Lab 5: Dihybrid Cross in Corn

Questions and Answers

Which of the following factors contributes to changes in allele frequencies?

Mutation

Natural selection

Genetic drift

All of the above (correct)

Tongue rolling has a clear anatomical advantage for individuals who can do it.

False

What is the genotype of an individual who is able to roll their tongue?

Dominant

___________ is the study of distribution and change in frequency of alleles within a population.

Population genetics Signup and view all the answers

Match the following traits with their description:

Tongue rolling = Ability to roll the tongue upward from the sides Allele frequency = Proportion of different alleles in a population Mutation = Change in DNA sequence Genetic drift = Random changes in allele frequencies Signup and view all the answers

What does the presence of hair on the middle joint of a finger indicate?

Dominant phenotype represented by H Signup and view all the answers

Natural selection is one of the conditions necessary for a population to be in Hardy-Weinberg Equilibrium.

False Signup and view all the answers

Name one of the five conditions that must be met for a population to be considered in Hardy-Weinberg Equilibrium.

No gene mutations or Random mating or No migration or No genetic drift or No natural selection Signup and view all the answers

The ___ phenotype is represented by the genotype hh.

recessive Signup and view all the answers

Match the following terms with their definitions:

Dominant phenotype = Presence of a trait even if only one allele is present Recessive phenotype = Absence of a trait when both alleles are recessive Hardy-Weinberg Equilibrium = State of allele frequencies remaining constant over time Random mating = Mating that occurs by chance among individuals Signup and view all the answers

What is the genetic trait associated with a hairline that forms a downward (V) shape at the center of the forehead?

Widow's peak Signup and view all the answers

The left thumb on top when clasping hands is a dominant trait.

True Signup and view all the answers

What type of earlobe is considered dominant?

Unattached Signup and view all the answers

If your earlobe hangs free, it is considered __________.

detached Signup and view all the answers

Match the following traits with their descriptions:

Widow's peak = V-shaped hairline Left thumb on top = Dominant hand clasping trait Detached earlobes = Free hanging earlobes Attached earlobes = Connected directly to the head Signup and view all the answers

What is the function of the Beta-lactamase gene in the pGLO plasmid?

It allows transformed bacteria to survive on plates with ampicillin. Signup and view all the answers

The AraC protein acts as a switch that turns the GFP gene ON and OFF depending on the presence of arabinose.

True Signup and view all the answers

What is the formula for calculating transformation efficiency?

(Number of Colonies on Plate / Amount of DNA plated (µg)) Signup and view all the answers

What is the primary purpose of analyzing the results in this genetics lab?

To determine the allele frequency for a common genetic trait Signup and view all the answers

Transformed bacteria can be used to generate __________ libraries.

cDNA Signup and view all the answers

The Hardy-Weinberg equation can be used to predict genetic variation in a population.

True Signup and view all the answers

What should students prepare to score the numbers of students according to their traits?

A table Signup and view all the answers

Match the applications of transformation with their descriptions:

To make multiple copies of DNA = Used in PCR and cloning In cloning procedures = Creates recombinant DNA for various applications To express large amounts of proteins and enzymes = Produces proteins for research or pharmaceuticals In DNA linkage studies = Analyzes genetic relationships and mapping Signup and view all the answers

In the experiment, the total number of students is expected to represent the contribution of different _____ groups in the country.

ethnic Signup and view all the answers

Match the following steps with their descriptions:

Step 1 = Count the students by sex. Step 2 = Prepare a table for scoring traits. Step 3 = Analyze results using Hardy-Weinberg equation. Step 4 = Take total class size for genetic traits. Signup and view all the answers

What is the purpose of shining UV light on the UV plate?

To cause mutations in the bacterial DNA Signup and view all the answers

Students should add tobacco extract to the water plate.

False Signup and view all the answers

What should be done to the plates after adding bacteria?

Let them dry for ~10 minutes. Signup and view all the answers

Students filter the extract through __________ into a bottle.

cheesecloth Signup and view all the answers

Match the step in the lab with its action:

Step 1 = Making tobacco extracts Step 2 = Adding extracts to the plates Step 3 = Adding bacteria and using UV light Signup and view all the answers

What law states that alleles for separate traits are passed independently of one another?

Law of Independent Assortment Signup and view all the answers

All kernels from the F1 generation are purple and round.

True Signup and view all the answers

In the F2 generation, what was the ratio of yellow to green kernels?

3:1 Signup and view all the answers

Kernels that have a wrinkled shape are categorized as __________.

sweet Signup and view all the answers

Match the following traits of corn kernels with their characteristics:

Purple kernels = Have anthocyanin pigment Yellow kernels = Colorless aleurone affects endosperm Starchy kernels = Round shape with low water content Sweet kernels = Wrinkled shape due to high water content Signup and view all the answers

Which trait is dominant in corn kernels?

Yellow color Signup and view all the answers

The round shape of kernels is associated with high concentrations of starch.

True Signup and view all the answers

What enzyme is defective in yellow kernels?

Pigment manufacture enzyme Signup and view all the answers

What is the first organism in which transformation was reported?

Streptococcus pneumoniae Signup and view all the answers

All bacteria are capable of taking up foreign DNA from the environment.

False Signup and view all the answers

What two key components are involved in the heat shock transformation method?

Calcium chloride and heat shock Signup and view all the answers

The gene for GFP can be turned on in transformed cells by adding __________ to the cell's nutrient medium.

arabinose Signup and view all the answers

Match the following terms with their correct definitions:

Competent cells = Cells that can take up foreign DNA pGLO plasmid = Contains the gene for GFP and antibiotic resistance GFP = Protein that causes fluorescence in jellyfish Heat shock = Method to induce DNA uptake by creating pores Signup and view all the answers

What color do transformed cells appear when grown on plates not containing arabinose?

White Signup and view all the answers

The GFP gene comes from a non-biological source.

False Signup and view all the answers

What is the main purpose of the transformation procedure in this lab?

To introduce the GFP gene into Escherichia coli Signup and view all the answers

What is one major effect of chemicals in tobacco on DNA?

They cause DNA damage and mutations Signup and view all the answers

Tobacco smoke contains fewer than 4,000 different chemicals.

False Signup and view all the answers

What visible change occurs in Serratia marcescens when exposed to UV light?

It grows white. Signup and view all the answers

Cigarette smoke can lead to serious diseases including and .

cancer, heart disease Signup and view all the answers

Match the following effects with their corresponding causes:

DNA damage = Free radicals from tobacco Visible change in bacteria = Exposure to UV light Cancer = Tobacco exposure Weak immune system = Smoking Signup and view all the answers

What is the primary purpose of the Ames Test?

To determine if substances can cause mutations Signup and view all the answers

The Ames Test was developed at Harvard University.

False Signup and view all the answers

What type of bacteria is primarily used in the Ames Test?

Salmonella typhimurium Signup and view all the answers

The Ames Test uses a strain of Salmonella typhimurium that cannot synthesize the essential amino acid __________.

histidine Signup and view all the answers

If a test substance causes mutations in the bacteria, what is likely to happen?

Colony growth will occur on histidine-deficient media Signup and view all the answers

Match the materials used in the Ames Test with their descriptions:

Agar plates = Used for growing bacteria Sterile saline solution = Used to dissolve test chemicals Histidine-free media = Media that lacks an essential nutrient Sterile filter paper discs = Used to apply test substances Signup and view all the answers

The number of bacterial colonies that grow indicates how non-mutagenic the test substance is.

False Signup and view all the answers

At what temperature is the Ames Test typically incubated?

37°C Signup and view all the answers

Study Notes

Dihybrid Cross in Corn and Mendel's Laws

Investigation of Mendel's law of independent assortment with traits of corn kernels: color (yellow/green) and shape (round/wrinkled).
Yellow is dominant over green, and round is dominant over wrinkled.
F1 generation from yellow round seeds crossed with green wrinkled seeds produced all yellow and round seeds.
F2 generation ratios: 9/16 yellow round, 3/16 yellow wrinkled, 3/16 green round, 1/16 green wrinkled.
Color trait ratio in F2: 3/4 yellow and 1/4 green; shape trait ratio: 3/4 round and 1/4 wrinkled, reflecting independent inheritance.
Corn kernels with high starch content are round; those with high sugar content are wrinkled due to water loss.

Population Genetics

Studies allele distribution and changes within populations over time.
General objectives: assess allele frequency changes, influence of mutation, migration, selection, genetic drift.
Human population traits analyzed, including tongue rolling, hairline shape, hand clasping, earlobe attachment, and mid-digital hair.
Traits are impacted by dominant and recessive alleles; e.g., tongue rolling is a dominant trait.

Hardy-Weinberg Equilibrium

Used to assess allele frequencies over time; requires five conditions: no mutation, no migration, random mating, no genetic drift, and no natural selection.
Key in determining population genetic structure and evolution.

Bacterial Transformation

Bacterial cells can uptake foreign DNA, creating competent cells, primarily using the heat shock method.
Transformation process includes calcium-rich environments and sudden temperature shifts to introduce plasmid DNA.
Plasmid pGLO contains the gene for GFP and a resistance gene for ampicillin.
Selection for transformed cells occurs by growth on antibiotic plates, revealing fluorescence in the presence of arabinose.

Tobacco-Induced Mutations

Cigarette smoke contains numerous chemicals, which can generate free radicals and DNA damage, leading to mutations.
Experiment with Serratia marcescens to investigate the mutagenic effects of tobacco extracts within two days.
Procedure involves creating tobacco extracts, applying them to agar plates, and exposing the plates to UV light for mutation.

Ames Test

A method developed by Dr. Bruce Ames to determine the mutagenic potential of substances using Salmonella typhimurium.
Test uses bacteria that cannot synthesize histidine; growth on histidine-deficient media indicates mutagenicity.
Connection between test substance and DNA alteration, resulting in colony growth, used to assess health risks of chemicals.

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Description

This lab explores Mendel's law of independent assortment through a dihybrid cross involving corn traits, specifically color and shape. Students will apply statistical analysis to the results, drawing conclusions about inheritance patterns. Engage with the principles of genetics and learn how traits are passed on from generation to generation.

Lab 5: Dihybrid Cross in Corn

Questions and Answers

Which of the following factors contributes to changes in allele frequencies?

Tongue rolling has a clear anatomical advantage for individuals who can do it.

What is the genotype of an individual who is able to roll their tongue?

___________ is the study of distribution and change in frequency of alleles within a population.

Match the following traits with their description:

What does the presence of hair on the middle joint of a finger indicate?

Natural selection is one of the conditions necessary for a population to be in Hardy-Weinberg Equilibrium.

Name one of the five conditions that must be met for a population to be considered in Hardy-Weinberg Equilibrium.

The ___ phenotype is represented by the genotype hh.

Match the following terms with their definitions:

What is the genetic trait associated with a hairline that forms a downward (V) shape at the center of the forehead?

The left thumb on top when clasping hands is a dominant trait.

What type of earlobe is considered dominant?

If your earlobe hangs free, it is considered __________.

Match the following traits with their descriptions:

What is the function of the Beta-lactamase gene in the pGLO plasmid?

The AraC protein acts as a switch that turns the GFP gene ON and OFF depending on the presence of arabinose.

What is the formula for calculating transformation efficiency?

What is the primary purpose of analyzing the results in this genetics lab?

Transformed bacteria can be used to generate __________ libraries.

The Hardy-Weinberg equation can be used to predict genetic variation in a population.

What should students prepare to score the numbers of students according to their traits?

Match the applications of transformation with their descriptions:

In the experiment, the total number of students is expected to represent the contribution of different _____ groups in the country.

Match the following steps with their descriptions:

What is the purpose of shining UV light on the UV plate?

Students should add tobacco extract to the water plate.

What should be done to the plates after adding bacteria?

Students filter the extract through __________ into a bottle.

Match the step in the lab with its action:

What law states that alleles for separate traits are passed independently of one another?

All kernels from the F1 generation are purple and round.

In the F2 generation, what was the ratio of yellow to green kernels?

Kernels that have a wrinkled shape are categorized as __________.

Match the following traits of corn kernels with their characteristics:

Which trait is dominant in corn kernels?

The round shape of kernels is associated with high concentrations of starch.

What enzyme is defective in yellow kernels?

What is the first organism in which transformation was reported?

All bacteria are capable of taking up foreign DNA from the environment.

What two key components are involved in the heat shock transformation method?

The gene for GFP can be turned on in transformed cells by adding __________ to the cell's nutrient medium.

Match the following terms with their correct definitions:

What color do transformed cells appear when grown on plates not containing arabinose?

The GFP gene comes from a non-biological source.

What is the main purpose of the transformation procedure in this lab?

What is one major effect of chemicals in tobacco on DNA?

Tobacco smoke contains fewer than 4,000 different chemicals.

What visible change occurs in Serratia marcescens when exposed to UV light?

Cigarette smoke can lead to serious diseases including ______ and ______.

Match the following effects with their corresponding causes:

What is the primary purpose of the Ames Test?

The Ames Test was developed at Harvard University.

What type of bacteria is primarily used in the Ames Test?

The Ames Test uses a strain of Salmonella typhimurium that cannot synthesize the essential amino acid __________.

If a test substance causes mutations in the bacteria, what is likely to happen?

Match the materials used in the Ames Test with their descriptions:

The number of bacterial colonies that grow indicates how non-mutagenic the test substance is.

At what temperature is the Ames Test typically incubated?

Study Notes

Dihybrid Cross in Corn and Mendel's Laws

Population Genetics

Hardy-Weinberg Equilibrium

Bacterial Transformation

Tobacco-Induced Mutations

Ames Test

Studying That Suits You

Description

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