The following reaction is responsible for some types of DNA damage due to sunlight. It represents a dimerization of two DNA base pairs, which blocks DNA transcription and replication. What type of reaction is it? What type of rotation do the atoms undergo? Draw a mechanism and predict the stereochemistry of the product cyclobutane. -NH -NH R-N R-N UV ight R-N R-N -NH -NH
Lipids
The heterogeneous classes of organic compounds that are not water-soluble but are dissolved in organic solvents that are non-polar in nature are termed lipids. They are a long chain of fatty acids and esters of alcohols. Lipids are generally seen in several plants, microorganisms, and animals. They are utilized as insulation, components of the cell membrane, hormones, and molecules for the storage of energy.
Glycerophospholipid
Glycerophospholipid is the most abundantly occuring phospholipids found in the biological membranes. Lipids include a group of organic compounds like fats, hormones, oils, waxes, vitamins etc. They are non-polar molecules and are insoluble in water. Lipids play an important role in biological systems. They are the building blocks of our cell membranes, store energy and are involved in signaling.
Structure Of Camphor
A terpene with the molecular formula of C10H16O is a waxy, white color solid known as camphor. It is flammable. It also possesses a very pungent taste and a strong odor. There are various sources for extracting camphor from natural products such as the wood of the tree of camphor laurel. Sublimation of wood and steam distillation are some of the methods involved in obtaining camphor.
Glycolipid In Organic Chemistry
Glycolipids are lipids that are an important class of organic compounds in chemistry that have simple to complex applications. They contain carbohydrates, fatty acids, sphingolipids or a glycerol group. In other words, they are the modifications of lipids like acylglycerols, prenols and ceramides. They are all part of a wider group of compounds known as glycoconjugates.
Diterpenoid
The terpenoid class includes diterpenoids, which are chemical compounds with 20 carbon atoms. They are made up of four isoprene units and are derived from geranylgeraniol, a C20 precursor. They have a C20H32 basic structure. These characteristics distinguish diterpenoids from simple terpenes, which have just 10 carbon atoms.
![## UV-Induced DNA Damage and Cyclobutane Formation
The following reaction is responsible for some types of DNA damage due to sunlight. It represents a dimerization of two DNA base pairs, which blocks DNA transcription and replication. This particular reaction is an example of a [2+2] cycloaddition reaction. Upon exposure to UV light, two adjacent pyrimidine bases (such as thymine or cytosine) form a cyclobutane pyrimidine dimer (CPD).
### Reaction Overview
**Reactants:**
- Two pyrimidine bases linked to adjacent deoxyribose units in DNA.
**Conditions:**
- UV light exposure.
**Product:**
- Cyclobutane pyrimidine dimer (a four-membered ring comprising the two pyrimidine rings).
### Mechanism and Stereochemistry
The mechanism of this [2+2] cycloaddition involves the excitation of the pyrimidine bases by UV light, leading to the formation of a cyclobutane ring:
1. **Excitation:** UV light excites the π-electrons of the pyrimidine bases.
2. **Rotation and Bond Formation:** The excited states of the pyrimidine bases enable them to rotate and align such that new C-C bonds form, resulting in the cyclobutane structure.
The stereochemistry of the product, cyclobutane, is influenced by the specific geometric arrangement of the bases during the reaction. Typically, the resulting cyclobutane ring has cis-syn stereochemistry, meaning that both pyrimidine bases are on the same side of the cyclobutane ring, which is the most common and biologically relevant form.
### Detailed Diagram Description
**Diagram Explanation:**
- **Left Side (Reactants):** Two identical structures (pyrimidine bases), each with a double-bonded O (carbonyl group) and an NH group (amide) linked to an R-group (representing the deoxyribose unit in DNA).
- **Center Condition:** UV light, indicating the energy source for the reaction.
- **Right Side (Product):** A single structure showing a cyclobutane ring with two attached pyrimidine bases, each retaining its carbonyl and amide groups.
### Biological Implications
Formation of the cyclobutane pyrimidine dimer is a significant form of UV-induced DNA damage. If not repaired by mechanisms such as nucleotide excision repair, these lesions can block DNA replication and](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F206206aa-1104-4dbc-9e08-21639f631eee%2F7194e740-4d9c-45fe-907a-ca35db7ff374%2F9f3g3f_processed.png&w=3840&q=75)
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