2.6 Structure of DNA and RNA Flashcards
Describe the structure of a single nucleotide.
Phosphate group bonded to a deoxyribose sugar which is binded to a base.
Describe the phosphate, sugar, and base of nucelotides.
Phosphate: acidic, negatively charged part of nucleic acid
Sugar: 5-carbon sugar
Base: Contains nitrogen and either has one or two rings of atoms
What kind of bonds are formed between nucleotides?
To chain nucleotides together, covalent bonds are formed between the phosphate of one nucleotide and the C3 of the pentose sugar of the next nucleotide.
What is the key factor to nucleic acids acting as a store of genetic information?
The four different nucleotides, as determined by the base, can be linked together in any sequence because the phosphate and the sugar used to link them is the same in every nucleotide.
Differentiate between DNA and RNA.
- The sugar in DNA is deoxyribose (containing one fewer oxygen) and is ribose in RNA.
- There are usually two polymers, or strands, of nucleotides in DNA but only one in RNA; viz. DNA is double-stranded while RNA is single-stranded.
- The four bases in DNA are adenine, cytosine, guanine, and thymine. In RNA, they are adenine, cytosine, guanine, and uracil.
How are the phosphate groups, sugars, and bases drawn in nucleotides?
Phosphate: circle.
Sugar: For pentose, a pentagon. For hexose, a hexagon.
Base: Rectangle
What holds the two strands of DNA together?
Hydrogen bonds between the bases.
Describe the structure of DNA.
DNA is a double helix made of two antiparallel strands of nucleotides linked by hydrogen bonding between complementary base pairs.
What is meant by antiparallel strands?
They run parallel but in opposite directions such that one is oriented in the direction of 5’ to 3’ while the other is oriented 3’ to 5’.
What are the two complementary base pairs in DNA?
Adenine (A)—-Thymine (T)
Guanine (G)—-Cytosine (C)
