Deck 9: What Genes Are

Question 1

The CRISPR-Cas9 complex cuts through both strands of DNA in two neighboring sites.The chromosome does not break apart because during normal repair processes,the DNA sequences between the cut sites are

A) replaced with normal pig DNA.
B) looped outward and remain attached to the chromosome.
C) removed and the remaining DNA is relinked.
D) reattached to the DNA but switched to the opposite direction.

Answer 1

C

Question 2

The two strands of a DNA molecule are held together by ________ bonds between their base pairs.

A) hydrogen
B) amino acid
C) phosphate
D) protein

Answer 2

A

Question 3

The CRISPR-Cas9 system is made up of two guide ________ molecules and two Cas9 ________ molecules.

A) RNA; protein
B) protein; RNA
C) DNA; protein
D) protein; DNA

Answer 3

A

Question 4

The hereditary genetic material present in all living cells is

A) carbohydrate.
B) protein.
C) DNA.
D) RNA.

Question 5

Researchers used the CRISPR system to make 455 different cuts in the porcine endogenous retrovirus (PERV)pol genes in the pig genome.All of the PERV genes were inactivated in the pig embryos even though only 20 percent of the resulting mutations were larger than nine base pairs.The resulting mutations were successful at knocking out the PERV genes because

A) even single point mutations can be enough to make a gene product useless or inactivate a gene.
B) large mutations are not useful in knocking out genes.
C) inactivating 20 percent of the PERV genes is just as good as inactivating 100 percent of the PERV genes.
D) only 20 percent of the PERV genes need to be inactivated to result in all of them being inactive.

Question 6

When examining the two complementary strands of nucleotides in one DNA molecule,it would be expected that the sum of ________ in one strand would be ________ the sum of the ________ in the other strand.

A) Gs and Cs; equal to; Gs and Cs
B) Ts and As; equal to; Cs and Gs
C) Ts and As; greater than; Ts and As
D) As and Cs; less than; Ts and Gs

Question 7

The order of the base pairs in a DNA molecule

A) differs from species to species.
B) is identical in all organisms.
C) is identical in organisms of the same species.
D) differs from cell to cell in a given organism.

Question 8

Along one side of a DNA molecule,the nucleotides are connected to each other by ________ bounds between ________.

A) covalent; phosphate groups and sugar molecules
B) hydrogen; adenine and guanine
C) covalent; bases and sugar molecules
D) hydrogen; adjacent sugar molecules

Question 9

If a segment of double-stranded DNA has 20 percent adenine (A),how much of it is cytosine (C)?

A) 20 percent
B) 30 percent
C) 40 percent
D) 60 percent

Question 10

When bases of DNA correctly bind to the complementary strand,

A) A always pairs with T.
B) A sometimes pairs with T.
C) A always pairs with C.
D) A sometimes pairs with C.

Question 11

Before using the CRISPR-Cas9 system to edit the pig genome,it is necessary to sequence the pig DNA to identify any copies of porcine endogenous retrovirus (PERV)DNA.Knowing the PERV DNA sequences will help researchers determine which ________ sequences to use as guides for the CRISPR-Cas9 complex.

A) DNA
B) RNA
C) protein
D) amino acid

Question 12

In a strand of double-stranded DNA,cytosine (C)will always be bound with

A) A.
B) T.
C) C.
D) G.

Question 13

Targeting the pol gene in pig DNA works to remove the 62 porcine endogenous retrovirus (PERV)genes because the pol gene is typically ________ in all 62 copies of PERV genes and ________ in other pig genes.

A) lacking; present
B) present; present
C) present; lacking
D) lacking; lacking

Question 14

What part of a nucleotide accounts for the genetic variation between individuals?

A) sugar
B) phosphate
C) nitrogenous base
D) polymerase

Question 15

When looking at a single-stranded piece of DNA,

A) G will always be next to C.
B) G will always be next to G.
C) G will sometimes be next to T.
D) G will never be next to A.

Question 16

The sequence of DNA differs among individuals within a species.This is the reason for

A) mutation.
B) protein structure.
C) base pairing.
D) variations in phenotypes.

Question 17

In a single strand of DNA,the total number of phosphate groups present is equal to the total number of ________ bases.

A) adenine
B) adenine and thymine
C) guanine and cytosine
D) adenine, thymine, guanine, and cytosine

Question 18

Which of the following is NOT a base found in DNA?

A) thymine
B) adenine
C) guanine
D) uracil

Question 19

Once attached to the proper DNA sequence,Cas9 proteins found in the CRISPR-Cas9 system ________ both strands of DNA.

A) polymerize
B) cleave
C) wind
D) unwind

Question 20

If one strand of DNA has the sequence CGATT,the sequence of the other strand of the same molecule will be

A) CGATT.
B) GCTUU.
C) TACGG.
D) GCTAA.

Question 21

When a cell divides,it

A) breaks down its DNA.
B) deletes old genetic information.
C) copies information from neighboring cells.
D) copies its own genetic information.

Question 22

Replication of DNA cannot begin until ________ bonds between ________ are broken.

A) phosphate; nucleotides
B) hydrogen; complementary bases
C) covalent; sugar molecules
D) hydrogen; nucleotides in one strand

Question 23

Once replication in a DNA molecule is complete,each new DNA molecule contains

A) one old strand and one new strand.
B) the paired old strands and the paired new strands.
C) new DNA polymerase.
D) a new sequence of nucleotides.

Question 24

The adenine bases in a DNA molecule are radioactively labeled.The DNA is then placed in a solution containing unlabeled nucleotides and the enzymes needed for DNA replication.The DNA molecule is allowed to replicate twice,forming four new DNA molecules.The radioactively labeled adenine would be found in

A) each of the eight strands.
B) two of the eight strands.
C) all but one strand.
D) six of the eight strands.

Question 25

It could help meet transplant needs to use a patient's own stem cells to grow a human liver in a pig embryo modified by CRISPR.As an additional and essential step in the process to ensure the liver is safe for the patient,CRISPR should be used to

A) knock out all of the pig brain genes to prevent the pig brain cells from infecting the patient.
B) insert human immune cell DNA into the pig embryo to make it more similar to the patient.
C) insert human hemoglobin DNA into the pig embryo to make it possible for the growing pig to support the human liver.
D) knock out all of the porcine endogenous retrovirus (PERV) genes to prevent infection of the human patient with porcine endogenous retroviruses.

Question 26

DNA replication

A) involves the copying of only the parts of a chromosome that encode protein.
B) occurs before mitosis in the cell cycle.
C) occurs immediately after mitosis.
D) converts the double helix to two single helices.

Question 27

The polymerase chain reaction (PCR)is used to

A) produce many copies of a selected DNA sequence.
B) insert DNA from one organism into a new host.
C) screen for a particular gene.
D) deliver DNA products into a human patient.

Question 28

A detective finds a miniscule spot of blood on a murder suspect's shirt.What method would the police lab be expected to use to get enough DNA from the blood droplet to perform DNA fingerprinting?

A) inserting the blood's DNA into viral DNA
B) polymerase chain reaction (PCR)
C) inserting the sample's DNA into a plasmid
D) DNA sequencing

Question 29

The DNA primers used in polymerase chain reaction (PCR)are

A) identical to the entire base sequence of one strand of the DNA.
B) produced when a gene of interest is read by restriction enzymes.
C) attached to the gene of interest by polymerase.
D) complementary to DNA sequences at both ends of the DNA sequence of interest.

Question 30

Damaged DNA may be repaired by a special class of

A) nucleotides.
B) proteins.
C) deoxyribose molecules.
D) phosphate bonds.

Question 31

The significance of specific base pairing in DNA is that

A) it stabilizes the sugar molecule.
B) it provides a method for making exact copies of DNA.
C) it prevents errors in DNA replication.
D) protein copies can be made directly from the DNA.

Question 32

The figure below shows the first cycle in polymerase chain reaction (PCR).The structure marked "P" in this figure

A) represents the heat-tolerant DNA polymerase used in PCR to copy the gene of interest.
B) represents a sequence of DNA complementary to parts of the gene being amplified that allows DNA polymerase to attach to the gene.
C) indicates where on the DNA that DNA polymerase should terminate replication.
D) indicates the location of the promoter for the gene being amplified.

Question 33

DNA polymerase is used by the cell to

A) perform gel electrophoresis procedures.
B) cure patients of certain genetic diseases.
C) make copies of a DNA sequence.
D) attach DNA fragments to each other.

Question 34

According to the infographic below,the number of references to CRISPR in the PubMed database ________ between 2014 and 2016.

A) quadrupled
B) more than tripled
C) doubled
D) more than quadrupled

Question 35

A segment of DNA in a test tube replicates and produces many copies of itself.What was probably in the test tube that enhanced this process?

A) repair enzymes
B) DNA polymerase
C) plasmids
D) a mutagen

Question 36

The figure below shows a short sequence of DNA.During DNA replication,the piece of DNA depicted in this figure will produce

A) one single-stranded molecule with the sequence CAGT.
B) two single-stranded molecules with the sequence GTCA.
C) one single-stranded molecule with the sequence CAGT and a separate single-stranded molecule with the sequence GTCA.
D) two double-stranded molecules that look just like the figure.

Question 37

The polymerase chain reaction (PCR)technique could be developed only after the discovery of bacterial enzymes that were able to withstand high temperatures.Why was it necessary to use such enzymes?

A) Only bacterial DNA can be copied using the PCR method, so bacterial enzymes were necessary.
B) Bacterial enzymes can bind to DNA outside of a cell.
C) DNA can be cut into fragments only at high temperatures.
D) The temperature required to separate DNA strands during PCR degrades other enzymes.

Question 38

A rapidly dividing cell is exposed to a chemical that converts the bond that forms between adenine and thymine to a stronger covalent bond.Which of the following is MOST likely to occur?

A) DNA replication would produce two molecules of DNA with mutations at every base that once held an A-T base pair.
B) DNA replication would not occur because the two nucleotide strands that make up the DNA molecule would not be able to separate.
C) DNA replication would occur more slowly because DNA repair proteins would have to fix the covalent bonds before replication could begin.
D) DNA replication would be faster because covalent bonds require less energy to break than hydrogen bonds.

Question 39

Viral DNA that has entered the pig genome and remains active is passed from generation to generation through

A) mutations.
B) histone proteins.
C) DNA replication.
D) CRISPR-Cas9.

Question 40

The first human trial using CRISPR and approved by NIH used the system to edit

A) a mutated gene in human embryos and cure a genetic blood disorder.
B) targeted genes in both human and mouse cells.
C) bacterial genomes.
D) a cancer patient's own immune system cells.

Question 41

Short lengths of DNA are wound around bundles of ________ to create a structure consisting of many nucleosomes strung together by strings of DNA.

Question 42

The CRISPR-Cas9 system is used to generate a ________ mutation when most of the pol gene is "knocked out" and any remnants of the pol gene are nonfunctional.

Question 43

The enzyme that copies DNA is called ________.

Question 44

A species that lacks DNA repair mechanisms is likely to have ________ variations between individuals than a species that possesses repair mechanisms because ________.

A) fewer; there are fewer ways to change the DNA
B) fewer; the repair mechanisms introduce more variation into the DNA sequence
C) more; more spontaneous mutations will go uncorrected
D) more; without a repair mechanism, the cell's DNA replication genes are inactivated

Question 45

The figure below illustrates DNA undergoing replication.The region indicated by the arrow represents a

A) single base pair.
B) mismatch error.
C) mutation.
D) transformation.

Question 46

After the CRISPR-Cas9 system cuts a segment of DNA,the cell's DNA repair process actually removes the DNA sequences between the cut sites.This repair process is most likely facilitated by BOTH ________.

Question 47

A protein binds to the outside of a DNA strand.This protein will NOT likely bind to the ________ of the DNA nucleotides.

Question 48

If the human transplant patient in the figure below needs a new kidney because of a genetic mutation that has made her own kidneys nonfunctional,what additional step would need to happen to produce a functional kidney for this patient?

A) The mutation that resulted in her nonfunctional kidneys should be edited or corrected before her stem cells are inserted into the pig embryo.
B) Mutated kidney genes can be easily corrected after the pig embryo begins to grow.
C) Nothing else needs to be done. The kidney genes in the patient's stem cells will have autocorrected themselves already.
D) The mutated kidney genes should be corrected after the human kidney is harvested from the pig and before it is implanted in the human.

Question 49

Which of the following will NOT generally cause mutations?

A) chemicals
B) radiation
C) viruses
D) DNA replication

Question 50

A strand of DNA has the sequence GCAATTCG.The sequence of the complementary strand is ________.

Question 51

In the first step of the polymerase chain reaction (PCR),the two strands of the DNA being amplified must be separated by exposing the DNA to high ________.

Question 52

If DNA polymerase did not have the ability to proofread,then DNA replication would

A) not proceed at all.
B) proceed more slowly.
C) result in more mutations.
D) result in additional copies of DNA.

Question 53

A scientist uses polymerase chain reaction (PCR)to compare the sequence of a disease gene and a healthy gene.The scientist finds that these two genes are identical except for one G in place of a T at position 256 in the gene.This type of mutation is a(n)

A) deletion.
B) insertion.
C) silent mutation.
D) substitution mutation.

Question 54

DNA fingerprinting is based on regions of DNA that are variable between individuals.Many of these differences between individuals produce no change in phenotype.This type of mutation is a(n)

A) deletion.
B) insertion.
C) silent mutation.
D) substitution mutation.

Question 55

The difference between the alleles of a single gene is

A) their DNA base sequences.
B) the way they are copied when the cell divides.
C) the type of lipid of which they are composed.
D) that they are not heritable.

Question 56

A permanent change in the DNA base sequence due to an uncorrected mismatch error is called a(n)

A) mutation.
B) replication.
C) repair protein.
D) insertion.

Question 57

A pig's pancreas is still not ready for transplant into a human even after inactivating all of the 62 porcine endogenous retrovirus (PERV)genes in a pig embryo.The pig's ________ system genes would need to be manipulated to help prevent organ rejection by the human.

A) nervous
B) immune
C) digestive
D) endocrine

Question 58

Which of the following must occur for a mismatch error to be repaired?

A) DNA repair proteins identify damaged DNA.
B) The sequence of nucleotides in the damaged DNA sequence guides the synthesis of the correct DNA sequence.
C) DNA-eating enzymes within the nucleus destroy entire strands of damaged DNA.
D) The damaged DNA undergoes DNA replication one more time.

Question 59

Mismatch errors are

A) almost always corrected by mutagens.
B) also called mutations.
C) almost always corrected by specialized proteins.
D) usually caused by mutated proteins.

Question 60

The CRISPR-Cas9 system is a combination of guide ________ and ________ proteins.

Question 61

Exposure to ultraviolet (UV)light can alter DNA sequences in a cell.Uncorrected,these changes can lead to skin cancer.Individuals who have a mutation in a gene that produces DNA ________ protein may be at an increased risk for skin cancer.

Question 62

MATCHING
Put the following in order from smallest to largest.
a.gene
b.base
c.nucleotide
d.genome
e.base pair
This is the smallest in size.

Question 63

A new copy of a double helix that is composed of a template strand and a newly replicated strand of DNA is created using ________ replication.

Question 64

A scientist used CRISPR-Cas9 to inactivate the pol gene for DNA polymerase in the porcine endogenous retrovirus (PERV)sequences of a pig embryo.The resulting pig embryo cells were then placed in proximity of human cells,but there was no infection of the human cells by the PERVs.Why were the PERVs no longer able to infect the human cells?

Question 65

Compare the segment of DNA for normal hemoglobin DNA with the segment for sickle-cell hemoglobin DNA below.Sickle-cell disease is caused by a ________ mutation.

Question 66

A chemical is found that binds to a replicating strand of DNA but does not allow the next nucleotide to bind to the growing chain.Explain how this chemical would affect cell division.

Question 67

Describe the building blocks of DNA and how they are bonded together to form the DNA double helix.

Question 68

You are working for a pharmaceutical company that hopes to produce genetically engineered human pancreatic amylase from rapidly reproducing E.coli cells.Your colleague has worked for months to isolate a minute amount of DNA that she suspects contains the gene for human pancreatic amylase.You need more of this DNA for testing and evaluation.Describe how you can easily produce millions of exact copies of this DNA.

Question 69

A mutation is due to the addition of two bases in a strand of DNA.This is called a(n)________.

Question 70

Nitrous acid is a chemical that can react with DNA and change cytosine to uracil.If a cell is exposed to nitrous acid and some of the cytosine nucleotides in a gene are converted to uracil nucleotides,what should happen when that cell replicates?

Question 71

Using the figure below,describe how the two guide RNA molecules in the CRISPR-Cas9 system find the target DNA sequence.

Question 72

When studying genomes of organisms,scientists often will only list the sequence of a single strand.Explain why the sequence of the second strand would be unnecessary information.

Question 73

What would you expect to find if you examined the DNA base-pair sequence of the allele for a mutated cystic fibrosis transmembrane regulator gene (CFTR)and compared it to the DNA base-pair sequence of the allele for a fully functional CFTR gene?

Question 74

Cooling cycles during PCR amplification of DNA enable enzymes to build two new strands of ________ through ________ base-pairing.

Question 75

A scientist adds a single polymerase and primer to a polymerase chain reaction (PCR)but does not add nucleotides.How many strands would be present after three replications if a single original strand was present? Explain your answer.

Question 76

The cells in tissue that produces mammalian sperm cells are rapidly reproducing to provide a continuous supply of sperm cells.Considering the effect of heat on double-stranded DNA,what is likely to happen to the production of mutation free sperm cells if this tissue is kept at a significantly warmer temperature than usual?

Question 77

MATCHING
Put the following in order from smallest to largest.
a.gene
b.base
c.nucleotide
d.genome
e.base pair
This is the second smallest in size.

Question 78

A chemical that disrupts hydrogen bonds is added to a test tube containing DNA.What would be the result of this reaction?

Question 79

Being in the sun for short stretches of time is not as likely to cause mutations as is being in the sun for long stretches of time.Explain why longer exposure to ultraviolet (UV)is more likely to cause mutations.

Question 80

Are mutations always harmful? Justify your answer using an example.