DNA and Biotechnology Flashcards
(37 cards)
Describe a nucleoside
Composed of a five carbon sugar bonded to a nitrogenous base and are formed by covalently linking the base to C-1’ of the sugar
Describe nucleotides
When one or more phosphate groups are attached to C-5’ of a nucleoside.
Why are nucleotides such ATP and ADP high energy compounds?
This is because of the energy associated with the repulsion between closely associated negative charges on the phosphate groups,
In what way is ATP formation an exception to a chemical rule?
Usually bond breaking is exothermic while bond making is usually endothermic
In ATP, due to all the negative charges in close proximity, removing the terminal phosphate from ATP actually release energy, which powers our cells
Differentiate the sugars in RNA and DNA
DNA- deoxyribose
RNA- ribose
Name the nucleoside and the nucleotides of the base, Adenine
Nucleoside- Adenosine (Deoxyadenosine)
Nucleosides- AMP( dAMP), ADP(dADP) , ATP(dATP)
Name the nucleoside and nucleotides of the base, Guanine
Nucleoside -Guanosine( deoxygysnosine)
Nucleotides- GMP( dGMP), GDP(dGDP) , GTP(dGTP)
What is the name of the nucleoside and nucleotides of the base, Cytosine?
Nucleoside- Cytidine (Deoxycytidine)
Nucleosides- CMP(dCMP), CDP(dCDP), CTP(dCTP)
What are the names of the nucleoside and nucleotides of the bases, uracil?
Nucleoside- Uridine(deoxyuridine)
Nucleotides - UMP( dUMP), UDP(dUDP), UTP(dUTP)
What are the nucleoside and nucleotides of the base, thymine?
Nucleoside- Deoxythimidine
Nucleotides- dTMP, dTDP, dTTP
What is the sugar phosphate backbone comprised of?
Nucleotides are joined by 3’-5’ phosphodiester bonds
Thus joins alternating sugars and phosphate groups
Why does DNA and RNA have an overall negative charge?
Phosphates of the sugar-phosphate backbone carry a negative charge
What is the function of the sugar-phosphate backbone?
Determines the directionality of the DNA and is always read from 5’ to 3’
What are purines? Give the 2 examples.
Purines contain two rings in the structure
Adenine and Guanine
How can DNA be written ?
5’— ATG—3’(or simply ATG, this is how DNA is read)
If written backwards- 3’—GTA—5’
The position of the phosphates may be shown pApTpG
The “d” may be used for deoxyribose : dAdTdG
What are Pyrimidines? Give the 3 examples
Three ring structures
Cytosine, thymine, uracil
Purines and pyrimidines are aromatic heterocyclic. What are the four specific rules of being aromatic ?
The compound is cyclic
The compound is planar
The compound is conjugated (has alternating single and multiple bonds, or lone pairs, creating atleast one unhybridized p-orbital for each atom in the ring)
The compound has 4n+2 (where n is any integer) pi electrons. This is Hückel’s rule
Why does benzene specifically, have the delocalization characteristic of aromatic compounds?
Carbon atoms in benzene are sp2 hybridized and each orbital overlaps equally with its two neighbors
This causes delocalised electrons to form to pi electron clouds, one above and below the plane of the ring
Why are aromatic molecules fairly unreactive?
The delocalisation of pi electrons of all aromatic rings
What are heterocyclic?
Structures that contain atleast two different structures in the ring
What are the key features of the Watson-Crick Model?
- The two DNA strands are anti parallel
- the sugar phosphate backbone is on the outside of the helix with the nitrogenous bases on the inside
- Complementary base pairing rules, the hydrogen bonds, hydrophobic interactions between bases, provides stability to the double helix structure
- Properties of Chargaff’s rules state that since the amount of A = the amount of T and amount of C= Amount of G, the number of purines = number of pyrimidines
What is B-DNA?
When the double helix DNA is a right-handed helix(most DNA)
Describe the turn and residues of B-DNA
B-DNA makes a turn every 3.4 Na and contains about 10 bases with that span
What are major and minor grooves in B-DNA?
They can be identified between interlocking strands and are often the site of protein building
