⚪️ PACOP: Module 2 combined (no red)

1. This region in the nucleus is the site of ribosome assembly.

A) nuclear membrane

B) nucleolus

C) chromatin

D) chromosome

B. nucleolus

2. Which of the following cellular structures is unique in eukaryotes?

A) plasma membrane

B) ribosomes

C) internal cellular membrane

D) golgi apparatus

C. internal cellular membrane

3. These organelles consist of membranous sacs containing powerful oxidase enzymes, and they use molecular oxygen (O2) to detoxify harmful substances

A) lysosomes

B) golgi apparatus

C) peroxisomes

D) mitochondria

C. peroxisomes

4. The cellular particles are often referred by their sedimentation coefficient value, for example, 70s ribosomes that is expressed in terms of 10^-13 seconds. The abbreviation "s" stands for

A) subunit

B) Svedberg

C) seconds

D) none of the above

B. Svedberg

5. These are organelles that contain the enzymes for pyruvate oxidation, citric acid cycle, beta-oxidation of fatty acids, oxidative phosphorylation, and ETC.

A) golgi apparatus

B) lysosomes

C) nucleus

D) mitochondria

D. mitochondria

6. Which of the following is/are true?

A) The endoplasmic reticulum is a system of fluid-filled cisterns

B) The smooth endoplasmic reticulum is responsible for protein synthesis

C) The rough endoplasmic reticulum is a site of lipid synthesis

D) All of the above

A. The ER is system of fluid-filled cisterns

7. Some organelles are specific to plant or animal cells. Which of the following organelles are present in plant cells only?

I. vacuole, II. Nuclear envelope, III. Cell wall, IV. lysosomes

A) I only

B) I and III

C) II and IV

D) I-IV

B. I and III

8. Viruses are not cellular, but are rather termed as "biological entities". The main reason why viruses are considered acellular entities is because

A) A virus contains only one type of nucleic acid, either DNA or RNA

B) A virus is very small compared to bacteria

C) A virus is pathogenic

D) Scientists cannot classify viruses under the 5 kingdoms of Whittaker

A. A virus contains only one type of nucleic acid, either DNA or RNA

9. _______ are small, extrachromosomal circular DNA molecules found in prokaryotes

A) nucleoli

B) genes

C) plasmids

D) histones

C. plasmids

10. Which of the following statements is/are correct regarding plasmids?

I. Plasmids are either DNA or RNA molecules

II. Plasmids are found in many types of bacteria

III. Plasmids replicate independently of the main chromosome

IV. Each cell contains only a single copy of plasmid

A) III only

B) I and III

C) II and III

D) II-IV

C. II and III

11. The diversity of the different cell types among various organisms lies in theirchemical nature. Which of the following pairs is/are accurate?

A) bacterial cell membrane-peptidoglycan

B) plant cell wall-cellulose

C) animal cell membrane-nucleic acid

D) none of the above

B. plant cell wall-cellulose

12. Which of the following statements is/are true of prions?

A) A prio is an infectious agent that contains both proteins and nucleic acid

B) The disease "bovine spongiform encephalogpathy" or "mad cow disease " is one disease attributed to prions

C) Both statements are correct

D) Both statements are false

B. T he disease "bovine spongiform encephalogpathy" or "mad cow disease " is one disease attributed to prions

13. Which of the following structures is/are present in the nucleus?

A) nuclear membrane

B) nucleoli

C) chromatin

D) all of the above

E) A and B only

D. All of the above

14. Which of the following is an active process?

A) Transport of molecules through protein pores

B) Transmembrane transport through carrier molecules

C) Both A and B

D) None of the above

D. None of the above

15. Which of the following statements differentiates simple passive diffusion from facilitated diffusion?

A) Facilitated diffusion is an active process

B) Facilitated diffusion is saturable, simple passive diffusion is not

C) Both statements are correct

D) None of the above

B. Facilitated diffusion is saturable, simple passive diffusion is not

16. Which of the following is affected by digitalis glycosides and ouabain?

A) sodium-glucose cotransport system

B) Ca-Na exchanger

C) Na-K pump

D) All of the above

C. Na-K pump

17. Which of the following ions is co-transported with glucose in the small intestine?

A) potassium

B) sodium

C) calcium

D) magnesium

B. Sodium

18. The nature of the cell wall of the bacteria is used in their classification. Which of the following is cross-linked, multi-layered polysaccharide-peptide complex used as the basis of Gram staining?

A) peptidoglycan

B) teichoic acids

C) ergosterol

D) phospholipids

A. peptidoglycan

19. Which of the following is not a biopolymer?

A) nucleic acids

B) carbohydrates

C) amino acids

D) lipids

D. lipids

20. Which of the following statements is/are correct?

A) Adenine is nucleoside

B) Adenosine is a nucleotide

C) Nucleotides are also known as nucleoside phosphates

D) All of the above

C. Nucleotides are also known as nucleoside phosphates

21. Which of the following is/are found inside the cytoplasm?

A) cytosol

B) inclusions

C) mitochondrion

D) all of the above

E) A and B only

D. All

22. Which of the following is a nucleoside?

A) guanine

B) guanosine

C) guanosine monophosphate

D) Any of the above

B. Guanosine

23. Which carbon in the sugars is responsible for the difference between the two nucleic acids?

A) carbon-1

B) carbon-2

C) carbon-3

D) none of the above

B. Carbon 2

24. Which of the following statements is/are true regarding nucleic acid primary structure?

A) DNA contains thymine, while RNA contains uracil

B) Adenine and guanine are pyrimidines

C) Uracil is apurine

D) All of the above

E) Only A and B

A. DNA contains thymine, RNA contains uracil

25. The ribose in RNA is converted to deoxyribose in DNA by replacing ___ in RNA with ___

A) hydroxyl group, hydrogen

B) hydrogen, hydroxyl group

C) oxygen, hydroxyl group

D) hydroxyl group, oxygen

A. hydroxyl group, hydrogen

26. What is wobble?

A) The ability of certain anticodons to pair with codons that differ at the third base

B) An error in translation induced by streptomycin

C) A mechanism that allows for a peptide extension in the 50s subunit of the ribosome

D) thermal motions leading to local denaturation of the DNA double helix

A. The ability of certain anticodons to pair with codons that differ at the third base

27. What type of bond connects successive monomer units through a phosphate residue attached to hydroxyl on the 5' carbon of one unit with the 3' hydroxyl of the next?

A) hydrogen bond

B) covalent bond

C) phosphodiester bond

D) None of the above

C. phosphodiester bond

28. Which of the following groups is responsible for the acidic character of nucleic acids?

A) Phosphate group

B) Nucleotides

C) A and B

D) None of the above; nucleic acid is a misnomer. Nucleic acids are not acidic

A. phosphate group

29. Which of the following are purine bases?

A) Adenine and Thymine

B) Adenine and Guanine

C) Cytosine and Thymine

D) Cytosine and Uracil

B. adenine and guanine

30. Which of the following nitrogenous bases is present only in DNA?

A) adenine

B) thymine

C) cytosine

D) uracil

B. thymine

31. Which of the following base pairs is bonded by a double bond?

A) Adenine and thymine

B) Cytosine and guanine

C) Adenine and guanine

D) Cytosine and thymine

A. adenine and thymine

32. How many hydrogen bonds are formed between cytosine and guanine?

A) one

B) two

C) three

D) no hydrogen bonds are formed between them

C. three

33. The DNA structure is a double helix containing chains which are complementary. Which of the following statements best describes complementarity?

A) In the chains, each end of the helix contains the 5' end of one strand and the 3' end of the other

B) Adenine binds to thymine, and cytosine binds to guanine

C) Several codons may code for the same amino acid

D) All of the above

B. Adenine binds to thymine, cytosine binds to guanine

34. Each end of the DNA double helix contains the 5' end of one strand and the 3' end of the other strand - this statement describes what characteristic of the DNA structure?

A) complementary

B) antiparallel

C) semiconservative replication

D) base pairing

B. antiparallel

35. What do you call the bond between the 1' carbon of the sugar and the base nitrogen?

A) hydrogen bond

B) covalent bond

C) phosphodiester bond

D) glycosidic bond

D. glycosidic bond

36. Which of the following statements is correct?

A) Some nucleic acid bases are capable of tautomerization

B) All enzymes are proteins

C) Both A and B

D) Both are incorrect

A. Some nucleic acid bases are capable of tautomerization

37. Which of the following statements best describes pyrimidine bases?

A) They have a 5-membered ring structure.

B) They have a 6-membered ring structure.

C) Adenine and guanine are pyrimidine bases.

D) Some examples include caffeine, theophylline and theobromine.

B. They have 6-membered ring structure

38. The primary difference between nucleosides and nucleotides is the presence of phosphate group in the former - this statement is:

A) True

B) False

B. False

39. Which of the following best describes the degeneracy of the genetic code?1

A) 1 codon = 1 amino acid

B) 1 codon = 6 amino acids

C) 6 codons = 1 amino acid

D) none of the above

C. 6 codons = 1 amino acid

40. Deoxyribonucleic acid is a double stranded polynucleotide. The base content of DNA displays three sets of equivalent pairs. Which f the following equations are true?

1. A = T, 2. C = G, 3. A + G = T + C, A + G is not always equal to T + C

A) 3 only

B) 1 and 2

C) 1, 2 and 3

D) 1, 2 and 4

C. 1, 2 and 3

41. Which of the following is the most common form of DNA?

A) A-DNA

B) B-DNA

C) Z-DNA

D) All of the following occur in the same frequency in nature.

A) A-DNA

42. When the two strands of the DNA double helix are separated, each strand can serve as a template for the replication of a new complementary strand. This describes _____

A) DNA replication

B) transcription

C) complementarity of base pairing

D) semiconservative replication

D. Semiconservative

43. Which fo the following is correct according to the Watson-Crick model for DNA?

1. DNA consists of a two-stranded double helix

2. Pairing is A-T and G-C

3. The primary structure of nucleic acids is composed of a double helix stabilized by H-bonds

4. The chains were complementary and antiparallel

A) 3 only

B) 1 and 2

C) 1, 2 and 3

D) 1, 2 and 4

D. 1, 2 and 4

44. The following base pairs forma minor groove

A) cytosine-guanine

B) adenine-thymine

C) adenine-uracil

D) A and B only

A. cytosine-guanine

45. These are discontinuous stretches in which the lagging strand is initially synthesized during DNA replication

A) enhancer

B) operon

C) Okazaki fragments

D) primer

C) Okazaki fragments

46. A short piece of nucleic acid (DNA or RNA), base-paired with a DNA template strand and provides a free 3'-OH end from which DNA polymerase can extend a DNA strand

A) enhancer

B) operon

C) Okazaki fragments

D) primer

D. primer

47. DNA polymerase type ___ has a 5' to 3' polymerase activity and a 3' to 5' proofreading exonuclease activity,

A) I

B) II

C) III

D) IV

C. III

48. This DNA polymerase is primarily involved in repairing DNA

A) DNA polymerase I

B) DNA polymerase II

C) DNA polymerase III

D) DNA polymerase IV

A. I

49. Which of the following statements is/are true regarding the secondary structure of nucleic acids?

A) Guanine forms base pairs with adenine via 2 hydrogen bonds

B) The B form of the DNA is the most common in biological systems

C) The breaking of H-bonds caused by high temperature is called melting

D) A and B

E) B and C

E. B and C

50. What is the sequence of the major events in DNA replication?

1. DNA ligase joins DNA fragments of the lagging strand, creating a single DNA molecule

2. DNA polymerase at the replication fork synthesizes DNA in 5' to 3' direction. There are two strands, the leading and the lagging strands.

3. DNA double helix is opened by helicase

4. Primase creates a temporary RNA primer for each DNA strand

5. DNA polymerase removes DNA primer and fills the gaps between Okazaki fragments

A) 1-3-5-4-2

B) 3-4-2-5-1

C) 1-2-5-4-3

D) 4-3-2-5-1

B. 3-4-2-5-1

51. This is a rare human disorder, which progresses to photosensitivity, caused by an inherited exonuclease deficiency

A) Xeroderma pigmentosa

B) Bloom's syndrome

C) Fanconi's anemia

D) Hodgkin's lymphoma

C) Fanconi's anemia

52. Alkylating agents are used in the treatment of Hodgkin's diseases and leukemias. Their main mechanism of action is to alkylate this nitrogenous base.

A) adenine

B) cytosine

C) guanine

D) thymine

C. guanine

53. The chemotherapeutic agent binds to bacterial RNA polymerase.

A) Pyrazinamide

B) Actinomycin D

C) Bleomycin

D) Rifampicin

D. Rifampicin

54. Which of the following statements is/are true?

A) RNA polymerase, unlike DNA polymerase does not require a primer

B) DNA polymerase is a nuclease

C) RNA polymerase is a nuclease

D) All of the above

E) A and B

E. A and B

55. Which of the following is a codon for methionine?

A) UAG

B) AUG

C) UGA

D) UAA

B. AUG

56. This DNA mutation occurs when a purine replaces a pyrimidine, or vice-versa

A) transitional

B) transversional

C) insertion

D) frame-shift

B. transversional

57. A purine replaces another purine in ____ mutations

A) transitional

B) transversional

C) insertion

D) frame-shift

A. transitional

58. Which of the following is/are point mutations?

A) insertion

B) deleation

C) transition

D) all of the above

E) A and B

D. all of the above

59. This mutagenic substance is obtained from smoking cigarettes. It intercalates with DNA and causes frameshifts

A) tar

B) nicotine

C) coal

D) benzopyrene

D. benzopyrene

60. This refers to the noncoding regions that alternate with coding regions in the polypeptide sequence,

A) exon

B) promoters

C) introns

D) repressor

C. introns

61. This DNA duplex has a special left-handed helical structure

A) A-DNA

B) B-DNA

C) Z-DNA

D) F-DNA

C. Z-DNA

62. Which of the following statements best describes the mechanism of action of Dactinomycin (Actinomycin D)?

A) binds to the bacterial RNA polymerase

B) binds to the 30s subunit

C) binds to 50s subunit

D) intercalate with the minor groove of the double helix

D. Intercalates with minor groove of the double helix

63. 2-Aminopyrine is no longer used clinically. It has been found out to replace adenine (6-aminopurine) or guanine in DNA resulting to bone marrow toxicity. 2-Aminopyrine exhibits what type of mutation?

A) transitional

B) transversional

C) frameshift

D) deletion

A. transitional

64. Which of the following is/are true regarding the central dogma of molecular biology?

A) Transcription is the synthesis of RNA from DNA

B) The process of replication produces new RNA.

C) Reverse transcription is impossible.

D) All of the above.

A. Transcription is the synthesis of RNA from DNA

65. Actinomycin D, an antineoplastic drug, intercalates between two GC pairs in DNA. Which of the following processes does it inhibit?

A) Translation

B) Transcription

C) DNA Repair

D) Replication

B. Transcription

66. Tumor-producing RNA viruses synthesize DNA from RNA in the process called ____.

A) transcription

B) reverse transcription

C) translation

D) reverse translation

B. reverse transcription

67. This enzyme is responsible for removing the RNA primer in DNA.

A) Excinuclease

B) DNA ligase

C) RNA polymerase

D) DNA polymerase

D. DNA polymerase

68. Which of the following pairs is an accurate pairing of the organism and its start codon?

A) eukaryote-formylmethionine

B) prokaryote-methionine

C) eukaryote-methionine

D) none of the above

C. eukaryote-methionine

69. Humans catabolize purines to _______.

A) urea

B) uric acid

C) allantoin

D) B and C

B. uric acid

70. This refers to the set of prokaryotic structural genes, which are transcribed as a unit, along with regulatory elements controlling their expression.

A) operon

B) operator

C) inducer

D) repressor

A) operon

71. When the serum urate levels exceed the solubility limit, the crystals of sodium urate accumulate in soft tissues and joints and causes an inflammatory reaction known as

A) Lesch Nyhan syndrome

B) osteomalacia

C) gouty arthritis

D) Von Gierke's disease

C. gouty arthritis

72. Which of the following statements about amino acids is true?

A) Acidic amino acids bear a positive charge at pH 7.0

B) All amino acids have a chiral carbon.

C) Lysine and arginine are basic amino acids.

D) All of the above.

C. Lysine and arginine are basic amino acids

73. This type of mutation occurs when the codon containing the changed base may become a termination codon.

A) nonsense

B) missense

C) silent

D) transitional

A. nonsense

74. The result of a point mutation that occurs when UCA (coding for serine) is converted to UCU (also coding for serine) is called

A) nonsense

B) missense

C) silent

D) transitional

C. silent

75. Glutamine and asparagines amino acids are ____.

A) acidic

B) basic

C) neutral

D) nonpolar

C. neutral

76. Which statement is true?

A) Cystine is a dimer of cysteine.

B) Cysteine is more stable that cystine.

C) Both statements are correct.

D) Both statements are false.

A. cystine is a dimer of cysteine.

77. Which of the following amino acids contain(s) basic side chains?

A) histidine

B) arginine

C) leucine

D) all of the above

E) A and B

E. A and B

78. Which of the following amino acids contain(s) side chains with sulfur atom?

A) methionine

B) cysteine

C) Both A and B

D) Neither A nor B

C. Both A and B

79. Which of the following maino acids is responsible for disrupting the alpha-helix because its imino group is not geometrically compatible with the righthanded spiral of the alpha helix?

A) proline

B) valine

C) leucine

D) glycine

A. proline

80. Which of the following amino acids has an imino group?

A) phenylalanine

B) proline

C) tyrosine

D) A and B

E) All of the above

B. proline

81. Which of the following amino acids possess(es) a hydroxyl group, which renders it/them polar?

A) serine

B) threonine

C) tyrosine

D) only A and B

E) All of the above

E. all of the above

82. What stabilizes the primary structure of proteins?

A) salt bridges

B) hydrophobic bonds

C) disulfide bonds

D) peptide bonds

E) All of the above

D. peptide bonds

83. Which of the following amino acids possesses a phenolic hydroxyl group?

A) serine

B) threonine

C) tyrosine

D) A and B

E) All of the above

C. tyrosine

84. The isoelectric pH is the pH midway between pK values on either side of the isoelectric process. Which of the following equations gives an accurate estimate of iPH?

A) pI = pK1 + pK2

B) pI = (pK1 + pK2)/2

C) pI = (pK1 + pK2) x 2

D) pI = pK1 > pK2

B. pI = (pK1 + pK2)/2

85. Using the equation of pI, calculate the pI (isoelectric pH) of alanine. pK1 (R-COOH) = 2.35; pK2 (R-NH3+) = 9.69.

A) 6.02

B) 12.04

C) 24.08

D) 5.0

A. 6.02

86. Thyroxine, which is chemically 3,5,3'5'-tetraiodothyronine, is used as a precursor for thyroid hormones. What type of biopolymer is thyroxine?

A) carbohydrate

B) lipid

C) protein

D) nucleic acid

C. protein

87. Peptide bond, a type of amide bond, binds the amino terminal of one amino acid to the carboxyl end of another. What type of process is involved in the formation of peptide bonds?

A) oxidation

B) hydration

C) reduction

D) dehydration

D. dehydration

88. Which of the following statements is correct?

A) The C-N bond in the peptide linkage has a partial double bond property that makes it rigid.

B) Neither the C=O nor the N-H in the peptide bond can dissociate.

C) Each amino acid in a polypeptide chain is called a residue.

D) All of the above.

D. all of the above

89. This structure of peptides refers to the order of amino acids in the polypeptide chain/s and the location of the disulfide bonds.

A) primary

B) secondary

C) tertiary

D) quaternary

A. primary

90. This refers to the spatial arrangements of amino acid residues close to one another in the linear sequence of a polypeptide chain.

A) primary

B) secondary

C) tertiary

D) quaternary

B. secondary

91. The overall arrangement and interrelationship of various regions or domains, and individual amino acid residues of a single polypeptide chain is ______.

A) primary

B) secondary

C) tertiary

D) quaternary

C. tertiary

92. Alpha-helix and beta-pleated sheets belong to what structure?

A) primary

B) secondary

C) tertiary

D) quaternary

B. secondary

93. Random coils and triple helices are examples to what protein structure?

A) primary

B) secondary

C) tertiary

D) quaternary

B. secondary

94. Fibrous and globular proteins belong to what protein structure?

A) primary

B) secondary

C) tertiary

D) quaternary

C. tertiary

95. The arrangement of polypeptide chains in relation to one another in a multi-chained protein refers to what structure?

A) primary

B) secondary

C) tertiary

D) quaternary

D. quaternary

96. What do you call the principal method for determining the primary structure of polypeptides? For its initial step, it utilizes phenylisocyanate, which combines with the terminal amino acid of the polypeptide.

A) Grignard

B) Edman

C) Molisch

D) Zollinger

B. Edman

97. Which of the following bonds are found in the quaternary structure of polypeptides?

1. Hydrogen, 2. Electrostatic, 3. Hydrophobic, 4. Covalent

A) 3 only

B) 1 only

C) 1-3

D) all of the above

C. 1-3

98. Denaturation is a randomization of the conformation of a polypeptide chain. Chemical agents like strong acids or bases, heat, detergents, etc. are involved in this process. Which of the following structure remain unaffected with denaturation?

1. Primary, 2. Secondary, 3. Tertiary, 4. Quaternary

A) 1 only

B) 1 and 2

C) 1-3 only

D) 1-4

A. 1 only

99. Which of the following statements is true?

A) Fibrous proteins are water-insoluble

B) Globular proteins are water-soluble

C) Proteins lose their biologic activity after denaturation.

D) Denaturation of proteins is sometimes irreversible.

E) All of the above.

E. AotA

100. Which of the following is/are example(s) of essential amino acids?

A) tyrosine

B) threonine

C) tryptophan

D) A and B

E) B and C

E. B and C