BIO130H1 Lecture 3: Week 3 Genomes & Chromosomes

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Getting the eukaryotic genome packed into cells: the chromosome solution. Karyotype artificial array of paired chromosomes in numerical order diagnostic aid. Karyotype: this is not how organized chromosomes actually are. Fish: label a probe fluorescently and see if it binds to an antiparallel target dna that you might be looking for. Use hybridization to paint an entire chromosome fluorescently, making it shine. Insert probe near chromosome, heat up and separate the chromosome and probe strand. Then, cool them down slowly so the probe realigns with the chromosome. If the target dna [you are looking for] is there, the probe will light up. There is a possibility that the probe or chromosome may aligh with each other. That is why you insert lots of probes. Each chromosome contains a single, long linear dna molecule & associated proteins called chromatin. A dna strand with proteins around it is called a chromatin while the two strand together are call a chromosome.

Related Questions

You decide to identify the CFTR mutation by analyzing the genomic DNA of your patients compared to healthy individuals. You specifically are looking to see whether a specific 3' gene truncation has occurred in the patients. You will determine this using hybridization techniques with samples from healthy and CF patients. Which of the following will allow you to accomplish this?

	Using an RNA probe complementary to the region not removed by the truncation.
	Using an RNA probe complementary to the region removed by the truncation.
	Using an DNA probe complementary to the region not removed by the truncation.
	Using an DNA probe complementary to the region removed by the truncation.

To conduct the hybridization experiment, you are trying to decide between using a DNA or RNA probe. Which would be ideal to use and why?

	As both are composed of nucleic acids, using either would result in identical results.
	An RNA probe because RNA has uracil bases.
	An RNA probe because it could also be used in a translation experiment.
	A DNA probe because it is more stable than RNA.
	A DNA probe because RNA cannot bind to DNA.

Imagine Hershey/Chase had used an RNA virus (genome composed of RNA) instead of a DNA virus in their experiment. Would radioactivity still have been found in the pellet?

	No, because only DNA can be labeled with radioactivity.
	No, because the RNA genome would not enter the bacteria upon infection.
	No, because while DNA and RNA nucleotides are similar, they are not identical.
	Yes, because DNA and RNA nucleotides are similar.
	Yes, because genome in any form (DNA, RNA, protein) would be labeled similarly.

The human genome consists mostly of non-coding DNA. Which of the following are benefits of this?

	Random DNA mutations generally won't affect RNA and protein function.
	It is faster to duplicate the genome when these are present.
	The existence of introns can lead to multiple variations of proteins encoded by a single gene.
	It is unlikely transposons would exist in the genome if there was too much protein coding DNA.

You accidentally add a mutant dNTP (which has an H instead of an OH connected to the 3â carbon) to a reaction where DNA is being replicated. Which of the following is true of this mutant dNTP?

	It can be incorporated into DNA strand but cannot form a phosphodiester bond with an incoming wild type dNTP
	It can be incorporated into a DNA strand but cannot base pair with a complementary nucleotide
	It can be incorporated into a DNA strand and can form a phosphodiester bond with an incoming dNTP, but only if it is another mutant dNTP
	It cannot be incorporated into a DNA strand.

Andrew Murray's sister, Andrea, is adding to her brother's work on chromosomes. She is using cells that are unable to synthesize adenine (âade) and histidine (âhis). The plasmid she is currently working with consists of an origin of replication and the Ade gene.

Following her transformation of the plasmid into her yeast, what media will the cells be plated on to select for cells that have picked up the plasmid?

	Media containing histidine
	Media containing adenine
	Media lacking adenine
	Media lacking histidine

She starts by attempting to add the centromere DNA into a plasmid containing the origin of replication. Unfortunately, when adding the centromere sequence, the origin of replication is removed, thus leaving a plasmid with only a centromere and selection marker. Following plasmid transformation, what growth result will she see on her plates?

	No colonies
	Little colonies
	Big colonies

She fixes the mistakes from the previous experiment and now has a complete plasmid (selection marker, origin of replication, centromere). She then inserts telomere sequences into the plasmid. How will this impact her transformation?

	It will not impact her transformation
	Her transformation will no longer work because plasmids donât require telomeres
	She will now see much larger colonies
	She will now see fewer but larger colonies
	She will now see smaller colonies

In the Meselson/Stahl experiment, E. coli were first grown in media containing heavy nitrogen, 15N, and then transferred to light nitrogen, 14N, at the beginning of the experiment.

Imagine that their data showed that replication occurs in a conservative manner instead of semi-conservative. What fraction of the DNA helices will consist of mixed DNA after 4 rounds of replication in this case?

	None
	More than 75%
	25-50%
	51-75%
	Less than 25%

peachmarten804

Question 1

1 pts

Cystic fibrosis is caused by nonsense and missense mutations in the CFTR gene, which encodes for a chloride channel. You are studying cystic fibrosis patients to determine what mutation they possess in the CFTR gene. The difference between the mutant and wild type CFTR genes can be uncovered by examining the CFTR:

	DNA
	mRNA
	protein
	tRNA

Question 2

1 pts

	Using an RNA probe complementary to the region not removed by the truncation.
	Using an RNA probe complementary to the region removed by the truncation.
	Using an DNA probe complementary to the region not removed by the truncation.
	Using an DNA probe complementary to the region removed by the truncation.

Question 3

1 pts

You would like to ensure that this experiment (to determine whether patients have a specific CFTR gene truncation using hybridization) is properly controlled. Which of the following samples must you test?

	The genomic DNA of a healthy individual who does not have cystic fibrosis.
	The genome of a CFTR patient known to have the specific truncation you are trying to identify.
	The genome of a CFTR patient with a missense mutation but full length gene.
	The genome of a healthy individual married to a CFTR patient with the specific truncation you are trying to identify.
	The genome of a patient with muscular dystrophy, which can be due to a trucation in the dystrophin gene.

Question 4

1 pts

To conduct the hybridization experiment, you are trying to decide between using a DNA or RNA probe. Which would be ideal to use and why?

	As both are composed of nucleic acids, using either would result in identical results.
	An RNA probe because RNA has uracil bases.
	An RNA probe because it could also be used in a translation experiment.
	A DNA probe because it is more stable than RNA.
	A DNA probe because RNA cannot bind to DNA.

Question 5

1 pts

Which of the following will lower the Tm of a given DNA strand?

	Increasing the percentage of GC base pairs.
	Raising the pH of the solution from neutral to basic.
	Decreasing the buffer concentration from 50mM NaCl to 5mM NaCl.
	None of the above.

Question 6

1 pts

One step of the Hershey/Chase experiment involved blending the virus/cell mixture before centrifugation and probing the pellet for radioactivity. Why was the blending step necessary?

	To collect the bacteria at the bottom of the tube.
	To break open the bacteria to release the genome.
	To separate the bacteria from the bacteriophages.
	To be able to detect the radioactivity.

Question 7

1 pts

Imagine Hershey/Chase had used an RNA virus (genome composed of RNA) instead of a DNA virus in their experiment. Would radioactivity still have been found in the pellet?

	No, because only DNA can be labeled with radioactivity.
	No, because the RNA genome would not enter the bacteria upon infection.
	No, because while DNA and RNA nucleotides are similar, they are not identical.
	Yes, because DNA and RNA nucleotides are similar.
	Yes, because genome in any form (DNA, RNA, protein) would be labeled similarly.

Question 8

1 pts

Griffith and Avery's transformation experiments allowed us to identify that DNA is our genetic information. Which of the following scenarios would result in bacterial cells that are capable of killing mice upon injection?

	Heat killed non-virulent bacteria is added to a live virulent bacteria strain.
	Heat killed virulent bacteria is added to a heat killed non-virulent bacteria strain.
	A heat killed virulent bacteria that is treated with a nuclease, is then added to a non-virulent bacteria strain.
	Heat killed mouse cells are added to a non-virulent bacteria.

Question 9

1 pts

The human genome consists mostly of non-coding DNA. Which of the following are benefits of this?

	Random DNA mutations generally won't affect RNA and protein function.
	It is faster to duplicate the genome when these are present.
	The existence of introns can lead to multiple variations of proteins encoded by a single gene.
	It is unlikely transposons would exist in the genome if there was too much protein coding DNA.

Question 10

1 pts

Following her transformation of the plasmid into her yeast, what media will the cells be plated on to select for cells that have picked up the plasmid?

	Media containing histidine
	Media containing adenine
	Media lacking adenine
	Media lacking histidine

tealcockroach755

HELP WITH BIO MULTI CHOICE QUESTIONS:

QUESTION 2

Which of the following structures discussed in class is NOT found on all bacteria?
Flagella
Capsid
Fimbria
Plasma membrane

QUESTION 3
You are presented with a strain of bacteria that is resistant to the antibiotic penicillin. What steps would you take to confirm that you have a resistant bacterium?
Perform a Gram stain to determine pink stained Gram-positive bacteria.
Perform a Gram stain to determine purple stained Gram-positive bacteria.
Perform a Gram stain to determine pink stained Gram-negative bacteria.
Perform a Gram stain to determine purple stained Gram-negative bacteria.

QUESTION 4
With respect to bacterial growth into a fresh culture tube containing nutrient broth, at which phase do organisms undergo binary fission the most rapidly?
Lag phase
Stationary
Exponential
death

QUESTION 5
How would antibiotic resistance be passed from one bacterium to another bacterium?
Through the flagella via a plasmid.
Through the sex pilus via chromosomal DNA.
Through the sex pilus via a plasmid.
Through the flagella via chromosomal DNA.

QUESTION 6
When an F plasmid integrates into the host chromosome, the strain is referred to as

Hfr.
F'.
F-.
F+.

QUESTION 7
If you remove the peptidoglycan layer from a Gram-positive cell, it would still stain purple with a Gram stain (T/F).
True
False

QUESTION 8
During infection with a bacteriophage, bacterial DNA is packaged into a capsid and will:

be integrated into the genome of a new bacterium upon ligation.
be integrated into the genome of a new virion upon recombination.
be integrated into the genome of a new bacterium upon recombination.
be integrated into the genome of a new virion upon liagation.

QUESTION 9
Which of the following statements best describes most bacteria?
They are generally harmful.
They are limited to living in a few habitats.
They are very common in the environment.
They are responsible for the âcommon cold.â

QUESTION 10
Prokaryotes lack some parts found in eukaryotic cells, including which item?
a nuclear membrane
DNA
one or more chromosomes
a plasma membrane
all of the above

QUESTION 11
With respect to gram negative bacteria, what is the order of the bacterial cell structure from outside to inside?
Thin peptidoglycan layer, plasma membrane

thick peptidoglycan layer, plasma membrane

outer membrane, thick peptidoglycan layer, plasma membrane

outer membrane, thin peptidoglycan layer, plasma membrane

QUESTION 12
In transformation, a piece of DNA from a dead host can be taken up by living host

True
False

BIO130H1 Lecture 3: Week 3 Genomes & Chromosomes

BIO130H1 Full Course Notes

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