Step 1: Understanding the Concept:
Chromosomes are complex, thread-like structures located within the nucleus of eukaryotic cells.
They carry genetic information in the form of genes.
The structural composition of a chromosome is not a single chemical substance but a mixture of genetic material and structural supporting materials.
Step 2: Detailed Explanation:
The main components of chromosomes are:
1. DNA (Deoxyribonucleic Acid): This is the primary nucleic acid that holds the hereditary code. DNA molecules are extremely long and must be tightly packed to fit inside the cell's nucleus.
2. Proteins: These are primarily "histone" proteins. DNA is negatively charged due to its phosphate groups. Histones are positively charged proteins around which the DNA wraps. This DNA-protein complex is called a "nucleosome".
Collectively, the mixture of DNA and proteins found in the nucleus is known as "chromatin". During cell division, this chromatin condenses further into the distinct shapes we recognize as chromosomes.
While small amounts of RNA (another nucleic acid) may also be associated with chromosomes during transcription, the bulk structural and chemical definition of a chromosome is a nucleoprotein complex consisting of proteins and nucleic acids.
Carbohydrates and lipids are components of the cell and its membranes but do not form the physical structure of chromosomes themselves.
Step 3: Final Answer:
Given the biological and chemical composition, chromosomes are primarily composed of both nucleic acids (DNA) and proteins (histones).
Thus, option (C) is the most accurate answer.