Gen Lab Quiz

The spectrophotometer measure what?

The absorption of light by molecules in a solution

The DNA in chromosome 1 is the largest molecule in the human cells. Its molecular mas is 155,376,000,000 Da. What would be the correct expression in scientific notation that describes the size of this molecule?

1.55376 × 10^11 Da

The molecular weight of insulin is 5,800 Da. If you dissolve 5.8g of insulin in water to make 1 liter (1L) solution, what will be the concentration of this solution? (*think molarity)

1mM

The largest human protein is titin. Its molecular mass is 3,816,030 Da. Which molecular mass correctly describes its size?

3.81603 MDa

Your DNA sample if made up of 2.808 × 10^4 Da human somatostatin gene, what would be the amount of mass in grams of this DNA molecule?

2.808 × 10^4 grams

(Bonus) You have 445 uL of DNA sample, with a concentration of 75 ng/uL. How much total DNA is present in your sample?

3,375 ng

(Bonus) Your DNA sample gives a A260/A280 reading of 1.4. What is the quality of your DNA?

Your protein is too contaminated

in minks, brown fur (B) is dominant to silver-blue fur (b). If two minks that have brown fur produce a litter of mink babies (kits) where some kits have brown fur and other kits have silver-blue fur, what are the parent minks’ genotypes?

Father: Bb (heterozygous), Mother: Bb (heterozygous)

Referring to question 1, how would you determine the genotype of a mink that displays brown fur?

cross the brown fur kit with a silver-blue fur mink to see if the litter has any kits that display silver-blue fur. If there are kits with silver-blue fur, the brown-furred parent must be heterozygous

Hornless (H) in cattle is dominant over horned (h). If a calf is brown without horns, and the mother cow is hornless while the father bull is horned, what is the genotype of the calf

Hh (heterozygous)

In corn plants, the size of an ear of corn is determined by a single locus with alternative traits. An ear of corn can either be long or short. Two corn plants that produce long ears are crossed, and the progeny of this cross has some corn plants that produce long ears of corn and some that produce short ears of corn. What can be deduced about the inheritance of ear size?

Long ear is the dominant trait

In humans, free earlobes (E) are dominant over attached earlobes (e). If a man with attached earlobes has a child with a woman who is homozygous for few earlobes, what is the probability that the child will have free earlobes? What is the probability that the child will have attached earlobes?

Free earlobes: 100%, attached earlobes: 0%

(Bonus) Crossing over is a cellular process that occurs during meiosis when homologous chromosomes exchange genetic material. I which phase of meiosis does this occur?

Prophase I

(Bonus) How many pairs of homologous chromosomes are found in the egg cell of humans?

None of the above

In a flowering plant, green stems (G) is dominant to white stems (g) and red flower (R) is dominant to yellow flower (r ). If a plant is heterozygous for both genes, what type of gametes will this plant produce, and in what proportion are these gametes produced?

There will be 4 gametes produced (GR, Gr, gR, gr) in a 1:1:1:1 ratio

In guinea pigs, hereditary heart diseases is a recessive trait. If two guinea pigs are asymptomatic carriers (heterozygous) for heart disease, and they produce a litter of 4 pups, what is the probability that all 4 of their pups will suffer heart disease? What is the probability that all 4 of their pups will be asymptomatic carriers for hereditary heart disease?

The probability is 1/256 that all of them will have heart disease; 1/16 that all of them will be carriers

In a flowering plant, green stems (G) is dominant to white stems (g), red flower (R) is dominant to yellow flower (r ), and normal fruit size (N) is dominant over dwarf fruit size (n). If a heterozygous plant (GgRrNn) is self pollinated, what proportion of the resulting progeny plants will have the phenotype of green stems, red flowers and normal sized fruit?

27/64

A cross made between two grape plants that have the following genotypes: PPLlrr x ppLlRr. What percentage of the progeny seedlings will have the following genotype: PpLlRr

1/4

What is the probability of having a child that phenotypically resembles the mother if the mother has a genotype of aa BB Cc dd Ee and the father has the genotype of Aa bb Cc Dd ee?

3/32

Hemophilia A is an x-linked recessive disorder. If a woman who is heterozygous for hemophilia marries a man who does not have hemophilia, what is the probability that if they have a son, he will have hemophilia

1/2

In the trihybrid grapevine PpLlRr how many different types of gametes can be produced with respect to the three genes of interest

8

Why did we include iminodiacetate ions (Chelex 100) into the reaction mix in which we boiled our cheek cells?

To keep metal ions away from the DNA that was released from our cells

A PCR cycle consists of three segments. In which segment does the Taq polymerase enzyme synthesize a new DNA strand?

Extension

In PCR, the number of DNA molecules increase according geometric growth, hence the name “chain reaction”. Which number sequence describes the way DNA molecules are amplified in PCR if the reaction starts with two template molecules?

4 8 16 32 64 128 256 512

In the PCR we performed in lab last week, the reaction amplified a specific DNA fragment from our 3.2 billion base pair-long genome. PCR amplified that fragment exclusively, and nothing else. What provides this incredibly high specificity of PCR?

The nucleotide sequence of the primers

What is a single nucleotide polymorphism (SNP)?

A one-nucleotide sequence difference at corresponding position in genomes of a species

(Bonus) Each taste bud can detect several different types of compounds depending on the ion channels and taste receptor proteins in its taste receptor cells. Which of the following does not need taste receptor proteins when it comes to taste?

Sour

(Bonus) What is the optimal temperature of Taq DNA polymerase?

72 Degrees C

The C → G nucleotide change in the 49th codon of the TA23R38 gene can be classified as a:

Single nucleotide polymorphism

Why did we use Haell restriction endonuclease to determine our TAS2R38 genotype?

This enzyme cleaves the PCR product of the wild-type taster allele, but not the PCR Product of the recessive non-taster allele

Electrophoresis separates DNA fragments based on their size. What is the most important physical or chemical basis of this separation?

The length of the DNA fragment

What was the purpose of glycerol in the gel loading buffer?

It mixes with DNA and pulls it to the bottom of the well when we load gel

Identify the correct order of lanes from left to right in the example below. The gel has the PCR-amplified DNA fragment of the TAS2R38 gene exposed to Haell, where T is the wild-type taster and t is the recessive non-tater allele

Tt, tt, TT

(Bonus) The marker we used to genotype the TAS2R38 gene was able to detect the T (TASTER) and t (NON-TASTER) alleles simultaneously in gel electrophoresis, allowing us to genotype us regardless of whether we are heterozygous or homozygous dominant or recessive. This marker can be classified as…

Codominant marker

(Bonus) During gel electrophoresis, we load our samples on the _____ end and they travel to the _____ end

negative; positive

Which one of the following statements accurately describes genotype frequency in a population?

Forty-five percent of Native Americans are homozygous dominant for the IB allele

The new Omicron variant of the SARS-CoV-2 virus is lethal to cats if they are homozygous recessive for a histoincompatibility complex gene (rr). If a cat is heterozygous (Rr) or homozygous dominant (RR) for this gene, it will survive the viral infection. You collected 1,000 stray cats from Springfield neighborhoods and inoculated all of them with the Omicron variant. The experiment led to 324 cats dying from Covid-19, and 676 cats surviving the disease. Which one of these population genetics indices can you determine or calculate from these data?

Observed frequency of the homozygous recessive (rr) genotypes

Population genetic studies in cats revealed that the dominant and recessive alleles (R and r alleles, respectively) of this gene are present in various cat species at very different frequencies. In the cheetah, the frequency of R is 1 (that is, p=1), and r is absent (that is, q=0), in the Florida panther (p=0.1 and q=0.9), in the tiger (p=0.2 and q=0.8), in the ion (p=0.5 and q=0.5), in the snow leopard (p=0.7 and q=0.3). Assuming Hardy-Weinberg equilibrium, which of these cat species has the highest frequency of heterozygotes in its population?

Lion

The X2 test (=goodness of fit test) is used to calculate the…

The probability that deviation from expected ratios is due to chance

There are a list of assumptions required in order for Hardy-Weinberg equilibrium to be met. Which of the following is not one of the assumptions?

Very small population (genetic drift must occur)

You have genotyped a large population of house cats with the R gene. You measure the genotype frequency of RR homozygotes to be 0.09, and the genotype frequency of Rr heterozygotes to be 0.42. Based on these data, what is the frequency of rr homozygous genotypes in this population?

0.49

If the population described in question #6 above is in Hardy-Weinberg equilibrium, what is the frequency of the dominant R allele?

0.30

The DNA method we used last week to extract plant DNA was designed to purify _______ DNA from plant cells, with emphasis on _______

All of the above; Mitochondria

How did we break down the cell wall when we extracted DNA from the plants?

By mechanical force applied by griding

Organic solvents are…

chemicals that dissolve apolar (hydrophobic) molecules

In a solution of DNA, precipitation is induced by the addition of…

(c) only a & b

What did CTAB (a strong detergent) do for us during plant DNA extraction?

Help break down lipids (phospholipid bilayer)

(Bonus) During DNA extraction, what molecules were found in the organic phase layer?

triglycerides, fatty acids, chlorophyll

(Bonus) Following chloroform extraction of the plant lysate, the chloroform phase turned green, because chlorophyll is ______

a hydrophobic molecule

The photo is the molecular structure of the world’s most commonly consumed drug: caffeine. Caffeine is actually a nitrogenous base. What component of the DNA is most similar to?

Adenine

What gives DNA a negative charge?

Phosphate group

A DNA sample is analyzed and you find that 22% is cytosine, how much uracil would you expect in the sample?

0%

The lagging strand is made in Okazaki fragments that are later joined by…

DNA ligase

Above is a diagram of two complementary strands of DNA. Based on the diagram, which end is identified correctly?

The C end is a 3’ end

(Bonus) Atoms along the sugar-phosphate backbone of the DNA are connected by…

Covalent bond

(Bonus) Classify the molecule on the above

A nucleoside composed of a purine and a deoxyribose

What does it mean to construct a recombinant plasmid?

Join genetic material (DNA) from multiple sources to form a circular, double-stranded DNA

What two features of the cloning vector facilitated its efficient ligation to the PCR product?

Vector-linked topoisomerase and “T-overhang”

What is the purpose of DNA ligase?

“Glues” DNA fragments together by forming a phosphodiester bond between them

What is the purpose of incubating cells with a liquid medium?

To provide a controlled, sterile environment with essential nutrients to support cell survival, growth, and multiplication

What kind of bond link dsDNA long term to prevent breakage?

Covalent

What antibiotic did we use for this lab?

Spectinomycin

Fill in the blanks: Why does the DNA remain bound to the silica (SiO2)? Ionic forces hold the ______________ charged DNA to the ______________ charged SiO2.

Negatively; positively

Which statement describes phylogenetics?

All of the above are true

To determine revolutionary relationships, scientists use all of the following except:

All of the above are correct

What is the term for the area of the cladogram with the orange circle?

Node

Which Cladogram shows the same relationship?

A and C

Which node is the most common ancestor for all lizards and snakes?

3

the COX1 gene encodes subunit 1 of cytochrome c oxidase, which is important for what?

The electron transport chain

Which is a basal taxon

Lissamphibia