Chapter 4 objectives Flashcards
nucleotide
Monomers that consist of a sugar, phosphate group and nitrogenous base to form a nucleic acid.
nitrogenous bases
The nitrogenous base is a nitrogen containing base. The bases in ribonucleotides are:
Cystosine
Guanine
Adenine
Thymine (DNA only)
Uracil (RNA only)
They are grouped in two categories - pyrimidine and purine.
pyrimidine
A structural group of a nitrogenous base. Includes the following molecules:
Cystosine
Thymine (DNA)
Uracil (RNA)
They are the smaller of the two structural groups.
purine
A structural group of the nitrogenous base. Includes the following molecules:
Guanine
Adenine
Purines are larger than pyramidines
Nucleoside
In a nucleic acid - a purine or pyrimidine base covalently linked to a ribose or deoxyribose sugar molecule
What are the three components of a nucleotide?
- A phosphate group
- A sugar
- A nitrogenous base
What is a sugar?
An organic compound with a carbonyl group (>C=O) and several hydroxyl groups (>C=O)
What are the two 5-carbon sugars that contribute to the structure of a nucleotide?
ribose, deoxyribose
Where does the phosphate group attach to the sugar?
The phosphate group in a nucleotide attaches to the 5’ (5 prime) carbon of the sugar.
Ribose
The sugar in the ribonucleotide. Ribose has an Hydroxyl (–OH) group on the 2’ carbon.
(5') ---- CH2 O (N) I / \ I (4') C / \ C (1') I \ H H / H C\ \_\_\_\_\_\_/C (3') I I (2') OH OH
Deoxyribose
The sugar in the deoxyribonucleotide. Deoxyribose has a Hydrogen (H) instead of Hydroxyl (–OH) bonded to the 2’ Carbon. Hint: Deoxy means lacking oxygen.
The sugar in the ribonucleotide. Ribose has an -OH (Hydroxyl) group on the 2’ carbon.
The sugar in the ribonucleotide. Ribose has an Hydroxyl (–OH) group on the 2’ carbon.
(5') ---- CH2 O (N) I / \ I (4') C / \ C (1') I \ H H / H C\ \_\_\_\_\_\_/C (3') I I (2') OH H
What is the 2’ deoxyribose?
Hydrogen
How do nucleotides form nucleic acids?
Through polymerization that involves the formation of a bond between the phosphate group of one nucleotide and the hydroxyl group at the 3’ of the sugar in another nucleotide. This is a condensation reaction that is called phosphodiester linkage.
What is the backbone of a nucleic acid?
Sugar-phosphate form the backbone that is directional in the 5’ –> 3’ direction. One strand of DNA will have an unlinked 5’ carbon (top) and an unlinked 3’ carbon (bottom)
Is polymerization endergonic or exergonic? Why?
The process is endergonic (Nonsponstaneous) due the attached phosphate groups that make the molecules phosphorylated. The phosphates groups raise the potential energy of substrate molecules to make an otherwise energonic reaction possible. These phosphorylated nucleotides are called “activated”