According top most recent studies, each chromosome consists of

Options

A. single double helical DNA which is higly coiled and folded
B. variable number of DNA helices, depending upon the length of chromosome
C. many small DNA helices, which are joined by peptide linkages
D. small DNA helices, wrapped around each other like a rope.

Explanation

### Step-by-Step Solution:

1. **Understanding Chromosomes**: Chromosomes are structures within cells that contain genetic material. Each chromosome is made up of DNA and proteins.

2. **Composition of DNA**: The primary component of chromosomes is DNA (deoxyribonucleic acid). DNA consists of a sugar-phosphate backbone and nitrogenous bases.

3. **Structure of DNA**: DNA is double-stranded, meaning it has two strands that run in opposite directions (antiparallel). The sugar in DNA is deoxyribose, and the strands are connected by base pairs (adenine pairs with thymine, and cytosine pairs with guanine).

4. **Coiling of DNA**: In eukaryotic cells, the length of DNA is quite extensive (about two meters). To fit this long DNA into the nucleus of a cell (which is only about 20 micrometers in diameter), DNA must be coiled and folded.

5. **Formation of Chromatin**: The DNA wraps around proteins called histones, forming a complex known as chromatin. This structure allows the DNA to be compacted and organized within the nucleus.

6. **Conclusion**: Therefore, according to recent studies, each chromosome consists of DNA that is highly coiled and folded, organized into chromatin with associated proteins.

### Final Answer:
Each chromosome consists of DNA that is coiled and folded into a structure called chromatin.

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