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2C MIDTERMS > BIOCHEM NUCLEOTIDES > Flashcards

BIOCHEM NUCLEOTIDES Flashcards

1
Q

are building blocks of
nucleic acids (DNA & RNA) and are
essential for several biological functions

A

Nucleotides

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2
Q

metabolic functions of Nucleotides

A
  • Energy metabolism (ATP)
  • Protein synthesis
  • Regulation of enzyme activity
  • Signal transduction (cAMP, cGMP)
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3
Q

also form
parts of coenzymes
and are intermediates
in metabolic pathways
such as sugar and lipid
synthesis.

A

Nucleotides

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4
Q

Structural Components of Nucleotides

A

Nitrogenous base, Pentose sugar, * Phosphate group

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5
Q
  • Ribose (RNA)
  • Deoxyribose (DNA)
A

Pentose sugar

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6
Q
  • Purines: Adenine (A), Guanine (G)
  • Pyrimidines: Cytosine (C), Thymine (T), Uracil (U)
A

Nitrogenous base

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7
Q

Double-ring
structure (e.g., Adenine,
Guanine)

A

Purines

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8
Q

Single-ring
structure (e.g., Cytosine,
Thymine, Uracil).

A

Pyrimidines

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9
Q

Purines and pyrimidines
exist primarily in ____ and
_________ tautomeric forms,
crucial for the integrity of
base pairing.

A

oxo, amino

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10
Q

Nucleosides are named
based on the ____________________

A

nitrogenous base

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11
Q

Nucleosides Consist of a ______
attached to a _______________ via an ______________________

A

base (purine/pyrimidine), sugar (ribose
or deoxyribose), N- glycosidic bond.

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12
Q

are named based
on the nucleoside and the
number of phosphate groups

A

Nucleotides

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13
Q

Nucleosides phosphorylated
at the _________ position of the
sugar, forming structures

A

3’ or 5’

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14
Q

a critical
nucleotide, consists of
adenine, ribose, and
three phosphate
groups

A

ATP

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15
Q

predominant form under physiological conditions

A

Anti Conformations

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16
Q

Nucleotides exhibit restricted rotation
around the glycosidic bond due to steric
hindrance, existing as ____ and ______
conformers,

A

syn, anti

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17
Q

Nucleotides are linked by ________ phosphodiester
bonds forming the backbone of DNA/RNA.

A

3’→5’

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18
Q

5’ and 3’ ends give the molecules _________, and
sequences are _______ from 5’ to 3’

A

direction, written

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19
Q

*DNA is more stable than RNA due to
the absence of a _______________ group,
reducing its susceptibility to hydrolysis

A

2’ hydroxyl

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20
Q

RNA and DNA modifications are important in
____________________ and __________________.

A

gene regulation, mRNA stability

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21
Q

is the main energy
currency in cells,

A

ATP

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22
Q

is crucial in protein
synthesis and signal transduction

A

GTP

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23
Q

ATP’s high energy comes from its two anhydride bonds, with hydrolysis releasing around ________

A

-30 kJ/mol

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24
Q

Serve as second messengers in cellular signaling pathways.

A

cAMP and cGMP

25
Q

mediates hormonal responses,

A

cAMP

26
Q

is
involved in processes like smooth muscle relaxation

A

cGMP

27
Q

ATP is __________ (~1 mmol/L), while cAMP is much _________ (~1 nmol/L), reflecting their distinct roles.

A

abundant, lower

28
Q

Many coenzymes, such as NAD, FAD, and
Coenzyme A, contain _____________________,
enabling them to participate in redox reactions
and metabolic pathways.

A

nucleotides (AMP)

29
Q

Acts as a methyl donor in numerous biochemical
reactions, essential for methylation processes.

A

S-Adenosylmethionine

30
Q

Anticancer Agents example

A

5-fluorouracil, 6- thioguanine

31
Q

Synthetic analogs like 5-fluorouracil and 6-
thioguanine disrupt ______ synthesis or
function by inhibiting _________ or
incorporating into nucleic acids.

A

DNA, enzymes

32
Q

These drugs are used to treat cancer,
suppress immune responses in organ
transplants, or treat viral infections (e.g.,
AZT for HIV)

A

Anticancer Agents

33
Q

__________________________ of nucleoside
triphosphates help distinguish the effects
of nucleotide binding from phosphoryl
transfer, valuable in studying enzyme
mechanisms.

A

Non-hydrolyzable analogs

34
Q

are synthesized de novo from amphibolic intermediates in human tissues, making them
dietarily nonessential

A

Purines and Pyrimidines

35
Q

Humans synthesize purines de novo, mainly
starting from _______________ and ______,
producing ________________________
through a series of regulated steps

A

ribose-5-phosphate, ATP, inosine monophosphate (IMP)

36
Q

IMP produces

A

AMP and GMP

37
Q

Phosphoryl transfer from ATP = ______ → _______

A

GDP, GTP

38
Q

Oxidative phosphorylation = ADP → _____

A

ATP

39
Q

PRPP (Phosphoribosyl pyrophosphate) is crucial, and its synthesis is regulated by ______________________ by AMP, ADP, GMP, and GDP

A

feedback inhibition

40
Q

Anticancer drugs, like methotrexate and 6-
mercaptopurine, inhibit steps in purine biosynthesis by blocking _________ or ________________

A

folate, glutamine analogs

41
Q

Purines can also be recycled through salvage pathways, converting bases to ___________ using _________

A

nucleotides, PRPP

42
Q

Phosphorylation of purine nucleotides is
catalyzed by ______________

A

adenosine kinase

43
Q

Pyrimidines, like ______________________
are also synthesized de novo.

A

uracil and cytosine,

44
Q

Unlike purines, PRPP is used only after
the _________________ is synthesized

A

pyrimidine ring

45
Q

The enzyme __________UTP controls early pyrimidine
biosynthesis.

A

CAD

46
Q

CAD is regulated at both transcriptional and
enzymatic levels, activated by ______ and inhibited
by _______

A

PRPP, UTP

47
Q

Pyrimidines are also recycled, but their catabolites are ______________________, making overproduction clinically insignificant.

A

highly water-soluble

48
Q

Purines are catabolized to _______.

A

uric acid

49
Q

Disorders in purine catabolism, like ______ (due to excess uric acid), result in inflammatory conditions

A

gout

50
Q

deposition of urate crystals occur in _______ and _______

A

tissues, joints

51
Q

defect in the HGPRT
(hypoxanthine-guanine phosphoribosyl transferase) enzyme

A

Lesch-Nyhan syndrome

52
Q
  • deficiencies in enzymes of pyrimidine biosynthesis
  • megaloblastic anemia and developmental delays
A

Orotic aciduria

53
Q
  • severe immunodeficiency caused by
A

Adenosine deaminase deficiency

54
Q
  • Impairs T-cell function caused by
A

purine nucleoside phosphorylase deficiency

55
Q

Pyrimidine catabolism produces ________, _____, and __________, which are water-soluble and excreted without issues

A

β-alanine,CO2, ammonia

56
Q

Disorders such as ____________________ arise
from deficiencies in dihydropyrimidine
dehydrogenase, leading to neurological
complications

A

β-hydroxybutyric aciduria

57
Q

Coordinated regulation between _______
and _____________ metabolism ensures
balance for nucleic acid biosynthesis

A

purine, pyrimidine

58
Q

Anticancer drugs (e.g., 5-fluorouracil,
methotrexate) exploit the______________ of purine synthesis, slowing cell division

A

folate dependence

2C MIDTERMS (14 decks)

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