Genetics - Exam 1 (Labs 1-4)

When using sterile technique, you are allowed to talk as long as you do not ingest bacteria.

False

Eating, chewing tobacco or gum and applying make-up are forbidden in the laboratory to prevent you from accidentally ingesting hazardous chemicals.

True

While in the laboratory, which protective gear must you wear?

Gloves, Safety Goggles, Covered shoes, long pants

What should you do to protect yourself from the equipment hazard of running a gel electrophoresis?

Turn off the power source before unplugging the gel box

When using sterile technique, you want to clear your work area and disinfect it with 70% isopropanol.

True

What should you do to protect yourself from the chemical hazard of running a gel electrophoresis?

Wear gloves

In order to withdraw 10 µL accurately, how far into the liquid do you place a pipet tip?

1-2 mm or 2-3 mm from the liquid surface depending on the tip size

In order to accurately pipet the volume you set, you must depress the plunger ___

to the first stop

For the minimum volume you can accurately pipet with a P-20 (2 µL), the volume display window will show which numbers going from top to bottom?

0-2-0

In gel electrophoresis, molecules are separated based on their mass and

charge

In tomatoes, two alleles of one gene determine the character difference of purple versus green stems, and two alleles of a separate, independent gene determine the character difference of “cut” versus “potato” leaf shape. Assign “H” to the dominant color allele and “h” to the recessive color allele. Assign “D” to the dominant leaf allele and “d” to the recessive leaf allele. The following table are results from three crosses of tomato plants.

Cross	Parental phenotypes	Purple, cut	Purple, potato	Green, cut	Green, potato
1	Purple, cut X purple, cut	90	30	30	10
2	Purple, cut X green, potato	400	0	400	0
3	Purple, potato X green, cut	80	80	80	80

Looking at cross #3, what is the likely phenotype of the green, cut parent?

hhDd

For this, you have 159 red kernels and 165 yellow kernels?

A) What is the null hypothesis for your data? In your answer, state the a priori probabilities you chose to test. Choose probabilities based on the number of red and yellow kernels.

b) What is the total number of offspring in your data set?

C) What is the expected values of red and yellow kernels?

D) Solve for the chi-squared value. What is it?

E) What are the degrees of freedom?

F) What is the probability associated with this chi-square value? Be more precise than >0.05.

G) What do you conclude about the null hypothesis? What is your evidence?

A) Any difference in the data and the expected values are only different by chance. 1/2 red, 1/2 yellow

B) 324

C) Red = 162, Yellow = 162

D) 0.112

E) 1

F) Between 0.9 and 0.5

G) We fail to reject the null hypothesis. The evidence is the calculations from above. We found our chi-square value and the degrees of freedom. Using the chart, we found our chi-squared value and looked at the probability above. Because it is to the left of the chart (to the left of 0.05), we fail to reject the null hypothesis because our data proves otherwise

If you reject the null hypothesis, are the data only different from the expected values by chance?

False

According to Mendel's theories, if a recessive and a heterozygotes for a gene are crossed, what is the probability that the offspring will have a recessive trait?

1/2

According to Mendel's theories, if two heterozygotes for a gene are crossed, what is the probability that the offspring will have a recessive trait?

1/4

If you were analyzing results from a dihybrid cross, how many degrees of freedom would you have? An example of results is 200 yellow, round; 195 yellow, wrinkled; 205 green, round; and 180 green, wrinkled.

3

In biology, if the chi-square probability is 0.5, we would ___ the null hypothesis

fail to reject

If you counted 300 red kernels and 80 yellow kernels on one cob, what would be the a priori probability of red kernels in the chi-square test?

3/4

A monohybrid cross between two plants with purple stem resulted in progeny plants with purple or green stems. Which trait, purple or green stems, is dominant?

purple

According to Mendel's theories, if two heterozygotes for a gene are crossed, what is the probability that the offspring will have a dominant trait?

3/4

Which of the following is a null hypothesis for a chi-square analysis?

Differences between observed values and values based on probability expectations are due to chance.

What was the independent variable of Mendel's experiment?

the traits of the parents

Mendel's Law of Segregation explains the results of his monohybrid crosses. Which result led him to propose that parents had two particles, one of which was inherited by each offspring?

One of the phenotypes was seen in more F2 offspring than the other phenotype. The F2 offspring ratio was always 3:1. 

Which of the following were key elements in Mendel's experimental design?

He collected thousands of pea seeds, he used peas because they had a short life cycle, he used math to see patterns in his results, Mother and father plants were true-breeding, he repeated his experiment with different traits, mother and father plants had opposite phenotypes.

A variable in Mendel's experiment was the number of offspring with a specific trait. In the scientific method, this variable is the ___ variable

dependent

Which of the following is an insightful observation about parents and children?

Children have features from both mother and father.

Mendel's Law of Segregation explains the results of his monohybrid crosses. Which result led him to propose that some alleles were dominant over other alleles?

The F1 offspring were all one phenotype, but the F2 had one of two different phenotypes.

Which of the following served as evidence for Hershey and Chase's conclusion? 

Viruses only inject their genetic material into cells.

DNA, not protein, is labeled with P-32.

Radioactivity was in the pellet when T2 is labeled with P-32.

In a suspension of E. coli and T2, the E. coli cells will pellet, but the T2 remains in suspension.

Which of the following describes a result in Hershey and Chase's experiment?

The radioactivity was found in the cell pellet at the bottom of the tube.

In the Hershey and Chase experiment, what is(are) the dependent variable(s)?

location of the radioactivity

In Hershey and Chase's experiment, what is the independent variable?

P-32 and S-35 radioisotopes

Which of the following is a likely hypothesis for the Hershey and Chase experiment?

Genetic material of the T2 virus is DNA.

Which model organism is a dicot mustard plant?

Arabidopsis thaliana

Which model organism is also known as a budding yeast?

Saccharomyces cerevisiae

Which model organism is the gut bacterium?

Escherichia coli

Which of the following is an invertebrate?

Drosophila melanogaster

In the modified Bloom's taxonomy of learning, what is the lowest level of learning?

remember

Which model organism is a prokaryote?

Escherichia coli

This principle of biology, the theory of ____, is the reason we can infer how human cells work based on what we learn from model organisms like yeast.

evolution

Which model organism is the lab fruitfly?

Drosophila melanogaster

Which model organism is a nematode?

Caenorhabditis elegans

What is the effect of penicillin and its chemical relative, ampicillin, on bacterial cells?

They inhibit cell wall biosynthesis.

Which protein does Amp^r code for?

beta-lactamase

The addition of a ___ nucleotide to the pGEM-T Easy plasmid makes attaching a PCR amplicon easier.

T

For transformation of E. coli, you must incubate the reagents/reactions of the transformation reaction at which temperature prior to the heat shock step?

ice temperature

In cloning a PCR amplicon into the pGEM-T plasmid vector, which color of transformed E. coli indicates plasmid with the inserted PCR amplicon?

white or beige

Which cellular macromolecule carries out resistance to antibiotics?

protein

How does the protein coded by Amp^r resists the effects of ampicillin?

It destroys ampicillin.

In the recovery phase after heat shock, cells were incubated with LB (no antibiotics) in order to do what?

transcribe and tranlate beta-lactamase

What are features of plasmid DNA?

may contain an antibiotic resistance gene, able to replicate independent of chromosomal DNA, circular DNA, small number of nucleotide pairs relative to chromosomal DNA, contains 1 or 2 genes necessary for functions needed to survive under special circumstances

What does it mean to clone a gene?

You ligate a fragment of DNA into a plasmid.

Competent cells were made for you, but if you had to make them yourself, which stage of growth in liquid LB culture would you harvest E. coli?

log stage

Which protein does lacZ code for?

beta-galactosidase

Which chemical reaction does ligase catalyze?

the formation of a phosphodiester bond

The ___ origin of replication of commercial plasmids allows a cell to have multiple copies the the plasmid DNA.

ColE1

For transformation of E. coli, what is the duration of the transformation (heat shock) step/incubation?

30 seconds

Nematode

Caenorhabditis Elegans

What are C. Elegant

invertebrates

Baker’s/Budding Yeast

Saccharomyces Cerevisicae

Mustard Plant

Arabidopsis Thailand

What is a mustard plant?

plant

Fruit Fly

Drosophila Melanogaster

What is a fruit fly?

invertebrate

House Mouse

Mus Musculus

House Mouse

most similar to humans, mammals

Bacterium

Escherichia Coli

E. Coli

Single celled prokaryote

Mendel’s Insightful Observations

Alleles

Mendel DV

traits of offspring

Evidence for Law of Segregation from Mendel

Monohybrid Cross: alleles segregate when gametes from one allele go to each gamete

Dominance

two alleles of a genotype are different, one shows dominance

Hersey & Chase Hypothesis

Do protein or DNA pass as genetic material through viruses?

Crucial Design Choices of Hershey and Chase Experiment

1) Radioactive isotopes present in DNA (32P) and proteins (35S) instead of C & H (which are present in both)

2) T2 virus with only DNA and protein

3) centrifuge

Hershey and Chase DV

virus with different radioisotopes

Hershey and Chase IV

bacteria

Hershey and Chase Results

DNA is the genetic material of phage. Radioactive isotope (for DNA) found in pellet.

Hershey and Chase Evidence

After centrifuging, radioactivity found in 32P phage pellet, whereas the 35S was found in the liquid

Priori Probability

?

How to calculate expected values in Chi-Squared

total # of individuals x priori probability

Calculating Chi-Squared Value

x² = Sigma (d²/e)

D² in Chi Square Equation

= (observed data - expected data)²

Degrees of Freedom

#of possibilites - 1

What steps are involved in gene cloning?

1) PCR amplifying gene

2) Ligate amplicon

3) Transform ligation products into e. coli

4) isolate plasmid DNA from transformants

5) analyze plasmid for gene of interest

Why is it important to incubate the competent cells and DNA on ice before the heat shock step?

because of the temperature gradient

Why are colonies white?

Because they have the amplicon inserted into the lacZ gene, disrupting b-galactosidase

Why are colonies blue?

They are blue if the b-galactosidase is present after the ampicillin and chemicals are added to the agar plate.