MENDELLIAN GENETICS LAB Click on a box to begin. SCIENCE 10 LIFE SCIENCES: GENETICS PART A Analyzing...

MENDELLIAN GENETICS LAB

Click on a box to begin.

SCIENCE 10 LIFE SCIENCES: GENETICS

PART AAnalyzing results

PART BPredicting results

PART CExplaining results

PART DExperimental design

Genome British Columbia, 2004 www.genomicseducation.ca

PART A: COMPLETE DOMINANCE

INTRODUCTION:

You’re back in 1865 and Gregor Mendel is getting ready to publish his results. Being a good scientist, he wants to check that his results are repeatable. You’ve just been hired by Mendel to study the heredity of two traits:

1. seed color: green or yellow

2. seed shape: smooth or wrinkled

yellow, winkled

green,

smoothyellow,

smooth

OBJECTIVE:

Mendel gives you three plants that produce the following seeds:

He asks you to breed new plants to determine the genotypes of these plants.

PROCEDURE:Click on the plants that you would like to cross.

self-fertilize

cross-fertilize

Click here when you have finished collecting all your data.

You need to select the plants that you want to

cross to see the data.

Click anywhere on this screen to go back.

You need to select the plants that you want to

cross to see the data.

Click anywhere on this screen to go back.

Click anywhere on this screen to go back.Remember to record this data in your data table.

self-fertilized

Click anywhere on this screen to continue.

DATA: self-fertilized

self-fertilized

cross-fertilized

What is the dominant allele for seed color?

ANALYSIS:

YELLOW GREEN

ANALYSIS:

YELLOW GREEN

Yellow

ANALYSIS:

YELLOW GREEN

Yellow

It is the more common color.A dominant allele always covers a recessive allele.

What is the recessive allele for seed shape?

ANALYSIS:

SMOOTH WRINKLED

ANALYSIS:

SMOOTH

Wrinkled

WRINKLED

ANALYSIS:

SMOOTH

Wrinkled

It is the less common shape.A recessive allele is always covered by a dominant allele.

WRINKLED

CONCLUSION:

If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the yellow, wrinkled seeds?A. YYSS C. YySsB. YYss D. Yyss

CONCLUSION:

Hint: A self-fertilized parent that produces offspring with the identical traits must be homozygous for both traits.

CONCLUSION:

Hint: A self-fertilized parent that produces offspring with the identical traits must be homozygous for both traits.

B. YYss

Ys Ys Ys Ys

YsYYss YYss YYss YYss

self-fertilized

CONCLUSION:

If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the green, smooth seeds?A. YySS C. yySSB. YySs D. yySs

CONCLUSION:

If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the green, smooth seeds?A. YySS C. yySSB. YySs D. yySs

C. yySS

yS yS yS yS

ySyySS yySS yySS yySS

self-fertilized

CONCLUSION:

If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the yellow, smooth seeds?A. YySs C. YYSsB. YySS D. YYSS

CONCLUSION:

If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the yellow, smooth seeds?A. YySs C. YYSsB. YySS D. YYSS

A. YySs

YS Ys yS ys

YSYYSS YYSs YySS YySs

YsYYSs YYss YySs Yyss

ySYySS YySs yySS yySs

ysYySs Yyss yySs yyss

self-fertilized

PART B: COMPLETE DOMINANCE (cont.)

INTRODUCTION:

Before giving Mendel your results from Part A, you decide to verify your results by self-fertilizing certain F1 offspring.

OBJECTIVES:

For the following crosses, predict the genotypes and phenotype ratios for the F2 offspring.

self-fertilized

YYss yySS

yySS YySs

self-fertilized

YySs YYss

self-fertilized

?For each cross, predict the genotype and phenotype ratio, then click on that box to see the expected results.

PROCEDURE:

YS Ys yS ys

YySs YySs

Phenotype ratio:

RESULTS:

YS Ys yS ys

YySs YySs

Phenotype ratio:

9 yellow, smooth

3 yellow, wrinkled

3 green, smooth

1 green, wrinkled

RESULTS:

yS yS yS yS

If homozygous, then phenotype ratio:

RESULTS: yySS yySS

yS yS yS yS

all green, smooth

RESULTS: yySS yySS

yS yS yS yS

all green, smooth

If heterozygous, then phenotype ratio:

RESULTS: yySS yySS

yS yS ys ys

ySyySS yySS yySs yySs

ysyySs yySs yyss yyss

Phenotype ratio:

RESULTS: yySs yySs

yS yS ys ys

ySyySS yySS yySs yySs

ysyySs yySs yyss yyss

Phenotype ratio:

12 green, smooth

4 green, wrinkled

RESULTS: yySs yySs

Ys Ys Ys Ys

RESULTS:

YYss YYss

Ys Ys Ys Ys

all yellow, wrinkled

RESULTS:

YYss YYss

Ys Ys Ys Ys

all yellow, wrinkled

If heterozygous, then phenotype ratio:

RESULTS:

YYss YYss

Ys Ys ys ys

ysYYss YYss yyss yyss

Phenotype ratio:

RESULTS:

Yyss Yyss

Ys Ys ys ys

ysYYss YYss yyss yyss

Phenotype ratio:

12 yellow, wrinkled

4 green, wrinkled

RESULTS:

Yyss Yyss

PART C: INCOMPLETE DOMINANCE

INTRODUCTION:

Mendel is impressed with your intelligence and hard work, so he decides to gives you another project to work on.

OBJECTIVES:

Given the following data, explain the results.

self-fertilized

ANALYSIS:

Phenotype ratios:

ANALYSIS:

Phenotype ratios:

F1 all medium

ANALYSIS:

Phenotype ratios:

F1 all medium

F2 1 long : 2 medium : 1 short

ANALYSIS:

Phenotype ratios:

F1 all medium

F2 1 long : 2 medium : 1 short

Intermediate phenotype and phenotype ratios indicates incomplete dominance.

If we use “L” for long size & “l” for short size. Note: There is insufficient information to determine which allele is more dominant, so long size was arbitrarily chosen as dominant.

F1 L L

L L l l

Phenotype ratio:

F1 L L

lLl Ll

L L l l

Phenotype ratio:

F1 L L

lLl Ll

LL l l

Phenotype ratio:

all medium

F2Phenotype ratio:

F2 L l

Phenotype ratio:

F2 L l

LLL Ll

lLl l l

Phenotype ratio:

F2 L l

LLL Ll

lLl l l

Phenotype ratio:

1 long

2 medium

1 short

PART D: CODOMINANCE

INTRODUCTION:

Mendel’s results were not well received by other scientists. With his extensive experience in growing pea plants, he pursues a career in farming. He decides to selectively breed a new type of corn that produces sweeter, saltier kernels. He starts with one plant that produces sweeter kernels and another plant that produces saltier kernels.

He performs several crosses and successfully produces a plant with sweeter, saltier kernels but discovers that his phenotype ratios are not consistent with his pea plant results. After examining his results, you suspect codominance. However, Mendel is not yet familiar with this concept.

OBJECTIVE:

Assuming that Mendel started with purebreds, design an experiment that illustrates this concept to Mendel. Include a hypothesis.

SAMPLE EXPERIMENT

PROCEDURE:

1. Cross-fertilize parents with each other

2. Cross-fertilize F1 with each parent to verify parents are purebreds

3. Self-fertilize F1 offspring and compare ratios

4. Repeat

EXPECTED RESULTS:

Using: A = sweet, a = not sweetB = salty, b = not salty

If parent plants are purebreds, then:

Positive results for codominance:

F1: all sweet, salty (AB)

F2: 1 sweet, not salty (AA)2 sweet, salty (AB)1 not sweet, salty (BB)

Negative results for codominance:i.e. positive results for separate 2 traits

F1: all sweet, salty (AaBb)

F2: 9 sweet, salty(1 AABB, 2 AABb, 2 AaBB, 4 AaBb)

3 sweet, not salty (1 AAbb, 2 Aabb)3 not sweet, salty (1 aaBB, 2 aaBb)1 not sweet, not salty (aabb)

MENDELLIAN GENETICS LAB Click on a box to begin. SCIENCE 10 LIFE SCIENCES: GENETICS PART A Analyzing...

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