Biology Quiz: Genetic Engineering

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12 Δεκ 2012 (πριν από 4 χρόνια και 8 μήνες)

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Biology
Test Preview
: Genetic Engineering


Questions 1
-
7

refer to the following list. Answers may be used more than once, or not at all.


___ 1.

Allows for rapid production
of
many copies of
a targeted
DNA
sequence

A.

DNA ligase

___ 2.

Seal gaps in sugar
-
phosphate backbon
es of newly synthesized DNA molecules.

B.

DNA polymerase

___ 3.

Used to describe genetically modified organisms.

C.

gel electrophoresis

___ 4.

A group of genetically identical organisms or cells.

D.

restriction enzymes

___ 5.

Proteins made by bacterial cells and used by biologists t
o cut the sugar
-
phosphate
backbones of DNA molecules.

E.

polymerase chain
reaction (PCR)

___ 6.

Separates fragments of DNA by the size of the molecules.

F.

transgenic

___ 7.

Bind to DNA at a specific nucleotide sequence and enable
sci
entists

to remove
specific sequences of
DNA from larger DNA molecules (such as chromosomes).

G.

clone



Questions
8
-
11

refer to the diagram below of some of the key components found inside a
n agarose

gel electrophoresis
chamber.
















___ 8.

Which of the following i
s true of the gel electrophoresis shown?

(A)

the power source has not been turned on yet

(B)

the three wells contained the same samples DNA molecules

(C)

Well #1 had fewer molecules of DNA than Well 2 or 3

(D)

Well #3 had more different sized molecules of DNA than Well 1
or 2


___ 9.

Which of the following is true of gel electrophoresis?

(A)

the longer a molecule of DNA, the slower it will move through agarose gel

(B)

DNA molecules with unknown base sequences are “read” by gel electrophoresis

(C)

gel electrophoresis separated DNA molecules b
ased on their base sequence

(D)

All of the above are true.




___ 10.

What causes the DNA to migrate from the wells toward the positive electrode?

(A)

DNA is positively charged too, and so was attracted to the positive electrode

(B)

DNA is negatively charged, and so was attra
cted to the positive electrode

(C)

DNA is polar and forms hydrogen bonds with the positive electrodes

(D)

DNA is electrically charged, and so cycles through an electric field


___ 11.

Which of the following statements is TRUE about the band of molecules labeled
X
?

(A)

It cont
ains DNA fragments that are shorter than the ones in any of the other bands.

(B)

It contains fewer DNA molecules than any of the other bands from lane 3.

(C)

It contains more negatively charged particles than any other band on the gel.

(D)

It contains fewer genes than

any of the other bands on the gel.


___ 12.

Two different molecules of DNA are cut with the same restriction enzyme. If the restriction enzyme used
produces “sticky ends” when it cuts, which of the following will be true?

(A)

the cut pieces from the two different mol
ecules will be able to hydrogen bond with each other

(B)

the cut pieces will have the same nucleotide sequences at the site where the enzyme made the cuts

(C)

the original molecules of DNA may have been cut in more than one place

(D)

All of the above are true.


Path of DNA

Wells containing soluti
ons
with DNA molecules of
different sizes

Positive Electrode

Negative Electrode

Bands of DNA
molecules visible
after staining

1

2

3



Power


Source

X

___ 13.

During

PCR, which step in the process is necessary to separate the two strands of a DNA molecule so that
DNA polymerase enzymes can use each as a template for making complementary copies of both?

(A)

addition of free nucleotides


(C) heating
to hybridize

(B)

addition o
f short “primers”


(D) cutting with restriction enzymes



___ 14.

During PCR, why are DNA polymerase enzymes from the heat
-
loving bacterium
Thermus aquaticus

used
?

(A)

the bacterium produces enzymes that can work equally fast in warm or cool temperatures

(B)

the bacteriu
m produces enzymes that are not denatured by temperatures up to 100C

(C)

the enzymes are denatured by heat and thus don’t interfere with the production of multiple copies of DNA

(D)

the enzymes are more accurate when copying DNA sequences than ones from most other

species


Questions
15
-
16

refer to the diagram of the restriction sites for several restriction enzymes. The arrows show where the
enzyme breaks the strands of a double helix.

___ 15.

A solution containing many copies of a bacterial plasmid (circular DNA) is divi
ded equally between four test
tubes. Each test tube is then treated with one of the four enzymes shown. Which enzyme will most likely result in
the highest number of different sized fragments of DNA after treatment?


___ 16.

After the restriction enzymes finish di
gesting the DNA, some of the DNA segment depicted below is added to
each tube. In which test tube will it be possible for this DNA to be joined by the enzyme
DNA ligase

to some of
the fragments produced by digestion?



G C T A A G

C G A T T C C T A G



___ 17.

Af
ter the restriction enzymes finish digesting the DNA, a solution containing short segments of RNA with the
base sequence


U U U C G A

is added to each test tube. In the tube with which enzyme will this RNA be
able to bind to the DNA?



___ 18.

Why is the
polymeras
e chain reaction (PCR)

used by molecular biologists?

(A)

used to make many copies of a specific DNA sequence, very quickly

(B)

used to make DNA polymerase enzymes for use in gel electrophoresis

(C)

breaks down DNA in the nucleus, producing free nucleotides for DNA rep
lication

(D)

cuts up DNA molecules into pieces small enough to be studied more carefully



___ 19.

Which statement about
restriction enzymes

is true?

(A)

they are enzymes produced by bacteria for making copies of their DNA

(B)

they are enzymes produced by bacteria for making
RNA copies of their DNA

(C)

each binds to a specific sequence of DNA and cuts the sugar
-
phosphate backbones at that site

(D)

each binds only to the ends of a DNA molecule, and cuts off several nucleotides from one strand,
producing “sticky end” on both sides.


___ 20.

Wh
ich correctly describes the function of the enzyme
DNA

polymerase
?

(A)

makes individual D
NA nucleotides

(B)

forms
hydrogen bonds between DNA nucleotides and free nucleotides in solution

(C)

forms covalent bonds between adjacent nucleotides in a growing strand of DNA

(D)


unzips” DNA, then forms covalent bonds between adjacent RNA nucleotides

(A)



(B)



(C)



(D)

Questions 21
-
23

refer to diagrams
below
showing the control of the
lac operon

in
Escherichia coli
.


___ 21.

When there is no lactose, what prevents
E. coli

from producing lactose
-
processi
ng enzymes?

(A)

the lactose is a structural part of the enzymes

(B)

if there is no lactose, the cell doesn’t want to produce the enzymes

(C)

when lactose is absent, a protein binds to the bacterium’s DNA and blocks transcription

(D)

when lactose is absent, the cell lacks
the energy needed to perform transcription and translation


___ 22.

What is the role of the
promoter that is associated with any gene or group of genes
?

(A)

it is a specific sequence of DNA bases to which RNA polymerase binds whenever transcription occurs

(B)

it is a prot
ein that carries RNA polymerase enzymes to the genes that are being activated

(C)

it prevents binding regulatory proteins that would block transcription

(D)

it binds activator proteins that stimulate transcription


___ 23.

Why is it important for the
E. coli

to turn on an
d off the enzyme
-
making machinery?

(A)

prevents wasteful production of enzymes

(B)

prevents the breakdown of lactose

(C)

causes lactose intolerance in humans

(D)

prevents lactose intolerance in humans


Free Response Questions

1.
A scientist is interested in a specific gen
e she has found on a large eukaryotic chromosome. She wants to eventually
produce a clone of bacteria with the gene so that the protein
product of the gene can be
produced
inexpensively
.
Describe how the following techniques might be employed by the resear
cher to establish a colony of bacteria that
possess the gene of interest. (
6
)




Cut DNA with restriction enzyme(s)



Perform PCR



Perform gel electrophoresis



Use radioactive DNA probe



Use DNA ligase







2
.
What is DNA fingerprinting? What genetic engineerin
g techniques are used when DNA fingerprints are made.
Explain why DNA from two different people
, despite the fact that the sequences are more than 99% equivalent,

would
produce
different DNA fingerprints that could be used to iden
tify the individuals. [4
]


3. What is the Human Genome Project? How might some of the genetic engineering techniques you’ve learned about
in this unit be applied to help complete the project? How might the information being gained from the project be useful
to
doctors and other sci
entists? [3
; see pages 249 and p. 267 to learn about the project and its potential benefits]


4. Outline the reasons why increased exposure to UV radiation from sunlight increases a person’s risk of skin cancer.
[3]