Gentics pre quizzes

Drosophila melanogaster is a good model organism because it

a)has a small genome
b)reproduces quickly
c)has many offspring
d)can be easily maintained in the lab

Human diseases can be studied in Drosophila because

about 75% of human disease-causing genes have related genes in Drosophila.

Drosophila is diploid, with ___ pairs of chromosomes.

4

Diploid organisms have two copies of every gene. The two copies are called alleles. The most common allele in a natural population of Drosophila is the

wild type allele

A wild type Drosophila allele is always symbolized

by adding a '+' sign as a superscript to the mutant allele symbol

Male Drosophila have

an X and a Y chromosome

What instrument will you use to examine flies today?

dissecting microscope

What will you be looking for as you examine flies referred to as the wild type flies?

distinguishing between males and females

Which of the following features are not used to distinguish female and male fruit flies?

the size of the eyes

What flies will you be scoring for phenotype using the dissecting microscope in this week's lab?

F1

What is the purpose of a reciprocal cross in Drosophila genetics?

To see if the trait in question is sex-linked or on an autosomal chromosome

You cross a white-eyed female fly with a male red-eyed fly. The reciprocal cross would be

a red-eyed female fly with a male white-eyed fly

separate molecules based on charge, size, and shape

gel electrophoresis set-up

precisely measure small amounts of liquid

micropipette

collects liquid or denser material at the bottom of a tube

microcentrifuge

Every amino acid has a name. The name has a three letter abbreviation and a one letter abbreviation. Consulting the table on page 1 of the activity, what is the name of the amino acid represented by the letter 'E'?

Glutamic acid

Amino acids are grouped into classes based on

the absence, presence, and nature of a charge associated with the R group

Hemoglobin is a

protein

What is the composition of a single molecule of hemoglobin?

two alpha polypeptides and two beta polypeptides

Sickle cell anemia is due to a mutation that

causes a change in the amino acid sequence of the beta subunit of hemoglobin

Beta thalassemia is due to a mutation that

causes reduced production of hemoglobin, but it does not affect the molecule's ability to function

The hemoglobin will be electrophoresed at pH 9.2. Why is this pH necessary?

So that hemoglobin will be negatively charged and migrate towards the anode.
So that hemoglobin will be negatively charged and migrate towards the positively charged electrode.

The samples being analyzed today differ in electrophoretic mobility due to their differing sizes.

False

How will you determine the DNA sequence difference between the WT allele and the one that is responsible for sickle cell anemia?

Align the two allele sequences and note any nucleotide difference.

Restriction endonucleases (aka restriction enzymes) are used to

cut DNA at specific sequences.

Plasmids are

small circular DNA molecules often found in bacteria.

is used to separate a mixture of different sized pieces of DNA.

Electrophoresis

Which of the four plasmids in our lab exercise should have the least amount of total DNA?

pUC18

When building a restriction digest in a microfuge tube, what component is usually added first?

nuclease-free water

During the lab you will prepare a 1.8% agarose gel. How much agarose will you weight to prepare 50 ml of a 1.8% agarose solution?

.9g (cross multiply)

Wearing gloves is mandatory during this lab when handling

ethidium bromide solutions or gels containing ethidium bromide.

What online database will you use to determine the expected sizes of restriction fragments generated when each of the four plasmids is digested?

NEB Cutter

After electrophoresis, how will the DNA on your gels be visible?

The ethidium bromide used in making the gel will attach to the DNA and fluoresce in UV light.

GPCRs like TAS2R38 in taste buds are important to taste perception because they

bind the taste compound and activate signaling pathways that ultimately leads to taste perception.

The TAS2R38 gene has a dominant allele that allows perception of

the bitter compound known as phenylthiocarbamide (PTC)

The most common difference between the dominant TAS2R38 allele and the recessive allele is

a single nucleotide polymorphism at base 145 that results in an amino acid difference in the protein

SNP is an acronym that stands for

single nucleotide polymorphism

PCR cannot be successfully performed without

DNA template
Primers for the region to be amplified
A thermostable DNA polymerase
DNA nucleotides (dNTPs)

If a single DNA molecule is amplified by PCR, how many total copies of the amplified target DNA sequence will there be after four cycles?

16

Heating the PCR reaction to 94 degrees Centigrade is necessary for each PCR cycle to

cause denaturation of the DNA so that it becomes single stranded

Why do we need to make up 5 times the needed amount of a PCR reaction mixture (called a Master Mix) when we are only running 4 reactions?

To make sure there is enough for all 4 reactions. This allows for any pipetting error.

The polymerase chain reaction (PCR) was used in this activity to

make many copies of a particular sequence that should be present in genomic DNA

The amplified sequence of the taster allele will have a restriction enzyme recognition sequence introduced into it by the forward primer. This technique is called

Derived Cleaved Amplified Sequence (dCAPS) genotyping

HaeIII is

a restriction enyzme.

How will you tell the difference between the taster and non-taster alleles?

The taster allele will be cut by the restriction enyzme, and the non-taster allele will not

Two bands, of 177 and 44 bp

TT

Three bands, of 221, 177, and 44 bp

Tt

A single 221 bp band

tt

Why do we need a 2% agarose gel for this lab exercise?

A higher percentage of agarose allows the very short segments of DNA to separate more in the gel.

The agarose gel has ethidium bromide added to it. What is the purpose of this?

So that DNA bands may be viewed with UV light.

During this activity, your are asked to prepare 50 ml of 2% agarose to prepare a gel for subsequent use. How much agarose (in grams) will you weigh into a tared weigh boat?

1

During this activity, your are asked to add 6X loading dye to a 10 microliter volume of undigested sample that has been transferred to a 0.5 mL microtube. What volume of loading dye (in microliters) will you add to these samples?

2

At the end of your the restriction digestion incubation period, your are asked to add 6X loading dye to each of the 16 microliter restriction digestion reactions that you prepared. What volume of loading dye (in microliters) will you add to these samples?

3.2

In the absence of evolutionary forces, allele and genotype frequencies will stay the same from generation to generation. This is the

Hardy-Weinberg principle

What is/are example(s) of evolutionary forces?

a)natural selection
b)mutation
c)migration

If a population is in Hardy-Weinberg equilibrium and we can observe the homozygous recessive phenotype, then we can predict the

a)proportion of homozygous dominants in the population
b)proportion of heterozygotes in the population
c)proportion of those with the dominant phenotype in the population

The dominant allele frequency is represented as

p

The frequency of the homozygous dominant genotype

p2

The equation:
(# of individuals of a given genotype in the population)/(total # of individuals in the population)
tells you the

genotypic frequency

In regards to the ability to taste PTC, tasting the paper tells us your _________, while performing the dCAPs analysis reveals your TAS238R _________.

phenotype; genotype

What is the purpose Microbial Source Tracking?

To identify the animal source that contributes to microbial contamination of an environmental sample.

In Microbial Source Tracking, the animal that is responsible for contamination is identified using DNA sequences from

bacterial strains that reside in its intestinal tract and specifically live in that animal.

General microbial contamination that is associated with animal waste can be determined using sequences in the 16S rRNA gene of

Bacteroides species

The PCR assay we will use for determining the presence of eDNA will

detect the presence of eDNA and quantify the amount.

When comparing qPCR vs. traditional PCR, the measurement of PCR product formation occurs

during each cycle of the reaction for qPCR; only after all cycles have ended for traditional PCR.

Check all those that are true for water sample collection and storage.

Sampling depth in the water body should not be more than 1 foot below the surface.
Samples should be kept on ice until they are brought to the lab for testing.

How will you concentrate the microbes containing the target DNA from your water sample?

200 mL