bio 230 exam 3 EXAM ELABORATIONS QUESTIONS
AND VERIFIED ANSWERS 2025 UPDATE | 100%
SOLVED!!
In 1952, Alfred Hershey and Martha Chase, working with a virus called T2,
conducted what is now considered a landmark experiment to determine whether
genes are made of DNA or protein. When this virus, which is made entirely of
DNA and protein, infects E. coli, it injects its genetic material into the bacterial
cell, leaving the empty virus head stuck to the cell surface.
IntroductionExams serve as a fundamental tool in evaluating a student's understanding of a subject, particularly in fields as diverse as business, law, and mathematics. These disciplines not only have distinct areas of focus
but also require unique approaches to
To determine whether it was DNA or protein that enters the infected bacterial
cell, the researchers radioactively labeled one batch of T2 with the isotope 35S,
which resulted in radiolabeled viral proteins, and a second batch of T2 with 32P,
which resulted in radiolabeled DNA. They then incubated the radioactive viruses
with E. coli. After allowing a few minutes for the viruses to transfer their genetic
material to the bacterial cells, the researchers used a blender to shear the empty
virus heads from the bacterial cell surface. They then used a cen - (ANSWER)32P
in the pellet, 35 S in the solution
Some applications in biology, such as polymerase chain reaction (PCR), require
melting the DNA double helix into single strands of DNA. This can be
accomplished by heating the DNA. As DNA is heated, why does the double helix
structure denature into single strands of DNA but not into individual nucleotides?
In other words, why do the single strands remain intact even though the double
helix does not? - (ANSWER)The double helix is held together with hydrogen
bonds, while the single strands are linked by phosphodiester bonds.
Another step in PCR requires small single-stranded DNA primers to anneal to a
target sequence on denatured DNA. Two primers are used. Ideally these primers
will have similar melting temperatures. The melting temperature is defined as the
, temperature at which 50% of the DNA is in the single-stranded form. Which of the
following primers will have the highest melting temperature? - (ANSWER)G G G G
AAATTTCCCC
Where is heterochromatin not commonly located? - (ANSWER)chromosomal
regions carrying genes that encode ribosomal proteins
IntroductionExams serve as a fundamental tool in evaluating a student's understanding of a subject, particularly in fields as diverse as business, law, and mathematics. These disciplines not only have distinct areas of focus
but also require unique approaches to
In the late 1920s, bacteriologist Fred Griffith was studying Streptococcus
pneumoniae. This bacterium comes in two forms: one that is highly infectious
(called the "S strain" because it forms colonies that appear smooth when grown
on a nutrient plate in the lab) and one that is relatively harmless (called the "R
strain" because its colonies appear rough). When injected into mice, the S strain is
lethal, whereas the R strain causes no ill effect. Griffith confirmed that when the S
strain is killed by heating, it is no longer infectious. But he then discovered that if
he injected mice with both the heat-killed S strain pneumococci and the live,
harmless R strain bacteria, the animals died of pneumonia. Furthermore, their
blood was swarming with live, S strain bacteria that, when grown in culture,
remained infectious and lethal.
Based on these results, what could Griffith conclude? - (ANSWER)Some substance
in the infectious S strain can change the harmless R strain into the more lethal
form.
The Encyclopedia of DNA Elements (ENCODE) project aims to discover functional
elements in DNA. One technique employed is DNase-seq. This technique employs
a DNase enzyme that digests accessible regions of chromatin, while inaccessible
regions remain undigested. The undigested DNA is then sequenced. Which of the
following is likely true of the DNase-seq results - (ANSWER)Unsequenced DNA is
likely part of euchromatin.
, Centromeric DNA is likely to be sequenced in all samples.
IntroductionExams serve as a fundamental tool in evaluating a student's understanding of a subject, particularly in fields as diverse as business, law, and mathematics. These disciplines not only have distinct areas of focus
but also require unique approaches to
In the 1920s, bacteriologist Fred Griffith demonstrated that a heat-killed,
infectious pneumococcus produced a substance that could convert a harmless
form of the bacterium into a lethal one. Fifteen years later, researchers prepared
an extract from the disease-causing S strain of pneumococci and showed that this
material could transform the harmless R-strain pneumococci cells into the
infectious S-strain form. This change to the bacteria was both permanent and
heritable, suggesting that this "transforming principle" represents the elusive
genetic material of the cells. The researchers subjected their extract to a variety
of tests to determine the chemical identity of the "transforming principle." In one
experiment, they treated the material with enzymes that destroy all proteins. This
treatment did not affect the ability of the extract to transform harmless bacteria
into an infectious form.
From this result, what c - (ANSWER)The genetic material is not protein.
What evidence suggests that the large amount of excess "junk" DNA in a genome
may serve an important function? - (ANSWER)A portion of "junk" DNA is highly
conserved in its DNA sequence among many different eukaryotic species.
One of the first steps in obtaining a karyotype (such as that shown below of a
cancer cell) is treating cells with a drug that stalls cells in mitosis. Why must cells
arrest in mitosis for karyotype analysis? - (ANSWER)Only mitotic chromosomes
are highly condensed and visible with a light microscope.
In their 1953 paper on the double-helical structure of DNA, Watson and Crick
famously wrote: "It has not escaped our notice that the specific pairing we have
, postulated immediately suggests a possible copying mechanism for the genetic
material." What did they mean? - (ANSWER)Each strand in a DNA double helix
contains all the information needed to produce a complementary partner strand.
Identify which statement(s) is/are true regarding telomere characteristics. -
(ANSWER)Only statements C and D are true regarding telomere characteristics.
IntroductionExams serve as a fundamental tool in evaluating a student's understanding of a subject, particularly in fields as diverse as business, law, and mathematics. These disciplines not only have distinct areas of focus
but also require unique approaches to
Which of the following statements is not true? - (ANSWER)A cell will temporarily
decondense its chromatin to silence genes during differentiation.
Which statement is true about the association of histone proteins and DNA? -
(ANSWER)Histone proteins have a high proportion of positively charged amino
acids, which bind tightly to the negatively charged DNA backbone.
Which of the following statements about nucleosomes is false? -
(ANSWER)Nucleosomes are found only in mitotic chromosomes.
How do chromatin-remodeling complexes work? - (ANSWER)They use the energy
from ATP hydrolysis to alter the arrangement of nucleosomes, rendering certain
regions of the DNA more accessible to other proteins
Once heterochromatin has been established, it will often spread until it
encounters which of the following? - (ANSWER)the barrier dna sequence
AND VERIFIED ANSWERS 2025 UPDATE | 100%
SOLVED!!
In 1952, Alfred Hershey and Martha Chase, working with a virus called T2,
conducted what is now considered a landmark experiment to determine whether
genes are made of DNA or protein. When this virus, which is made entirely of
DNA and protein, infects E. coli, it injects its genetic material into the bacterial
cell, leaving the empty virus head stuck to the cell surface.
IntroductionExams serve as a fundamental tool in evaluating a student's understanding of a subject, particularly in fields as diverse as business, law, and mathematics. These disciplines not only have distinct areas of focus
but also require unique approaches to
To determine whether it was DNA or protein that enters the infected bacterial
cell, the researchers radioactively labeled one batch of T2 with the isotope 35S,
which resulted in radiolabeled viral proteins, and a second batch of T2 with 32P,
which resulted in radiolabeled DNA. They then incubated the radioactive viruses
with E. coli. After allowing a few minutes for the viruses to transfer their genetic
material to the bacterial cells, the researchers used a blender to shear the empty
virus heads from the bacterial cell surface. They then used a cen - (ANSWER)32P
in the pellet, 35 S in the solution
Some applications in biology, such as polymerase chain reaction (PCR), require
melting the DNA double helix into single strands of DNA. This can be
accomplished by heating the DNA. As DNA is heated, why does the double helix
structure denature into single strands of DNA but not into individual nucleotides?
In other words, why do the single strands remain intact even though the double
helix does not? - (ANSWER)The double helix is held together with hydrogen
bonds, while the single strands are linked by phosphodiester bonds.
Another step in PCR requires small single-stranded DNA primers to anneal to a
target sequence on denatured DNA. Two primers are used. Ideally these primers
will have similar melting temperatures. The melting temperature is defined as the
, temperature at which 50% of the DNA is in the single-stranded form. Which of the
following primers will have the highest melting temperature? - (ANSWER)G G G G
AAATTTCCCC
Where is heterochromatin not commonly located? - (ANSWER)chromosomal
regions carrying genes that encode ribosomal proteins
IntroductionExams serve as a fundamental tool in evaluating a student's understanding of a subject, particularly in fields as diverse as business, law, and mathematics. These disciplines not only have distinct areas of focus
but also require unique approaches to
In the late 1920s, bacteriologist Fred Griffith was studying Streptococcus
pneumoniae. This bacterium comes in two forms: one that is highly infectious
(called the "S strain" because it forms colonies that appear smooth when grown
on a nutrient plate in the lab) and one that is relatively harmless (called the "R
strain" because its colonies appear rough). When injected into mice, the S strain is
lethal, whereas the R strain causes no ill effect. Griffith confirmed that when the S
strain is killed by heating, it is no longer infectious. But he then discovered that if
he injected mice with both the heat-killed S strain pneumococci and the live,
harmless R strain bacteria, the animals died of pneumonia. Furthermore, their
blood was swarming with live, S strain bacteria that, when grown in culture,
remained infectious and lethal.
Based on these results, what could Griffith conclude? - (ANSWER)Some substance
in the infectious S strain can change the harmless R strain into the more lethal
form.
The Encyclopedia of DNA Elements (ENCODE) project aims to discover functional
elements in DNA. One technique employed is DNase-seq. This technique employs
a DNase enzyme that digests accessible regions of chromatin, while inaccessible
regions remain undigested. The undigested DNA is then sequenced. Which of the
following is likely true of the DNase-seq results - (ANSWER)Unsequenced DNA is
likely part of euchromatin.
, Centromeric DNA is likely to be sequenced in all samples.
IntroductionExams serve as a fundamental tool in evaluating a student's understanding of a subject, particularly in fields as diverse as business, law, and mathematics. These disciplines not only have distinct areas of focus
but also require unique approaches to
In the 1920s, bacteriologist Fred Griffith demonstrated that a heat-killed,
infectious pneumococcus produced a substance that could convert a harmless
form of the bacterium into a lethal one. Fifteen years later, researchers prepared
an extract from the disease-causing S strain of pneumococci and showed that this
material could transform the harmless R-strain pneumococci cells into the
infectious S-strain form. This change to the bacteria was both permanent and
heritable, suggesting that this "transforming principle" represents the elusive
genetic material of the cells. The researchers subjected their extract to a variety
of tests to determine the chemical identity of the "transforming principle." In one
experiment, they treated the material with enzymes that destroy all proteins. This
treatment did not affect the ability of the extract to transform harmless bacteria
into an infectious form.
From this result, what c - (ANSWER)The genetic material is not protein.
What evidence suggests that the large amount of excess "junk" DNA in a genome
may serve an important function? - (ANSWER)A portion of "junk" DNA is highly
conserved in its DNA sequence among many different eukaryotic species.
One of the first steps in obtaining a karyotype (such as that shown below of a
cancer cell) is treating cells with a drug that stalls cells in mitosis. Why must cells
arrest in mitosis for karyotype analysis? - (ANSWER)Only mitotic chromosomes
are highly condensed and visible with a light microscope.
In their 1953 paper on the double-helical structure of DNA, Watson and Crick
famously wrote: "It has not escaped our notice that the specific pairing we have
, postulated immediately suggests a possible copying mechanism for the genetic
material." What did they mean? - (ANSWER)Each strand in a DNA double helix
contains all the information needed to produce a complementary partner strand.
Identify which statement(s) is/are true regarding telomere characteristics. -
(ANSWER)Only statements C and D are true regarding telomere characteristics.
IntroductionExams serve as a fundamental tool in evaluating a student's understanding of a subject, particularly in fields as diverse as business, law, and mathematics. These disciplines not only have distinct areas of focus
but also require unique approaches to
Which of the following statements is not true? - (ANSWER)A cell will temporarily
decondense its chromatin to silence genes during differentiation.
Which statement is true about the association of histone proteins and DNA? -
(ANSWER)Histone proteins have a high proportion of positively charged amino
acids, which bind tightly to the negatively charged DNA backbone.
Which of the following statements about nucleosomes is false? -
(ANSWER)Nucleosomes are found only in mitotic chromosomes.
How do chromatin-remodeling complexes work? - (ANSWER)They use the energy
from ATP hydrolysis to alter the arrangement of nucleosomes, rendering certain
regions of the DNA more accessible to other proteins
Once heterochromatin has been established, it will often spread until it
encounters which of the following? - (ANSWER)the barrier dna sequence
