Download Unit 2 Review (B5-B8)

Review sheet for test B5 – B8 ANWERS
DNA review
1. What bonds hold complementary bases between 2 strands of DNA together? Hydrogen bonds
2. What bonds exist between sugars and phosphates? Covalent bonds
3. Describe how DNA is like a ladder. Sides (made of deoxyribose sugare & phosphate) and
rungs (made of nitrogenous bases)
4. Explain the 3 steps of DNA replication. 1) DNA helicase unzips DNA by breaking the hydrogen
bonds that exist between the 2 strands of DNA; 2) DNA polymerase assists with correct
placement of incoming DNA nucleotides; 3) DNA polymerase assist with covalently bonding
of the backbone of the new strand
5. Why is DNA replication termed “semi-conservative”? has half the parent strand and half is new
therefore the parent strand is “half” conserved in each new double helix
6. What role does DNA polymerase play in DNA replication? Covently bonds backbone of new
strand and proofreads to ensure correct base pairing
7. Define recombinant DNA. DNA of 2 species combined (therapeutic intent)
8. What is a transgenic organism? Organism with foreign DNA inserted
9. What are 3 uses for recombinant DNA? Bacteria, plants, animals, xenoplantation
10. Explain how gene therapy is used to help those with genetic diseases. What are some problems?
Expensive, hard to control placement of insertion, eugenics, can be dangerous to health
Protein Synthesis review
11. Describe the process by which mRNA is formed for protein synthesis. DNA opened,
complementary RNA nucleotide bind with DNA strand (gene) with the help of RNA
polymerase, strand then leaves through nuclear pore and moves into cytoplasm.
12. What is the process called? Transcription
13. What enzyme is responsible for unzipping DNA for mRNA to be assembled off of it? DNA helicase
14. What is the process by which a protein forms at a ribosome called? Translation
15. What is the function of the following in protein synthesis?
a) DNA - template
b) mRNA – copy of gene/DNA that moves into cytoplasm
c) tRNA – brings aa’s to ribosome
d) rRNA – with proteins is called a ribosome which is the site of protein synthesis
16. Where are the following usually found in cells?
a) mRNA – nucleus & cytoplasm
b) tRNA - cytoplasm
c) rRNA – made is nucleolus, functions in cytoplasm (ribosome)
17. What is a polyribosome and what is its function? Many ribosomes working together to mark
large protein quickly
18. Give one role of each of the following in the process of translation
a) Ribosome – site that synthesizes proteins
b) tRNA – brings aa
c) mRNA – “recipe” or instructions on how to make specific protein
19. Describe the difference between a codon and an anticodon – codon is on mRNA; anticodon is
on tRNA;
20. Describe anticodon to codon complementary base pairing. tRNA’s anticodon with its specific aa
will base pair with mRNA’s codon that has been created from the gene/DNA
21. What bonds form between amino acids? peptide
22. What mRNA sequence signals the end of an amino acid sequence? STOP which codes for a
release factor protein
23. If this is the strand of DNA ….complete the rest:
DNA:
TAA
CGC
AAG
CCC
TGG
GAC
mRNA:
AUU
GCG
UUC
GGG
ACC
CUG
tRNA:
UAA
CGC
AAG
CCC
UGG
GAC
AA’s:
Iso
Ala
Phe
Gly
Thr
Leu
24. Give one example of an environmental mutagen and explain how it could cause a change in the
production of mRNA in a cell. Chemical, radiation, biological – causes mutations that affect
proteins.
25. What is the anticodon for tryptophan. mRNA codon is UGG so tRNA anticodon is ACC
26. Describe one way in which each of the following pairs of molecules are functionally related in the
process of protein synthesis.
a) DNA and mRNA: DNA has code for proteins in its genes; mRNA is the copy of that
gene
b) mRNA and tRNA: mRNA has template to make proteins & tRNA brings the aa’s that
correspond to that message sent from the DNA
c) tRNA and amino acids: tRNA picks up correct aa & takes to ribosome
d) Protein and rRNA: rRNA, along with proteins, makes up ribosome which is the site of
protein synthesis
27. What is the purpose of transcription during protein synthesis? Recipe from nucleus to cytoplasm
28. What occurs during translation? Protein made – see steps in your notes
29. In an experiment conducted to study protein synthesis, radioactive thymine and radioactive uracil
were added to a culture of human cells. A few hours later, the culture was analyzed and
radioactive mRNA was found.
a) Explain how an mRNA molecule is produced - transcription
b) Explain why the mRNA produced is radioactive – radioactive uracil as a nucleotide to
make up mRNA
c) In a different experiment, radioactive uracil was added to a culture of human cell
undergoing DNA replication. What will be the characteristic of the resulting DNA in terms
of radioactivity? Explain. DNA would not be radioactive because DNA is not make
with uracil
30. Name the process shown above and explain how the molecule that is produced is used to
determine the sequence of amino acids in a protein. Transcription; mRNA (molecule X) contains
triplet codons needed to instruct which tRNA anticodon to base pair. Each tRNA will bring
its specific aa to build protein based on the instructions sent from DNA
31. A segment of hemoglobin has the following sequence of amino acids:
Leucine-threonine-proline-glutamate-glutamate
The same segment of hemoglobin found in people who have sickle-cell anemia has the following sequence:
Leucine-threonine-proline-valine-glutamate
Using the codon chart in your text, explain how DNA is different in people with sickle-cell anemia.
Glutamate’s codon is GAG whereas valine’s codon is GUG which means that in DNA there was a
point mutation (substitution) from T to A at the second base with the triplet
32. Complete the following table.
TRANSLATION
REPLICATION
Product
Polypeptide chain
DNA strand
Location
Cytoplasm
nucleus
33. What is the specific function of ribosomes? Protein synthesis
34. What organelle is involved in producing rRNA – which is used to make ribosomes? nucleolus
35. How do polyribosomes and ribosomes differ in their structure and function? Polyribosomes are
just many ribosomes working on one mRNA strand at once. Both still synthesize proteins.
36. The heredity material found in cells is
a) DNA
c) mRNA
b) rRNA
d) ATP
37. Which is not a major function of the genetic material?
a) Store information
c) Replicate itself
b) Catalyze chemical reactions
d) Undergo mutations
38. In the Watson-Crick model of DNA, the “steps” of the ladder are composed of
a) Sugars
c) Two purines
b) A purine and a pyrimidine
d) Two pyrimidines
39. That amount of adenine is always equal to the amount of ___ in DNA
a) cytosine
c) guanine
d) thymine
b) uracil
40. Which of the following have nitrogenous bases correctly paired in DNA?
a) Adenine-guanine; thymine-cytosine
b) Adenine-uracil; guanine-cytosine
c) Adenine-cytosine; guanine – thymine
d) Adenine- thymine; guanine-cytosine
41. The enzyme used to join complementary DNA nucleotides together is
a) DNA polymerase
c) Helicase
b) RNA polymerase
d) Lipase
42. Which of the following is not true about DNA?
a) Has a double helix
b) Bases are held together by hydrogen bonds
c) Contains adenine, cytosine, guanine, uracil
d) Has a deoxyribose sugar
43. Which of the following statements about DNA replication is not correct
a) Unwinding of the DNA molecule occurs as hydrogen bonds break
b) Each base is paired with another exactly like it
c) The process is known as semi conservative replication because the old strand is
conserved in the new molecule
d) Complementary base pairs are held together by hydrogen bonds
44. A nucleotide contains
a) DNA and RNA
b) A sugar, phosphate, and a nitrogen base
c) Complementary purines and pyrimidines
d) RNA, protein, and lipids
45. DNA serves as the template for the direct synthesis of
a) DNA
c) enzymes
b) tRNA
d) proteins
46. Which of the following is not true about RNA?
a) RNA transfers messages from DNA to ribosomes
b) RNA contains the sugar ribose
c) RNA forms a double helix
d) RNA is single stranded
47. Prior to protein synthesis, the DNA
a) Attracts tRNA’s with appropriate amino acids
b) Serves as a template for the production of mRNA
c) Adheres to ribosomes for protein synthesis
d) Contains anticodons that become codons
48. Which of the following nucleotide bases is found only in RNA, not in DNA?
a) Guanine
c) Thymine
d) Uracil
b) Adenine
49. The function of transfer RNA is to
a) Carry amino acids to ribosomes
b) Transfer nucleotides to the nucleus
c) Turn DNA on and off
d) Act as a site for protein synthesis
50. The genetic code consists of___ bases that stand for one amino acid
c) 3
a) 1
b) 2
d) 4
51. Messenger RNA is produced in the
c) Nucleus
a) Cytoplasm
b) Ribosomes
d) Endoplasmic reticulum
52. In modern biochemical genetics, the flow of inherited information is from
c) DNA→protein→RNA
a) protein→RNA→DNA
b) DNA→
→RNA→
→protein
d) RNA→DNA→protein
53. Which is directly responsible for the sequence of amino acids in a protein?
a) The sequence of anticodons
b) The number of codons in mRNA
c) The sequence of codons in mRNA
d) The enzyme that attaches the amino acid to tRNA
54. Transcription of part of a DNA molecule with a nucleotide sequence of A-A-A-C-A-A-C-T-T results
in a mRNA molecule with the complementary sequence of :
a) G-G-G-A-G-A-A-C-C
c) T-T-T-G-A-A-G-C-C
b) U-U-U-G-U-U-G-A-A
d) C-C-C-A-C-C-T-C-C
55. During the process of transcription, the information in
a) Protein is converted into RNA information
b) DNA is converted into protein information
c) DNA is converted into RNA information
d) RNA is converted into DNA information
56. If one strand of DNA has the base sequence AAGCAA, the complementary DNA strand has which
of the following sequences?
a) UUCGUU
c) AAGCAA
d) TTCGTT
b) TTCGTG
57. For translation to take place, which of the following would not be required to be present?
a) DNA
c) ribosome
b) mRNA
d) rRNA
58. Which of the following processes does not take place during translation?
a) Attachment of ribosome to rRNA
b) Growth of a polypeptide chain
c) Binding of tRNA molecules to the ribosome
d) Production of mRNA
59. Which is the process that synthesizes mRNA?
a) Translation
c) Transposition
b) Transcription
d) Transformation
60. In the above diagram, if adenine is located on strand 4, then on strand 2 at the same location ___
must be present
a) Adenine
c) Cytosine
b) Thymine
d) Guanine
61. In the diagram above, when replication is finished, strand 1 and 2 will have the same base
composition as:
c) Strands 3 and 4
a) Strands 2 and 3
b) Strands 1 and 3
d) Strands 1 and 4
62. If a mutation occurred, then
a) The code would change
b) Some particular codon or codons would change
c) Some particular anticodon or anticodons would change
d) All of the above
e) Only a and b
63. The___ of a tRNA molecule will attract the codon of a mRNA molecule.
a) DNA sequence
c) Amino acid binding site
b) Anticodon
d) RNA polymerase
64. How does the anticodon differ from the codon? The anticodon….
a) Contains thymine, but the codon contains uracil
b) Attaches to ribosomes, but the codon attaches to amino acids
c) Is a sequence of three bases complementary to the bases of a codon
d) Stands for a particular amino acid, but the codon codes for nucleotide bases
65. Which of the classes of RNA molecules is linked with proteins in forming the large and small
subunits of a cytoplasmic structure?
a) rRNA
c) mRNA
b) tRNA
d) complementary RNA
66. All nucleotides are made up of __3___ parts: a base, a sugar and __phosphate group___
67. In DNA the base adenine is always paired with a base ___thymine___
68. DNA is double stranded. It is made up of two _nucleotide__strands
69. In RNA the base thymine is replaced by _uracil__
70. A mutation is a change in the sequence of __bases__ within a DNA molecule
71. Each tRNA has an __anticodon_ at one end and a specific __aa__ at the other
72. DNA contains a _code__ for protein synthesis; it is a ___triplet___code because three bases
indicate one particular ___aa____. During transcription, __m_ RNA is produced having bases that
are _complementary_ to the bases in DNA. Thus it is said that DNA serves as a _template_ for
mRNA production. The bases in DNA are called the code, and the bases in mRNA are called
__codons_. mRNA moves into the cytoplasm and becomes associated with the _ribosome__
which contain __r_ RNA molecules. Also in the cytoplasm there are ____t__ RNA molecules with
an _anticodon_ at one end and one of the twenty amino acids at the other. During translation the
tRNA molecules bring amino acids to the ribosomes in the order dictated by the DNA code; thus
the original sequence of bases in DNA orders the _sequence__of amino acids in a protein.
3, 1,
73. Which of the following pairs in not a valid comparison between DNA and RNA
DNA
RNA
a) double helix
single-stranded
b) replicates
duplicates
c) deoxyribose
ribose
d) thymine
uracil
74. Put phrases 1-6 in order to describe protein synthesis.
1) mRNA is produced in the nucleus
2) ribosomes move along mRNA
3) DNA has a code
6, 5, 2, 4
4) polypeptide units
5) tRNA brings amino acids to ribosomes
6) mRNA moves to ribosomes
75. Use the table of mRNA codons to answer the questions below.
a) The codon for tryptophan is __UGG__
b) For leucine, there are ____6______ different codons
c) The codon GAU is for __asparate___
d) In a stop codon, if the second base is G, the first and third bases are _U_ and _A_
76. Label (1) to (4) in the diagram below. Put the following phrases in the correct order, and write them
in the correct area on the diagram
___3____ recombined plasmid is reintroduced into the bacterium
___1____plasmid is removed from E. coli
___4 ___recombined plasmid functions and replicates normally
1
__ 2____foreign DNA is incorporated into the plasmid
2
3
4