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Biochemistry-Nucleic acids > Introduction to Nucleic Acids > Flashcards

Introduction to Nucleic Acids Flashcards

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1
Q

T or F: Information encoded in a DNA molecule is transcribed via
synthesis of an RNA molecule

A

True

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2
Q

T or F: The sequence of the RNA molecule is “read” and is translated into
the sequence of amino acids in a protein

A

True

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3
Q

The Central Dogma

A

a theory stating that genetic information flows only in one direction, from DNA, to RNA, to protein, or RNA directly to protein. Includes
Replication
Transcription
Translation

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4
Q
  1. Replication
A

Dna replication yields 2 molecules identical to the O.G one , ensuring transmission of genetic info. to daughter cells

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5
Q
  1. Transcription
A

It uses DNA as a template to make an RNA (mRNA) molecule. During transcription, a strand of mRNA is made that is complementary to a strand of DNA.Jul

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6
Q
  1. Translation
A

3-base codons on the mRNA corresponds to specific amino acids direct sequence of building a protein. Codons are recognized by tRNAs (transfer RNAs) carrying appropriate amino acids. Ribosomes are the “machinery” for protein synthesis

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7
Q

DNA stands for

A

Deoxyribonucleic Acid

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8
Q

RNA stands for

A

Ribonucleic acid

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9
Q

Nucleotides are composed of 3 things..

A

-A pentose sugar (Ribose or Deoxyribose)
-A nitrogenous base
-one phosphate group

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10
Q

Nucleosides are composed of

A

-Sugar and Base only

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11
Q

Pyrimidines include:

A
  1. Cytosine (C)
  2. Uracil (U) – RNA only
  3. Thymine (T) – DNA only
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12
Q

Pyrimidines form bonds to a…

A

5-C sugar via their N1 atoms

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13
Q

Purines include:

A
  1. Adenine (A)
  2. Guanine (G)
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14
Q

Purines form bonds to a

A

5-C sugar via their N9 atoms

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15
Q

The aromaticity and electron-rich nature of pyrimidines and purines enable them to
undergo

A

Keto-enol tautomerism

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16
Q

Tautomers

A

are isomers (constitutional isomers) of organic compounds that readily
interconvert by a chemical reaction called tautomerization

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17
Q

T or F:Protonation states of the nitrogens determines whether they can serve as H-bond donors or acceptors

A

True

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18
Q

T or F: Aromaticity also doesnt account for strong absorption of UV light

A

true

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19
Q

Primed numbers, indicate

A

Atoms in sugar

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20
Q

Non-primed numbers, indicate

A

atoms in base

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21
Q

phosphate group may be attached to the sugar at either of two positions

A
  • if at C3’, it is called a 3’ nucleotide
  • if at C5’, it is called a 5’ nucleotide
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22
Q

Importance of Nucleotides

A
  1. form polymers-Nucleic Acids
    * Functions are information storage and transfer
    * “Management for genetic information”
  2. Participate in Metabolic Reactions
    * ex: ATP
    * energy carrier/transfer agent
    * provides energy
    * FYI: Humans typically recycle their weight of ATP
    each day
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23
Q

how is the sequence read

A

always read 5’ to 3’

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24
Q

T or F: Phosphates in these polynucleotides are acidic (lose proton easily)

A

true

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25
Polyanions
carry negative charges
26
At physiological pH,nucleic acids are
polyanions
27
pApUpCpG or pAUCG “p” on left side of a nucleotide indicates
5' phosphoryl group
28
If deoxyribose (2'-H) then d(pATCG) "d" designates
Deoxy (slide 21)
29
DNA is Important because:
contains genetic information
30
RNA is important because:
makes protein base on instruction of DNA
31
T or F: If RNA is damaged , it can't be degraded and regenerated
False it can
32
Why does DNA contain Thymine?
Because Cytosine deaminates to form uracil but repair enzymes recognize this as "mutations" and replace the Us w/C's
33
How would the repair enzymes distinguish natural U from mutant U?
Nature solves this by using Thymine (5methyl-u) in place of uracil
34
Why is DNA 2'-deoxy and RNA is not?
-Vicinal OH groups (2' and 3') in RNA make it more susceptible to hydrolysis -DNA lacking 2'OH is more stable Genetic material must be more stable RNA is designed to be used and then broken down
35
Are Nucleic Acids Susceptible to Hydrolysis?
* DNA is not susceptible to base * RNA is hydrolyzed by dilute base
36
Know mechanism of Alkaline Hydrolysis of RNA
Draw it
37
Nucleic Acid Structure: DNA and RNA
DNA- double helix RNA- single stranded can form stem loop structures
38
“Chargaff’s rules”
suggested that A&T bases pair together and that G&C bases pair together
39
Base Pairs
A:T base pair has 2 hydrogen bonds * G:C base pair has 3 hydrogen bonds
40
Base Stacking
van der Waals interactions between adjacent base pairs * G:C-rich regions are more stable
41
Palindromes
A special feature of DNA
42
Why are Palindromes Important?
-Palindromes mark the beginning of a gene -Palindromes mark the end of a gene -Participate in control of gene function -identify break points in DNA sequences (restriction enzymes)
43
Different classes of Nucleic Acids? DNA
one type, one purpose
44
Different classes of Nucleic Acids? RNA
*ribosomal RNA * messenger RNA * transfer RNA
45
1. messenger RNA (mRNA)
carries the message for protein synthesis
46
2.ribosomal RNA (rRNA)
the basis of structure and function of ribosomes in translation of mRNA producing protein
47
3.transfer RNA
carries the amino acids for protein synthesis
48
RNA Structure
* RNA primarily occurs as single strands * Can participate in base-pairing * A:U, G:C * Form stem-loop structures
49
RNA Functions
1. Bacterial Ribosomes 2. Transfer RNA molecules (tRNAs) 3. ribozymes- catalytically active RNA
50
DNA structure
double helix, unique higher order structure that is stable, allows for access during replication and transcription
51
The B-form of the DNA double helix...
the pitch (the distance required to complete one helical turn) is 3.4 nm
52
Histone Proteins
-are proteins -5 major classes 1. H1 2. H2A 3. H2B 4. H3 5. H4 2-5 Amino acid sequence is conserved * Histones are post- translationally modified and these modifications are linked to transcriptional activation or silencing
53
Nucleosomes
"beads on a string" 146 bp DNA- Histone core of nucleosome 55bp DNA - Linker DNA of Nucleosome
54
Chromatin
complex of DNA and proteins that can condense into 30 nm fibers * Two classes of chromatin: (1) Heterochromatin (condensed) and (2) euchromatin (expanded) which functions of chromatin are to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis, and to control gene expression and DNA replication
55
Heterochromatin (condensed)
-acetylation and methylation Heterochromatin is silent for gene expression
56
euchromatin (expanded)
-deacetylation and de methylation is active for gene expression
57
Chromatin state is dictated by histone protein modifications
acetylation and methylation
58
Chromosomes
composed of fibers of condensed chromatin that fold with protein scaffolds to form chromosomes
59
Small nuclear RNAs (snRNA
associate with proteins forming small nuclear ribonucleoprotein particles (snRNPs) and are involved in processing eukaryotic gene transcripts into mature mRNA for transport to cytoplasm (where transcription occurs in nucleus and translation occurs in cytoplasm
60
Regulatory Roles
RNA molecules aid in regulating processes such as gene expression, chromatin organization, and programmed cell death
61

Biochemistry-Nucleic acids (2 decks)

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