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Biochemistry > Nucleic Acids And Nucleotides > Flashcards

Nucleic Acids And Nucleotides Flashcards

1
Q

1.Sugar derivative of nucleotide that participates in the synthesis of glycogen?

  1. A lipid derivative of nucleotide that participates in lipid biosynthesis?
  2. Name 2 nucleotides as second messengers for hormonal actions?
  3. Which nucleotide donates sulfate and which gives methyl groups in biological reactions?
  4. Which nucleotides are involved in signal transduction pathways?
A
  1. UDP-glucose
  2. CDP-acylglycerol
  3. cAMP & cGMP
  4. Sulfate—- Phosphoadenosinephosphosulfate (PAPS)
    Methyl groups—-S-adenosylmethionine (SAM)
  5. GTP & GDP
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2
Q
  1. What type of compounds are the nitrogenous bases?
  2. How many types of bases? How are they numbered?
  3. Name the bases?
  4. Difference between thymine & uracil?
A
  1. Heterocyclic aromatic
  2. Purines (double ring)—-anticlockwise
    Pyrimindines (single ring)—–clockwise
  3. Purines
    Adenine
    Guanine
    Pyrimidine
    Cytosine
    Thymine (DNA)
    Uracil (RNA)
  4. Methyl group in thymine
    Absent in uracil
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3
Q
  1. What is tautomerism of nitrogenous bases?
  2. Which nitrogenous form does not exhibit tautomerism?
A
  1. Existence in Keto (lactam)
    & enol (lactim) form is known as tautomerism
  2. A purine — adenine
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4
Q
  1. free state bases as intermediates in purine synthesis?
  2. free state bases as end product in purine degradation?
    These are?
  3. What types of bases are present in plants?
A
  1. Hypoxanthine & Xanthine
  2. Uric acid
    (All above 3 are purines)
  3. Methylated purines
    Caffeine—-coffee
    Theophylline—tea
    Theobromine—-cocoa
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5
Q
  1. Pentoses are bound to nitrogenous base by?
    In case of purine The bond is formed between?
    And the bond formed is?
  2. In case of pyrimidine
    The glycosidic linkage is between?
  3. Hydroxyl group of adenosine is esterified ?
  4. The anionic properties of nucleotides are due to?
A
  1. B-N-glycosidic bonds
    N9—-Purine ring
    C1—-pentose sugar
    (N9—–C1)
    —covalent bond
  2. N1—-Pyrimidine ring
    C1—-pentose sugar
  3. With phosphates to produce:
    5’ (more common)
    3’
    Monophosphates
  4. Negative charges contributed by phosphate groups
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6
Q

Synthetic analogues of nucleotides that are used for the treatement of:
1. Cancer by interefering with DNA replication
2. Neurological disease?
3. Used to suppress immunological rejection during transplantation?
4. Gout & hyperurecima (high uric acid in blood)?
5. AIDs?

A
  1. Arabinosylcytosine
  2. Arabinosyladenosine—-viral encephalitis (swollen brain)
  3. Azathioprine(gets degraded to 6-mercaptopurine)
  4. Allopurinol
  5. Zidovudine (AZT) &
    Didanosine
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7
Q

1.The monomeric deoxynucleotides in DNA are held together by?

  1. What is chargaffs’s rule?
  2. Chargaffs rule is not obeyed by?
A
  1. 3’-5’ phosphodiester bridges
  2. Molar equivalence between purines & pyrimidines
    A=T (2hydrogen bonds)
    G=C (3 hydrogen bonds)
  3. RNA & single stranded DNA
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8
Q
  1. Width/diameter of double helix?
  2. Each turn is ____ A°? With ____pairs of nucleotides at a distance of____?
  3. What is a template strand?
  4. What are the major (wide) and minor (narrow) grooves along the phosphodiester backbone for?
A
  1. 20 A° (2nm)
  2. 34 A° (3.4nm)
    10 base pairs
    3.4 A°
  3. Genetic information resides on one of the 2 strands—-template strand/sense strand
    The opposite strand —- antisense strand
  4. Proteins interact with DNA at these grooves
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9
Q
  1. The double helical structure of DNA exists in how many form?
  2. Which one is proposed by watson & crick?
  3. Which sided are B A Z?
  4. Circular DNA is present in?
  5. The length of DNA in base pair & contour length of diploid human cell?
A
  1. 6
    A
    B
    C
    D
    E
    Z
  2. B
  3. B—- right handed—-10 base pairs
    A—- right handed—-11 base pairs
    Z—- left handed—-12 base pairs
  4. Bacteria
    Extrachromosomal DNA of plasmids
    Mitochondria
    Choloroplast
  5. Bp = 6×10^9
    Contour length= 2 meters
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10
Q
  1. DNA lengths in smallest & the largest chromosome?
  2. Denaturation of DNA effects _____ bonds only?
  3. Loss of helical structure can be measured by.
  4. What is hyperchromicity?
  5. What is melting temperature?
  6. What decreases the melting temperature, destabilizing hydrogen bonds?
A

Smallest—-34Mb
Largest—-263Mb

  1. Hydrogen bonds
  2. Increase in absorbance at 260 nm (spectrophotometer)
  3. Increase in absorbance of purines & pyrimidines following denaturation
  4. At which half of helical DNA is lost
  5. Formamide
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11
Q
  1. What is nucleoid? How does it differ from nucleus?
  2. What is plasmid?
  3. Histone is acidic or basic?
  4. The core has how many histone molecules? And how many turns of DNA around each histone and called what?
  5. Basic unit of chromatin?
A
  1. The nucleoid is a region within prokaryotic cells where the genetic material, such as the DNA, is located. It’s like the “command center” of the cell where the genetic instructions are stored.
    (Like nucleus in Eukaryotes but nucleoid doesnot have a membrane)
  2. Plasmids are small, circular DNA molecules that are separate from the chromosomal DNA in bacteria
  3. Basic in nature
  4. Core—-2 molecules of histones
    H2A
    H2B
    H3
    H4
    -2 turns of DNA and is called nucleosome
  5. Nucleosome
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12
Q
  1. Nucleosomes are separated by?
  2. Beads on a string is termed as? And further gives what structure?
  3. How many histones in every turn of 30nm fibre?
A
  1. Spacer DNA to which H1 proteins are attached?
  2. 10nm fibre
    ——gives 30nm fibre
    (Solenoid structure)
  3. 6 histones
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13
Q
  1. Why RNA is susceptible to alkali hydrolysis and DNA is not?
    WhAt is the product formed?
  2. RNA can be identified by?
A
  1. Bcz RNA—-hydroxyl group at 2’ position but DNA doesn’t
    - 2’,3’ cyclic diesters
  2. Orcinol colour reaction
    Due to ribose
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14
Q

1.Types of RNA & their cellular composition?

  1. Where is mRNA synthesized and as what?
  2. The mRNA is capped at which end and tail is at which end?
  3. What is the function of cap & tail?
  4. How many specie of tRNA?
A
  1. Messenger RNA—-5-10%
    Transfer RNA—-10-20%
    Ribosomal RNA—-50-80%
  2. In the nucleus as heterogenous nuclear RNA
  3. Capped at—–5’-terminal end (by 7-methylguanosinetriphosphate)
    Tail at—–3’-terminal end (a polymer of adenylateresidues called as poly A tail)
  4. Cap—- recognition of mRNA for protein synthesis
    - prevent hydrolyses by 5’ exo-nucleases

Tail—- stabilize mRNA
- prevent hydrolyses by 3’ exo-nucleases

  1. 20 species for 20 amino acids
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15
Q
  1. Structure of which RNA resembles a clover leaf?
  2. What are the arms of clover leaf?
  3. Base pair in tRNA?
  4. Which RNAs inhibit gene expression and what is their target?
  5. Which catalytic RNA cleaves precursors of tRNA to generate mature tRNA?
A
  1. tRNA
  2. The acceptor arm
    - capped with CCA(5’—3’)
    - amino acid attaches at 3’

The anticodon arm
- 3 nucleotide bases (anticodon)
- recognize triplet codon of mRNA

The D-arm
- dihydrouridine present

The T¥C arm
- sequence of
T + pseudouridine +C

The variable arm
2 types
• (class I tRNAs):
–75%
–3-5 basepair length
• (class II tRNAs):
–13-20 basepair length

  1. The acceptor arm - 7bp
    The T¥C arm - 5bp
    The anticodon arm - 5bp
    The D arm - 4bp
  2. MicroRNAs (miRNA) & SilencingRNAs (siRNA)
    -form RNA-RNA hybrids with target:
    mRNA
  3. Ribonuclease P
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16
Q
  1. What are the catalytic RNAs or non-protein catalysts?
  2. Nucleic acid analogues are also called?
  3. Examples of artificial nucleic acids?
  4. What are the 2 major nucleoprotein complexes that eukaryotic ribosomes are composed of?
  5. Which is the soluble RNA? And how many nucleotides in its molecules?
    What is its weight?
A
  1. Ribozymes
  2. Xenoz nucleic acids (XNA)
  3. Peptide nucleic acid (PNA)
    Glucol nucleic acid (GNA)
    Threose nucleic acid (TNA)
    (PNA & GNA—- investigate origin of life)
  4. 60-S subunit
    Contains:
    28S RNA
    5S RNA
    5.8S RNA
    40-S subunit
    18S RNA
  5. tRNA
    -71-80 (mostly 75) nucleotides
    - weight= 25,000
17
Q
  1. Which antitumor drug can produce bent DNA structure and damage it?
  2. Precursor for mRNA?
  3. Which RNA is mostly present in bacteria and adds peptide tags to protein for degradation?
  4. Ribozyme for
    DNA cleavage
    RNA splicing?
    Peptide bond formation in protein biosynthesis?
  5. Which RNA specifies the sequence of amino acid in protein synthesis?
A
  1. Cisplastin
  2. Heterogenous nuclear RNA
  3. Transfer-messenger RNA
  4. DNA—self-splicing RNA
    RNA—RNAs of splicesome
    Peptide bond—rRNA
  5. mRNA
18
Q
  1. Nucleic acid synthesis is reduced by deficiency of which vitamin?
  2. How many nitrogens and carbons in purines & pyrimidine.
A
  1. Folic acid
  2. Purine
    N—-4
    C—-5
    Pyrimidine
    N—-2
    C—–4

Biochemistry (11 decks)

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