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What charge does a phosphate group have a neutral pH?
Negatively charged
Where is the phosphate group attached to a nucleotide?
Attached to C5' position on the ribose (pentose) ring
How many phosphate groups do nuleic acids contain?
Nucleic acids contain one phosphate group per nucleotids
What is Pentose?
A five-carbon sugar
What is deoxyribose?
A pentose molecule with no O atom on carbon 2'
Why are carbon atoms in pentose numbered with primes?
Has carbon atoms numbered with primes to distinguish them from the atoms in nitrogen bases
What are nucleobases?
Derivatives of pyrimidine or purine
Are nucleo bases planar?
yes, they are planar or almost planar structures
What kind of light do nucleobases absorb?
Absorb UV light around 250-270nm
What is the general structure of a nucleobase?
Nitrogen-containing heteroaromatic molecules
In all nucleotides, where is the phosphate group located?
At the 5' position
What is the backbone of DNA/RNA made of?
Alternating phosphate and sugar groups
As a rule, how are DNA/RNA polymers written?
From 5' to 3'
How are nucleosides in DNA/RNA polymers linked?
By a phospho-diester linkage
Which end of the DNA/RNA poymers are phosphorylated?
5'
What are DNA/RNA polymers less than 50 nucleotides refered to as?
Oligonucleotides
What are DNA/RNA polymers sensitive to?
Alkaline hydrolysis
Which is more sensitive to Alkaline hydrolysis, DNA or RNA?
RNA, due to 2' OH
What do phosphodiester bonds do in DNA?
Link successive nucleotide units
Why are nucleic acids highly polar?
The backbone of alternating pentose and phosphate groups
Why are the ends named 5' and 3'?
The 5' and of the macromolecule lacks a nucleotide at the 5' position and the 3' end lacks a nucleotide at the 3' position
What happens in RNA hydrolysis under Alkaline conditions?
The 2' hydroxul acts as a nucleophile in an intamolecular displacement.
The 2',3'- cyclic monophosphate derivative is further hydrolyzed to a mizture of 2'- and 3'-monophosphates
Why is DNA stable under Alkaline conditions?
It lacks 2' hydroxyls
What do nucleic acid polymers do?
Mediate the storage and transfer of genetic material
What are the 3 'game-changer' experiments?
Griffit- 'Transforming Principle'- 1928
Avery-McLaeod-McCarty- 'DNA fractions'-1943
Hershey and Chase- Bacteriophage- 1952
Who discovered the 'transforming principle'?
Griffith
What was the conclusion of the 'Transforming Principle' experiment?
A transforming material (unlikely proteins) crossed from the heat ikilled virulent S strain to the non-virulent R live strain
What was the conclusion of Aver-McLaeod-McCarty expriment?
The transforming factor is DNA
What is the conclusion of the Hershey and Chase experiment?
The injected material from the Bacteriophage was
32
P labeled. Consequently, DNA is responsible for the storage and transferred of genetic material
Who discovered the double helix?
James Watson and Francis Crick
What was the key to the discoverey of the double helix?
Recognition of base pairing
What is Chargaff's rule?
The percentge of G+Cs and A+Ts were equal
A+G=T+C
How are base pairs joined?
Hydrogen bonds
Is the double helix right-handed or left-handed?
Right-handed
What points towards the outside of the double helix?
phosphate groups
What is the width of the double helix?
2.0nm (20A)
How far apart are the bases along the helix axis?
0.34 nm (3.4A)
How long is the pitch of the helix?
3.6nm (36A)
How many nucleotides per turn of the helix?
10.4
What is 'Central Dogma'?
refers to the flow of information from genes to proteins
What is the first step in the 'Central Dogma'?
DNA replication
What were the postulated methods of DNA replication?
Semi-conservative
Conservative
Dispersive
What was the conclusion of the Meselson-Stahl experiment (1957)?
Experimental evidence confirmed that DNA replication is Semi-conservative
Is DNA bidirectional?
yes
What does DNA polymerase do?
Catalyze the stepwise addition of deoxyribonucleotides (5'-3')
What are the characteristics of DNA Polymerase I?
It has 5'-3' polymerase activity
It has 3'-5' exonuclease activity (proof reading)
It has 5'-3' exonuclease activity (removes added primers)
Requires a DNA template
It is moderately processive (dissociates after adding 20 dNTPs)
All three activites on a single polypeptide
What are the characteristics of DNA polymerase II?
It has 5'-3' polymerase activity
It has 3'-5' exonuclease activity (proof reading)
Does NOT 5'-3' exonuclease activity
Requires DNA template
It is highly processice (synthesizes 1000 dNTPs/second)
It is made up of 10 subunits
Which enzyme is responsible for the unwinding of the DNA double helix?
DNA helicase
What is used to keep the DNA strands separate?
Single Strand Binding proteins
What releases the stress of the DNA unwinding through transient DNA cut and ligation?
Topoisomerase
Which enzyme does not require a free 3'OH group to add compimerntary base pairs?
Primase
What are Okazaki fragments?
Short DNA fragments compimentary to the lagging strang sequence
How is the RNA primer removed?
Removed by 5'-3' exonuclease activity of DNA Polymerase I
What enzyme joins the DNA fragments on the lagging strand?
DNA Ligase
How can DNA be denatured?
Changes to pH or temperature?
Author
Morgan.liberatore
ID
119585
Card Set
Biochem 3
Description
Biochem 3- Nucleic Acids
Updated
12/2/2011, 11:48:27 PM
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