UVA BIO 2100 - Exam 5 Questions and Answers
Question 1.
Describe what a gene "knockout" organism is, common reasons for producing them, the
role of embryonic stem cells and powerful selection strategies in their production, what
chimeric animals are, and the role of breeding in producing homozygous gene KOs
Correct Answer: knockout- deliberately turning off the function go a gene, not
excising it but making it nonfunctional, produced to see what the function and
effect of certain genes is, harder to make because have to isolate the gene
wanted specific in terms of location, works with embryonic stem cells
(pluripotent) - have potential to become any cell in the body, 1st have to make
cells w one nonfunctional allele and then turn into animals, not to excise but to
exchange nonfunctional, clone b2 micro globulin, disrupt gene by adding
another in the middle of it, this gene is resistant to disease, add another gene
flanking it that is susceptibility to a gene, only some will incorporate at right
position, homologous recombination - similar sequences will swap, only regions
of homology will swap, but can expose to diseases and then only ones
incorporated will have resistance to drug and no susceptibility, then are left
with embryonic stems cells with one functional allele and one non functional,
these will be inserted into the embryo and uterus, will be chimeras, some cells
will have nonfunctional and some will have normal, same with their germ cells,
breeding 50/50 chance, if mate chimera with another heterozygous for the
allele, 25% will have homologous for the nonfunctional
Question 2.
describe what iPSCs (induced pluripotent stem cells) are, how they can increase our
understanding of developmental biology, and their therapeutic potential, noting how they
may complement gene therapy approaches
Correct Answer: ipsc are stem cells from adults created by using cells like skin
cells, presented with a cocktail, these cells become less differentiated,
morphologically look similar to embryonic stem cells and express the same
proteins, could take these out of a person, specialize them for a certain tissues
and then put them back in? express all the same genes as embryonic,
Question 3.
explain how it was discovered that secreted proteins move from ER to Golgi to outside the
cell
Correct Answer: pulse-chase experiment pulse - radioactive amino acids were
included when the proteins were undergoing processes chase- time after when
nonradioactive amino acids present radioactive proteins synthesized during
pulse can be tracked when in chase to see where they are depending length of
chase, can see them at Er, Golgi, or leaving the cell
Question 4.
analyze/interpret Western blot data
Correct Answer: Western blots - show which proteins are present,
Question 5.
Define "operon"
Page 1
, Correct Answer: entire unit functioning in regulation of gene expression,
involves operator, promotor, DNA, etc.
Question 6.
Distinguish non-homologous end joining (NHEJ) and homology directed repair (HDR),
noting their significance following Cas9 activity
Correct Answer: non homologous end joining - two ends of two random
chromosomes are joined together, if they are different numbers this can cause
translocation and mutations, can effectivley knock out gene due to translocation
but could have downstream affects homology directed repair - used when a
homologue is used as a template for a copy of DNA, the DNA is cut out and then
uses homologue as copy to make the wild type form, can be used in CRISPR by
flooding the cell with what we want, the wild type allele
Question 7.
Describe the typical effect of methylation of promotor CpG islands
Correct Answer: methylation prevents translation from occurs at CpG islands,
this is passed on to daughter cells through semiconservative replication
Question 8.
Explain how DNAase-susceptibility experiments provide evidence of chromatin structure at
particular loci, interpret such experimental data, and predict chromatin structure in
relation to gene expression
Correct Answer: DNAase suseptibility occurs to chromatin that is more exposed,
genes that are more expressed will be more exposed and therefore more
susceptible to the DNAase, more open chromatin - more expressed
Question 9.
Explain the challenges that remain in exploiting Cas9 editing in humans
Correct Answer: ethical - required using frozen embryos, embryos killed after
use biological- not using embryos that are genetically identical to the person,
can lead to rejection not all human disease is due to gene defects, don't want
changes in some places not planned for, also created chimeras sometimes,
cannot due selective breeding in humans
Question 10.
Describe a typical replication cycle of an animal virus and explain why viruses typically
replicate and cause disease in only certain species and replicate in only certain cell types
Correct Answer: tropism - only certain cells affected, and only certain species
bind to the hosts cell receptor, enter the cell through endocytosis and the
envelope combines with plasma membrane, use host ribosome to form rdrp
complex and replicated the RNA/DNA and use it to form new capsid protein
shells and copies of the viral genome, also contain non structural proteins which
inhibit protein synthesis and other functions of the host causing disease and
then death, once replicated they leave cell to infect others
Question 11.
Describe what "conditional" gene knockouts are, their significance, the role of the
bacteriophage Cre-Lox system in their generation, what "floxed", "knock-in", and
Page 2
Question 1.
Describe what a gene "knockout" organism is, common reasons for producing them, the
role of embryonic stem cells and powerful selection strategies in their production, what
chimeric animals are, and the role of breeding in producing homozygous gene KOs
Correct Answer: knockout- deliberately turning off the function go a gene, not
excising it but making it nonfunctional, produced to see what the function and
effect of certain genes is, harder to make because have to isolate the gene
wanted specific in terms of location, works with embryonic stem cells
(pluripotent) - have potential to become any cell in the body, 1st have to make
cells w one nonfunctional allele and then turn into animals, not to excise but to
exchange nonfunctional, clone b2 micro globulin, disrupt gene by adding
another in the middle of it, this gene is resistant to disease, add another gene
flanking it that is susceptibility to a gene, only some will incorporate at right
position, homologous recombination - similar sequences will swap, only regions
of homology will swap, but can expose to diseases and then only ones
incorporated will have resistance to drug and no susceptibility, then are left
with embryonic stems cells with one functional allele and one non functional,
these will be inserted into the embryo and uterus, will be chimeras, some cells
will have nonfunctional and some will have normal, same with their germ cells,
breeding 50/50 chance, if mate chimera with another heterozygous for the
allele, 25% will have homologous for the nonfunctional
Question 2.
describe what iPSCs (induced pluripotent stem cells) are, how they can increase our
understanding of developmental biology, and their therapeutic potential, noting how they
may complement gene therapy approaches
Correct Answer: ipsc are stem cells from adults created by using cells like skin
cells, presented with a cocktail, these cells become less differentiated,
morphologically look similar to embryonic stem cells and express the same
proteins, could take these out of a person, specialize them for a certain tissues
and then put them back in? express all the same genes as embryonic,
Question 3.
explain how it was discovered that secreted proteins move from ER to Golgi to outside the
cell
Correct Answer: pulse-chase experiment pulse - radioactive amino acids were
included when the proteins were undergoing processes chase- time after when
nonradioactive amino acids present radioactive proteins synthesized during
pulse can be tracked when in chase to see where they are depending length of
chase, can see them at Er, Golgi, or leaving the cell
Question 4.
analyze/interpret Western blot data
Correct Answer: Western blots - show which proteins are present,
Question 5.
Define "operon"
Page 1
, Correct Answer: entire unit functioning in regulation of gene expression,
involves operator, promotor, DNA, etc.
Question 6.
Distinguish non-homologous end joining (NHEJ) and homology directed repair (HDR),
noting their significance following Cas9 activity
Correct Answer: non homologous end joining - two ends of two random
chromosomes are joined together, if they are different numbers this can cause
translocation and mutations, can effectivley knock out gene due to translocation
but could have downstream affects homology directed repair - used when a
homologue is used as a template for a copy of DNA, the DNA is cut out and then
uses homologue as copy to make the wild type form, can be used in CRISPR by
flooding the cell with what we want, the wild type allele
Question 7.
Describe the typical effect of methylation of promotor CpG islands
Correct Answer: methylation prevents translation from occurs at CpG islands,
this is passed on to daughter cells through semiconservative replication
Question 8.
Explain how DNAase-susceptibility experiments provide evidence of chromatin structure at
particular loci, interpret such experimental data, and predict chromatin structure in
relation to gene expression
Correct Answer: DNAase suseptibility occurs to chromatin that is more exposed,
genes that are more expressed will be more exposed and therefore more
susceptible to the DNAase, more open chromatin - more expressed
Question 9.
Explain the challenges that remain in exploiting Cas9 editing in humans
Correct Answer: ethical - required using frozen embryos, embryos killed after
use biological- not using embryos that are genetically identical to the person,
can lead to rejection not all human disease is due to gene defects, don't want
changes in some places not planned for, also created chimeras sometimes,
cannot due selective breeding in humans
Question 10.
Describe a typical replication cycle of an animal virus and explain why viruses typically
replicate and cause disease in only certain species and replicate in only certain cell types
Correct Answer: tropism - only certain cells affected, and only certain species
bind to the hosts cell receptor, enter the cell through endocytosis and the
envelope combines with plasma membrane, use host ribosome to form rdrp
complex and replicated the RNA/DNA and use it to form new capsid protein
shells and copies of the viral genome, also contain non structural proteins which
inhibit protein synthesis and other functions of the host causing disease and
then death, once replicated they leave cell to infect others
Question 11.
Describe what "conditional" gene knockouts are, their significance, the role of the
bacteriophage Cre-Lox system in their generation, what "floxed", "knock-in", and
Page 2
