DNA Flashcards
Nucleoside
Pentose sugar bonded to a nitrogenous base at C1
Nucleotide
One or more phosphate groups attached to the C5 of the pentose sugar of the nucleoside
Difference between ribose and deoxyribose
Ribose is a 5 atom ring with four C and O at the top.
-CH2-OH is bound to C4 and -OH bound to C2 and C3
Deoxyribose is the same without the -OH on C2
Does breaking bonds between phosphate groups in ATP release or require energy?
Releases energy (exothermic) due to negative charges in close proximity
Is T found in DNA or RNA?
DNA
Is U found in DNA or RNA?
RNA
Are DNA and RNA positively or negatively charged and why?
Negative - phosphate groups
What direction is DNA read?
5’ to 3’
How is the backbone of DNA created?
Phosphate group links the 3’ C of one ribose to the 5’ of the next
What is found on the 3’ end of DNA?
-OH on C3
What is found on the 5’ end of DNA?
-OH or phosphate group attached to C5
What direction is DNA written?
5’ to 3’
How many rings do purines have?
Two
Which bases are purines?
A and G
How many rings do pyrimidines have?
Three
Which bases are pyrimidines?
C, T, U
Huckel’s rule
Aromatic compounds have 4n+2 pi electrons
Antiparallel
Two strands of DNA are oriented in opposite directions
How many bonds exist between A and T?
Two
How many bonds exist between C and G?
Three
Chargaff’s rules
Same amount of purines and pyrimidines in a DNA strand due to complementary base pairing
B-DNA
Right-handed helix with a turn every 10bp and 3.4 nm
Z-DNA
Left-handed helix with a turn every 12 bp and 4.6 nm
Replisome is also known as
Replication complex
Replication complex is also known as
Replisome
Replisome / replication complex
Set of specialized proteins that assist the DNA polymerases
How does the number of origins of replication distinguish between eukaryotes and prokaryotes?
Prokaryotes have one, eukaryotes have MANY
Helicase
Enzyme responsible for unwinding the DNA ahead of DNA polymerase
Single-stranded binding proteins
Bind to the unraveled strand to prevent reassociation of the DNA and prevent degradation by nucleases
Topoisomerases
Relieve stress from supercoiling by nicking the strands and then sealing them
Semiconservative
In each new DNA strand, one strand is parent and one is daughter DNA
DNA polymerase
Reads the parent DNA strand and synthesizes new daughter strand
In what direction does DNA polymerase read and create new DNA strands?
Reads the parent 3’ to 5’ and creates the new strand 5’ to 3’
Does the leading or lagging strand have more RNA primers?
Lagging
Okazaki fragments
Small strands produced on the lagging strand due to uni-directionality of DNA polymerase
Is DNA polymerase III found in eukaryotes or prokaryotes?
Pro
Do prokaryotic cells have telomeres?
No
Do eukaryotic cells have telomeres?
Yes
