl

GGll

GGLl

GGll

GgLL

GglL

GgLL

GglL

GgLl

Ggll

GgLl

Ggll

Questions 1. What are the possible F1 genotypes (these must now have four alleles) and their percentages (4 pts)? 1.GGLL: 12.5% 2. GGlL: 25% 3.GGll: 12.5% 4. GgLL:12.5% 5. GglL:25% 6. Ggll:12.5% 2. Recall that GG and Gg individuals are gray bodied, while gg individuals are black bodied and that LL and Li individuals have long wings, while ll individuals have vestigial wings. What are the phenotypes of the resulting offspring and what are the percentages of these phenotypes (2 pts)? 1. GGLL: 75% (gray body with long wings) 2. GGll: 25% (gray body with vestigial Experiment 6 Exercise 3: Inheritance of Human Traits Read over the Inheritance of Human Traits Introduction under the Week 6 Experiment link in our course before beginning. Procedure A. For each of the heritable traits describe below, determine which form you have (dominant form or recessive form). This is your phenotype.

B. Record your phenotype information in Table 2 below. Then, enter the possible genotype(s) you have based on your phenotype.

Updated October 2013

C. Answer the questions found following Table 2 below. Description of Heritable Traits Possible Alleles

Dominant Form

Recessive Form

Ear lobes

E or e

Detached (Free)

Attached

Hairline

W or w

Widows peak

Straight

Trait

Examples

Widow’s peak

Tongue rolling

T or t

Able to roll

Unable to roll

Hand folding

R or r

Right thumb on top

Left thumb on top

Chin

C or c

Cleft chin

No cleft chin

Updated October 2013

Straight

F or f

Can fold tongue backwards

Cannot fold tongue backwards

Thumb

H or h

Straight thumb (cannot bend backwards)

Hitchhiker’s thumb (can bend it backwards)

Little Finger

B or b

Bent inwards

Straight

Middigital hair

M or m

Hair on fingers

No hair on fingers

Tongue folding

An example is shown as to what should be entered in RED. Please correct the entry for “Ear lobes” based on your personal data. For the Genotypes, please use the letters provided above (8 pts). Table 2. Your phenotypes and genotypes. Trait

Updated October 2013

Phenotype

Genotype

Ear lobes

Detached

Ee

Hairline

Widows Peak

WW

Tongue Rolling

Able to Roll

Tt

Hand Folding

Right Thumb Top

Rr

Chin

No Cleft Chin

cc

Tongue Folding

Can Fold tongue

Ff

Thumb

Straight Thumb

Hh

Straight

bb

Hair on Fingers

Mm

Little Finger Mid-digital Hair

Questions 1. Which traits did you have that were dominant (1 pts)? Detached, Widows Peak, Able to Roll, Right Thumb Top, Can Fold tongue, Straight Thumb, Hair on Fingers

2. Which traits did you have that were recessive (1 pts)? Cleft Chin, Straight little finger

3. What does it mean to be homozygous for a trait? Cite source(s) used (1 pts). “If an organism has two copies of the same allele, for example AA or aa, it is homozygous for that trait.” Metzler, K. (n.d.). What is Homozygous? - Definition, Traits & Example. Retrieved November 29, 2014, from http://education-portal.com/academy/lesson/what-is-homozygous-definition-traitsexample.html#lesson

4. What does it mean to be heterozygous for a trait? Cite source(s) used (1 pts). “If the organism has one copy of two different alleles, for example Aa, it is heterozygous.” Metzler, K. (n.d.). What is Homozygous? - Definition, Traits & Example. Retrieved November 29, 2014, from http://education-portal.com/academy/lesson/what-is-homozygous-definitiontraits-example.html#lesson

5. Define genotype and phenotype? Cite source(s) used (1 pts). “Phenotype this is the "outward, physical manifestation" of the organism. These are the physical parts, the sum of the atoms, molecules, macromolecules, cells, structures, Updated October 2013

metabolism, energy utilization, tissues, organs, reflexes and behaviors; anything that is part of the observable structure, function or behavior of a living organism.” “Genotype this is the "internally coded, inheritable information" carried by all living organisms. This stored information is used as a "blueprint" or set of instructions for building and maintaining a living creature. These instructions are found within almost all cells (the "internal" part), they are written in a coded language (the genetic code), they are copied at the time of cell division or reproduction and are passed from one generation to the next ("inheritable"). These instructions are intimately involved with all aspects of the life of a cell or an organism. They control everything from the formation of protein macromolecules, to the regulation of metabolism and synthesis.” Genotype and Phenotype Definition. (n.d.). Retrieved November 29, 2014, from http://www.brooklyn.cuny.edu/bc/ahp/BioInfo/GP/Definition.html 6. Which traits do you know for sure that you were homozygous (1 pts)? My traits that are homozygous are my hairline, Cleft Chin, Straight little finger.

Week 6 Experiment Grading Rubric Component Experiment 6 Exercise 1 Experiment 6 Exercise 2

Experiment 6 Exercise 3

Expectation

Points

Correctly perform and record the outcome of five monohybrid crosses (Table 1).

5

Demonstrate an understanding of the possible outcomes of monohybrid crosses with respect to genotypes and phenotypes (Questions 1-2).

5

Determine the correct parental gametes and conduct a dihybrid cross.

5

Correctly evaluate the outcome of a dihybrid cross (Questions 1-2).

6

Correctly recognize one’s phenotype and assigns the correct genotype (Table 2).

8

Demonstrate an understanding of dominant and recessive traits, genotype vs phenotype and homozygous vs heterozygous (Questions 16).

6

TOTAL

Updated October 2013

35 pts...