Final answer:
The term for a section of a DNA molecule that codes for proteins is an exon. Exons are spliced together to form a coding sequence in mRNA for protein synthesis, and this process takes place in the ribosome. Nucleotides make up codons, which are part of genes that are organized into chromosomes.
Step-by-step explanation:
The term for a section of a DNA molecule that codes for proteins is known as an exon. Unlike introns, which are noncoding regions, exons contain the information necessary to code for the amino acids that make up proteins. After the process of transcription, introns are removed, and exons are spliced together to form a continuous coding sequence in the messenger RNA (mRNA). This mRNA then carries the code for the protein synthesis within the ribosome, which is the cellular machinery responsible for assembling proteins.
When placing the units of genetic material in order from smallest to largest, the order is: C) nitrogen base, D) nucleotide, E) codon, B) gene, A) chromosome. Each nucleotide consists of a nitrogen base, a sugar molecule, and a phosphate group, and it is the basic building block of DNA. A codon, which comprises three nucleotides, corresponds to a single amino acid or a stop signal during protein synthesis.