Unformatted text preview: Bil 255
Directions: T est #2 –
Form 0 04 April Choose the BEST answer from among the choices given. 1. When DNA synthesis is initiated at an origin of replication, the two parental strands are replicated (think carefully) ?
a) In opposite directions
b) In same direction
c) One continuously and one discontinuously
d) a and c apply
e) b and c apply 2. DNA synthesis is always initiated by ?
a) An RNA primer
b) A guanosine cap c) A deoxyribonucleotide triphosphate 3. Mistakes in DNA synthesis are, to a large extent, avoided because DNA polymerase has ?
a) Proofreading function
b) Mismatch repair enzymes correct DNA after synthesis
apply c) Both a and b 4. Some mutations (base changes in DNA) are phenotypically silent (i.e., have no biological effect).
Their most likely location is in ?
b) Introns 5. RNA is synthesized by copying DNA ?
a) Both strands of DNA are transcribed to yield double stranded RNA
b) At any position in genome only one strand of DNA is transcribed 6. RNA molecules have ?
a) No secondary structure 7. Messenger RNA ?
a) Codes for proteins b) Fold at random
b) c) Can fold using base pairing rules into unique structures Is the only RNA transcribed from DNA c) a and b apply 8. Messenger RNA’s differ in procaryotes and eucaryotes ?
Procaryotic messages are polycistronic (code for more than one protein) and eucaryotic messages often
only code for one protein
Procaryotic messages code for one protein, eucaryotic messages code for multiple proteins 9. Eucaryotic messengers RNA’s have ?
a) A poly A tail at 5' end and a methyl G cap at 3' end
b) A poly A tail at 3' end and a methyl G cap at 5' end 10. Exons are assembled into mature mRNA ?
a) Same sequence in every cell
b) Alternative splicing of primary transcripts occurs in different cell types
11. The boundary between exons and introns is ?
a) Precisely defined so that splicing always occurs at the same site
b) The boundary is variable and splicing can occur in many regions for the same exon/intron boundary
12. The nucleotide sequence of a small fragment of messenger RNA is AUGCUCAGCGUU. The genetic code is
attached to the last page of the exam. You conclude that the amino acid sequence of the protein coded by this
message contains the sequence ?
c) There is not enough information to decide
13. The function of tRNA’s is to translate mRNA sequence ?
a) There is only one tRNA for each amino acid
c) There are multiple tRNA’s for all amino acids b) There are multiple tRNA’s for some amino acids Bil 255 Test # 2 – Glaser – Form 0 – pg 2 14. In general, the DNA in each cell of the body of a eucaryotic organism, for example man, is ?
a) Different in each cell type
b) The same in each cell type
15. Amino acids are covalently attached to tRNA to form amino-acyl tRNA’s ?
a) The amino acid is attached to the anticodon on tRNA
b) The amino acid is attached to 3' hydroxyl at terminal adenine on tRNA
c) Neither statement applies
16. Proteins and mRNA’s, once made in a cell ?
a) Remain for the life time of the cell b) Are continuously degraded at rates specific for each molecule 17. The minimal components required for function of a eucaryotic chromosome are ?
b) Replication origin
c) Telomere and telomerase d) All apply 18. Proteins that control gene expression, i.e., frequency of transcription, bind to ?
a) Single bases in DNA
b) Multiple bases in DNA
c) Bind to DNA in either the major or minor groove
d) a and c apply
e) b and c apply
19. In procaryotes the synthesis of enzymes required to make essential amino acids/vitamins/sugars depends on the
availability of these in the fluid in which cells grow. Repressors are best described as ?
a) Proteins that control nutrient uptake by cells
b) Proteins that bind to DNA at promoter regions, dependent on concentration of specific ligands in cells,
for example, an amino acid
c) Are a component of RNA polymerase
20. In eucaryotic cells all RNA molecules are ?
a) Made by the same RNA polymerase
b) Made by different RNA polymerases 21. A given regulatory protein may ?
a) Control expression of a single gene b) Can control expression of multiple genes 22. When E. coli is grown in the presence of streptomycin (an antibiotic), approximately 5 colonies grow from 108 cells.
A strain of E. coli defective in the proofreading mechanism of DNA polymerase grows poorly under normal
conditions. When tested for its ability to grow in the presence of streptomycin you expect: How many colonies per
108 cells ?
a) 5 colonies
b) > 5 colonies
c) < 5 colonies
23. A strain of E. coli containing an integrated F-plasmid in the genomic DNA is also resistant to rifampicin, and able to
grown in the absence of tryptophan. You observe that rifampicin resistance is transferred, at high frequency while
the ability of the recipient cells to grown in the absence of tryptophan is observed with low frequency. You
conclude ? (pick best answer)
a) The two genes are on different chromosomes
b) The location of rifampicin resistance gene is close to the site of integration of F-plasmid and the tryptophan
gene is distal
The location of rifampicin resistance gene is close to the beginning site for DNA transfer and the tryptophan
gene is remote from this site
24. You chemically link the amino acid alanine (Ala) labeled with 14C to the tRNA for leucine. You use this molecule in
an in vitro system to synthesize a protein using the appropriate mRNA, ribosomes, etc. The initial coding
sequence for this protein is : AUG-UUU-GCU-CUU-GCG
You expect to find radioactive alanine ? (think carefully)
a) In position 1 and 3
b) In position 3
c) In position 4
d) In position 5
25. Homologous recombination occurs between DNA molecules, which at the site of recombination have ?
a) Highly different nucleotide sequences
b) Identical or nearly identical nucleotide sequences Bil 255 Test # 2 – Glaser – Form 0 – pg 3 26. Retroviruses contribute to genetic diversity because ? (think carefully and pick the best answer)
a) They contain RNA instead of DNA
They contain reverse transcriptase
c) Their genome is inserted as DNA into chromosomes
d) During transcription and packaging of virus they sometimes (rarely) incorporate a host gene into viral
particle as RNA
27. Restriction enzymes cleave DNA ?
a) At random sites
b) At unique sequences
d) a and c apply
e) b and c apply c) The sequence at the site is often a palindrome Note Questions 28 - 30 are related
28. You clone the portion of mouse DNA that codes for the enzyme hexokinase (involved in glycolysis), as well as, a
small portion of adjacent DNA. You sequence a portion of this DNA and you use it to identify clones for the
same DNA region (coding for hexokinase) from pig/human/horses/baboons, using hybridization and a radioactive
oligonucleotide with the mouse sequence as a probe. In order to accomplish this you hybridize the protein to your
clones at ?
a) High stringency
b) Low stringency
c) It does not matter, either will work
29. Having obtained clones for the gene for hexokinase from mouse/pig/horse/baboon/human, you examine their pattern
of cleavage by restriction enzymes. You expect the ?
a) Pattern to be totally different
b) Pattern of cleavage of baboon and human genes to be more similar than mouse and human
c) Pattern of cleavage of baboon and human genes to be as different from each other as mouse and human
30. You completely sequence the hexokinase genes from all species and you compare the sequences, not only at
nucleotide level, but also of the protein (i.e., hexokinase) for which they code. You expect ?
a) More divergence in introns than in exons
b) Less divergence in introns than in exons
c) The amino acid sequence of protein to be more related than nucleotide sequence
d) a and c apply
e) b and c apply
31. You wish to code the gene for red hair, so everyone can look like Luis Glaser. You determine a partial amino acid
sequence of a protein that determines hair color as :
and after looking up the
genetic code (attached), you synthesize an oligonucleotide probe to identify the gene from a genome library. The
oligonucleotide that you synthesize has the sequence : GCC-UUC-GGU-GGG-UUA and you fail to find, even
after five years of work, any sign of the gene. You should have ?
a) Come to class more often
b) Synthesized a series of random oligonucleotides
c) Synthesized all possible oligonucleotides that can code for the amino acid sequence above
32. The effect of cholesterol on a lipid bilayer is to ?
a) Make it more fluid
b) Restrict mobility
33. The region of a membrane protein that traverses the lipid bilayer is usually arranged on ?
a) An extended chain of amino acids
b) An α helix
c) A pleated sheet
34. Tight junctions ?
a) Promote movement of proteins in membranes
35. For all cells is ?
Na+ inside > Na+ outside b) b) Restrict movement of proteins in membranes Na+ outside > Na+ inside Bil 255 Test # 2 – Glaser – Form 0 – pg 4 36. Glucose and mannose are monosaccharides of identical size (Mol wt. 180), yet glucose readily enters muscle cells and
mannose does not. The concentration of glucose in the intracellular fluid (cytoplasm) is never higher than in
extracellular fluid and often lower. Based on these observations, you expect glucose entry into muscles to be ?
a) Via a pore
b) By a glucose specific carrier
c) by a Na+/glucose cotransporter (symport)
37. Which of the following statements is correct regarding ATP driven pumps ?
a) The only ATP driven pump is the Na+/K+ ATPase
b) Eucaryotes contain a variety of ATP driven pumps including Na+/K+ ATPase, Ca++ ATPase & H+ ATPase
c) All ATP driven pumps are in the cytoplasmic membrane
d) b and c are correct
38. Ribozymes are ?
a) Enzymes that cleave ribonucleotide
c) Enzymes that cleave RNA at specific sequences d) b) RNA's with catalytic activity
a and b apply
e) b and c apply 39. Na+/H+ antiport is one of the primary regulators of intracellular pH. When the fluid surrounding a cell contains no
Na+ would you expect the cell’s cytoplasm ?
a) To become more acid
b) To become more alkaline
40. A particular cell type can potentially utilize 3 different regulatory proteins that control gene expression to generate
different phenotypes by utilizing any possible combination of these proteins from 0 to 3. How many potential
phenotypes can arise ?
d) none of these is correct
41. Consult the following restriction fragment length polymorphism made by hybridization to a DNA probe after digestion
of human DNA with restriction enzyme. Think carefully: based on this evidence alone ?
a) infant X is the child of Parents B
b) Infant Y is the child of parents A
c) One infant is the child of neither Parents A or B
d) a and c apply
e) b and c apply 42. To create a transgenic cow that would synthesize a human protein in milk, you would ?
a) Inject total human DNA into the mammary gland
b) Select embryonal stem cells (ES) transfected with a human gene under control of a promoter expressed in all
c) Select embryonal stem cells (ES) transfected with a human gene under control of a DNA sequence specific
for proteins secreted in milk such as lactalbumin and transfer these cells to early blastulas
d) None of the above
43. A cDNA library is prepared from muscle cells & liver cells. You expect the genes found in these two libraries to be?
a) The same
b) Partially overlapping
c) Totally different
44. Hershey showed that when a bacteriophage was labeled with 32P (to label DNA) and 35S (to label protein) the
production of new phage by E. coli resulted from ?
a. The injection of 32P and 35S labeled material into E. coli
b. The injection of 35S labeled material
c. The injection of 32P labeled material
45. Single strand DNA binding protein is required to ?
a. Identify the origin of replication
b. Prevent base pairing in lagging strand Bil 255 Test # 2 – Glaser – Form 0 – pg 5 The following two questions (46 & 47) are related.
46. The following is the nucleotide sequence, starting with AUG for a normal cellular protein, and three mutant forms
(a genetic code is attached at the end of the exam).
__ AUGUUAAGAUUCAAA _ _ __
Mutant 1 __ AUGUGAAGAUUCAAA _ __ __ Mutant 2 __ AUGUUAAGGUUCAAA _ __ __ Mutant 3 __ AUGUUAAGGUUCCAN _ __ __ You examine the cells containing each of these mutations for presence of normal or mutant proteins and you find one
of them has no measurable protein. This cell is ?
a) Mutant 1
b) Mutant 2
c) Mutant 3
47. You examine these same cells to determine which has a fully functional protein. The choices are ?
a) Mutant 1
b) Mutant 2
c) Mutant 3
d) None of these is correct
48. The sequence cleaved by the enzyme HaeIII is …………………………………………> --- GG __ CC--Using a probe for a portion of the sequence of the gene for Malterase, you obtain
--- CC __ GG--the following results in normal and mutant live cells, after cleavage of the DNA,
electrophoresis and assay with the probe.
DNA sequencing shows a single base change and a single amino acid has been
changed in Malterase. Using the genetic code, can you distinguish
which of the following alternatives is possible ?
a) Glycine – Arginine
b) Proline – Isoleucine
c) Proline – Threonine
49. Many amino acids are specified by multiple code words often differing from each other at the third base, but in many
cases differing in all three positions. The amino-acyl tRNA synthetase for the amino acid recognizes all of the
tRNA’s that code for that amino acid. Would you conclude from this statement that ?
a) This enzyme functions exclusively by recognizing the anticodon in the tRNA
b) This enzyme at a minimum must recognize another feature of the tRNA in addition to the anticodon sequence.
50. You develop, in the laboratory, a new E. coli strain that has a CAP protein that binds to appropriate DNA sequence
independent of the concentration of cAMP in the cells. You expect to see ß-galactosidase synthesis in these cells:
a) Only when cells are grown without glucose
b) Only when cells are grown in the presence of a beta-galactoside
c) Both a and b must attain Bil 255 Test # 2 – Glaser – Form 0 – pg 6 SECOND LETTER
U C UUU A UCU UAU UUC
TC UCC s er UAC cys
UGC C UAA stop UGA stop A UUG UCG UAG stop UGG trp G CUU CCU CAU CUC l eu CCC pro CCA CAC CGU
his CAA CUG CCG CAG AUU ACU
ACC AAC AUC ile AUA ACA
met val ACG AAG a sn ala GAC GUA GCA
GCG GAG CGG G
U AGC s er AGG GGC C
A arg GGU
a sp GAA GUG C G
U gly C GGA
D A AGA
lys GAU GCC arg AGU AAA GCU GUU
GUC thr CGC U CGA
gln AAU AUG G U UCA l eu CUA
U G A GGG G L
View Full Document
- Fall '08