Molecular Exam 3

Front 1

Which of the following processesdoes NOT occur in the eukaryotic nucleus?

A. RNAsplicing

B. DNA replication

C. RNAcapping

D. tRNAcharging

Back 1

D. tRNA Charging

Front 2

Accordingto the wobble hypothesis, a U in the 5' position of the anticodoncanpair with_____. A. U or C

B. A or G

C. A, C, or G

D.Only A

Back 2

B. A or G

Front 3

Howmany aminoacyl-tRNAsynthetasesare present for the 61 codons?

A. 1

B. 3

C. 20

D. 61

Back 3

C. 20

Front 4

Which of the following is notinvolved in the initiation of translation?

A.mRNA

B.ribosomal subunits

C.initiator tRNA

D.RNA polymerase

Back 4

?

Front 5

Aminoacyl-tRNAsynthetasesare ___________________.

A.enzymeswhichcharge a tRNAwith its appropriate amino acid.

B.enzymes thatsynthesize tRNAs

C.enzymes thatadd tRNAto the 5' end of an amino acid.

D.enzymes thatadd an amino acid to the 5' end of tRNA

Back 5

A.enzymes which charge a tRNA with its appropriate amino acid.

Front 6

Whichof the following combinations are correctly matched?

A.70S –ribosome

B.anticodon –mRNA

C.codon –tRNA

D. A andB

Back 6

A. 70s - Ribosomes

Front 7

The specifictRNAthatbindstothe tRNAsynthetasehas_____.

A. a specificanticodon that corresponds to the specific amino acid.

B. a specificcodon that corresponds to the specific amino acid.

C. a specificanticodon that corresponds to the specific synthetase.

D. a specificcodon that corresponds to the specific synthetase

Back 7

C. a specific anticodon that corresponds to the specific synthetase.

Front 8

TheShine-Dalgarnosequence is found on the ________.

A. small ribosomalsubunit

B. large ribosomalsubunit

C. initiator tRNA

D. mRNA

Back 8

D. mRNA

Front 9

Whichfeature is NOT found in bacterial mRNA?

A. 5’ untranslatedregion

B. Cap onthe 5’ end

C. polycistronicmRNA

D. Shine-Dalgarnosequence

Back 9

B. Cap on the 5' end

Front 10

Duringtranslation elongation, amino acids are brought to the ribosome with the help of_____.

A. EF-G

B. EF-Tu

C. RF1

D.RF2

Back 10

B. EF-Tu

Front 11

Therelease factor that recognizes a stop codon in eukaryotes is____.

A. RF1

B. RF3

C. eRF1

D.eRF3

Back 11

C. eRF1

Front 12

Translationisterminated when a stop codon is presented at the____.

A. A site

B. P site

C. E site

D. either A orP site

Back 12

A. A site

Front 13

Whichenzyme is incorrectly matched to its function?

A. RNA polymerase-- transcription

B. aminoacyl-tRNAsynthetase-- attaches an amino acid toa tRNA

C. PolyAPolymerase-- translation

D. Guanylyltransferase-- mRNA capping

Back 13

C. PolyA Polymerase -- translation

Front 14

To begin the process of forming a "charged" transfer RNA, a specific aminoacyl tRNA synthetase binds _____ to its active site.

A)a particular amino acid.

B)a molecule of ATP.

C)a molecule of AMP.

D)a particular amino acid and a molecule of ATP.

E)a particular amino acid and a molecule of AMP.

Back 14

D)a particular amino acid and a molecule of ATP.

Front 15

The specific transfer RNA that then binds to the synthetase has...

A)a specific anticodon that corresponds to the specific amino acid.

B)a specific codon that corresponds to the specific amino acid.

C)a specific anticodon that corresponds to the specific synthetase.

D)a specific codon that corresponds to the specific synthetase.

E)a specific synthetase that corresponds to the specific codon.

Back 15

A)a specific anticodon that corresponds to the specific amino acid.

Front 16

The charged tRNA molecule is then released from the aminoacyl tRNA synthetase and is used in the process of...

A)transcription.

B)translation.

C)transduction.

D)transformation.

E)transmogrification.

Back 16

B)translation.

Front 17

The RNA sequence in the anticodon region as well as other parts of the tRNA molecule, such as the acceptor stem, are important for recognition between the tRNA and the aminoacyl tRNA synthetase.

A)True

B)False

Back 17

True

Front 18

A charged tRNA molecule consists of a tRNA molecule and a corresponding amino acid.

A)True

B)False

Back 18

True

Front 19

Which of the following occurs as the ribosome shifts down the mRNA by a distance of one codon? A)the tRNA that was in the A site picks up another amino acid

B)the tRNA that was in the A site releases the growing polypeptide chain

C)the tRNA that was in the A site moves into the P site

D)the tRNA that was in the P site moves into the A site

E)the tRNA that was in the P site picks up another amino acid

Back 19

C)the tRNA that was in the A site moves into the P site

Front 20

A certain polypeptide is 100 amino acids in length. During translation of this polypeptide, how many amino acids entered through the A site of the ribosome?

A)1

B)9

C)50

D)99

E)100

Back 20

D)99

Front 21

The large ribosomal subunit joins the translation initiation complex after the small subunit has already joined.

A)True

B)False

Back 21

true

Front 22

Elongation of the polypeptide chain is terminated when a stop codon enters the P site of the ribosome.

A)True

B)False

Back 22

false

Front 23

Which of the following is not involved in the initiation of translation?

A)mRNA

B)ribosomal subunits

C)initiator tRNA

D)RNA polymerase

E)all of the above are involved

Back 23

D) RNA polymerase

Front 24

The Shine-Dalgarno sequence is found on the ________.

A)small ribosomal subunit

B)large ribosomal subunit

C)initiator tRNA

D)mRNA

E)IF3

Back 24

D) mRNA

Front 25

Which of the following binds to the initiation complex first?

A)IF2

B)IF3

C)initiator tRNA

D)large ribosomal subunit

Back 25

B) IF3

Front 26

The initiation factors IF2 and IF3 use the energy of ATP to link the ribosomal subunits.

A)True

B)False

Back 26

False

Front 27

If IF1 is not present, elongation would not occur.

A)True

B)False

Back 27

False

Front 28

During translation elongation, amino acids are brought to the ribosome with the help of

A)EF-T.

B)EF-Tu.

C)EF-Ts.

D)EF-Tm.

E)EF-Tz.

Back 28

B) EF-Tu

Front 29

Which of the following statements about peptidyl transferase is TRUE?

A)It catalyzes the formation of peptide bonds.

B)It is present in the 50S ribosomal subunits.

C)It is a protein.

D)A and B

E)A, B and C

Back 29

D) A and B

Front 30

Translocation is promoted by the elongation factor EF-G.

A)True

B)False

Back 30

True

Front 31

An uncharged tRNA is one that is not carrying an amino acid.

A)True

B)False

Back 31

False

Front 32

The protein that promotes translation termination is called

A)terminator.

B)polypeptidase.

C)release factor.

D)doomsday factor.

E)X factor.

Back 32

C) Release factor

Front 33

The lac repressor binds to what site within the lac operon?

A)lacZ

B)lacO

C)lacA

D)lacl

E)lacP

Back 33

B) lacO

Front 34

Which of the following is not part of the lac operon?

A)lacO

B)lacZ

C)lacA

D)lacl

E)lacP

Back 34

D) lacI

Front 35

The lac repressor is inactivated by binding to which of the following?

A)lactose

B)betagalactosidase

C)transcription factors

D)glucose

E)allolactose

Back 35

E) allolactose

Front 36

The polycistronic mRNA is transcribed from the lac operon when lactose is present in the cell.

A)True

B)False

Back 36

True

Front 37

The lac repressor protein is active in the absence of lactose within the cell.

A)True

B)False

Back 37

True

Front 38

The trp operon consists of ________ structural genes.

A)one

B)two

C)three

D)four

E)five

Back 38

E) five

Front 39

In the absence of tryptophan, the trp repressor is

A)active and can bind to the operator.

B)active and cannot bind to the operator.

C)inactive and cannot bind to the promoter.

D)inactive and can bind to the operator.

E)inactive and cannot bind to the operator

Back 39

E) inactive and cannot bind to the operator

Front 40

In the presence of tryptophan, tryptophan binds to the

A)operator.

B)promoter.

C)RNA polymerase.

D)trp genes.

E)trp repressor.

Back 40

E) trp repressor

Front 41

In the presence of tryptophan, transcription of the trp operon is on.

A)True

B)False

Back 41

False

Front 42

An operon is a group of genes that is under the control of a singe operator site.

A)True

B)False

Back 42

True

Front 43

In the lytic cycle of phage replication

A)phage genes integrate into the host cell genome and are not expressed

B)phage genes exist as prophage

C)phage DNA remains inside the protein coat

D)phage nucleic acid is replicated and phage genes are expressed, making new phage protein and lysing the host cell

Back 43

D)phage nucleic acid is replicated and phage genes are expressed, making new phage protein and lysing the host cell

Front 44

A prophage is

A)phage DNA integrated into host cell genome

B)phage DNA being actively expressed
C)phage protein left outside the bacterium

D)toxic to the host bacterial cell

Back 44

A)phage DNA integrated into host cell genome

Front 45

Which of the following can cause a phage in the lysogenic stage to revert to the lytic stage?

A)lack of nutrients

B)ultraviolet light

C)a competing phage

D)darkness

E)an electrical charge

Back 45

B)ultraviolet light

Front 46

In the lysogenic stage of phage replication, the host cell is lysed.

A)True

B)False

Back 46

False

Front 47

Once a phage becomes lysogenic, it will remain lysogenic and never be lytic again.

A)True

B)False

Back 47

False

Front 48

RNA polymerase binds to the

A)operator.

B)promoter.

C)regulator.

D)terminator.

E)enhancer.

Back 48

B) Promoter

Front 49

The most efficient control of eukaryotic gene expression is achieved at the level of

A)replication.

B)transcription initiation.

C)post-transcription.

D)translation initiation.

E)post-translation.

Back 49

B) Transcription initiation

Front 50

At which of the following level(s) can gene expression be regulated in eukaryotes?

A)passage of mRNA through the nuclear membrane

B)destruction of the mRNA

C)rate of protein synthesis

D)A and B

E)A, B and C

Back 50

E) A, B, and C

Front 51

The addition of a phosphate to a protein after it is produced is an example of post-transcriptional modification.

A)True

B)False

Back 51

False

Front 52

The exons of eukaryotic mRNA are removed and the introns are spliced together.

A)True

B)False

Back 52

False

Front 53

The basic subunit of chromatin is...

A)DNA

B)nucleosome

C)histone proteins

D)HO gene

E)histone acetyltransferase

Back 53

B) nucleosome

Front 54

Which of the following can physically block interactions between promoter DNA sequences and the proteins needed to initiate transcription?

A)RNA

B)nucleosome

C)histone proteins

D)HO gene

E)histone acetyltransferase

Back 54

C) Histone Proteins

Front 55

During chromatin remodeling, which of the following is acetylated to loosen its contact with the DNA?

A)DNA

B)nucleosome

C)histone proteins

D)HO gene

E)histone acetyltransferase

Back 55

C) Histone Proteins

Front 56

Chromatin rearrangement modifies the histone - DNA structure so that translation can occur.

A)True

B)False

Back 56

False

Front 57

The activities of Swi/Snf and the histone acetyltransferase modify the chromatin structure of the HO promoter region into a more open conformation.

A)True

B)False

Back 57

True

Front 58

Assembly of basal transcription factors begins at the ________ sequence in the promoter.

A)GGCC.

B)AATT.

C)ACGT.

D)GAGA.

E)TATA.

Back 58

E) TATA

Front 59

Which of the following statements about basal transcription factors is TRUE?

A)they are essential for transcription

B)they cannot increase the rate of transcription by themselves

C)they can decrease the rate of transcription by themselves

D)A and B

E)A, B and C

Back 59

D) A and B

Front 60

Which of the following statements about enhancers is TRUE?

A)they are sequences to which activators bind

B)they are found in the promoter of a gene

C)they are only found in certain chromosomal locations

D)A and B

E)A, B and C

Back 60

A)they are sequences to which activators bind

Front 61

The interaction of activators, coactivators and basal transcription factors involves the formation of a loop in the DNA.

A)True

B)False

Back 61

True

Front 62

Regulatory proteins called repressors can decrease the rate of transcription by binding to the promoter.

A)True

B)False

Back 62

False

Front 63

A Barr body is typically found in the nucleus of

A)female gametes only.

B)male gametes only.

C)female somatic cells only.

D)male somatic cells only.

E)both male and female somatic cells.

Back 63

C) Female somatic cells only

Front 64

Which of the following statements about the Xist gene is TRUE?

A)It is located in the Xic region of the X chromosome.

B)It encodes an RNA that will coat an X chromosome to promote its compaction.

C)It functions in the initiation phase of X inactivation.

D)A and B

E)A, B and C

Back 64

D) A and B

Front 65

A cell with three X chromosomes will contain

A)no Barr bodies.

B)1 Barr body.

C)2 Barr bodies.

D)3 Barr bodies.

E)4 Barr bodies.

Back 65

C) 2 Barr Bodies

Front 66

Once a cell undergoes X chromosome inactivation, all of its daughter cells will have the same X chromosome inactivated.

A)True

B)False

Back 66

True

Front 67

X chromosome inactivation equalizes the gene dosage between mammalian males and females.

A)True

B)False

Back 67

True